Building an empty module with profiling requires profiling libraries for integer-gmp

{-# LANGUAGE NoImplicitPrelude #-}
module A where

$ ghc-stage2 -prof -c A.hs

Top level:
    Failed to load interface for ‛GHC.Integer.Type’
    Perhaps you haven't installed the profiling libraries for package ‛integer-gmp’?
    Use -v to see a list of the files searched for.

I can't built module A without profiling libraries for integer-gmp, even though I don't use integer-gmp anywhere in the module.

This happens because the Tidy Core pass attempts to look up the mkInteger name (in order to desugar integer literals) even when there are no integer literals in the module.

The obvious fix is to lazily look up mkInteger in Coreprep.lookupMkIntegerName:

diff --git a/compiler/coreSyn/CorePrep.lhs b/compiler/coreSyn/CorePrep.lhs
index 5e0cd65..9836982 100644
--- a/compiler/coreSyn/CorePrep.lhs
+++ b/compiler/coreSyn/CorePrep.lhs
@@ -56,6 +56,7 @@ import Config
 import Data.Bits
 import Data.List        ( mapAccumL )
 import Control.Monad
+import System.IO.Unsafe ( unsafeInterleaveIO )
 \end{code}

 -- ---------------------------------------------------------------------------
@@ -1119,6 +1120,7 @@ lookupMkIntegerName dflags hsc_env
       else if thisPackage dflags == integerPackageId
       then return $ panic "Can't use Integer in integer"
       else liftM tyThingId
+         $ unsafeInterleaveIO
          $ initTcForLookup hsc_env (tcLookupGlobal mkIntegerName)

 mkInitialCorePrepEnv :: DynFlags -> HscEnv -> IO CorePrepEnv

This way, we don't attempt to look up mkInteger until we actually need it, i.e. if there are integer literals that we must desugar.

Relevant commits are 2ef5cd26 and fdd552e0

Trac metadata

Trac field	Value
Version	7.7
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler (Type checker)
Test case
Differential revisions
BlockedBy
Related
Blocking
CC
Operating system
Architecture

changed weight to 5

added Tbug Trac import typechecker labels

I don't really know if I like this patch. It seems very fragile and most of the code has been refactored now. I think Herbert should take a look, but I hope he'd agree. :)

Trac metadata

Trac field	Value
Component	Compiler (Type checker) → Compiler

removed typechecker label

tbh, I've got a bad gut feeling too... this should be fixed properly, but I'm not sure how yet...

changed milestone to %8.0.1

Milestone renamed

added integer-gmp label

Trac metadata

Trac field	Value
Component	Compiler → Profiling

added typechecker label

added Pnormal label