Re: Help needed: Updating GHC to 8.4.3

[Timothy Sample]

Hi Ricardo,

Ricardo Wurmus <address@hidden> writes:

> Hi Ludo,
>
>> Hello,
>>
>> Ricardo Wurmus <address@hidden> skribis:
>>
>>> GHC 8.0 had been patched with
>>> "ghc-dont-pass-linker-flags-via-response-files.patch" to avoid using
>>> response files with the linker, because our ld-wrapper doesn’t seem to
>>> behave right in some edge case that GHC depends on.  I tried porting the
>>> patch to GHC 8.4.3 by applying this snippet:
>>
>> I think this patch predates the addition of support for response files
>> in ld-wrapper.  That support is not entirely faithful (see the FIXME in
>> ld-wrapper.in), but I think it’s good enough for GHC.
>>
>> Could you maybe try removing the patch and see if it works better?
>
> I did try to build GHC 8.4.3 without any patches first, but this failed
> (with the same errors and warnings when trying to set up the tests).
> Only then did I try to port the patch from 8.0.x to 8.4.3.

I had some success with GHC 8.4.3.  It turns out that the warnings exist
for 8.0.2 as well.  I’m not sure what they are about, but they are not a
new problem.

The new problem is that the stage-2 GHC compiler is not using the
ld-wrapper.  This is due to some changes to their Autoconf scripts which
add “-fuse-ld=bfd” to the later-stage compilers’ “gcc” invocations by
default.  Since “ld.bfd” does not point to the ld-wrapper, the wrapper
gets bypassed.

There are two easy solutions to this:

  1. Use the “--disable-ld-override” configure flag.
  2. Set the “LD” environment variable.

I got the package to build using option 1.  However, it didn’t work
because it expected all the build tools (“gcc”, “ld”, etc.) to be in
“PATH”.  They traded “AC_PATH_” for “AC_CHECK_”, setting the variables
to just the command names.  Nix uses option 2 and sets explicit paths
for all the tools via environment variables.  I think we have to do the
same.

Also, I didn’t need the response files patch, and the
“native-search-paths” field needs to be updated.

Hope that helps!


-- Tim