[GHC] #11495: TH_spliceE5_prof is failing with release candidate 8.0.1

[GHC]

#11495: TH_spliceE5_prof is failing with release candidate 8.0.1
-------------------------------------+-------------------------------------
        Reporter:  thomie            |                Owner:
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.0.1
       Component:  Compiler          |              Version:  8.0.1-rc1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
-------------------------------------+-------------------------------------
Description changed by thomie:

@@ -31,1 +31,2 @@
- `compiler/ghci/Linker.hs` Simon suggests that passing `-dynamic`:
+ `compiler/ghci/Linker.hs` Simon suggests that passing `-dynamic` is
+ necessary:

New description:

 `TH_spliceE5_prof` looks like this:
 {{{
 TH_spliceE5_prof::
         $(RM) TH_spliceE5_prof*.o TH_spliceE5_prof*.hi
 TH_spliceE5_prof*.dyn_o TH_spliceE5_prof*.dyn_hi TH_spliceE5_prof
         '$(TEST_HC)' $(TEST_HC_OPTS) $(HC_OPTS) $(ghcThWayFlags) --make
 -v0 TH_spliceE5_prof.hs -c
         '$(TEST_HC)' $(TEST_HC_OPTS) $(HC_OPTS) --make -v0
 TH_spliceE5_prof.hs -prof -auto-all -osuf .p.o -o $@
         ./$@
 }}}

 In 4905b83a2d448c65ccced385343d4e8124548a3b, Simon added that
 `$(ghcThWayFlags)` to the first compilation command. With a release
 compiler, `ghcThWayFlags` defaults to `-dynamic`. But compiling with
 `-dynamic` doesn't produce `.dyn_o` files (you need `-dynamic-too` for
 that, which is enabled by `-XTemplateHaskell`, but **not** when compiling
 with `-dynamic`), so the second compilation results in:

 {{{
 TH_spliceE5_prof.hs:8:17: fatal:
     cannot find object file ‘./TH_spliceE5_prof_Lib.dyn_o’
     while linking an interpreted expression
 make[1]: *** [TH_spliceE5_prof] Error 1

 *** unexpected failure for TH_spliceE5_prof(normal)
 }}}


 Not passing `-dynamic` fixes the test. But in the function `failNonStd` in
 `compiler/ghci/Linker.hs` Simon suggests that passing `-dynamic` is
 necessary:
 {{{
     Cannot load -prof objects when GHC is built with -dynamic
     To fix this, either:
       (1) Use -fexternal-interprter, or
       (2) Build the program twice: once with -dynamic, and then
           with -prof using -osuf to set a different object file suffix.
 }}}


 Some ideas for a solution:
  * change that message to not mention `-dynamic`
  * always turn on `-dynamic-too` when `-XTemplateHaskell` is on, also when
 using `-dynamic`
  * find the place where `.dyn_o` is expected, and teach it that `.o` might
 also be ok.
  * make `-fexternal-interpreter` the default. Delete the test and a whole
 bunch of other stuff.

 It's all such a mess.

--

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11495#comment:1>
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