diff options
Diffstat (limited to 'compiler/GHC/Tc/Gen/HsType.hs')
| -rw-r--r-- | compiler/GHC/Tc/Gen/HsType.hs | 9 |
1 files changed, 5 insertions, 4 deletions
diff --git a/compiler/GHC/Tc/Gen/HsType.hs b/compiler/GHC/Tc/Gen/HsType.hs index dd31ef586d..10a8953d29 100644 --- a/compiler/GHC/Tc/Gen/HsType.hs +++ b/compiler/GHC/Tc/Gen/HsType.hs @@ -4094,10 +4094,11 @@ more. So I use a HACK: ordinary tuples we don't have the same limit as for constraint tuples (which need selectors and an associated class). -* Because it is ill-kinded, it trips an assert in writeMetaTyVar, - so now I disable the assertion if we are writing a type of - kind Constraint. (That seldom/never normally happens so we aren't - losing much.) +* Because it is ill-kinded (unifying something of kind Constraint with + something of kind Type), it should trip an assert in writeMetaTyVarRef. + However, writeMetaTyVarRef uses eqType, not tcEqType, to avoid falling + over in this scenario (and another scenario, as detailed in + Note [coreView vs tcView] in GHC.Core.Type). Result works fine, but it may eventually bite us. |