[GHC] #13355: gmp doesn't build correctly when cross-compiling with clang

[GHC]

#13355: gmp doesn't build correctly when cross-compiling with clang
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           Reporter:  rwbarton       |             Owner:  (none)
               Type:  bug            |            Status:  new
           Priority:  normal         |         Milestone:
          Component:  Build System   |           Version:  8.1
           Keywords:                 |  Operating System:  Unknown/Multiple
       Architecture:                 |   Type of failure:  Building GHC
  Unknown/Multiple                   |  failed
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):                 |         Wiki Page:
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 The commit in #8497 added this to `libraries/integer-gmp/gmp/ghc.mk`:
 {{{
 CLANG = $(findstring clang, $(shell $(CC_STAGE1) --version))

 ifeq "$(CLANG)" "clang"
 CCX = $(CLANG)
 else
 CCX = $(CC_STAGE1)
 endif
 }}}
 and does the build with `$(CCX)` rather than `$(CC_STAGE1)`.

 However, when cross-compiling, `$(CC_STAGE1)` could be a clang cross-
 compiler, but then it's certainly not right to use `$(CLANG) = clang`, as
 that is presumably not a cross-compiler.

 I don't understand why the issue in #8497 arose in the first place, so
 it's unclear to me how to proceed here.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13355>
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