GHCi ignores .dyn_o files

With both .o and .dyn_o object files available, GHCi 7.8.2 ignores the dynamic object files.

$ cat >Foo.hs <<EOF
module Foo where

foo :: IO ()
foo = print "Foo"
EOF

$ ghc -Wall -c -dynamic-too -o Foo.o Foo.hs

$ ghci
GHCi, version 7.8.2: http://www.haskell.org/ghc/  :? for help
Loading package ghc-prim ... linking ... done.
Loading package integer-gmp ... linking ... done.
Loading package base ... linking ... done.
> :l Foo
[1 of 1] Compiling Foo              ( Foo.hs, interpreted )
Ok, modules loaded: Foo.
> 

As rwbarton mentioned on IRC, the reason becomes apparent with ghci -ddump-if-trace

FYI: cannot read old interface file:
    mismatched interface file ways (wanted "dyn", got "")

This happens both on OS X and Linux.

Trac metadata

Trac field	Value
Version	7.8.2
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	GHCi
Test case
Differential revisions
BlockedBy
Related
Blocking
CC	hvr
Operating system
Architecture

mentioned in issue #8736 (closed)

changed weight to 5

added GHCi Tbug Trac import labels

added linking label

It also ignores the .dyn_o file even if there is no .o file, with no pertinent output from -ddump-if-trace:

*** Checking old interface for main:F:
[1 of 1] Compiling F                ( F.hs, interpreted )

(I am running 7.8.2.20140630.)

changed title from GHCi ignores .dyn_hi files to GHCi ignores .dyn_o files

closed

See #8736 (closed). As a workaround you can use -dynamic, not -dynamic-too. That will create dynamic-style .o and .hi files.

Trac metadata

Trac field	Value
Resolution	Unresolved → ResolvedDuplicate

added Pnormal label