[GHC] #13696: rts/linker/ElfTypes.h does not compile on most of UNREG arches (and some registerised arches)

[GHC]

#13696: rts/linker/ElfTypes.h does not compile on most of UNREG arches (and some
registerised arches)
-------------------------------------+-------------------------------------
        Reporter:  slyfox            |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.0.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D3583
       Wiki Page:                    |
-------------------------------------+-------------------------------------

Comment (by Sergei Trofimovich <slyfox@…>):

 In [changeset:"d5414dd61b540be3b3945c321065a1c70c7962ac/ghc" d5414dd/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="d5414dd61b540be3b3945c321065a1c70c7962ac"
 rts/linker/ElfTypes.h: restore powerps (and others) support

 GHC build fails for powerpc-unknown-linux-gnu
 and hppa-unknown-linux-gnu targets as:
   rts_dist_HC rts/dist/build/RtsStartup.o
     rts/linker/ElfTypes.h:23:4: error:
          error: #error "Unsupported arch!"

 Before the change code tried to whitelist architectures
 and classify them into ELF32/ELF64. It does not work
 for UNREG arches like 'hppa', 'sparc64', 'm68k', 'mips'.

 It is nuanced for things like mips64 and x86_64:
     'mips64-unknown-linux-gnu-gcc -mabi=64' is ELFCLASS64
     'mips64-unknown-linux-gnu-gcc'          is ELFCLASS32
     'x86_64-pc-linux-gnu-gcc'               is ELFCLASS64
     'x86_64-pc-linux-gnu-gcc -mx32'         is ELFCLASS32
 Here it's not enough to know HOST_ARCH. We really need to
 know ABI.

 The change uses '__LP64__' as a proxy for ELFCLASS64.

 Signed-off-by: Sergei Trofimovich <slyfox at gentoo.org>

 Reviewers: angerman, simonmar, austin, bgamari, erikd

 Reviewed By: angerman, bgamari, erikd

 Subscribers: rwbarton, thomie

 GHC Trac Issues: #13696

 Differential Revision: https://phabricator.haskell.org/D3583
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13696#comment:4>
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