wiki:WikiStart

Version 6 (modified by bgamari, 2 weeks ago) (diff)

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Welcome to the GHC Developer Wiki

This is the home for GHC developers. If you're only interested in using GHC, then you probably want ​the GHC home page. If you are an aspiring GHC developer, and just want to get started, read the Newcomers page (which is always in the sidebar under "Joining in").

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Status updates

  • Forthcoming planned releases:
    • 8.0.1 (0 open tickets with priority high or highest)
  • Total open tickets: 1769 (

    #149
    missed CSE opportunity
    #229
    Integer overflow in array allocation
    #314
    #line pragmas not respected inside nested comments
    #344
    arrow notation: incorrect scope of existential dictionaries
    #345
    GADT - fundep interaction
    #367
    Infinite loops can hang Concurrent Haskell
    #418
    throwTo to a thread inside 'block'
    #487
    powerpc/linux segfaulting binaries
    #552
    GHCi :m doesn't restore default decl
    #589
    Various poor type error messages
    #781
    GHCi on x86_64, cannot link to static data in shared libs
    #797
    nofib tests fail on Windows due to different EOL convention in output files
    #806
    hGetBufNonBlocking doesn't work on Windows
    #816
    Weird fundep behavior (with -fallow-undecidable-instances)
    #917
    -O introduces space leak
    #926
    infinite loop in ShutdownIOManager()
    #947
    ghc -O space leak: CSE between different CAFs
    #1012
    ghc panic with mutually recursive modules and template haskell
    #1057
    Implicit parameters on breakpoints
    #1087
    bang patterns with infix ops
    #1147
    Quadratic behaviour in the compacting GC
    #1158
    Problem with GADTs and explicit type signatures
    #1168
    Optimisation sometimes decreases sharing in IO code
    #1171
    GHC doesn't respect the imprecise exceptions semantics
    #1216
    Missed opportunity for let-no-esape
    #1290
    ghc runs preprocessor too much
    #1308
    Type signature in warning is wrong
    #1330
    Impredicativity bug: Church2 test gives a rather confusing error with the HEAD
    #1400
    :set +r doesn't work for interpreted modules
    #1466
    Stack check for AP_STACK
    #1487
    unix package: test needed for getLoginName
    #1498
    Optimisation: eliminate unnecessary heap check in recursive function
    #1526
    -fobject-code doesn't apply to expressions typed at the prompt
    #1530
    debugging :steps inside TH spliced code need to be bypassed
    #1544
    Derived Read instances for recursive datatypes with infix constructors are too inefficient
    #1612
    GHC_PACKAGE_PATH and $topdir bug
    #1614
    Type checker does not use functional dependency to avoid ambiguity
    #1620
    ModBreaks.modBreaks_array not initialised
    #1687
    A faster (^)-function.
    #1693
    Make distclean (still) doesn't
    #1727
    Precedence and associativity rules ignored when mixing infix type and data constructors in a single expression
    #1831
    reify never provides the declaration of variables
    #1853
    hpc mix files for Main modules overwrite each other
    #1928
    Confusing type error message
    #2028
    STM slightly conservative on write-only transactions
    #2031
    relocation overflow
    #2057
    inconsistent .hi file error gets ignored
    #2132
    Optimise nested comparisons
    #2140
    cpuTimePrecision is wrong
    #2147
    unhelpful error message for a misplaced DEPRECATED pragma
    #2189
    hSetBuffering stdin NoBuffering doesn't work on Windows
    #2224
    -fhpc inteferes/prevents rewrite rules from firing
    #2255
    Improve SpecConstr for free variables
    #2256
    Incompleteness of type inference: must quantify over implication constraints
    #2260
    Non-ideal error message for misplaced LANGUAGE pragma
    #2273
    inlining defeats seq
    #2289
    Needless reboxing of values when returning from a tight loop
    #2346
    Compilation of large source files requires a lot of RAM
    #2356
    GHC accepts multiple instances for the same type in different modules
    #2370
    num009 fails on OS X 10.5?
    #2374
    MutableByteArray# is slower than Addr#
    #2387
    Optimizer misses unboxing opportunity
    #2401
    aborting an STM transaction should throw an exception
    #2408
    threadWaitRead on mingw32 threaded causes internal error
    #2439
    Missed optimisation with dictionaries and loops
    #2496
    Invalid Eq/Ord instances in Data.Version
    #2607
    Inlining defeats selector thunk optimisation
    #2625
    Unexpected -ddump-simpl output for derived Ord instance and UNPACKed fields
    #2642
    Improve SpecConstr for join points
    #2710
    -main-is flag in {-# OPTIONS #-} pragma not fully supported
    #2731
    Avoid unnecessary evaluation when unpacking constructors
    #2776
    Document -pgmL (Use cmd as the literate pre-processor)
    #2786
    Blackhole loops are not detected and reported in GHCi
    #2805
    Test ffi009(ghci) fails on PPC Mac OS X
    #2926
    Foreign exported function returns wrong type
    #2933
    LDFLAGS ignored by build system
    #2940
    Do CSE after CorePrep
    #3034
    divInt# floated into a position which leads to low arity
    #3048
    Heap size suggestion gets ignored when -G1 flag is passed
    #3055
    Int / Word / IntN / WordN are unequally optimized
    #3061
    GHC's GC default heap growth strategy is not as good as other runtimes
    #3070
    floor(0/0) should not be defined
    #3073
    Avoid reconstructing dictionaries in recursive instance methods
    #3081
    Double output after Ctrl+C on Windows
    #3094
    Some GHC.* module should export word size and heap object header size
    #3107
    Over-eager GC when blocked on a signal in the non-threaded runtime
    #3134
    encodeFloat . decodeFloat
    #3138
    Returning a known constructor: GHC generates terrible code for cmonad
    #3184
    package.conf.d should be under /var, not /usr
    #3231
    Permission denied error with runProcess/openFile
    #3238
    CInt FFI exports do not use C int in _stub.h header file
    #3333
    GHCi doesn't load weak symbols
    #3353
    Add CLDouble support
    #3373
    GHC API is not thread safe
    #3397
    :step hangs when -fbreak-on-exception is set
    #3458
    Allocation where none should happen
    #3549
    unlit does not follow H98 spec
    #3571
    Bizzarely bloated binaries
    #3588
    ghc -M should emit dependencies on CPP headers
    #3606
    The Ord instance for unboxed arrays is very inefficient
    #3628
    exceptions reported to stderr when they propagate past forkIO
    #3676
    realToFrac doesn't sanely convert between floating types
    #3711
    Bad error reporting when calling a function in a module which depends on a DLL on Windows
    #3765
    Rules should "look through" case binders too
    #3766
    Parsing of lambdas is not consistent with Haskell'98 report.
    #3767
    SpecConstr for join points
    #3781
    Improve inlining for local functions
    #3782
    Data Parallel "Impossible happened" compiler error
    #3831
    SpecConstr should exploit cases where there is exactly one call pattern
    #3872
    New way to make the simplifier diverge
    #3881
    section parse errors, e.g. ( let x=1 in x + )
    #3903
    DPH bad sliceP causes RTS panic "allocGroup: requested zero blocks"
    #3937
    Cannot killThread in listen/accept on Windows threaded runtime
    #3960
    ghc panic when attempting to compile DPH code
    #3995
    Comment delimiters ignored inside compiler pragma
    #3998
    strace breaks System.Process(?)
    #4005
    Bad behaviour in the generational GC with paraffins -O2
    #4012
    Compilation results are not deterministic
    #4017
    Unhelpful error message in GHCi
    #4022
    GHC Bindist is Broken on FreeBSD/amd64
    #4043
    Parsing of guards, and type signatures
    #4048
    ghc-pkg should check for existence of extra-libraries
    #4049
    Support for ABI versioning of C libraries
    #4081
    Strict constructor fields inspected in loop
    #4101
    Primitive constant unfolding
    #4105
    ffi005 fails on OS X
    #4140
    dynHelloWorld(dyn) fails in an unreg build
    #4144
    Exception: ToDo: hGetBuf - when using custom handle infrastructure
    #4150
    CPP+QuasiQuotes confuses compilation errors' line numbers
    #4162
    GHC API messes up signal handlers
    #4176
    reject unary minus in infix left hand side function bindings that resolve differently as expressions
    #4245
    ghci panic: thread blocked indefinitely in an MVar operation
    #4288
    Poor -fspec-constr-count=n warning messages
    #4296
    The dreaded SkolemOccurs problem
    #4301
    Optimisations give bad core for foldl' (flip seq) ()
    #4308
    LLVM compiles Updates.cmm badly
    #4372
    Accept expressions in left-hand side of quasiquotations
    #4413
    (^^) is not correct for Double and Float
    #4451
    Re-linking avoidance is too aggressive
    #4471
    Incorrect Unicode output on Windows Console
    #4505
    Segmentation fault on long input (list of pairs)
    #4820
    "Invalid object in isRetainer" when doing retainer profiling in GHC 7 branch
    #4824
    Windows: Dynamic linking doesn't work out-of-the-box
    #4831
    Too many specialisations in SpecConstr
    #4833
    Finding the right loop breaker
    #4836
    literate markdown not handled correctly by unlit
    #4861
    Documentation for base does not include special items
    #4899
    Non-standard compile plus Template Haskell produces spurious "unknown symbol" linker error
    #4942
    GHC.ConsoleHandler does not call back application when Close button is pressed
    #4945
    Another SpecConstr infelicity
    #5041
    Incorrect Read deriving for MagicHash constructors
    #5051
    Typechecker behaviour change
    #5063
    unix package has untracked dependency on libbsd
    #5071
    GHCi crashes on large alloca/allocaBytes requests
    #5142
    stub header files don't work with the MS C compiler
    #5188
    Runtime error when allocating lots of memory
    #5224
    Improve consistency checking for family instances
    #5262
    Compiling with -O makes some expressions too lazy and causes space leaks
    #5267
    Missing type checks for arrow command combinators
    #5291
    GhcDynamic build fails on Windows: can't find DLLs
    #5298
    Inlined functions aren't fully specialised
    #5302
    Unused arguments in join points
    #5305
    crash after writing around 40 gigabytes to stdout
    #5320
    check_overlap panic (7.1 regression)
    #5326
    Polymorphic instances aren't automatically specialised
    #5340
    wrong warning on incomplete case analysis in conjunction with empty data declarations
    #5355
    Link plugins against existing libHSghc
    #5369
    Reinstate VECTORISE pragmas with expressions as right-hand sides
    #5378
    unreg compiler: warning: conflicting types for built-in function ‘memcpy’
    #5400
    GHC loops on compiling with optimizations
    #5444
    Slow 64-bit primops on 32 bit system
    #5448
    GHC stuck in infinite loop compiling with optimizations
    #5463
    SPECIALISE pragmas generated from Template Haskell are ignored
    #5466
    Documentation for Chan could be better
    #5470
    The DPH library needs to support PData and PRepr instances for more than 15-tuples
    #5495
    simple program fails with -shared on mac
    #5522
    mc03 -O -fliberate-case -fspec-constr runs out of memory
    #5539
    GHC panic - Simplifier ticks exhausted
    #5611
    Asynchronous exception discarded after safe FFI call
    #5615
    ghc produces poor code for `div` with constant powers of 2.
    #5620
    Dynamic linking and threading does not work on Windows
    #5641
    The -L flag should not exist
    #5642
    Deriving Generic of a big type takes a long time and lots of space
    #5645
    Sharing across functions causing space leak
    #5646
    Initialise tuples using pragmas
    #5654
    Profiling semantics bug
    #5692
    Source code with large floating constants in exponential notation cannot be compiled
    #5702
    Can't vectorise pattern matching on numeric literals
    #5722
    GHC inlines class method forever
    #5761
    Getting stdout and stderr as a single handle from createProcess does not work on Windows
    #5775
    Inconsistency in demand analysis
    #5777
    core lint error with arrow notation and GADTs
    #5780
    -faggressive-primops change caused a failure in perf/compiler/parsing001
    #5786
    Dynanmic way fails when GHC built with LLVM backend
    #5797
    readRawBufferPtr cannot be interrupted by exception on Windows with -threaded
    #5807
    DPH library functions don't work without -fvectorise.
    #5840
    Extend the supported environment sizes of vectorised closures
    #5902
    Cannot tell from an exception handler whether the exception was asynchronous
    #5928
    INLINABLE fails to specialize in presence of simple wrapper
    #5954
    Performance regression 7.0 -> 7.2 (still in 7.4)
    #5957
    signatures are too permissive
    #5959
    Top level splice in Template Haskell has over-ambitious lexical scope?
    #5974
    Casts, rules, and parametricity
    #5987
    Too many symbols in ghc package DLL
    #6004
    dph-lifted-vseg package doesn't provide Data.Array.Parallel.Prelude.Float module
    #6034
    Parse error when using ' with promoted kinds
    #6040
    Adding a type signature changes heap allocation into stack allocation without changing the actual type
    #6047
    GHC retains unnecessary binding
    #6065
    Suggested type signature causes a type error (even though it appears correct)
    #6070
    Fun with the demand analyser
    #6087
    Join points need strictness analysis
    #6092
    Liberate case not happening
    #6101
    Show instance for integer-simple is not lazy enough
    #6107
    GHCi runtime linker cannot link with duplicate common symbols
    #6113
    Profiling with -p not written if killed with SIGTERM
    #6166
    Performance regression in mwc-random since 7.0.x
    #7026
    Impredicative implicit parameters
    #7044
    reject reading rationals with exponent notation
    #7045
    The `Read` instance of `Rational` does not support decimal notation
    #7057
    Simplifier infinite loop regression
    #7063
    Register allocators can't handle non-uniform register sets
    #7066
    isInstance does not work for compound types
    #7078
    Panic using mixing list with parallel arrays incorrectly
    #7080
    Make RULES and SPECIALISE more consistent
    #7098
    GHC 7.4.1 reports an internal error and core dumps while using DPH
    #7102
    Type family instance overlap accepted in ghci
    #7109
    Inlining depends on datatype size, even with INLINE pragmas
    #7114
    Cannot recover (good) inlining behaviour from 7.0.2 in 7.4.1
    #7141
    Inlining the single method of a class can shadow rules
    #7161
    hSetNewlineMode and hSetEncoding can be performed on closed and semi-closed handles
    #7190
    GHC's -fprof-auto does not work with LINE pragmas
    #7198
    New codegen more than doubles compile time of T3294
    #7206
    Implement cheap build
    #7240
    Stack trace truncated too much with indirect recursion
    #7245
    INLINEing top-level patterns causes ghc to emit 'arity missing' traces
    #7246
    Callstack depends on way (prof, profasm, profthreaded
    #7258
    Compiling DynFlags is jolly slow
    #7259
    Eta expansion of products in System FC
    #7273
    Binary size increase in nofib/grep between 7.6.1 and HEAD
    #7277
    Recompilation check fails for TH unless functions are inlined
    #7287
    Primops in RULES generate warnings
    #7289
    Mingw FPU init not Windows compatible.
    #7296
    ghc-7 assumes incoherent instances without requiring language `IncoherentInstances`
    #7297
    LLVM incorrectly hoisting loads
    #7298
    GHCi is setting stdin/stdout to NoBuffering in runghc when DYNAMIC_GHC_PROGRAMS=YES
    #7307
    Share top-level code for strings
    #7309
    The Ix instance for (,) leaks space in range
    #7320
    GHC crashes when building on 32-bit Linux in a Linode
    #7325
    threadDelay mistreats minBound and maxBound in some configurations
    #7336
    Defined but not used is not detected for data types with instances
    #7353
    Make system IO interruptible on Windows
    #7367
    float-out causes extra allocation
    #7373
    When building GHC: Failed to load interface for `GHC.Fingerprint'
    #7374
    rule not firing
    #7378
    Identical alts/bad divInt# code
    #7380
    Panic: mkNoTick: Breakpoint loading modules with -O2 via API
    #7388
    CAPI doesn't work with ghci
    #7398
    RULES don't apply to a newtype constructor
    #7411
    Exceptions are optimized away in certain situations
    #7428
    GHC compile times are seriously non-linear in program size
    #7430
    GHC API reports CPP errors in confusing ways
    #7437
    peculiar behaviour with default instances and type variables
    #7443
    Generated C code under -prof -fprof-auto -fprof-cafs very slow to compile
    #7450
    Regression in optimisation time of functions with many patterns (6.12 to 7.4)?
    #7461
    Error messages about "do" statements contain false information
    #7503
    Bug with PolyKinds, type synonyms & GADTs
    #7511
    Room for GHC runtime improvement >~5%, inlining related
    #7535
    Using -with-rtsopts=-N should fail unless -threaded is also specified
    #7539
    Hard ghc api crash when calling runStmt on code which has not been compiled
    #7542
    GHC doesn't optimize (strict) composition with id
    #7543
    Constraint synonym instances
    #7593
    Unable to print exceptions of unicode identifiers
    #7596
    Opportunity to improve CSE
    #7602
    Threaded RTS performing badly on recent OS X (10.8?)
    #7610
    Cross compilation support for LLVM backend
    #7611
    Rewrite rules application prevented by type variable application (map id vs. map (\x -> x))
    #7621
    Cross-build for QNX ARM smashes stack when using FunPtr wrappers
    #7624
    Handling ImplicitParams in Instance Declaration
    #7634
    MD5 collision could lead to SafeHaskell violation
    #7644
    Hackage docs for base library contain broken links
    #7655
    7.6.2 Segmentation Fault/Bus Error in large exponentation
    #7665
    dynamicToo001 fails on Windows
    #7668
    Location in -fdefer-type-errors
    #7670
    StablePtrs should be organized by generation for efficient minor collections
    #7679
    Regression in -fregs-graph performance
    #7687
    ghc panic on TH and deriveJSON
    #7723
    iOS patch no 12: Itimer.c doesn't work on iOS
    #7779
    building GHC overwrites the installed package database if GHC_PACKAGE_PATH is set
    #7789
    GHCI core dumps when used with VTY
    #7803
    Superclass methods are left unspecialized
    #7828
    RebindableSyntax and Arrow
    #7831
    Bad fragmentation when allocating many large objects
    #7836
    "Invalid object in processHeapClosureForDead" when profiling with -hb
    #7842
    Incorrect checking of let-bindings in recursive do
    #7849
    Error on pattern matching of an existential whose context includes a type function
    #7897
    MakeTypeRep fingerprints be proper, robust fingerprints
    #7930
    Nested STM Invariants are lost
    #7944
    GHC goes into an apparently infinite loop at -O2
    #7960
    Compiling profiling CCS registration .c file takes far too long
    #7966
    'make distclean' does not work in nofib
    #7983
    Bug in hsc2hs --cross-safe
    #7985
    Allow openFile on unknown file type
    #7988
    Big integers crashing integer-simple on qnxnto-arm with unregisterised build
    #7997
    waitForProcess and getProcessExitCode are unsafe against asynchronous exceptions
    #8014
    Assertion failure when using multithreading in debug mode.
    #8023
    dph-examples binaries don't use all CPUs
    #8025
    "During interactive linking, GHCi couldn't find the following symbol" typechecker error with TemplateHaskell involved
    #8032
    Worker-wrapper transform and NOINLINE trigger bad reboxing behavior
    #8036
    Demand analyser is unpacking too deeply
    #8040
    installed include/HsVersions.h wants to #include "../includes/ghcautoconf.h"
    #8042
    `:load *` and `:add *` misbehave in presence of `-fobject-code`
    #8048
    Register spilling produces ineffecient/highly contending code
    #8082
    Ordering of assembly blocks affects performance
    #8095
    TypeFamilies painfully slow
    #8118
    <stdout>: commitAndReleaseBuffer: invalid argument (invalid character)
    #8123
    GHCi warns about -eventlog even though it's sometimes necessary
    #8127
    iOS patch no 19: Linking
    #8128
    Standalone deriving fails for GADTs due to inaccessible code
    #8144
    Interface hashes include time stamp of dependent files (UsageFile mtime)
    #8147
    Exponential behavior in instance resolution on fixpoint-of-sum
    #8151
    ghc-7.4.2 on OpenIndiana (Solaris) createSubprocess fails
    #8156
    amd64 + in-tree gmp build broken
    #8159
    Uses of Binary decode should have a proper error message
    #8173
    GHC uses nub
    #8177
    Roles for type families
    #8195
    Different floating point results with -msse2 on 32bit Linux
    #8198
    One-shot mode is buggy w.r.t. hs-boot files
    #8211
    ghc -c recompiles TH every time while --make doesn't
    #8224
    Excessive system time -- new IO manager problem?
    #8228
    GHC built under Windows does not generate dyn_hi files
    #8258
    GHC accepts `data Foo where` in H2010 mode
    #8265
    getTokenStream fails for source using cpp
    #8279
    bad alignment in code gen yields substantial perf issue
    #8281
    The impossible happened: primRepToFFIType
    #8285
    unexpected behavior with encodeFloat on large inputs
    #8293
    user001 spuriously fails if getGroupEntryForID correctly fails
    #8303
    defer StackOverflow exceptions (rather than dropping them) when exceptions are masked
    #8316
    GHCi debugger segfaults when trying force a certain variable
    #8318
    GHC does not infer type of `tagToEnum#` expression
    #8319
    Simplifier ticks exhausted (need -fsimpl-tick-factor=955)
    #8327
    Cmm sinking does not eliminate dead code in loops
    #8332
    hp2ps does not escape parentheses
    #8336
    Sinking pass could optimize some assignments better
    #8338
    Incoherent instances without -XIncoherentInstances
    #8346
    Rank 1 type signature still requires RankNTypes
    #8362
    Filesystem related tests failed on solaris (SmartOS)
    #8363
    Order matters for unused import warnings when reexporting identifiers
    #8378
    Cross-compiling from x86_64-unknown-linux-gnu to x86_64-sun-solaris2 with mkGmpConstants workaround fails to build objects for integer-gmp
    #8388
    forall on non-* types
    #8399
    Of Bird tacks and non-blank blank lines
    #8406
    Invalid object in isRetainer() or Segfault
    #8420
    Spurious dynamic library dependencies
    #8422
    type nats solver is too weak!
    #8426
    one-shot compilation + TH doesn't see instances that is seen in batch mode
    #8447
    A combination of type-level comparison and subtraction does not work for 0
    #8457
    -ffull-laziness does more harm than good
    #8472
    Primitive string literals prevent optimization
    #8484
    Compile-time panic
    #8487
    Debugger confuses variables
    #8510
    Clear up what extensions are needed at a Template Haskell splice site
    #8520
    ghc.exe: internal error: loadArchive: error whilst reading `C'
    #8523
    blowup in space/time for type checking and object size for high arity tuples
    #8524
    GHC is inconsistent with the Haskell Report on which Unicode characters are allowed in string and character literals
    #8527
    The ordering of -I directives should be consistent with the ordering of -package directives
    #8532
    Hyperbolic arc cosine fails on (-1) :: Complex r.
    #8556
    Invalid constructor names are accepted in data declarations
    #8572
    Building an empty module with profiling requires profiling libraries for integer-gmp
    #8573
    "evacuate: strange closure type 0" when creating large array
    #8589
    Bad choice of loop breaker with INLINABLE/INLINE
    #8591
    Concurrent executions of ghc-pkg can cause inconstant package.cache files
    #8604
    Some stack/vmem limits (ulimit) combinations causing GHC to fail
    #8611
    nofib’s cacheprof’s allocations nondeterminisitic
    #8623
    Strange slowness when using async library with FFI callbacks
    #8627
    mallocForeignPtrBytes documentation unobvious regarding memory alignment
    #8629
    Option 'split-objs' being ignored when trying to reduce object code size in iOS cross-compilation
    #8635
    GHC optimisation flag ignored when importing a local module with derived type classes
    #8648
    Initialization of C statics broken in threaded runtime
    #8657
    -fregs-graph still has a limit on spill slots
    #8662
    GHC does not inline cheap inner loop when used in two places
    #8666
    integer-gmp fails to compile on Debian Squeeze
    #8668
    SPECIALIZE silently fails to apply
    #8671
    Rebindable syntax creates bogus warning
    #8684
    hWaitForInput cannot be interrupted by async exceptions on unix
    #8694
    ghc -M doesn't handle addDependentFile or #included files
    #8708
    Kind annotation in tuple not parsed
    #8713
    Avoid libraries if unneeded (librt, libdl, libpthread)
    #8730
    Invalid Unicode Codepoints in Char
    #8731
    long compilation time for module with large data type and partial record selectors
    #8732
    Global big object heap allocator lock causes contention
    #8733
    I/O manager causes unnecessary syscalls in send/recv loops
    #8740
    Deriving instance conditionally compiles
    #8763
    forM_ [1..N] does not get fused (10 times slower than go function)
    #8774
    Transitivity of Auto-Specialization
    #8784
    Makefile missing a dependency
    #8808
    ImpredicativeTypes type checking fails depending on syntax of arguments
    #8814
    7.8 optimizes attoparsec improperly
    #8827
    Inferring Safe mode with GeneralizedNewtypeDeriving is wrong
    #8847
    Int64 ^ Int64 broken by optimization on SPARC
    #8862
    forkProcess does not play well with heap or time profiling
    #8871
    No-op assignment I64[BaseReg + 784] = I64[BaseReg + 784]; is generated into optimized Cmm
    #8872
    hsc cast size warnings on 32-bit Linux
    #8887
    Double double assignment in optimized Cmm on SPARC
    #8901
    (very) bad inline heuristics
    #8905
    Function arguments are always spilled/reloaded if scrutinee is already in WHNF
    #8922
    GHC unnecessarily sign/zero-extends C call arguments
    #8925
    :print and :sprint sometimes fully evaluates strings
    #8948
    Profiling report resolution too low
    #8949
    switch -msse2 to be on by default
    #8953
    Reification drops necessary kind annotations
    #8956
    Parser error shadowed by "module ‘main:Main’ is defined in multiple files" error
    #8964
    split_marker_entry assert breaks -split-objs and -ddump-opt-cmm
    #8971
    Native Code Generator for 7.8 is not as optimized as 7.6.3...
    #8981
    ghc-pkg complains about missing haddock interface files
    #8982
    Cost center heap profile restricted by biography of GHC segfaults
    #8990
    Performance tests behave differently depending on presence of .hi file (even with -fforce-recomp)
    #8995
    When generalising, use levels rather than global tyvars
    #9007
    fails to build with hardening flags enabled (relocation R_X86_64_32 against `stg_CHARLIKE_closure'...)
    #9020
    Massive blowup of code size on trivial program
    #9034
    GHCi panics when given C++ object file on GNU/Linux
    #9041
    NCG generates slow loop code
    #9046
    Panic in GHCi when using :print
    #9059
    Excessive space usage while generating code for fractional literals with big exponents
    #9074
    GHC 7.8.2's ghci does not track missing symbols when loading non-Haskell object files
    #9076
    GHC.Exts docs don't contain all primops
    #9079
    Foreign.C.Types in haskell2010
    #9088
    Per-thread Haskell thread list/numbering (remove global lock from thread allocation)
    #9095
    make sdist picks up test files
    #9121
    Presence of dyn_o files not checked upon recompilation
    #9123
    Need for higher kinded roles
    #9135
    readProcessWithExitCode leaks when the program does not exist
    #9136
    Constant folding in Core could be better
    #9157
    cmm common block not eliminated
    #9173
    Better type error messages
    #9176
    GHC not generating dyn_hi files
    #9198
    large performance regression in type checker speed in 7.8
    #9210
    "overlapping instances" through FunctionalDependencies
    #9219
    Parallel build proceeds despite errors
    #9221
    (super!) linear slowdown of parallel builds on 40 core machine
    #9223
    Type equality makes type variable untouchable
    #9232
    Stats file has wrong numbers
    #9235
    Simplifier ticks exhausted on recursive class method
    #9237
    GHC not recognizing INPUT(-llibrary) in linker scripts
    #9246
    GHC generates poor code for repeated uses of min/max
    #9247
    Document -XDatatypeContexts in flag reference
    #9248
    Document -XHaskell98 and -XHaskell2010 in flag reference
    #9249
    Link to "latest" user's guide
    #9267
    Lack of type information in GHC error messages when the liberage coverage condition is unsatisfied
    #9274
    GHC panic with UnliftedFFITypes+CApiFFI
    #9277
    GHCi panic: Loading temp shared object failed: Symbol not found
    #9278
    GHCi crash: selector _ for message _ does not match selector known to Objective C runtime
    #9279
    Local wrapper function remains in final program; result = extra closure allocation
    #9280
    GHCi crash: illegal text-relocation to _ in _ from _ in _ for architecture x86_64; relocation R_X86_64_PC32 against undefined symbol _ can not be used when making a shared object
    #9283
    bad autoconf variable names
    #9287
    changed dependency generation
    #9292
    Race condition when multiple threads wait for a process
    #9298
    ghc.exe: internal error: evacuate: strange closure type 365488164
    #9307
    LLVM vs NCG: floating point numbers close to zero have different sign
    #9308
    nofib fannkuch-redux runs perpetually with -fllvm
    #9314
    Each object file in a static archive file (.a) is loaded into its own mmap()ed page
    #9315
    Weird change in allocation numbers of T9203
    #9320
    Inlining regression/strangeness in 7.8
    #9347
    forkProcess does not acquire global handle locks
    #9349
    excessive inlining due to state hack
    #9353
    prefetch primops are not currently useful
    #9358
    Improve flag description in the user guide
    #9364
    GHCi (or haskeline?) confused by non-single-width characters
    #9370
    unfolding info as seen when building a module depends on flags in a previously-compiled module
    #9386
    GHCi cannot load .so in ./
    #9388
    Narrow the scope of the notorious "state hack"
    #9399
    CPP does not process test case enum01.hs correctly
    #9406
    unexpected failure for T7837(profasm)
    #9420
    Impredicative type instantiation without -XImpredicativeTypes
    #9421
    Problems and workarounds when installing and using a 32bit GHC on 64bit Linux machine
    #9432
    IncoherentInstances are too restricted
    #9434
    GHC.List.reverse does not fuse
    #9438
    panic: loading archives not supported
    #9445
    GHC Panic: Tick Exhausted with high factor
    #9450
    GHC instantiates Data instances before checking hs-boot files
    #9453
    The example for GHC Generics is kinda broken
    #9456
    Weird behavior with polymorphic function involving existential quantification and GADTs
    #9457
    hsc2hs breaks with `--cflag=-Werror` in cross-compilation mode
    #9468
    Internal error: resurrectThreads: thread blocked in a strange way: 10
    #9470
    forkProcess breaks in multiple ways with GHC 7.6
    #9481
    Linker does not correctly resolve symbols in previously loaded objects
    #9494
    Probable data corruption with GHCi 7.8.* and Zlib
    #9503
    Cross compiling with mingw uses wrong gcc
    #9504
    LLVM backend TBAA is too aggressive
    #9509
    No automatic specialization of inlinable imports in 7.8
    #9512
    T9329 fails test on unregisterised i386, amd64
    #9517
    hp2ps generates invalid postscript file
    #9520
    Running an action twice uses much more memory than running it once
    #9525
    +RTS -xc stack trace sometimes reported twice
    #9533
    Signed/unsigned integer difference between compiled and interpreted code
    #9539
    TQueue can lead to thread starvation
    #9547
    Empty constraint tuples are mis-kinded
    #9553
    GHC under Windows with TH can't tell that gtk-win32-2.0 is in gtk-win32-2.0-0 (note the -0 suffix)
    #9557
    Deriving instances is slow
    #9562
    Type families + hs-boot files = unsafeCoerce
    #9570
    cryptarithm1 (normal) has bimodal runtime
    #9573
    Add warning for invalid digits in integer literals
    #9577
    String literals are wasting space
    #9587
    Type checking with type functions introduces many type variables, which remain ambiguous. The code no longer type checks.
    #9599
    app runs 10 times faster when compiled with profilling information than without it
    #9607
    Programs that require AllowAmbiguousTypes in 7.8
    #9614
    ghc --print-(gcc|ld)-linker-flags broken
    #9625
    ghc: panic using --enable-executable-dynamic
    #9627
    Type error with functional dependencies
    #9630
    compile-time performance regression (probably due to Generics)
    #9631
    Comment in GHC.Base about GHC.Prim does not appear to be correct
    #9636
    Function with type error accepted
    #9643
    ghci must be restarted to use break point more than once?
    #9655
    Do not UNPACK strict fields that are very wide
    #9660
    unnecessary indirect jump when returning a case scrutinee
    #9666
    runtime crashing with +RTS -w -h
    #9669
    Long compile time/high memory usage for modules with many deriving clauses
    #9672
    Error message too long (full case statement printed)
    #9675
    Unreasonable memory usage on large data structures
    #9678
    Warning about __sync_fetch_and_nand semantics from gcc
    #9686
    Link option detection does not work for incremental builds on Windows
    #9693
    Reloading GHCi with Template Haskell names can panic GHC
    #9696
    readRawBufferPtr and writeRawBufferPtr allocate memory
    #9701
    GADTs not specialized properly
    #9704
    GHC fails with "Loading temp shared object failed"
    #9708
    Type inference non-determinism due to improvement
    #9709
    Make restarts itself sometimes, and that's OK
    #9717
    More lazy orphan module loading
    #9725
    Constraint deduction failure
    #9729
    GHCi accepts invalid programs when recompiling
    #9730
    Polymorphism and type classes
    #9737
    List ANN in pragmas chapter of user manual
    #9755
    Unhelpful error message when -XScopedTypeVariables is omitted
    #9765
    Strange behavior of GC under ghci
    #9775
    "Failed to remove" errors during Windows build from hsc2hs
    #9780
    dep_orphs in Dependencies redundantly records type family orphans
    #9792
    map/coerce rule does not fire until the coercion is known
    #9798
    Frustrating behaviour of the INLINE pragma
    #9806
    malloc and mallocArray ignore Storable alignment requirements
    #9809
    Overwhelming the TimerManager
    #9811
    constant folding with infinities is wrong
    #9813
    Error when reifying type constructor
    #9821
    DeriveAnyClass support for higher-kinded classes + some more comments
    #9825
    ghc "panic! (the 'impossible' happened)" building vimus on NixOS
    #9841
    Touching a file that uses TH triggers TH recompilation flood
    #9854
    Literal overflow check is too aggressive
    #9868
    ghc: panic! Dynamic linker not initialised
    #9877
    ForeignImport coercion evaluated before typechecking
    #9885
    ghc-pkg parser eats too much memory
    #9916
    ghc -e ":foo bar" exit status is inconsistent
    #9918
    GHC chooses an instance between two overlapping, but cannot resolve a clause within the similar closed type family
    #9932
    GHC fails to build when cross compiling for mingw with the message "Threads not supported"
    #9936
    Data.Fixed truncates 5.17 to 5.16
    #9940
    GHCi crashes when I hold down control-c for a short time, and then hold down any key that would normally result in typing.
    #9944
    Performance issue re: simple loop
    #9979
    Performance regression GHC 7.8.4 to GHC HEAD
    #9980
    TcS monad is too heavy
    #9981
    Potential typechecker regression in GHC 7.10.1RC
    #9982
    cross building integer-gmp is running target program on build host
    #9983
    configure script invokes ghc with LDFLAGS during cross-builds
    #9985
    GHC panic with ViewPatterns and GADTs in a proc pattern
    #9989
    GHCI is slow for precompiled code
    #9992
    Constructor specialization requires eta expansion
    #10005
    Operations on string literals won't be inlined
    #10007
    Fix misattribution of Cost Centre profiles to lintAnnots
    #10010
    LLVM/optimized code for sqrt incorrect for negative values
    #10012
    Cheap-to-compute values aren't pushed into case branches inducing unnecessary register pressure
    #10022
    Clean up GHC.RTS.Flags
    #10027
    Importing constructor of associated data type fails
    #10032
    binary distributions not working --with-system-libffi
    #10037
    Several profiling tests give different results optimised vs. unoptimised
    #10044
    Wrong line number reported with CPP and line beginning with #
    #10046
    Linker script patch in rts/Linker.c doesn't work for (non-C or non-en..) locales
    #10053
    Regression on MacOS platform, error in ghci calling main after loading compiled code: "Too late for parseStaticFlags..."
    #10056
    Inconsistent precedence of ~
    #10059
    :i doesn't work for ~
    #10062
    Codegen on sequential FFI calls is not very good
    #10065
    Definition of fix lacks commentary
    #10069
    CPR related performance issue
    #10077
    Providing type checker plugin on command line results in false cyclic import error
    #10083
    ghc: panic! (the 'impossible' happened)
    #10097
    GHC 7.11 errors on dictionary casting tricks
    #10106
    GHC doesn't warn on typos in language pragmas
    #10111
    hp2ps silently discards samples
    #10114
    Kind mismatches with AnyK in rank-2 types
    #10117
    Change the scheme for reporting redundant imports
    #10120
    Unnecessary code duplication from case analysis
    #10124
    Simple case analyses generate too many branches
    #10141
    Kind inference regression in closed type families
    #10144
    Variant of runGhc which accepts prelude for setting up DynFlags
    #10160
    GHCi :sprint has odd/unhelpful behavior for values defined within the REPL
    #10161
    GHC does not relink if a library's code changed
    #10167
    Error with dash character
    #10169
    bracket not running the final action on termination through SIGTERM
    #10171
    runghc has problem when the argument list is too big
    #10173
    Panic: Irrefutable pattern failed for pattern Data.Maybe.Just
    #10174
    AArch64 : ghc-stage2 segfaults compiling libraries/parallel
    #10178
    hs-boot/hsig ambiguity empty data declaration or type with no constructors
    #10179
    Kinds missing from types in ghci
    #10183
    Warning for redundant constraints: interaction with pattern matching
    #10184
    Coercible solver incomplete with recursive newtypes
    #10185
    Coercible solver incomplete with non-variable transitivity
    #10187
    Panic: RegAlloc.Liveness.computeLivenss; SCCs aren't in reverse dependent order; bad blockId c8xHd
    #10189
    explicit promotions of prefix data constructors can't be parsed naturally
    #10193
    TypeRep Show instance doesn't add parens around type operators
    #10199
    Sending SIGINT to a program that uses forkOS may crash with various errors
    #10221
    LLVM backend does not work on OSX
    #10227
    Type checker cannot deduce type
    #10228
    Increased memory usage with GHC 7.10.1
    #10229
    setThreadAffinity assumes a certain CPU virtual core layout
    #10241
    BlockedIndefinitelyOnMVar thrown to the thread which is not blocked indefinitely
    #10245
    panic in new integer switch logic with "out-of-range" literals
    #10246
    Literal Pattern match loses order
    #10249
    GHCi leaky abstraction: error message mentions `ghciStepIO`
    #10262
    Improve documentation of module signatures
    #10270
    inconsistent semantics of type class instance visibility outside recursive modules
    #10271
    Typed Template Haskell splice difficulty when resolving overloading
    #10295
    Putting SCC in heavily inlined code results in "error: redefinition of global"
    #10301
    Plugins/dynamic loading subtly broken (it seems)
    #10311
    package name returned from tyConPackage is garbled
    #10328
    Control.Monad exports lead to weird Haddocks
    #10330
    Better Template Haskell error message locations
    #10332
    AArch64 : divbyzero test fails
    #10333
    hs-boot modification doesn't induce recompilation
    #10334
    __ctzdi2/si2/__clzdi2/si2 unknown symbols in ghc-prim on non-shared libs platform
    #10337
    One-shot module loops have hard to understand messages
    #10338
    GHC Forgets Constraints
    #10341
    hs-boot files can have bogus declarations if they're not exported
    #10346
    Cross-module SpecConstr
    #10347
    Spurious "unused constructor" warning with Coercible
    #10353
    Haddock for Data.List should list instances
    #10355
    Dynamic linker not initialised
    #10367
    "ghc: panic! (the 'impossible' happened)"
    #10371
    GHC fails to inline and specialize a function
    #10373
    Haiku: ghc-stage1 compiler crashes at exit
    #10374
    Can't build GHC with a dynamic only GHC installation
    #10378
    min/max for Double/Float instances are incorrect
    #10381
    Type-checking failure with RankNTypes and RebindableSyntax
    #10385
    Annotation restriction is not respected while generating Annotation via TH
    #10387
    toRational should error out on NaN and Infinity values for Double/Floats
    #10401
    state hack-related regression
    #10411
    Neighbour let-bindings are not reported as relevant
    #10412
    isAlphaNum includes mark characters, but neither isAlpha nor isNumber do
    #10417
    Rule matching not "seeing through" floating and type lambda (and maybe cast)
    #10418
    Incorrect RULE warning on constructor, and inablilty to {-# INLINE [0] #-} constrcutor
    #10421
    exponential blowup in inlining (without INLINE pragmas)
    #10424
    Build path leaks into ABI hashes
    #10434
    SPECIALISE instance does not specialize as far as SPECIALISE for type signatures
    #10436
    Excessive numbers of packages loaded for TH
    #10437
    RunHaskell error in HSExtra on Win64
    #10440
    Float out just gets floated in
    #10454
    ghc.exe: warning: _tzset from msvcrt is linked instead of __imp__tzset
    #10456
    Wrong CPP during cross-compilation
    #10469
    ghc crash on arm with -j2: internal error: scavenge: unimplemented/strange closure type
    #10470
    Allocating StablePtrs leads to GC slowdown even after they're freed
    #10477
    Tab-completing in a directory with Unicode heiroglyph crashes ghci
    #10482
    Not enough unboxing happens on data-family function argument
    #10484
    hPutBuf crashes when trying to write a large string to stdout (resource exhausted)
    #10490
    Missing binder type check in coercion equality test?
    #10504
    GHC panics with dsImpSpecs on SPECIALISE pragma with -fhpc enabled
    #10506
    SourceNotes are not applied to all identifiers
    #10509
    UnicodeSyntax documentation lists wrong symbols
    #10510
    Testsuite driver does not run tests in parallel on Windows
    #10524
    PolyKinds doesn't interact well with DeriveFunctor
    #10526
    Overlapping instances, incoherence, and optimisation
    #10531
    modules that can be linked successfully when compiled with optimizations, fail to link with: multiple definition of `__stginit_ZCMain'
    #10542
    Incorrect Unicode input on Windows Console
    #10554
    Replacing existing attachment with the same name doesn't work
    #10555
    RULE left-hand side too complicated to desugar
    #10560
    -f and -O options interact in non-obvious, order dependent ways
    #10572
    Type signatures are not implicitly quantified over TH type variables
    #10576
    REPL returns list of all imported names when operator completion requested
    #10577
    Use empty cases where appropriate when deriving instances for empty types
    #10582
    Tiny bug in lexer around lexing banana brackets
    #10583
    Chaos in Lexeme.hs
    #10584
    Installation of SFML failed
    #10587
    Suspending and unsuspending ghci kills and spawns threads
    #10594
    the ghc-7.10.1-x86_64-apple-darwin.tar.bz2 doesn't install /sw/lib/ghc-7.10.1/ghcpr_8TmvWUcS1U1IKHT0levwg3/GHC
    #10595
    BuiltinRules override other rules in some cases.
    #10598
    DeriveAnyClass and GND don't work well together
    #10599
    Template Haskell doesn't allow `newName "type"`
    #10600
    -fwarn-incomplete-patterns doesn't work with -fno-code
    #10616
    Panic in ghci debugger with PolyKinds and PhantomTypes
    #10617
    Panic in GHCi debugger with GADTs, PolyKinds and Phantom types
    #10623
    Handling of ASCII encodings introduced in D898 breaks Unicode terminal detection
    #10626
    Missed opportunity for SpecConstr
    #10631
    Report of GHC Panic
    #10643
    GHC cannot import submodules when run from subfolder
    #10647
    Notice about lack of SIMD support.
    #10648
    Some 64-vector SIMD primitives are absolutely useless
    #10651
    Type checking issue with existential quantification, rank-n types and constraint kinds
    #10671
    inplace/bin/ghc-stage1 doesn't respect --with-ld override
    #10675
    GHC does not check the functional dependency consistency condition correctly
    #10684
    Error cascade when unrelated class derivation fails
    #10686
    Process stops responding to sigINT
    #10695
    Trac errors when creating a ticket with a Blocking: field
    #10698
    Forall'd variable ‘$rcobox’ is not bound in RULE lhs
    #10701
    -fth-dec-file uses qualified names from hidden modules
    #10702
    -fth-dec-file uses qualified names in binding positions
    #10707
    -fth-dec-file outputs invalid case clauses
    #10709
    Using ($) allows sneaky impredicativity on its left
    #10730
    Spectral norm allocations increased 17% between 7.6 and 7.8
    #10731
    System.IO.openTempFile is not thread safe on Windows
    #10732
    Legal Bang Patterns cannot parse
    #10746
    No non-exhaustive pattern match warning given for empty case analysis
    #10749
    Boot file instances should imply superclasses
    #10761
    GHC panic when compiling vimus: failed to map segment from shared object
    #10768
    Location information of LHsModule is incorrect
    #10770
    Typeable solver has strange effects
    #10771
    Installation of Ivory - Static flags have not been initialised
    #10774
    Use `Natural` rather than `Integer` in `GHC.TypeLits`
    #10778
    GHC doesn't infer all constrains
    #10779
    .so files in 64-bit Debian builds are 4% larger than they have to be
    #10783
    Partial type signatures should work in pattern synonym signatures
    #10792
    Bounded Enums [minBound..maxBound] produces runtime error
    #10793
    Incorrect blocked on MVar detection
    #10799
    "I found a duplicate definition for symbol: __x86.get_pc_thunk.bx" in package network
    #10807
    PatternGuards and MultiWayIf layout rules
    #10808
    Odd interaction between record update and type families
    #10812
    High memory usage after performing GC
    #10816
    Fixity declaration for associated type rejected
    #10818
    GHC 7.10.2 takes much longer to compile some packages
    #10822
    GHC inconsistently handles \\?\ for long paths on Windows
    #10830
    maximumBy has a space leak
    #10835
    Regression in standalone Data deriving for phantom types
    #10838
    hsig files don't have good enough error checking for wired-in types
    #10840
    Periodic alarm signals can cause a retry loop to get stuck
    #10852
    ghc 7.8.4 on arm - panic: Simplifier ticks exhausted
    #10853
    Refine addTopDecls
    #10856
    Record update doesn't emit new constraints
    #10857
    "ghci -XMonomorphismRestriction" doesn't turn on the monomorphism restriction
    #10859
    Generated Eq instance associates && wrongly
    #10860
    setnumcapabilities001: internal error: ASSERTION FAILED: file rts/Schedule.c, line 400
    #10861
    `configure -C` yields different results on second run
    #10875
    Unexpected defaulting of partial type signatures and inconsistent behaviour when -fdefer-typed-holes is set.
    #10878
    Near doubling of generated code size for compiler/cmm/PprC.hs with commit 5d57087e31
    #10881
    internal error: evacuate: strange closure type 5101248
    #10905
    Incorrect number of parameters in "role" errors
    #10920
    ghci can't load local Prelude module
    #10922
    String inlining is inconsistent
    #10923
    GHC should recompile if flags change
    #10930
    missing empty-Enumeration and out-of-range warning for `Natural`
    #10937
    "ghc -no-link --make A.hs -o foo" does something silly
    #10940
    Random number chosen by openTempFile is always 1804289383846930886
    #10944
    powModInteger slower than computing pow and mod separately
    #10946
    Typed hole inside typed Template Haskell bracket causes panic
    #10951
    HPC program has poor error reporting / strange CLI in general
    #10952
    Use IPids instead of package keys in HPC tix files
    #10957
    getExecutablePath adds " (deleted)" suffix if executable was deleted under linux
    #10958
    "Annotating pure code for parallelism" docs based on old par/pseq primitives
    #10965
    GHC Panic on import with 'OPTIONS_GHC -fobject-code -O'
    #10966
    dirtiness checking isn't keeping track of which source file contained Main
    #10975
    At program exit, finalizer runs while foreign function is running
    #10980
    Deriving Read instance from datatype with N fields leads to N^2 code size growth
    #10987
    -i option requires named module
    #10990
    Checking whether a default declaration is an instance of a defaultable typeclass is broken
    #10992
    Performance regression due to lack of inlining of `foldl` and `foldl'`.
    #10993
    Bad error message reported when -XBinaryLiterals is not enabled
    #10995
    Existentials in newtypes
    #10996
    family is treated as keyword in types even without TypeFamilies enabled
    #10998
    Parser should suggest -XMagicHash
    #11004
    hsc2hs does not handle single quotes properly
    #11005
    GHC's build system can't deal with ghc install path with multiple spaces in it
    #11006
    Warning: Glomming in Main
    #11008
    Difficulties around inferring exotic contexts
    #11009
    Errors reading stdin on Windows
    #11013
    GHC sometimes forgets to test for hs-boot consistency
    #11023
    ghci and ghc-pkg disagree about what's exposed
    #11029
    Performance loss due to eta expansion
    #11032
    Missing result type handling for State# s in foreign import prim.
    #11033
    ghc 7.10.2 testsuite: "DoParamM(normal)" test fails
    #11034
    ghc 7.10.2 testsuite: "T367(normal)" test compilation fails
    #11040
    Split SRT tables on Mac OS
    #11042
    Template Haskell / GHCi does not respect extra-lib-dirs
    #11045
    Loading temp shared object failed - undefined symbol
    #11046
    lookupTypeName does not support type operators not starting with :
    #11050
    [bug] ModOrigin: hidden module redefined
    #11054
    GHC on Windows could not use more than 64 logical processors
    #11058
    selected processor does not support ARM mode
    #11062
    Type families + hs-boot files = panic
    #11066
    Inacessible branch should be warning - otherwise breaks type soundness?
    #11068
    Make Generic/Generic1 methods inlinable
    #11069
    :cd in GHCi unloads modules
    #11070
    Type-level arithmetic of sized-types has weaker inference power than in 7.8
    #11075
    Confusing parallel spark behaviour with safe FFI calls
    #11084
    Some type families don't reduce with :kind!
    #11092
    ApiAnnotations : make annotation for shebang
    #11095
    -O0 -g slows GHC down on list literals (compared to -O0 without -g)
    #11099
    Incorrect warning about redundant constraints
    #11101
    Expand Template Haskell type splices before quantification
    #11106
    Turning on optimizer changes behavior in 7.10.3
    #11107
    Can't use type wildcard infix
    #11108
    Weak references related crash
    #11110
    GHCi documentation says ":show packages" gives a list of packages currently loaded
    #11113
    Type family If is too strict
    #11117
    mdo blocks in error messages are shown modified
    #11124
    GHC does not shadow -package-name/-this-package-key
    #11126
    Entered absent arg in a Repa program
    #11131
    Eta reduction/expansion loop
    #11141
    Better error message when instance signature is incorrect
    #11146
    Manual eta expansion leads to orders of magnitude less allocations
    #11151
    T3064 regresses with wildcard refactor
    #11153
    building lens-4.12.3 impossible happened: dupe _hs_primitive_memcpy
    #11165
    Testsuite framework failures are too easy to ignore and too hard to find
    #11180
    A program writing to a read-only stdout should not succeed
    #11181
    Program hangs forever in sched_yield() / yield() unless -N is limited
    #11184
    panic tcMonoExpr _ with bad indentation in TH code
    #11188
    Confusing "parse error in pattern" for spurious indentation.
    #11196
    TypeInType performance regressions
    #11197
    Overeager deferred type errors
    #11198
    TypeInType error message regressions
    #11201
    ghc --make on Haskell and non-Haskell inputs can silently clobber input
    #11203
    Kind inference with SigTvs is wrong
    #11204
    Recompilation checking stochastically broken on Darwin
    #11207
    GHC cannot infer injectivity on type family operating on GHC.TypeLits' Nat, but can for equivalent type family operating on user-defined Nat kind
    #11212
    Should be more liberal parsing pattern synonyms with view patterns
    #11214
    Remove JavaScriptFFI from --supported-extensions list
    #11215
    Line endings in quasiquotations are not normalised
    #11216
    RebindableSyntax with pattern guards needs `fail`
    #11226
    Performance regression (involving sum, map, enumFromThenTo)
    #11228
    Interaction between ORF and record pattern synonyms needs to be resolved.
    #11247
    Weird error from running runghc on an invalid input filename
    #11251
    isInstance does not work on Typeable with base-4.8 anymore
    #11253
    Duplicate warnings for pattern guards and relevant features (e.g. View Patterns)
    #11259
    Use system runtime linker in GHCi on PowerPC 64 bit
    #11260
    Re-compilation driver/recomp11 test fails
    #11261
    Implement DWARF debugging on powerpc64
    #11262
    Test print022: wrong stdout on powerpc64
    #11263
    "Simplifier ticks exhausted" that resolves with fsimpl-tick-factor=200
    #11267
    Can't parse type with kind ascription with GHCi's :kind command
    #11271
    Costly let binding gets duplicated in IO action value
    #11272
    Overloaded state-monadic function is not specialised
    #11282
    Error warns about non-injectivity of injective type family
    #11288
    Thread blocked indefinitely in a Mvar operation
    #11293
    Compiler plugins don't work with profiling
    #11297
    CmmSwitchTest is broken on 32-bit platforms
    #11301
    Using GHC's parser and rendering the results is unreasonably difficult
    #11306
    Do not generate warning in `do` when result is of type `Void`.
    #11307
    Regresssion: parsing type operators
    #11310
    Surprising accepted constructor for GADT instance of data family
    #11312
    GHC inlining primitive string literals can affect program output
    #11315
    GHC doesn't restore split objects
    #11317
    Test prog003 fails with segfault on Windows (GHCi)
    #11319
    ImpredicativeTypes even more broken than usual
    #11323
    powerpc64: recomp015 fails with redundant linking
    #11325
    Type of hole does not get refined after pattern matching on [GADT] constructors
    #11327
    GHC doesn't create dyn_o-boot files
    #11333
    GHCi does not discharge satisfied constraints
    #11337
    Unwind information incorrect between Sp adjustment and end of block
    #11338
    Unwind information is incorrect in region surrounding a safe foreign call
    #11339
    Possible type-checker regression in GHC 8.0
    #11346
    GHCi can crash when tabbing a filename
    #11353
    DWARF call frame information incorrect in the presence of unsafe foreign calls
    #11360
    Test "termination" doesn't pass with reversed uniques
    #11368
    Pattern synonym name is mangled when patterns are non-exhaustive
    #11369
    Suppress redundant-constraint warnings in case of empty classes
    #11371
    Bogus in-scope set in substitutions
    #11375
    Type aliases twice as slow to compile as closed type families.
    #11380
    Compiling a 10.000 line file exhausts memory
    #11382
    Optimize Data.Char
    #11384
    Error says to fix incorrect return type
    #11400
    * is not an indexed type family
    #11406
    RTS gets stuck in scheduleDetectDeadlock()
    #11409
    Cannot instantiate literals using TypeApplications
    #11415
    pandoc-types fails to build on 4 GB machine
    #11421
    adding a PartialTypeSignatures to a binding affected by MonoLocalBinds leads compile-time failure
    #11424
    "Occurs check" not considered when reducing closed type families
    #11427
    superclasses aren't considered because context is no smaller than the instance head
    #11431
    GHC instantiates levity-polymorphic type variables with foralls
    #11435
    Evidence from TC Plugin triggers core-lint warning
    #11436
    ValueError: invalid literal for int() with base 10: '#11238'
    #11437
    Don't put static (version-based) feature gates in compilerInfo
    #11443
    SPECIALIZE pragma does not work + compilation times regression in GHC 8.0-rc1
    #11444
    8.0 rc1 panics in applyTypeToArgs
    #11449
    Treat '_' consistently in type declarations
    #11468
    testsuite should ignore config files
    #11474
    incorrect redundant-constraints warning
    #11475
    Lint should check for inexhaustive alternatives
    #11476
    gcc leaves undeleted temporary files when invoked with a response file
    #11484
    Type synonym using -XTypeInType can't be spliced with TH
    #11490
    check architecture before attempting to load object files
    #11495
    TH_spliceE5_prof is failing with release candidate 8.0.1
    #11498
    GHC requires kind-polymorphic signatures on class head
    #11499
    Loading temp shared object failed in GHCi
    #11501
    Building nofib/fibon returns permission denied
    #11503
    TypeError woes (incl. pattern match checker)
    #11505
    Boot file problem
    #11506
    uType_defer can defer too long
    #11509
    Incorrect error message in StandaloneDeriving: "The data constructors of <typeclass> are not all in scope"
    #11511
    Type family producing infinite type accepted as injective
    #11513
    Work out when GADT parameters should be specified
    #11514
    Impredicativity is still sneaking in
    #11515
    PartialTypeSignatures suggests a redundant constraint with constraint families
    #11517
    ghc -haddock fails to parse doc comments in closed type families
    #11518
    Test TcCoercibleFail hangs with substitution sanity checks enabled
    #11522
    maxStkSize can overflow
    #11523
    Infinite Loop when mixing UndecidableSuperClasses and the class/instance constraint synonym trick.
    #11525
    Using a dummy typechecker plugin causes an ambiguity check error
    #11526
    unsafeLookupStaticPtr should not live in IO
    #11527
    Pattern match translation suboptimal
    #11529
    Show instance of Char should print literals for non-ascii printable charcters
    #11532
    ghc: panic! occured
    #11536
    Multitude of different error messages when installed package is missing a module
    #11538
    Wrong constants in LL code for big endian targets
    #11540
    ghc accepts non-standard type without language extension
    #11542
    Profiling call count frequently 0 when it shouldn't be
    #11545
    Strictness signature blowup
    #11546
    Compiler warning: cast from pointer to integer of different size
    #11547
    Accessing shadowed definitions in GHCi
    #11548
    Absolutely misleading error message on kind error
    #11549
    Add -fshow-runtime-rep
    #11553
    `round (± ∞ :: Double)` not infinite
    #11554
    Self quantification in GADT data declarations
    #11556
    GHC recompiles unchanged hs-boot files
    #11559
    Building a cross-compiler for MIPS target on Mac OS X host fails
    #11560
    panic: isInjectiveTyCon sees a TcTyCon
    #11564
    Possible overzealous unfolding
    #11566
    I don't need madvise MADV_DONTNEED
    #11568
    Regression in nofib/shootout/k-nucleotide
    #11571
    Need more intelligent conditionalization of libgcc rts symbols for x32
    #11574
    schedule: re-entered unsafely on minimal hello world program on arm
    #11575
    Program crashes only when compiled via LLVM
    #11577
    GHCi accepts invalid programs when recompiling
    #11578
    Fix GHC on AArch64/Arm64
    #11584
    [Template Haskell] Language.Haskell.TH.Syntax.hs contains misleading comment
    #11587
    Place shared objects in LIBDIR
    #11591
    thread blocked indefinitely in an MVar operation
    #11592
    Self-kinded type variable accepted
    #11596
    ghci gets confused if a file is deleted
    #11598
    Cache coercion kinds and roles
    #11599
    Why is UndecidableInstances required for an obviously terminating type family?
    #11602
    Exponential behaviour in typeKind, unifyTys etc
    #11604
    Build system fails after submodule update
    #11605
    GHC accepts overlapping instances without pragma
    #11606
    name shadowing warnings don't trigger on standalone declarations in ghci
    #11617
    DYLD_LIBRARY_PATH ignored on Mac OS X 10.11.x
    #11621
    GHC doesn't see () as a Constraint in type family
    #11622
    Annotating types in type familiy equations without parentheses
    #11628
    Unexpected results with Read/Show
    #11629
    reify returns Dec that use ConT instead of PromotedT
    #11630
    More precise LANGUAGE pragma when forall is used
    #11632
    Data.Char repeated readLitChar barfs on output from show "ó1"
    #11634
    Bang patterns bind... unexpectedly. Deserves loud warning
    #11640
    Panic because of "updateRole"
    #11645
    Heap profiling - hp2ps: samples out of sequence
    #11647
    GHCi does not honour implicit `module Main (main) where` for re-exported `main`s
    #11650
    Documentation does not mention that default definitions for Alternative(some, many) can easily blow up
    #11655
    Ambiguous types in pattern synonym not determined by functional dependencies
    #11656
    Alllow static pointers to local closed definitions
    #11668
    SPEC has a runtime cost if constructor specialization isn't performed
    #11669
    Incorrectly suggests RankNTypes for ill-formed type "forall a. Eq a. Int"
    #11670
    Generalisation behaviour of partial type signatures
    #11672
    Poor error message
    #11677
    Dramatic de-optimization with "-O", "-O1", "-O2" options
    #11691
    Documentation indicates RelaxedPolyRec is optional
    #11695
    On GHCi prompt the arrow (movement) keys create strange character sequences
    #11700
    pattern match bug
    #11703
    Segmentation fault/internal error: evacuate: strange closure type 15 with GHC.Generics
    #11704
    Word and Int literals not correctly truncated when cross compiling 64 -> 32 bit
    #11715
    Constraint vs *
    #11719
    Cannot use higher-rank kinds with type families
    #11721
    GADT-syntax data constructors don't work well with TypeApplications
    #11722
    No TypeRep for unboxed tuples
    #11730
    GHC panics ('unload: no interpreter") during T10052 test
    #11740
    RFC kind synonyms
    #11744
    Latest Xcode update violates POSIX compliance of `nm -P`
    #11747
    `Strict` causes core lint error
    #11760
    runST with lazy blackholing breaks referential transparency
    #11761
    autoconf 2.69 breaks configure
    #11764
    ghc internal error building llvm-general-3.5.1.2
    #11766
    Lazy application gives "No instance" error while strict application works
    #11771
    ghc.exe: `panic'! (the 'impossible' happened); thread blocked indefinitely in an MVar operation
    #11773
    linux/powepc : ghc-stage1 segfaults when building unregisterised
    #11774
    Regression on GHC 8 branch (vs 7.10.3) when using the GHC API to parse code that uses TH
    #11777
    RTS source code issues
    #11780
    GHC stage-2 build fails with "relocation R_X86_64_PC32 against `exitStaticPtrTable' can not be used when making a shared object"
    #11783
    Very large slowdown when using parallel garbage collector
    #11784
    panic "hscCmmFile: no_mod" with `-v2 and above
    #11786
    Need -fno-print-explicit-runtime-reps to work on IfaceType, else RuntimeRep leaks
    #11792
    Optimised unsafe FFI call can get wrong argument
    #11794
    Switch to LLVM 3.8
    #11798
    Recompiling with -fhpc flag added does nothing
    #11812
    Template Haskell can induce non-unique Uniques
    #11819
    Full validation issues for 8.0.1
    #11821
    Internal error: not in scope during type checking, but it passed the renamer
    #11822
    Pattern match checker exceeded (2000000) iterations
    #11826
    unsafe causes bug, news @ 11
    #11827
    InteractiveEval error handling gets a boot ModSummary instead of normal ModSummary
    #11829
    C++ does not catch exceptions when used with Haskell-main and linked by ghc
    #11830
    Disabling idle GC leads to freeze
    #11831
    Illegal Instruction when running byte operations in ghci
    #11832
    Allow reify to yield types in the current declaration group
    #11833
    GHC can't derive instance of polykinded typeclass for newtype that requires a class constraint
    #11834
    GHC master, not compiling on Archlinux
    #11835
    ApplicativeDo failed to desugar last line with pure $ <expr>
    #11836
    Hello World Bug - silent stdout errors
    #11837
    GHC fails to unify kinds when deriving polykinded typeclass instance for polykinded newtype
    #11941
    stage restriction mentioned when an identifier is out of scope
    #11944
    Simplifier ticks exhausted When trying UnfoldingDone ip_X7RI
    #11946
    Provide a `make uninstall` target
    #11954
    Associated pattern synonyms not included in haddock
    #11955
    Haddock documentation for pattern synonyms printed with explicit forall quantifiers
    #11956
    on osx 10.11 haddock --hyperlinked-source on ghc source fails with file resource exhausted
    #11957
    DataKinds: lifting constructors whose identifier is a single character
    #11959
    Importing doubly exported pattern synonym and associated pattern synonym panics
    #11960
    GHC parallel build failure during "make"
    #11961
    PatBind test suite failure with `-DDEBUG`
    #11963
    GHC introduces kind equality without TypeInType
    #11964
    Without TypeInType, inconsistently accepts Data.Kind.Type but not type synonym
    #11965
    USE_PTHREAD_FOR_ITIMER causes unnecessary wake-ups
    #11966
    Surprising behavior with higher-rank quantification of kind variables
    #11968
    Document AMP in the deviations from the standard
    #11970
    Simplify Parent for patten synonyms
    #11974
    `default` declaration doesn't allow higher-kinded types
    #11976
    Error message mentions impredicative polymorphism
    #11977
    ghc doesn't agree with its own inferred pattern type
    #11978
    running a profiled build of shake test suite with rts args +RTS -hb -N10 triggers SIGSEGV
    #11981
    unknown symbol `__udivti3' when BuildFlavour = perf-llvm
    #11982
    Typechecking fails for parallel monad comprehensions with polymorphic let
    #11983
    Can't use IntPtr or WordPtr in a foreign import
    #11984
    Pattern match incompleteness / inaccessibility discrepancy
    #11985
    Core lint error on record syntax update/pattern synonym
    #11987
    Allow record wildcards with pattern synonyms which are defined in GHCi
    #11988
    All ghc-compiled binaries seg-fault (on Windows)
    #11989
    Performance bug reading large-exponent float without explicit type
    #11990
    Custom Type Error not getting triggered in the nested Type function call
    #11994
    ghci not applying defaulting when showing type
    #11995
    Can't infer type

    bugs,

    #307
    Implicit Parameters and monomorphism
    #436
    Declare large amounts of constant data
    #472
    Supertyping of classes
    #728
    switch to compacting collection when swapping occurs
    #750
    Set -M, -H, -c and other memory-related values based on available virtual/physical memory
    #849
    Offer control over branch prediction
    #860
    CPP fails when a macro is used on a line containing a single quote character
    #881
    Improve space profiling for references
    #989
    Build GHC on Windows using Microsoft toolchain
    #1192
    GHC-only IOErrorType constructors, and is*Error(Type) functions
    #1231
    deprecation warnings are reported too often
    #1262
    RecursiveDo in Template Haskell
    #1273
    would like to print partial application values when at a breakpoint
    #1311
    newtypes of unboxed types disallowed - documentation bug and/or feature request
    #1318
    add warning for prefix negate operator and flag to replace it with negative numeric literals
    #1365
    -fbyte-code is ignored in a OPTIONS_GHC pragma
    #1379
    Allow breakpoints and single-stepping for functions defined interactively
    #1399
    better support for developing threaded applications in ghci
    #1409
    Allow recursively dependent modules transparently (without .hs-boot or anything)
    #1420
    Automatic heap profile intervals
    #1444
    Template Haskell: add proper support for qualified names in non-splicing applications
    #1451
    Provide way to show the origin of a constraint
    #1475
    Adding imports and exports with Template Haskell
    #1532
    Implicit parameters are not available in breakpoints
    #1534
    [Debugger] Watch on accesses of "variables"
    #1628
    warning(s) for using stolen syntax that's not currently enabled
    #1768
    More flexible type signatures for data constructors
    #1791
    heap overflow should generate an exception
    #1800
    Template Haskell support for running functions defined in the same module
    #1826
    unable to list source for <exception thrown> should never occur
    #1885
    Improve CPR analysis
    #1894
    Add a total order on type constructors
    #1921
    change default to support extensions that involve a change of syntax
    #1965
    Allow unconstrained existential contexts in newtypes
    #1974
    length "foo" doesn't work with -XOverloadedStrings
    #2041
    Allow splicing in concrete syntax
    #2075
    hpc should render information about the run in its html markup
    #2101
    Allow some form of type-level lemma
    #2119
    explicitly importing deprecated symbols should elicit the deprecation warning
    #2135
    Warn if functions are exported whose types cannot be written
    #2168
    ghci should show haddock comments for identifier
    #2180
    Any installed signal handler stops deadlock detection, but XCPU never happens in a deadlock
    #2200
    big static random access arrays
    #2207
    Load the interface details for GHC.* even without -O
    #2215
    :disable command to disable breakpoints
    #2258
    ghc --cleanup
    #2269
    Word type to Double or Float conversions are slower than Int conversions
    #2333
    Emit a warning if an INLINE function is a loop breaker
    #2340
    Improve Template Haskell error recovery
    #2344
    oddity with package prefixes for data constructors
    #2345
    :browse limitations (browsing virtual namespaces, listing namespaces)
    #2365
    Warn about usage of `OPTIONS_GHC -XLanguageExtension`
    #2403
    caching for runghc (runhaskell)
    #2427
    Allow compilation of source from stdin
    #2460
    provide -mwindows option like gcc
    #2465
    Fusion of recursive functions
    #2522
    Warning for missing export lists
    #2550
    Add an option to read file names from a file instead of the command line
    #2551
    Allow multiple modules per source file
    #2595
    Implement record update for existential and GADT data types
    #2598
    Avoid excessive specialisation in SpecConstr
    #2600
    Bind type variables in RULES
    #2614
    Enumeration of values for `Sys.Info.os`, `Sys.Info.arch`
    #2630
    installed packages should have a src-dirs field, for access to optionally installed sources
    #2640
    Treat -X flags consistently in GHCi
    #2641
    Revise the rules for -XExtendedDefaultRules
    #2648
    Report out of date interface files robustly
    #2708
    Error message should suggest UnboxedTuples language extension
    #2721
    Newtype deriving doesn't work with type families
    #2737
    add :tracelocal to ghci debugger to trace only the expressions in a given function
    #2742
    The -> in ViewPatterns binds more weakly than infix data constructors.
    #2803
    bring full top level of a module in scope when a breakpoint is hit in the module
    #2867
    Make a way to tell GHC that a pragma name should be "recognised"
    #2893
    Implement "Quantified contexts" proposal
    #2895
    Implement the "Class System Extension" proposal
    #2896
    Warning suggestion: argument not necessarily a binary operator
    #2945
    add command :mergetrace
    #2946
    tracing should be controled by a global flag
    #2950
    show breakpoint numbers of breakpoints which were ignored during :force
    #2986
    :info printing instances often isn't wanted
    #3000
    :break command should recognize also nonexported top level symbols in qualified IDs
    #3021
    A way to programmatically insert marks into heap profiling output
    #3052
    ghc FFI doesn't support thiscall
    #3085
    warn about language extensions that are not used
    #3122
    Enhance --info
    #3123
    make INLINE work for recursive definitions (generalized loop peeling/loop unrolling)
    #3192
    Add dynCompileCoreExpr :: GhcMonad m => Bool -> Expr CoreBind -> m Dynamic to ghc-api
    #3205
    Generalized isomorphic deriving
    #3215
    Valgrind support
    #3282
    How to start an emacs editor within ghci asynchronously with :edit filename.hs :set editor emacs & don't go
    #3283
    Selective disabling of unused bind warnings
    #3314
    Add compilation date to +RTS --info
    #3372
    Allow for multiple linker instances
    #3427
    control what sort of entity a deprecated pragma applies to
    #3452
    Show type of most recent expression in GHCi
    #3464
    Find import declaration importing a certain function
    #3483
    Some mechanism for eliminating "absurd" patterns
    #3490
    Relax superclass restrictions
    #3517
    GHC has lots of extra hidden IOErrorType values
    #3541
    Allow local foreign imports
    #3545
    As-patterns for type signatures
    #3547
    Improve granularity of UndecidableInstances
    #3557
    CPU Vector instructions in GHC.Prim
    #3577
    Complete support for Data Parallel Haskell
    #3583
    Default view patterns
    #3601
    When running two or more instances of GHCi, persistent history is only kept for the first one
    #3615
    GHCi doesn't allow the use of imported data contructors
    #3619
    allow to set ghc search path globally (a'la CPATH)
    #3632
    lift restrictions on records with existential fields, especially in the presence of class constraints
    #3645
    Layout and pragmas
    #3701
    allow existential wrapper newtypes
    #3744
    Comparisons against minBound/maxBound not optimised for (Int|Word)(8|16|32)
    #3753
    Make ghci's -l option consistent with GNU ld's -l option
    #3769
    Add manpages for programs installed alongside ghc
    #3786
    showing function arguments when stopped at its definition
    #3869
    RTS GC Statistics from -S should be logged via the eventlog system
    #3870
    Avoid Haddock-links to the Prelude
    #3895
    "Fix" pervasive-but-unnecessary signedness in GHC.Prim
    #3919
    Or-patterns as GHC extension
    #3980
    System.Posix.Signals should provide a way to set the SA_NOCLDWAIT flag
    #3984
    Handle multiline input in GHCi history
    #4016
    Strange display behaviour in GHCi
    #4020
    Please consider adding support for local type synonyms
    #4052
    Two sided sections
    #4091
    Parse error on curried context of instance declaration
    #4092
    Floating point manipulation : ulp and coerce IEEE-754 Double# into Word64#
    #4096
    New primops for indexing: index*OffAddrUsing# etc
    #4102
    Bit manipulation built-ins
    #4114
    Add a flag to remove/delete intermediate files generated by GHC
    #4180
    do not consider associativity for unary minus for fixity resolution
    #4222
    Template Haskell lets you reify supposedly-abstract data types
    #4259
    Relax restrictions on type family instance overlap
    #4316
    Interactive "do" notation in GHCi
    #4329
    GHC.Conc modifyTVar primitive
    #4370
    Bring back monad comprehensions
    #4385
    Type-level natural numbers
    #4442
    Add unaligned version of indexWordArray#
    #4453
    Allow specifying .hi files of imports on command line in batch mode
    #4459
    Polymorphic Data.Dynamic
    #4470
    Loop optimization: identical counters
    #4479
    Implement Dot as Postfix Function Apply
    #4520
    startup code on Windows should use SetDllDirectory("")
    #4806
    Make error message more user friendly when module is not found because package is unusable
    #4815
    Instance constraints should be used when deriving on associated data types
    #4823
    Loop strength reduction for array indexing
    #4879
    Deprecate exports
    #4894
    Missing improvement for fun. deps.
    #4900
    Consider usage files in the GHCi recompilation check
    #4913
    Make event tracing conditional on an RTS flag only
    #4937
    Remove indirections caused by sum types, such as Maybe
    #4955
    increase error message detail for module lookups failure due to hi references
    #4959
    Warning about variables with leading underscore that are used anyway
    #4980
    Warning about module abbreviation clashes
    #5016
    Make Template Haskell: -ddump-splices generate executable code
    #5059
    Pragma to SPECIALISE on value arguments
    #5073
    Add blockST for nested ST scopes
    #5075
    CPR optimisation for sum types if only one constructor is used
    #5108
    Allow unicode sub/superscript symbols in operators
    #5171
    Misfeature of Cmm optimiser: no way to extract a branch of expression into a separate statement
    #5197
    Support static linker semantics for archives and weak symbols
    #5218
    Add unpackCStringLen# to create Strings from string literals
    #5219
    need a version of hs_init that returns an error code for command-line errors
    #5266
    Licensing requirements and copyright notices
    #5288
    Less noisy version of -fwarn-name-shadowing
    #5324
    Locally-scoped RULES
    #5344
    CSE should look through coercions
    #5392
    Warnings about impossible MPTCs would be nice
    #5416
    Local modules and Template Haskell declaration splices
    #5467
    Template Haskell: support for Haddock comments
    #5556
    Support pin-changing on ByteArray#s
    #5590
    "guarded instances": instance selection can add extra parameters to the class
    #5619
    Shorter qualified import statements
    #5672
    parBufferWHNF could be less subtle
    #5813
    Offer a compiler warning for failable pattern matches
    #5823
    FFI and CAPI needs {-# INCLUDE #-} back?
    #5834
    Allow both INLINE and INLINABLE for the same function
    #5835
    Make better use of known dictionaries
    #5850
    Greater customization of GHCi prompt
    #5910
    Holes with other constraints
    #5918
    hsc2hs forces wordsize (i.e. -m32 or -m64) to be the choice of GHC instead of allowing a different (or no/default choice)
    #5927
    A type-level "implies" constraint on Constraints
    #5941
    Add compilation stage plugins
    #5972
    option to suppress (Monomorphic) record selector functions
    #5985
    Type operators are not accepted as variables in contexts
    #6024
    Allow defining kinds alone, without a datatype
    #6030
    Typeclass constraint should pick the OverloadedString type.
    #6077
    Respect XDG_CONFIG_HOME
    #6089
    Allow declaration splices inside declaration brackets
    #7048
    Add the ability to statically define a `FunPtr` to a haskell function
    #7081
    arrow analogs of lambda case and multi-way if
    #7104
    Add tryWriteTBQueue to Control.Concurrent.STM.TBQueue
    #7105
    Better names for derived SCCs of instances
    #7140
    Allow type signature in export list
    #7152
    Add flag to configure that skips overwriting of symlinks on install
    #7158
    GHCi commands case insensitive
    #7169
    Warning for incomplete record field label used as function
    #7181
    Add documentation on heap-profile file format.
    #7204
    Use a class to control FFI marshalling
    #7261
    ghci's :info and :browse break encapsulation
    #7275
    Give more detailed information about PINNED data in a heap profile
    #7283
    Specialise INLINE functions
    #7285
    mkWeakMVar is non-compositional
    #7291
    hp2ps should cope with incomplete data
    #7300
    Allow CAFs kept reachable by FFI to be forcibly made unreachable for GC
    #7330
    Data Parallel Haskell (DPH) isn't usable yet.
    #7331
    Allow the evaluation of declaration splices in GHCi
    #7335
    Need for extra warning pragma for accidental pattern matching in do blocks
    #7337
    GHC does not generate great code for bit-level rotation
    #7395
    DefaultSignatures conflict with default implementations
    #7401
    Can't derive instance for Eq when datatype has no constructor, while it is trivial do do so.
    #7413
    runghc (runhaskell) should be able to reload code on editing
    #7414
    plugins always trigger recompilation
    #7492
    Generic1 deriving: Can we replace Rec1 f with f :.: Par1?
    #7494
    Allow compatible type synonyms to be the return type of a GADT data constructor.
    #7495
    generalizing overloaded list syntax to Sized Lists, HLists, HRecords, etc
    #7606
    Stride scheduling for Haskell threads with priorities
    #7635
    SafeHaskell implying other options
    #7637
    split-objs not supported for ARM
    #7647
    UNPACK polymorphic fields
    #7662
    Improve GC of mutable objects
    #7741
    Add SIMD support to x86/x86_64 NCG
    #7763
    Resource limits for Haskell
    #7808
    data families and TH names do not mix well (e.g. cannot use TH deriving)
    #7845
    RebindableSyntax should allow rebinding tuples and lists
    #7860
    Add more bit fiddling functions to 'integer-gmp'
    #7870
    Compilatio​n errors break the complexity encapsulat​ion on DSLs, impairs success in industry
    #7952
    Can cost-centre annotations be included in -ddump-simpl?
    #7977
    Optimization: Shift dropped list heads by coeffecient to prevent thunk generation
    #8012
    Warn when using Enum instance for Float or Double
    #8015
    Show warning when file-header pragma is used after module keyword
    #8043
    Feature Request : Qualified module exports
    #8045
    Move I/O manager benchmarks into the GHC tree
    #8046
    Make the timer management scale better across multicore
    #8061
    Support for Complex Double in Foreign Function Interface
    #8086
    Minimal install for GHC
    #8099
    Alternate syntax for indicating when a function is "fully applied" for purposes of inlining
    #8107
    need types to express constant argument for primop correctness
    #8109
    Type family patterns should support as-patterns.
    #8150
    Foreign export requires redundant type signature
    #8161
    Associated type parameters that are more specific than the instance header
    #8165
    Use GeneralizedNewtypeDeriving to automatically create associated type families
    #8171
    Extending ExtendedDefaultRules
    #8199
    Get rid of HEAP_ALLOCED on Windows (and other non-Linux platforms)
    #8206
    Add support for Portable Native Client
    #8207
    Pretty Printer for textual version of Language (name) in DynFlags
    #8220
    Macros / functions for source location
    #8252
    prefetch# isn't as general as it should be (currently the general version isn't type safe)
    #8263
    allow duplicate deriving / standalone deriving
    #8288
    add idris style EDSL support for deep embedding lambdas
    #8299
    Add richer data model address arithmetic: AddrDiff and AddrInt (ie d Int_ptr_diff and Int_ptr_size)
    #8300
    split-objs doesn't split on LLVM
    #8304
    more lenient operator sections (RelaxedSections extension)
    #8311
    suboptimal code generated for even :: Int -> Bool by NCG (x86, x86_64)
    #8321
    improve basic block layout on LLVM backend by predicting stack/heap checks
    #8325
    Pattern guards in anonymous functions
    #8354
    Add INLINE (or at least INLINABLE) pragmas for methods of Ord in ghc-prim
    #8364
    equip GHC with an accurate internal model of floating point
    #8372
    enable -dcmm-lint by default for .cmm input files
    #8398
    reify module list in TH
    #8404
    Default to turning on architecture specific optimizations in the codegen
    #8423
    Less conservative compatibility check for closed type families
    #8429
    GHC.Base.{breakpoint, breakpointCond} do nothing
    #8441
    Allow family instances in an hs-boot file
    #8460
    Annotation reification with types in TH
    #8473
    Generate table of cost-centre numbers with source locations
    #8477
    Allow inferring ambiguous types
    #8501
    Improve error message when using rec/mdo keyword without RecursiveDo extention.
    #8504
    Provide minor GC residency estimates
    #8516
    Add (->) representation and the Invariant class to GHC.Generics
    #8560
    Derive some generic representation for GADTs
    #8581
    Pattern synonym used in an expression context could have different constraints to pattern used in a pattern context
    #8583
    Associated pattern synonyms
    #8605
    Alternative, guard-like syntax for view patterns
    #8610
    Rebuild on a definition-based granularity
    #8619
    Support anonymous string literals in C-- (OR) give better ASSERT failure messages in C--
    #8634
    Relax functional dependency coherence check ("liberal coverage condition")
    #8642
    Allow GHCi to print non-pretty forms of things.
    #8643
    Silent name shadowing
    #8673
    GHC could generate GADT record selectors in more cases
    #8679
    Extend FunD data constructor with information about type signature
    #8685
    -split-objs doesn't work for executables
    #8695
    Arithmetic overflow from (minBound :: Int) `quot` (-1)
    #8697
    Type rationals
    #8707
    Kind inference fails in data instance definition
    #8751
    Show parenthesised output of expressions in ghci
    #8761
    Make pattern synonyms work with Template Haskell
    #8772
    ghci should save history more often
    #8779
    Exhaustiveness checks for pattern synonyms
    #8809
    Prettier error messages?
    #8812
    Make *_stub.c files available again
    #8816
    Make SPARC registerised again.
    #8822
    Allow -- ^ Haddock syntax on record constructors
    #8828
    Type pattern synonyms
    #8844
    Pseudo terminal and process-1.2.0.0
    #8875
    Track Exceptions
    #8881
    No way to unsubscribe a bug
    #8903
    Add dead store elimination
    #8914
    Remove unnecessary constraints from MonadComprehensions and ParallelListComp
    #8924
    Text.ParserCombinators.ReadP needs some kind of "commit" or "cut" to force a single parse..
    #8927
    Multiple case match at once
    #8930
    GHC API: List of available Pragmas
    #8944
    Warn instead of stopping on misplaced Haddock comments
    #8955
    Syscall intrinsic
    #8967
    Add syntax for creating finite maps and sets
    #8989
    nofib should record and report more fine-grained binary size information
    #8996
    mark more things as const in C codegen
    #8997
    Warn about unused parameters in recursive definitions
    #9030
    An async exception handler that blocks throwTo until handler finishes running
    #9051
    Report heap profile data in eventlog
    #9052
    Support a "stable heap" which doesn't get garbage collected
    #9089
    Local .ghci_history
    #9091
    print and/or apply constraints when showing info for typed holes
    #9112
    support for deriving Vector/MVector instances
    #9118
    Can't eta-reduce representational coercions
    #9120
    Cache intermediate powers
    #9137
    A way to match RULES only for literals
    #9143
    feature request: way to set actual program argv
    #9180
    New magic function `staticError`
    #9182
    Empty case analysis for function clauses
    #9183
    GHC shouldn't expand constraint synonyms
    #9192
    Add sameByteArray#
    #9197
    FFI types should be usable in foreign import decls without revealing representations
    #9214
    UNPACK support for sum types
    #9244
    Compiler could warn about type variable shadowing, and hint about ScopedTypeVariables
    #9269
    Type families returning quantified types
    #9289
    add anyToAddr# :: (#a#)-> Addr# primop (inverse of addrToAny#)
    #9291
    Don't reconstruct sum types if the type subtly changes
    #9319
    nofib-analyze doesn’t provide per-benchmark compile time/alloc numbers
    #9321
    Support for waiting on multiple MVars
    #9328
    MINIMAL pragma should supprt negation
    #9334
    Implement "instance chains"
    #9342
    Branchless arithmetic operations
    #9350
    Consider using xchg instead of mfence for CS stores
    #9351
    add ability to version symbols .c for packages with C code
    #9352
    Allow `State# s` argument/result types in `ccall` FFI imports
    #9365
    Make command key in GHCi configurable
    #9376
    More informative error messages when closed type families fail to simplify
    #9392
    "\n" is displayed weirdly in error messages
    #9394
    Show data/type family instances with ghci's :info command
    #9419
    Machine-readable output for profiling
    #9427
    Do finer-grained dependency analysis to infer more general kinds on type/class declarations
    #9429
    Alternative to type family Any
    #9431
    integer-gmp small Integer multiplication does two multiplications on x86
    #9441
    CSE should deal with letrec
    #9447
    Add support for resizing `MutableByteArray#`s
    #9476
    Implement late lambda-lifting
    #9478
    Partial type signatures
    #9498
    GHC links against unversioned .so files
    #9518
    Improve error message for unacceptable role annotations
    #9522
    SPECIALISE pragmas for derived instances
    #9571
    nofib should use criterion-style bootstrapping/sampling
    #9601
    Make the rewrite rule system more powerful
    #9617
    Implement `quot` and `rem` using `quotRem`; implement `div` and `mod` using `divMod`
    #9622
    GHCi command to solve a constraint
    #9624
    "Unlikely constraint" recognition
    #9642
    LANGUAGE pragma synonyms
    #9645
    Optimize range checks for primitive types
    #9649
    symbols should/might be type level lists of chars
    #9659
    Offer branchless conditional (CMOV) primop
    #9661
    Branchless ==# is compiled to branchy code
    #9667
    Type inference is weaker for GADT than analogous Data Family
    #9671
    Allow expressions in patterns
    #9685
    GHC fails to build with mingw32-make on Windows
    #9688
    Improve the interaction between CSE and the join point transformation
    #9690
    in GHCi map `:editNNN` to $EDITOR +NNN
    #9699
    TH function to list names in scope
    #9700
    Support C structures in Haskell FFI
    #9702
    Offer a weaker name shadowing warning
    #9724
    reexport IsList class from a trustworthy module
    #9731
    Inductive type definitions on Nat
    #9743
    Expose ghc-bin code as a library
    #9748
    Disambiguate IO actions in GHCi with :set +t
    #9756
    Warn about unnecessary unsafeCoerce
    #9784
    Improve error message for misplaced quote inside promoted qualified type
    #9789
    Make GHC accept .format+lhs as extension for literate haskell files
    #9790
    Produce coercion rules for derived Functor instances
    #9793
    Some as-patterns could be accepted in pattern synonyms
    #9795
    Debug.Trace.trace is too strict
    #9819
    Create typesafe method of obtaining dictionary types from class definitions, and constraint objects from dictionary types
    #9835
    Add bindings for marshaling to/from mpz_t
    #9846
    GHC --make should also look for .hi, not only for .hs
    #9864
    Need realloc/resize feature for mallocForeignPtrBytes allocated memory
    #9866
    ssh pubkey self-mgmt
    #9883
    Make OverloadedLists more usable by splitting the class interface
    #9898
    Wanted: higher-order type-level programming
    #9908
    Improve enumFromX support for OverloadedLists
    #9923
    Offer copy-on-GC sliced arrays
    #9931
    Option to truncate Show output in ghci REPL
    #9938
    GHC's link step needs to be told which packages to link
    #9946
    Expose the source location of template-haskell Names
    #9948
    Recommend class constraint instead of instance constraint
    #9974
    Allow more general structural recursion without UndecidableInstances
    #9990
    Top level module identifiers shadow imported identifiers
    #9993
    PostfixOperators doesn't work for types
    #9995
    :info enhancements
    #10016
    UNPACK support for existentials
    #10049
    Lower level memcpy primop
    #10055
    Offer PolyKinded instances for Data.Fixed.HasResolution
    #10063
    State a law for foldMap
    #10064
    Add support for "foo"## literals to MagicHash
    #10071
    Implement deprecation-warnings for class-methods to non-method transitions
    #10073
    Idris REPL is pretty and we can too
    #10076
    Don't suppress warnings in the presence of errors
    #10084
    Data.List should have a takeLastN function
    #10087
    DefaultSignatures: error message mentions internal name
    #10089
    feature: warn about unused data definitions (with typeclass instances)
    #10116
    Closed type families: Warn if it doesn't handle all cases
    #10150
    Suppress orphan instance warning per instance
    #10163
    Export typeRepKinds in Data.Typeable
    #10204
    Odd interaction between rank-2 types and type families
    #10225
    GHC does not specialize based on type equality
    #10235
    Get profiling info without stopping program
    #10323
    Add Android and iOS Operating Systems in Trac
    #10324
    our rts/ghc-prim/base shared library tricks don't work on Android
    #10327
    Devise workaround for how infinite types prevent closed type family reduction
    #10331
    Accept HsSyn in splices and generate it in quotes (ghc-api)
    #10336
    Support qualified self {-# SOURCE #-} import
    #10343
    Make Typeable track kind information better
    #10350
    Should be able to specify path for eventlog output.
    #10383
    AArch64: get GHC Calling convention working
    #10391
    Ability to get export list of TH reified module
    #10431
    EqualityConstraints extension?
    #10453
    \case should trigger auto-multiline mode in ghci
    #10465
    Make listArray non-strict in structure of argument list
    #10478
    Shorter import syntax
    #10505
    more specific types in the generated *_stub.h files
    #10514
    Generic for existential types
    #10604
    Make Generic1 kind polymorphic
    #10606
    avoid redundant stores to the stack when examining already-tagged data
    #10607
    Auto derive from top to bottom
    #10613
    Mechanism for checking that we only enter single-entry thunks once
    #10614
    Show constraints in ``Found hole...''
    #10621
    Handle annotations in hsig/boot files
    #10635
    -fwarn-redundant-constraints should not be part of -Wall
    #10652
    Better cache performance in Array#
    #10674
    Expose OSThreadID and assorted functions from Haskell
    #10681
    Teach GHC to interpret all hs files as two levels of hs-boot files (abstract types only/full types + values)
    #10708
    Rejection of constant functions defined using conditional pattern matching
    #10723
    Make declarations in signatures "weakly bound" until they are used
    #10741
    add flag to dump module and package dependencies
    #10756
    Allow users to indicate inaccessible patterns
    #10776
    DataKinds promotion of String -> Symbol and Natural -> Nat
    #10789
    Notify user when a kind mismatch holds up a type family reduction
    #10794
    Extension request: "where" clauses in type signatures
    #10798
    Signatures with only types should not be included in unit keys
    #10803
    New SignatureSections extension
    #10804
    Rules conditional on strictess properties
    #10809
    Add prefetch{Small}{Mutable}Array[0..3]#
    #10823
    Don't mark functions with annotations as dead
    #10827
    GHCi should support interpeting multiple packages/units with separate DynFlags
    #10832
    Generalize injective type families
    #10833
    Use injective type families when dealing with givens
    #10841
    Run handler on STM retry
    #10842
    "Reactive" Template Haskell
    #10843
    Allow do blocks without dollar signs as arguments
    #10869
    Option to dump preprocessed source
    #10871
    Implement "fat" interface files which can be directly compiled without source
    #10887
    Please export GhcMake.downsweep and make it return a partial module graph in case of errors
    #10893
    Consistent error message suggestions for using language extensions
    #10903
    Add an option to infer CallStack implicit parameters
    #10906
    `SPECIALIZE instance` could be better
    #10912
    Support for out of the box static linking
    #10915
    Statistical profiling support in the RTS
    #10925
    GHC should inform where unknown identifiers originate whenever possible
    #10933
    REMOVED pragma
    #10956
    Allow default keyboard behavior to be easily overriden
    #10963
    Beginner-targeted language extension
    #10972
    Add a :binfo (beginner info) GHCi command
    #10976
    Applicative Comprehensions
    #10978
    Anonymous type instances
    #10985
    When a "non-exhaustive pattern"-error occurs, output the arguments (if possible)
    #10986
    GHC should delete all temporary files it creates in /tmp
    #11011
    Add type-indexed type representations (`TypeRep a`)
    #11012
    Support for unicode primes on identifiers.
    #11014
    re-order GHC type errors for clarity
    #11035
    Add implicit call-stacks to partial functions in base
    #11078
    Access to module renaming with reifyModule, in TemplateHaskell
    #11080
    Open data kinds
    #11081
    Implement Introspective Template Haskell
    #11094
    Cost-center heap profiler should be able to emit samples to eventlog
    #11096
    Builtin encoder/decoder should be used for Latin-1
    #11115
    Indicate missing associated type instances
    #11134
    Limit frequency of idle GCs
    #11140
    add command-line option to GHC to dump raw parse trees of Haskell programs
    #11143
    Feature request: Add index/read/write primops with byte offset for ByteArray#
    #11169
    Remove the word "skolem" from user error messages
    #11179
    Allow plugins to access "dead code"
    #11186
    Give strong preference to type variable names in scope when reporting hole contexts
    #11191
    provide `make uninstall`
    #11219
    Implement fine-grained `-Werror=...` facility
    #11243
    Flag to not expand type families
    #11270
    "Unusable UNPACK pragma" warnings should be printed even without -O
    #11281
    Way to run --make and -M simultaneously
    #11285
    Split objects makes static linking really slow
    #11286
    ghc-pkg library
    #11309
    Warn on shady data constructor export
    #11335
    Add instance (Ix a, Read a, Read b) => Read (UArray a b)
    #11342
    Character kind
    #11343
    Unable to infer type when using DuplicateRecordFields
    #11349
    [TypeApplications] Create Proxy-free alternatives of functions in base
    #11350
    Allow visible type application in patterns
    #11352
    Allow applying type to label
    #11373
    GHC should support static archive creation on all systems
    #11377
    Template Haskell only imports
    #11378
    Use the compiler that built ghc for dynamic code loading, for cross-compiling
    #11385
    Unify named wildcards in different type applications
    #11387
    Typecasting using type application syntax
    #11393
    Ability to define INLINE pragma for all instances of a given typeclass
    #11398
    Type application for operator sections
    #11403
    Provide a way to make fast in-calls into Haskell
    #11418
    Suggest correct spelling when module is not found because of typo
    #11425
    The GHC API doesn't provide a good hscTarget option for tooling
    #11439
    Request for comments: Allow duplicate type signatures
    #11441
    RFC: Inline intermediate languages (Core, STG, Cmm, even StrictCore)
    #11457
    Run type-checker plugins before GHC's solver
    #11461
    Allow pattern synonyms to be bundled with type classes?
    #11469
    GHCi should get LANGUAGE extensions/defaulting from the module whose full top-level scope is visible
    #11470
    Support changing cross compiler target at runtime
    #11482
    Turn -fdefer-typed-holes on by default
    #11483
    Ghci should TAB-complete keywords, not only identifiers
    #11534
    Allow class associated types to reference functional dependencies
    #11561
    Have static ghci link against its own copy of its libraries
    #11565
    Restore code to handle '-fmax-worker-args' flag
    #11581
    TypeError requires UndecidableInstances unnecessarily
    #11593
    Template Haskell: Add a way to get names that are neither capturable nor capturing.
    #11594
    closed empty type families fully applied get reduced lazily when in a constraint tuple and fully applied
    #11618
    Supporting echoing the C compiler invocation instead of the GHC invocation when building the RTS
    #11620
    RFC: Type-class type signatures (:: Constraint)
    #11636
    Promoting newtype destructor
    #11638
    referring to the existential type from a GADT pattern match with a type application
    #11641
    Allow wildcards for parameters functionally determined (also type synonyms)
    #11646
    Make pattern synonym export type mismatch a warning
    #11652
    Cyclical dependencies aren't reported in pure functions
    #11658
    Type synonym with context in pattern synonym
    #11671
    Allow labels starting with uppercase with OverloadedLabels
    #11682
    :main doesn't use a bound thread
    #11686
    implicit call stacks should provide a way to get the calling function's name
    #11690
    stage 1 compiler silently ignores plugins
    #11692
    Suggest default definition of Applicative
    #11693
    Add `When` type family
    #11706
    Increase precedence of lexps (if-then-else, case-of, do, lambda and let-in)
    #11713
    STM Finalizers
    #11714
    Kind of (->) type constructor is overly constrained
    #11717
    Way to dump cmm only once
    #11718
    Disable the Preview button on trac
    #11727
    Allow one type signature for multiple pattern synonyms
    #11736
    Allow unsaturated uses of unlifted types in Core
    #11738
    A command to remove modules from the target list
    #11743
    Add unicode support for TH quotes (`[| |]`)
    #11765
    Allow documentary type signatures
    #11768
    Need a way to attach Haddock documentation to derived instances
    #11769
    Support and redistributables for ARM64 (64bit)
    #11782
    Teach ghc-pkg to read multiple registrations from command line
    #11788
    Enable Thin Library support for the Runtime linker on Windows.
    #11789
    Flag suggestion does not always work
    #11796
    Warn about unwanted instances in a modular way
    #11799
    Legend for hpc markup colors
    #11801
    RFC: Make browse command display everything unqualified
    #11805
    Ability to use record fields for automatic derivation of user-defined classes.
    #11807
    -fforce-relink / -fforce-link option
    #11815
    Data.List: Add a function to get consecutive elements (mapConsecutives)
    #11817
    Add proper support for weak symbols to the runtime linker
    #11825
    Pretty printer doesn't display functional dependency with ‘→’
    #11950
    Eventlog should include delimiters showing when the process writes to the .eventlog file
    #11953
    Export Word32#, Word64# on all architectures
    #11962
    Support induction recursion
    #11967
    Custom message when showing functions, comparing functions, ...
    #11971
    Unify error messages that suggest enabling extensions
    #11975
    New GHCi command to print out the type of an expression without instantiating
    #11992
    RFC, add Suc to base
    #11993
    RFC, allow local bindings in pattern synonyms

    feature requests,

    #602
    Warning Suppression
    #605
    Optimisation: strict enumerations
    #609
    Useful optimisation for set-cost-centre
    #618
    Dependency caching in ghc --make
    #624
    Program location for thread error messages
    #634
    Implement a more efficient TArray
    #701
    Better CSE optimisation
    #855
    Improvements to SpecConstr
    #888
    Implement the static argument transformation
    #932
    Improve inlining
    #1016
    Avoidance of unaligned loads is overly conservative
    #1349
    Generalise the ! and UNPACK mechanism for data types, to unpack function arguments
    #1371
    Add -O3
    #1377
    GHCi debugger tasks
    #1572
    Make it easy to find documentation for GHC and installed packages
    #1574
    Broken link testing
    #1600
    Optimisation: CPR the results of IO
    #1631
    Make the External Package Table contain ModDetails not ModIface
    #1880
    Unify flag descriptions to generate both docs and code
    #2123
    implement waitForProcess using signals
    #2725
    Remove Hack in compiler/nativeGen/X86/CodeGen.hs
    #2968
    Avoid generating C trigraphs
    #2988
    Improve float-in
    #3024
    Rewrite hp2ps in Haskell
    #3251
    split rts headers into public and private
    #3355
    Refactor Template Haskell syntax conversions
    #3379
    GHC should use the standard binary package
    #3384
    Add HsSyn prettyprinter tests
    #3462
    New codegen: allocate large objects using allocateLocal()
    #3511
    port GHC to OpenBSD/sparc64 (unregisterised is fine)
    #3559
    split ghci modules off into their own package
    #3713
    Track -dynamic/-fPIC to avoid obscure linker errors
    #3755
    Improve join point inlining
    #3946
    Better diagnostic when entering a GC'd CAF
    #4121
    Refactor the plumbing of CafInfo to make it more robust
    #4211
    LLVM: Stack alignment on OSX
    #4243
    Make a proper options parser for the RTS
    #4281
    Make impredicativity work properly
    #4295
    Review higher-rank and impredicative types
    #4374
    Remove in-tree gmp
    #4941
    SpecConstr generates functions that do not use their arguments
    #4960
    Better inlining test in CoreUnfold
    #5140
    Fix LLVM backend for PowerPC
    #5143
    Soft heap limit flag
    #5567
    LLVM: Improve alias analysis / performance
    #5791
    Defer other kinds of errors until runtime, not just type errors
    #5793
    make nofib awesome
    #6017
    Reading ./.ghci files raises security issues
    #7782
    flag to run the demand analysis a second time
    #7790
    Add dummy undefined symbols to indicate ways
    #7829
    make better/more robust loopbreaker choices
    #7917
    update documentation of InstalledPackageInfo
    #8050
    add a required wrapper around plugin installers
    #8096
    Add fudge-factor for performance tests run on non-validate builds
    #8226
    Remove the old style -- # Haddock comments.
    #8238
    Implement unloading of shared libraries
    #8272
    testing if SpLim=$rbp and Sp=$rsp changed performance at all
    #8287
    exploring calling convention changes and related engineering for 7.10
    #8290
    lookupSymbol API is unsafe
    #8308
    Resurrect ticky code for counting constructor arity
    #8313
    Poor performance of higher-order functions with unboxing
    #8315
    Improve specialized Hoopl module
    #8317
    Optimize tagToEnum# at Core level
    #8323
    explore ways to possibly use more tag bits in x86_64 pointers
    #8326
    Place heap checks common in case alternatives before the case
    #8396
    cleanup / refactor native code gens
    #8440
    Get rid of the remaining static flags
    #8488
    Annotations should not distinguish type and value
    #8489
    clean up dependency and usages handling in interface files
    #8578
    Improvements to SpinLock implementation
    #8597
    Git Hook script to prevent large binary blobs being checked in
    #8598
    IO hack in demand analyzer gets in the way of CPR
    #8655
    Evaluate know-to-terminate-soon thunks
    #8767
    Add rules involving `coerce` to the libraries
    #8782
    Using GADT's to maintain invariant in GHC libraries
    #8910
    cross compiling for x86_64 solaris2
    #9133
    Improve parser error reporting in `ghc-pkg`
    #9251
    ghc does not expose branchless max/min operations as primops
    #9276
    audit ghc floating point support for IEEE (non)compliance
    #9285
    IO manager startup procedure somewhat odd
    #9374
    Investigate Static Argument Transformation
    #9403
    Make --show-iface more human readable
    #9496
    Simplify primitives for short cut fusion
    #9505
    Bounded instance for Word (and possibly others) uses explicitly unboxed literals
    #9511
    Remove deprecated -fglasgow-exts from NoFib suite
    #9534
    IEEE Standard 754 for Binary Floating-Point Arithmetic by Prof. W. Kahan, UCB
    #9542
    GHC-IO-Handle-Text.hPutStr' and writeBlocks look like they need refactoring
    #9572
    nofib target for just building should be part of validate
    #9588
    Add `MonadPlus (Either e)` and `Alternative (Either e)` instances
    #9596
    Create monoidal category framework for arrow desugarer
    #9674
    Foldable doesn't have any laws
    #9716
    The list modules need a bit of post-BBP shaking
    #9718
    Avoid TidyPgm predicting what CorePrep will do
    #9719
    Improve `mkInteger` interface
    #9735
    Template Haskell for cross compilers (port from GHCJS)
    #9758
    By default, testsuite should clean up after successful tests
    #9786
    Make quot/rem/div/mod with known divisors fast
    #9797
    Investigate rewriting `>>=` to `*>` or `>>` for appropriate types
    #9805
    Use TrieMaps to speed up type class instance lookup
    #9832
    Get rid of PERL dependency of `ghc-split`
    #9837
    Introduce a logging API to GHC
    #10068
    Make the runtime reflection API for names, modules, locations more systematic
    #10074
    Implement the 'Improved LLVM Backend' proposal
    #10143
    Separate PprFlags (used by Outputable) from DynFlags
    #10172
    Cross-platform sed
    #10181
    Lint check: arity invariant
    #10266
    Split base for Backpack
    #10303
    Make it easier to print stack traces when debugging GHC itself
    #10319
    Eta expand PAPs
    #10344
    Make BranchList simpler
    #10352
    Properly link Haskell shared libs on ELF systems
    #10448
    Implement rest of "Add bifunctor related classes to base"-Proposal
    #10450
    Poor type error message when an argument is insufficently polymorphic
    #10536
    Clear up how to turn off dynamic linking in build.mk
    #10601
    GHC should be distributed with debug symbols
    #10640
    Document prim-ops
    #10680
    Make Backpack order-independent (again)
    #10710
    More self-explanatory pragmas for inlining phase control
    #10739
    Resuscitate the humble ticky-ticky profiler
    #10740
    Ensure that ticky, profiler, and GC allocation numbers agree
    #10766
    user manual: INLINE's interaction with optimization levels is not clear
    #10844
    CallStack should not be inlined
    #10854
    Remove recursive uses of `pprParendHsExpr` from `HsExpr.ppr_expr`
    #10858
    Smaller generated Ord instances
    #10892
    ApplicativeDo should use *> and <*
    #10909
    Test suite: Support non-utf8 locale
    #10913
    deprecate and then remove -fwarn-hi-shadowing
    #10918
    Float once-used let binding into a recursive function
    #10941
    Large heap address space breaks valgrind
    #10961
    Make it possible to purely use the parser
    #10962
    Improved arithmetic primops
    #11024
    Fix strange parsing of BooleanFormula
    #11031
    Record Pattern Synonym Cleanup
    #11091
    Fix MonadFail warnings
    #11138
    Kill the terrible LLVM Mangler
    #11149
    Unify fixity/associativity of <>-ish pretty-printing operators
    #11158
    Combine exprIsTrivial and cpe_ExprIsTrivial
    #11221
    Remove -fwarn-context-quantification
    #11238
    Redesign the dynamic linking on ELF systems
    #11295
    Figure out what LLVM passes are fruitful
    #11359
    Consider removing RelaxedLayout and friends
    #11366
    Control.Exception.assert should perhaps take an implicit call stack
    #11392
    Decide and document how semicolons are supposed to work in GHCi
    #11394
    Base should use native Win32 IO on Windows
    #11445
    Turn on SplitSections by default
    #11472
    Remove CallStack CPP guards in GHC 8.2
    #11477
    Remove -Wamp
    #11493
    Merge compact normal forms
    #11502
    Scrutinize use of 'long' in rts/
    #11528
    Representation of value set abstractions as trees causes performance issues
    #11551
    Get doctests into testsuite
    #11557
    Unbundle Cabal from GHC
    #11609
    Document unicode report deviations
    #11610
    Remove IEThingAll constructor from IE datatype
    #11613
    Add microlens to testsuite
    #11616
    Kinds aren't instantiated
    #11654
    User Guide: Generate command line options table from ghc-flags directives
    #11660
    Remove Type pretty-printer in favor of IfaceType
    #11735
    Optimize coercionKind
    #11739
    Simplify axioms; should be applied to types
    #11749
    Add long forms for multi-character short-form flags and possibly deprecate short forms
    #11757
    Turn on (and require) C99/C11 mode by default
    #11758
    Drop x86_64 binutils <2.17 hack
    #11767
    Add @since annotations for base instances
    #11778
    Preserve demandInfo on lambda binders in the simpifier
    #11785
    Kinds should be treated like types in TcSplice
    #11791
    Remove the `isInlinePragma prag` test
    #11802
    Make a Win32 release
    #11808
    nofib's cryptarithm1 regresses due to deferred inlining of Int's Ord operations
    #11816
    Refactor SymbolInfo out of Linker.c
    #11958
    Improved testing of cross-compiler
    #11980
    Testsuite: run each test in its own /tmp directory, after copying required files

    tasks)

  • The May 2015 Status Report.

Notices

  • Volunteer your machine as a GHC builder. This will help us find and fix issues with GHC on your platform.
  • Internships at Microsoft Research, Cambridge, working on Haskell and GHC.

Developer Documentation

  • The GHC Commentary Documentation on the design, architecture, and implementation of GHC itself, with references to the actual source code.
  • Debugging GHC All aspects of debugging, testing, and benchmarking GHC.