Simon Peyton Jones pushed to branch wip/T26868 at Glasgow Haskell Compiler / GHC Commits: 9831385b by Vladislav Zavialov at 2026-03-27T17:22:30-04:00 Infix holes in types (#11107) This patch introduces several improvements that follow naturally from refactoring HsOpTy to represent the operator as an HsType, aligning it with the approach taken by OpApp and HsExpr. User-facing changes: 1. Infix holes (t1 `_` t2) are now permitted in types, following the precedent set by term-level expressions. Test case: T11107 2. Error messages for illegal promotion ticks are now reported at more precise source locations. Test case: T17865 Internal changes: * The definition of HsOpTy now mirrors that of OpApp: | HsOpTy (XOpTy p) (LHsType p) (LHsType p) (LHsType p) | OpApp (XOpApp p) (LHsExpr p) (LHsExpr p) (LHsExpr p) This moves us one step closer to unifying HsType and HsExpr. * Ignoring locations, the old pattern match (HsOpTy x prom lhs op rhs) is now written as (HsOpTy x lhs (HsTyVar x' prom op) rhs) but we also handle (HsOpTy x lhs (HsWildCardTy x') rhs) Constructors other than HsTyVar and HsWildCardTy never appear in the operator position. * The various definitions across the compiler have been updated to work with the new representation, drawing inspiration from the term-level pipeline where appropriate. For example, ppr_infix_ty <=> ppr_infix_expr get_tyop <=> get_op lookupTypeFixityRn <=> lookupExprFixityRn (the latter is factored out from rnExpr) Test cases: T11107 T17865 - - - - - 5b6757d7 by mangoiv at 2026-03-27T17:23:19-04:00 ci: build i386 non-validate for deb12 This is a small fix that will unlock ghcup metadata to run, i386 debian 12 was missing as a job. - - - - - 196cc1fa by Simon Peyton Jones at 2026-03-30T12:45:45+01:00 Add Invariant (NoTypeShadowing) to Core This commit addresses #26868, by adding a new invariant (NoTypeShadowing) to Core. See Note [No type-shadowing in Core] in GHC.Core - - - - - 56ab30db by Simon Peyton Jones at 2026-03-30T12:51:31+01:00 Major refactor of free-variable functions For some time we have had two free-variable mechanims for types: * The "FV" mechanism, embodied in GHC.Utils.FV, which worked OK, but was fragile where eta-expansion was concerned. * The TyCoFolder mechanism, using a one-shot EndoOS accumulator I finally got tired of this and refactored the whole thing, thereby addressing #27080. Now we have * `GHC.Types.Var.FV`, which has a composable free-variable result type, very much in the spirit of the old `FV`, but much more robust. (It uses the "one shot trick".) * GHC.Core.TyCo.FVs now has just one technology for free variables. All this led to a lot of renaming. There are couple of error-message changes. The change in T18451 makes an already-poor error message even more mysterious. But it really needs a separate look. - - - - - 112 changed files: - .gitlab/generate-ci/gen_ci.hs - .gitlab/jobs.yaml - .gitlab/rel_eng/mk-ghcup-metadata/mk_ghcup_metadata.py - compiler/GHC/Core.hs - compiler/GHC/Core/Coercion.hs - compiler/GHC/Core/FVs.hs - compiler/GHC/Core/Lint.hs - compiler/GHC/Core/Opt/DmdAnal.hs - compiler/GHC/Core/Opt/SetLevels.hs - compiler/GHC/Core/Opt/Specialise.hs - compiler/GHC/Core/Rules.hs - compiler/GHC/Core/Subst.hs - compiler/GHC/Core/TyCo/FVs.hs - compiler/GHC/Core/TyCo/Rep.hs - compiler/GHC/Core/TyCo/Subst.hs - compiler/GHC/Core/Type.hs - compiler/GHC/Core/Unify.hs - compiler/GHC/Hs/Type.hs - compiler/GHC/Hs/Utils.hs - compiler/GHC/HsToCore/Binds.hs - compiler/GHC/HsToCore/Quote.hs - compiler/GHC/HsToCore/Ticks.hs - compiler/GHC/Iface/Ext/Ast.hs - compiler/GHC/Iface/Syntax.hs - compiler/GHC/Parser.y - compiler/GHC/Parser/PostProcess.hs - compiler/GHC/Rename/Bind.hs - compiler/GHC/Rename/Env.hs - compiler/GHC/Rename/Expr.hs - compiler/GHC/Rename/Expr.hs-boot - compiler/GHC/Rename/Fixity.hs - compiler/GHC/Rename/HsType.hs - compiler/GHC/Rename/Lit.hs - compiler/GHC/Rename/Module.hs - compiler/GHC/Rename/Pat.hs - compiler/GHC/Rename/Splice.hs - compiler/GHC/Rename/Splice.hs-boot - compiler/GHC/Rename/Utils.hs - compiler/GHC/Tc/Deriv.hs - compiler/GHC/Tc/Errors.hs - compiler/GHC/Tc/Errors/Hole.hs - compiler/GHC/Tc/Gen/App.hs - compiler/GHC/Tc/Gen/HsType.hs - compiler/GHC/Tc/Gen/Pat.hs - compiler/GHC/Tc/Gen/Sig.hs - compiler/GHC/Tc/Instance/Family.hs - compiler/GHC/Tc/Instance/FunDeps.hs - compiler/GHC/Tc/Module.hs - compiler/GHC/Tc/Solver/Solve.hs - compiler/GHC/Tc/TyCl/Utils.hs - compiler/GHC/Tc/Types/Constraint.hs - compiler/GHC/Tc/Types/Evidence.hs - compiler/GHC/Tc/Utils/TcMType.hs - compiler/GHC/Tc/Utils/TcType.hs - compiler/GHC/Tc/Utils/Unify.hs - compiler/GHC/Tc/Validity.hs - compiler/GHC/ThToHs.hs - compiler/GHC/Types/Name/Set.hs - + compiler/GHC/Types/Var/FV.hs - compiler/GHC/Types/Var/Set.hs - compiler/GHC/Utils/EndoOS.hs - − compiler/GHC/Utils/FV.hs - compiler/Language/Haskell/Syntax/Type.hs - compiler/ghc.cabal.in - testsuite/tests/count-deps/CountDepsAst.stdout - testsuite/tests/count-deps/CountDepsParser.stdout - testsuite/tests/cpranal/should_compile/T18401.stderr - testsuite/tests/deriving/should_fail/deriving-via-fail4.stderr - testsuite/tests/indexed-types/should_fail/T2693.stderr - testsuite/tests/interface-stability/base-exports.stdout - testsuite/tests/parser/should_compile/DumpParsedAst.stderr - testsuite/tests/parser/should_compile/DumpRenamedAst.stderr - testsuite/tests/parser/should_fail/T17865.stderr - testsuite/tests/partial-sigs/should_compile/T10403.stderr - + testsuite/tests/partial-sigs/should_compile/T11107.hs - + testsuite/tests/partial-sigs/should_compile/T11107.stderr - testsuite/tests/partial-sigs/should_compile/T12844.stderr - testsuite/tests/partial-sigs/should_compile/T15039a.stderr - testsuite/tests/partial-sigs/should_compile/T15039b.stderr - testsuite/tests/partial-sigs/should_compile/T15039c.stderr - testsuite/tests/partial-sigs/should_compile/T15039d.stderr - testsuite/tests/partial-sigs/should_compile/all.T - testsuite/tests/partial-sigs/should_fail/T10999.stderr - testsuite/tests/partial-sigs/should_fail/T12634.stderr - testsuite/tests/polykinds/T15789.stderr - testsuite/tests/polykinds/T18451.stderr - testsuite/tests/polykinds/T7328.stderr - testsuite/tests/simplCore/should_compile/DsSpecPragmas.stderr - testsuite/tests/simplCore/should_compile/T24229a.stderr - testsuite/tests/simplCore/should_compile/T24229b.stderr - testsuite/tests/simplCore/should_compile/T24359a.stderr - testsuite/tests/simplCore/should_compile/T26116.stderr - testsuite/tests/simplCore/should_compile/T4908.stderr - testsuite/tests/simplCore/should_compile/spec-inline.stderr - testsuite/tests/typecheck/no_skolem_info/T20063.stderr - testsuite/tests/typecheck/should_compile/T25180.stderr - testsuite/tests/typecheck/should_compile/free_monad_hole_fits.stderr - testsuite/tests/typecheck/should_fail/T10971d.stderr - testsuite/tests/typecheck/should_fail/T12589.stderr - testsuite/tests/typecheck/should_fail/T13311.stderr - testsuite/tests/typecheck/should_fail/T17773.stderr - testsuite/tests/typecheck/should_fail/T2846b.stderr - testsuite/tests/typecheck/should_fail/T7851.stderr - testsuite/tests/typecheck/should_fail/T8603.stderr - utils/check-exact/ExactPrint.hs - utils/haddock/haddock-api/src/Haddock/Backends/Hoogle.hs - utils/haddock/haddock-api/src/Haddock/Backends/LaTeX.hs - utils/haddock/haddock-api/src/Haddock/Backends/Xhtml/Decl.hs - utils/haddock/haddock-api/src/Haddock/Convert.hs - utils/haddock/haddock-api/src/Haddock/GhcUtils.hs - utils/haddock/haddock-api/src/Haddock/Interface/Rename.hs - utils/haddock/haddock-api/src/Haddock/Interface/RenameType.hs The diff was not included because it is too large. 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