Slow validate failures

[Ömer Sinan Ağacan]

Hi all,

I have a patch that effects profiling code and I realized neither `./validate
--fast` nor `./validate` test the "prof" way so I tried `./validate --slow`. I
saw that even on a clean branch I get 250 unexpected failures and 6 unexpected
passes. I had a quick look at logs. Most of the failures seem to be in these
formats:

-
    Compile failed (exit code 1) errors were:
    T6005a.hs:1:1: fatal:
        Cannot load -prof objects when GHC is built with -dynamic
        To fix this, either:
          (1) Use -fexternal-interpreter, or
          (2) Build the program twice: once with -dynamic, and then
              with -prof using -osuf to set a different object file suffix.

-
    Compile failed (exit code 1) errors were:

    T5984_Lib.hs:3:8: error:
        Could not find module ‘Prelude’
        Perhaps you haven't installed the "p_dyn" libraries for
package ‘base-4.10.0.0’?
        Use -v to see a list of the files searched for.

    T5984_Lib.hs:5:1: error:
        Could not find module ‘Language.Haskell.TH’
        Perhaps you haven't installed the "p_dyn" libraries for
package ‘template-haskell-2.12.0.0’?
        Use -v to see a list of the files searched for.

But there are also some serious-looking failures, like

    =====> hpc_fork(hpc) 5717 of 5834 [6, 245, 0]
    ...
    +++ "/tmp/ghctest-yrj0el9g/test
spaces/../../libraries/ghc-compact/tests/compact_share.run/compact_share.run.stdout.normalised"
2017-03-24 00:38:02.486282332 +0300
    @@ -1,4 +1,4 @@
     275599
    -3801088
    +6291456
     275599
    -2228224
    +3506176

So it seems at this point there's basically no realiable way to test profiling
changes. I was wondering if someone here know anything about these. If anyone's
interested, I pushed test output of `./validate --slow` here: (9.2M file)
https://gist.githubusercontent.com/osa1/7cbcc8303f1e213a10accf0bcd9b5ab2/raw/75371245bba2918f4ec97675abea9af661c77b25/gistfile1.txt

Ömer