diff options
| author | Simon Peyton Jones <simonpj@microsoft.com> | 2017-06-29 15:26:54 +0100 |
|---|---|---|
| committer | Simon Peyton Jones <simonpj@microsoft.com> | 2017-06-29 15:30:53 +0100 |
| commit | 3b0e7555fafe73b157a96ca48d8ddc04ad81b231 (patch) | |
| tree | ea37a910eade51e2346a2e9d49ca8f266974fcf7 /compiler/typecheck/TcPat.hs | |
| parent | 54ccf0c957a279c20e1a37a5a462612af8036739 (diff) | |
| download | haskell-3b0e7555fafe73b157a96ca48d8ddc04ad81b231.tar.gz | |
Fix lexically-scoped type variables
Trac #13881 showed that our handling of lexically scoped type
variables was way off when we bring into scope a name 'y' for
a pre-existing type variable 'a', perhaps with an entirely
different name.
This patch fixes it; see TcHsType
Note [Pattern signature binders]
Diffstat (limited to 'compiler/typecheck/TcPat.hs')
| -rw-r--r-- | compiler/typecheck/TcPat.hs | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/compiler/typecheck/TcPat.hs b/compiler/typecheck/TcPat.hs index faadcb3fa3..d10d8474b5 100644 --- a/compiler/typecheck/TcPat.hs +++ b/compiler/typecheck/TcPat.hs @@ -406,8 +406,8 @@ tc_pat penv (ViewPat expr pat _) overall_pat_ty thing_inside tc_pat penv (SigPatIn pat sig_ty) pat_ty thing_inside = do { (inner_ty, tv_binds, wcs, wrap) <- tcPatSig (inPatBind penv) sig_ty pat_ty - ; (pat', res) <- tcExtendTyVarEnv2 wcs $ - tcExtendTyVarEnv tv_binds $ + ; (pat', res) <- tcExtendTyVarEnv2 wcs $ + tcExtendTyVarEnv2 tv_binds $ tc_lpat pat (mkCheckExpType inner_ty) penv thing_inside ; pat_ty <- readExpType pat_ty ; return (mkHsWrapPat wrap (SigPatOut pat' inner_ty) pat_ty, res) } |