THE CURSE ("unexpected" testsuite failures)

[Isaac Dupree]

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?)

-Isaac