Compiling bytestring-mmap with -fvia-C yields broken .s file, two .size directives

[jeffwheeler]

I tried to install the bytestring-mmap package, which specifies in its cabal file the option -fvia-C (when this is removed, the package compiles fine).

I'm using GHC 7.0.2 (installed Haskell Platform recently) on x86_64 (Ubuntu 11.04). On my system, I can reliably reproduce with simply

$ cabal install bytestring-mmap-0.2.1

To get the .s file I attached, you need to unpack the package, edit the cabal file to include the GHC option -keep-tmp-files, and then cabal install there. The error shows the location of the .s file:

bytestring-mmap-0.2.1$ cabal install
Resolving dependencies...
Configuring bytestring-mmap-0.2.1...
Preprocessing library bytestring-mmap-0.2.1...
Building bytestring-mmap-0.2.1...
[1 of 3] Compiling System.IO.Posix.MMap.Internal ( System/IO/Posix/MMap/Internal.hs, dist/build/System/IO/Posix/MMap/Internal.o )
/tmp/ghc1834_0/ghc1834_0.s: Assembler messages:

/tmp/ghc1834_0/ghc1834_0.s:859:0:
     Error: .size expression for __stginit_bytestringzmmmapzm0zi2zi1_SystemziIOziPosixziMMapziInternal does not evaluate to a constant
cabal: Error: some packages failed to install:
bytestring-mmap-0.2.1 failed during the building phase. The exception was:
ExitFailure 1

[jeffwheeler]

broken .s file

[josh]

Same problem here with ghc 7.0.2 and curl-1.3.6

[josh]

Downgrading to binutils 2.20 works around this issue. binutils 2.21 added checking for .size directives.

[simonmar]

Yes, that does look a bit bogus. -fvia-C is deprecated, but we need to either fix the bug or disable it.

[igloo]

I'll close this as a duplicate of #5050, which includes a minimal testcase.