THE CURSE ("unexpected" testsuite failures)

[Simon Marlow]

Isaac Dupree wrote:
> for example here is my result of running indexed-types/GADT11 test 
> explicitly:
> 
> =====> GADT11(normal)
> cd . && 
> '/Users/me/modified/ghcAlexSpeedTest/compiler/stage1/ghc-inplace' 
> -no-recomp -dcore-lint -dcmm-lint -Di386_unknown_linux  -c GADT11.hs 
>  >GADT11.comp.stderr 2>&1
> Actual stderr output differs from expected:
> --- /dev/null    2008-05-23 14:11:52.000000000 -0400
> +++ ./GADT11.comp.stderr.normalised    2008-06-02 20:10:19.000000000 -0400
> @@ -0,0 +1,8 @@
> +WARNING: file Coercion.lhs line 388
> +Strange! Type mismatch in trans coercion, probably a bug
> +main:ShouldCompile.Z{tc r6G} = t_a8c{tv} [tau]
> +WARNING: file Coercion.lhs line 388
> +Strange! Type mismatch in trans coercion, probably a bug
> +main:ShouldCompile.S{tc r6E}
> +  (main:ShouldCompile.Sum{tc r6C}
> +     main:ShouldCompile.Z{tc r6G} n{tv a7M} [sk]) = t_a84{tv} [tau]
> *** unexpected failure for GADT11(normal)
> 
> 
> Now, I do compile with -DDEBUG on (or maybe I don't for 'validate' 
> builds, I can't tell)... could that be related? (and if so, do those 
> WARNINGS indicate a bug in GHC or are they innocuous / should be 
> ignored?  Or is it just always a bad idea to run the testsuite / the 
> validate with DEBUG-ghc?)  (Is there any way to query a built GHC to 
> find out whether debugIsOn?)

DEBUG will cause tests to fail due to unexpected debugging output, as you 
noticed.

Fortunately you caught me in a "just fix it" mood, so I just fixed it.  We 
now have a flag -dno-debug-output that suppresses the traces emitted by a 
DEBUG compiler from time to time, and the testsuite passes this flag by 
default.  I'm validating with -DDEBUG right now to check it works properly, 
then I'll push the change.

Cheers,
	Simon