Re: #10170: Find versioned versions of LLVM tools

#10170: Find versioned versions of LLVM tools
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        Reporter:  erikd             |                Owner:  erikd
            Type:  bug               |               Status:  closed
        Priority:  normal            |            Milestone:  8.0.1
       Component:  Compiler (LLVM)   |              Version:  7.11
      Resolution:  fixed             |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D745
       Wiki Page:                    |
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Comment (by jberryman):

 Hi, this seems to have regressed. Should I open a new ticket? I'd like for
 ghc to look for versioned llvm executables in the PATH and prefer those
 over the unversioned names (if they exist).

 If #10074 is stalled this change seems sufficient to me. As it stands
 using multiple ghc versions with fllvm side by side is pretty inconvenient
 (or else I haven't figured out the trick).

 {{{
 $ echo $PATH
 /home/me/Code/NOT_MY_CODE/spack/bin:/usr/lib/llvm-6.0/bin:/home/me/.cargo/bin:/usr/local/go/bin:/home/me/.rbenv/shims:/home/me/.rbenv/bin:/home/me/.play-2.2.2:/home/me/.node/bin:/usr/local/node/bin:/home/me/.local/bin:/home/me/.cabal/bin:/usr/local/bin:/usr/bin:/bin:/usr/local/games:/usr/games:/usr/local/go/bin:/home/me/.gem/ruby/2.2.0/bin:/home/me/.go/bin
 $ which opt
 /usr/lib/llvm-6.0/bin/opt
 $ ghc --make -fforce-recomp -fllvm hello.hs -o hello_llvm
 [1 of 1] Compiling Main             ( hello.hs, hello.o )
 Linking hello_llvm ...
 $ export
 PATH=/home/me/.cargo/bin:/usr/local/go/bin:/home/me/.rbenv/shims:/home/me/.rbenv/bin:/home/me/.play-2.2.2:/home/me/.node/bin:/usr/local/node/bin:/home/me/.local/bin:/home/me/.cabal/bin:/usr/local/bin:/usr/bin:/bin:/usr/local/games:/usr/games:/usr/local/go/bin:/home/me/.gem/ruby/2.2.0/bin:/home/me/.go/bin
 $ which opt
 opt not found
 $ which opt-6.0
 1 ↵
 /usr/bin/opt-6.0
 $ ghc --make -fforce-recomp -fllvm hello.hs -o hello_llvm
 [1 of 1] Compiling Main             ( hello.hs, hello.o )

 <no location info>: error:
     Warning: Couldn't figure out LLVM version!
              Make sure you have installed LLVM 6.0
 ghc: could not execute: opt
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10170#comment:19>