[Git][ghc/ghc][wip/T24676] Wibbles

[Simon Peyton Jones (@simonpj)]

Simon Peyton Jones pushed to branch wip/T24676 at Glasgow Haskell Compiler / GHC


Commits:
b6a7f3de by Simon Peyton Jones at 2024-06-04T14:48:35+01:00
Wibbles

- - - - -


4 changed files:

- compiler/GHC/Tc/Gen/App.hs
- compiler/GHC/Tc/Utils/TcType.hs
- testsuite/tests/typecheck/should_fail/T8450.hs
- testsuite/tests/typecheck/should_fail/T8450.stderr


Changes:

=====================================
compiler/GHC/Tc/Gen/App.hs
=====================================
@@ -119,8 +119,7 @@ Note [Instantiation variables are short lived]
   variables can be unified with a polytype (by `qlUnify`).
 
 * By the time QL is done, all filled-in occurrences of instantiation variables
-  have been zonked away with `qlZonkTcType` (see "Crucial step" in tcValArgs).
-  See also Note [QuickLook zonking] in GHC.Tc.Zonk.TcType
+  have been zonked away with `zonkTcType` (see "Crucial step" in tcValArgs).
 
   See Section 4.3 "Applications and instantiation" of the paper.
 
@@ -294,7 +293,8 @@ Now we split into two cases:
        Note [Unify with expected type before typechecking arguments]
 
    5.2 Check the arguments with `tcValArgs`. Importantly, this will monomorphise
-       all the instantiation variables of the call.  See Note [qlMonoTcType]
+       all the instantiation variables of the call.
+       See Note [Monomorphise instantiation variables].
 
    5.3 Use `zonkTcType` to expose the polymophism hidden under instantiation
        variables in `app_res_rho`, and the monomorphic versions of any
@@ -526,7 +526,6 @@ tcValArg do_ql (EValArg { ea_ctxt   = ctxt
          -- Then Theta = [p :-> forall a. a->a], and we want
          -- to check 'e' with expected type (forall a. a->a)
          -- See Note [Instantiation variables are short lived]
-         -- and Note [QuickLook zonking] in GHC.Tc.Zonk.TcType
        ; Scaled mult exp_arg_ty <- case do_ql of
               DoQL -> liftZonkM $ zonkScaledTcType sc_arg_ty
               NoQL -> return sc_arg_ty


=====================================
compiler/GHC/Tc/Utils/TcType.hs
=====================================
@@ -699,7 +699,7 @@ data TcLevel = TcLevel Int#
              | QLInstVar
   -- See Note [TcLevel invariants] for what this Int is
   -- See also Note [TcLevel assignment]
-  -- See also Note [The TcLevel QLInstVar]
+  -- See also Note [The QLInstVar TcLevel]
 
 {-
 Note [TcLevel invariants]
@@ -734,7 +734,7 @@ Note [TcLevel invariants]
 The level of a MetaTyVar also governs its untouchability.  See
 Note [Unification preconditions] in GHC.Tc.Utils.Unify.
 
-  -- See also Note [The TcLevel QLInstVar]
+  -- See also Note [The QLInstVar TcLevel]
 
 Note [TcLevel assignment]
 ~~~~~~~~~~~~~~~~~~~~~~~~~


=====================================
testsuite/tests/typecheck/should_fail/T8450.hs
=====================================
@@ -7,5 +7,8 @@ runEffect = undefined
 run :: forall a. a
 run = runEffect $ (undefined :: Either a ())
 
-{-  Either a () ~ Either Bool alpha
-    a ~ alpha -}
\ No newline at end of file
+{-
+r:=a
+Expected: Either Bool a
+Actual:   Either a ()
+-}


=====================================
testsuite/tests/typecheck/should_fail/T8450.stderr
=====================================
@@ -1,11 +1,15 @@
-
-T8450.hs:8:7: error: [GHC-25897]
-    • Couldn't match expected type ‘a’ with actual type ‘()’
+T8450.hs:8:18: error: [GHC-25897]
+    • Couldn't match type ‘a’ with ‘Bool’
+      Expected: Either Bool a
+        Actual: Either a ()
       ‘a’ is a rigid type variable bound by
         the type signature for:
           run :: forall a. a
         at T8450.hs:7:1-18
-    • In the expression: runEffect $ (undefined :: Either a ())
+    • In the first argument of ‘runEffect’, namely
+        ‘(undefined :: Either a ())’
+      In the expression: runEffect (undefined :: Either a ())
       In an equation for ‘run’:
-          run = runEffect $ (undefined :: Either a ())
+          run = runEffect (undefined :: Either a ())
     • Relevant bindings include run :: a (bound at T8450.hs:8:1)
+



View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/b6a7f3de755306e5188e420f0d4f38b6a1bebab5

-- 
View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/b6a7f3de755306e5188e420f0d4f38b6a1bebab5
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