#6063: GHC's build-time ld-flag checks are problematic ---------------------------------+------------------------------------------ Reporter: parcs | Owner: thoughtpolice Type: bug | Status: new Priority: high | Milestone: 7.8.1 Component: Compiler | Version: 7.4.1 Keywords: | Os: Linux Architecture: Unknown/Multiple | Failure: GHC doesn't work at all Difficulty: Unknown | Testcase: Blockedby: | Blocking: Related: #4862 | ---------------------------------+------------------------------------------ Comment(by thoughtpolice): I have a patch for this now. I decided to generalize it a little and added functionality to generally detect linker information at runtime, and distinguish between several cases. I have verified it works and am validating on my Mac OS X machine and my other Linux machines. I will set up a Windows machine as well. I'd like some code review before I push this patch to the tree directly. If Ian or anyone else would like to give feedback, please do so. If there aren't any complaints I'll push this myself. @nh2 - no, this was not fixed in that work. The issue is a little more complicated. Please see my commit message and patch which details the issue fairly clearly. {{{ commit e1825358b318f847aca19a230fb0a4377830d767 Author: Austin Seipp <aseipp@pobox.com> Date: Sat May 4 16:07:22 2013 -0500 Detect linker information at runtime. Fixes Trac #6063 Previously, we did ./configure time checks to see if 'GNU ld' supported certain options. If it does, we bake those options into the link step. See Trac #5240. Ergo, this is a build-time configuration. Unfortunately, the linker we use at runtime can change for several reasons. One is that the user specifies -pgml 'foo'. The other is if /usr/bin/ld or whatnot literally *changes* from when GHC was built. Obviously, not every linker supports these options, like GNU gold, and that would lead to linking failure. This is Trac #6063. What this ultimately means is that we need to check at runtime what linker we're using. Always. This is actually a little bit complicated because we normally use the C compiler as our linker. Also, OS X does not support gold OR ld, Windows only has GNU ld, etc. Finally, this patch also unconditionally gives '--hash-size=31' and '--reduce-memory-overheads' to the system linker if it's GNU ld. These options have been supported for 8+ years from what I can see, and there are probably a lot of *other* reasons why GHC would not work with such an ancient binutils, all things considered. See Note [Run-time linker info] in SysTools for more details. There are plenty of comments as well in the surrounding code. Signed-off-by: Austin Seipp <aseipp@pobox.com> }}} -- Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/6063#comment:12> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler