Simon Peyton Jones pushed to branch wip/T26004 at Glasgow Haskell Compiler / GHC
Commits:
-
ca6cd646
by Simon Peyton Jones at 2025-04-30T08:44:33+01:00
2 changed files:
Changes:
| ... | ... | @@ -1433,6 +1433,8 @@ decideAndPromoteTyVars top_lvl rhs_tclvl infer_mode name_taus psigs wanted |
| 1433 | 1433 | (can_quant_cts, no_quant_cts) = approximateWCX wanted
|
| 1434 | 1434 | can_quant = ctsPreds can_quant_cts
|
| 1435 | 1435 | no_quant = ctsPreds no_quant_cts
|
| 1436 | + can_quant_tvs = tyCoVarsOfTypes can_quant
|
|
| 1437 | + no_quant_tvs = tyCoVarsOfTypes no_quant
|
|
| 1436 | 1438 | |
| 1437 | 1439 | -- Step 2 of Note [decideAndPromoteTyVars]
|
| 1438 | 1440 | -- Apply the monomorphism restriction
|
| ... | ... | @@ -1448,19 +1450,19 @@ decideAndPromoteTyVars top_lvl rhs_tclvl infer_mode name_taus psigs wanted |
| 1448 | 1450 | ++ tau_tys ++ post_mr_quant)
|
| 1449 | 1451 | co_var_tvs = closeOverKinds co_vars
|
| 1450 | 1452 | |
| 1451 | - -- outer_tvs are mentioned in `wanted, and belong to some outer level.
|
|
| 1453 | + -- outer_tvs are mentioned in `wanted`, and belong to some outer level.
|
|
| 1452 | 1454 | -- We definitely can't quantify over them
|
| 1453 | 1455 | outer_tvs = outerLevelTyVars rhs_tclvl $
|
| 1454 | - tyCoVarsOfTypes can_quant `unionVarSet` tyCoVarsOfTypes no_quant
|
|
| 1456 | + can_quant_tvs `unionVarSet` no_quant_tvs
|
|
| 1455 | 1457 | |
| 1456 | 1458 | -- Step 3 of Note [decideAndPromoteTyVars], (a-c)
|
| 1457 | 1459 | -- Identify mono_tvs: the type variables that we must not quantify over
|
| 1458 | 1460 | mono_tvs_without_mr
|
| 1459 | 1461 | -- This does not work well (#26004)
|
| 1460 | 1462 | -- | is_top_level = outer_tvs
|
| 1461 | - | otherwise = outer_tvs -- (a)
|
|
| 1462 | - `unionVarSet` tyCoVarsOfTypes no_quant -- (b)
|
|
| 1463 | - `unionVarSet` co_var_tvs -- (c)
|
|
| 1463 | + | otherwise = outer_tvs -- (a)
|
|
| 1464 | + `unionVarSet` no_quant_tvs -- (b)
|
|
| 1465 | + `unionVarSet` co_var_tvs -- (c)
|
|
| 1464 | 1466 | |
| 1465 | 1467 | -- Step 3 of Note [decideAndPromoteTyVars], (d)
|
| 1466 | 1468 | mono_tvs_with_mr
|
| ... | ... | @@ -1792,11 +1792,11 @@ approximateWCX wc |
| 1792 | 1792 | = case classifyPredType (ctPred ct) of
|
| 1793 | 1793 | -- See the classification in Note [ApproximateWC]
|
| 1794 | 1794 | EqPred eq_rel ty1 ty2
|
| 1795 | - | not encl_eqs -- See Wrinkle (W1)
|
|
| 1796 | - , quantify_equality eq_rel ty1 ty2
|
|
| 1797 | - -> add_to_quant
|
|
| 1798 | - | otherwise
|
|
| 1799 | - -> acc -- add_to_no_quant ToDo: never return equalities under an equality
|
|
| 1795 | + | encl_eqs -> acc
|
|
| 1796 | + | quantify_equality eq_rel ty1 ty2 -> add_to_quant
|
|
| 1797 | + | otherwise -> add_to_no_quant
|
|
| 1798 | + -- encl_eqs: See Wrinkle (W1)
|
|
| 1799 | + -- ToDo: explain acc
|
|
| 1800 | 1800 | |
| 1801 | 1801 | ClassPred cls tys
|
| 1802 | 1802 | | Just {} <- isCallStackPred cls tys
|
| ... | ... | @@ -1852,7 +1852,7 @@ We proceed by classifying the constraint: |
| 1852 | 1852 | |
| 1853 | 1853 | Wrinkle (W1)
|
| 1854 | 1854 | When inferring most-general types (in simplifyInfer), we
|
| 1855 | - do *not* float an equality constraint if the implication binds
|
|
| 1855 | + do *not* quantify over equality constraint if the implication binds
|
|
| 1856 | 1856 | equality constraints, because that defeats the OutsideIn story.
|
| 1857 | 1857 | Consider data T a where { TInt :: T Int; MkT :: T a }
|
| 1858 | 1858 | f TInt = 3::Int
|