ASSERT failed! file basicTypes/MkId.lhs line 643

[batterseapower]

This is exposed by running the testsuite on a stage2 compiler with -DDEBUG. The tests triggering it are: * gadt/ubx-records * gadt/records

The affected context is:

    mk_alt data_con
      =   ASSERT2( data_ty `tcEqType` field_ty, 
                   ppr data_con $$ ppr data_ty $$ ppr field_ty )
          mkReboxingAlt rebox_uniqs data_con (ex_tvs ++ co_tvs ++ arg_vs) rhs
      where
           -- get pattern binders with types appropriately instantiated
        arg_uniqs = map mkBuiltinUnique [arg_base..]
        (ex_tvs, co_tvs, arg_vs) = dataConOrigInstPat arg_uniqs data_con 
                                                      scrut_ty_args

The precise error is:

=====> ubx-records(normal)
cd . && '/Users/mbolingbroke/Programming/Checkouts/ghc.working/compiler/stage2/ghc-inplace' -fforce-recomp -dcore-lint -dcmm-lint -Di386_apple_darwin  -dno-debug-output -o ubx-records ubx-records.hs    >ubx-records.comp.stderr 2>&1
Compile failed (status 256) errors were:
ghc-6.9.20080614: panic! (the 'impossible' happened)
  (GHC version 6.9.20080614 for i386-apple-darwin):
	ASSERT failed! file basicTypes/MkId.lhs line 643
main:Main.T1{d r6q}
ipv_B3{tv} [tv]
a{tv a6G} [tv]

[igloo]

I can't reproduce this with ./validate --slow; did someone fix it?

[simonpj]

This one is fixed by

Mon Aug 11 13:35:26 BST 2008  simonpj@microsoft.com
  * Fix Trac #2367: selectors for GADTs

I've re-enabled these tests for a fast validate (I think).

Merge this to 6.8 if we release it. Simon

[igloo]

We won't be releasing 6.8.4.