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| author | sheaf <sam.derbyshire@gmail.com> | 2021-10-21 11:20:57 +0200 |
|---|---|---|
| committer | Marge Bot <ben+marge-bot@smart-cactus.org> | 2021-10-22 10:58:44 -0400 |
| commit | 77c6f3e6be3b94c48ec6c9b7015dab69ae47564e (patch) | |
| tree | e95282805588c9a03c95b86947b3d67406799d60 /compiler/GHC/Tc | |
| parent | 7f4e0e91530117fd4d477d553a7f03993b86fe74 (diff) | |
| download | haskell-77c6f3e6be3b94c48ec6c9b7015dab69ae47564e.tar.gz | |
Use tcEqType in GHC.Core.Unify.uVar
Because uVar used eqType instead of tcEqType, it was possible
to accumulate a substitution that unified Type and Constraint.
For example, a call to `tc_unify_tys` with arguments
tys1 = [ k, k ]
tys2 = [ Type, Constraint ]
would first add `k = Type` to the substitution. That's fine, but then
the second call to `uVar` would claim that the substitution also
unifies `k` with `Constraint`. This could then be used to cause
trouble, as per #20521.
Fixes #20521
Diffstat (limited to 'compiler/GHC/Tc')
| -rw-r--r-- | compiler/GHC/Tc/Utils/TcType.hs-boot | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/compiler/GHC/Tc/Utils/TcType.hs-boot b/compiler/GHC/Tc/Utils/TcType.hs-boot index 6b808dd7ab..2a7a34dc97 100644 --- a/compiler/GHC/Tc/Utils/TcType.hs-boot +++ b/compiler/GHC/Tc/Utils/TcType.hs-boot @@ -2,6 +2,8 @@ module GHC.Tc.Utils.TcType where import GHC.Utils.Outputable( SDoc ) import GHC.Prelude ( Bool ) import {-# SOURCE #-} GHC.Types.Var ( TcTyVar ) +import {-# SOURCE #-} GHC.Core.TyCo.Rep +import GHC.Utils.Misc ( HasDebugCallStack ) data MetaDetails @@ -10,3 +12,5 @@ pprTcTyVarDetails :: TcTyVarDetails -> SDoc vanillaSkolemTv :: TcTyVarDetails isMetaTyVar :: TcTyVar -> Bool isTyConableTyVar :: TcTyVar -> Bool + +tcEqType :: HasDebugCallStack => Type -> Type -> Bool |