Marge Bot pushed to branch wip/marge_bot_batch_merge_job at Glasgow Haskell Compiler / GHC Commits: f8cfb1a5 by Hécate Kleidukos at 2026-10-04T19:36:39+02:00 [CLC 341] Strict variants of mutable types This commit is the implementation of CLC Proposal 341 https://github.com/haskell/core-libraries-committee/issues/341 - - - - - 485dea82 by Rodrigo Mesquita at 2026-10-05T03:32:22-04:00 ttg: HsModuleName in the AST, ModuleName in GHC This commit makes the AST fully independent from GHC by parsing a "module name" as an `HsModuleName (= HText)` rather than constructing an `ModuleName (= FastString)` straight away. In the GHC side, everything remains as a `ModuleName`. We turn AST `HsModuleName`s into fast strings with the cheap `mkFastStringShortText` when we process the AST for manipulation within the compiler. There are no performance regressions introduced by this approach. This is the final piece of #21592 Alternative plans were discussed in gitlab.haskell.org/ghc/ghc/-/merge_requests/16546#note_694647, but the Simon suggested one won in simplicity and performance when compared against my attempt at implementing my original plan of having a family `ModuleNameP`. - - - - - 102 changed files: - + changelog.d/clc-341-strict-mutable-data-types - compiler/GHC.hs - compiler/GHC/Builtin/Modules.hs - compiler/GHC/ByteCode/Asm.hs - compiler/GHC/ByteCode/Show.hs - compiler/GHC/Core/DataCon.hs - compiler/GHC/Core/Opt/CallerCC/Types.hs - compiler/GHC/Driver/Backpack.hs - compiler/GHC/Driver/Main/Compile.hs - compiler/GHC/Driver/Pipeline.hs-boot - compiler/GHC/Driver/Pipeline/Execute.hs - compiler/GHC/Driver/Pipeline/Phases.hs - compiler/GHC/Hs/Doc.hs - compiler/GHC/Hs/Dump.hs - compiler/GHC/Hs/Expr.hs - compiler/GHC/Hs/ImpExp.hs - compiler/GHC/Hs/Lit.hs - compiler/GHC/HsToCore/Docs.hs - compiler/GHC/HsToCore/Quote.hs - compiler/GHC/Iface/Errors/Types.hs - compiler/GHC/Iface/Ext/Ast.hs - compiler/GHC/Iface/Ext/Debug.hs - compiler/GHC/Iface/Ext/Types.hs - compiler/GHC/Parser.y - compiler/GHC/Parser/Errors/Types.hs - compiler/GHC/Parser/Header.hs - compiler/GHC/Parser/Lexer.x - compiler/GHC/Parser/PostProcess.hs - compiler/GHC/Parser/String.hs - compiler/GHC/Rename/Env.hs - compiler/GHC/Rename/Names.hs - compiler/GHC/Rename/Unbound.hs - compiler/GHC/StgToJS/Linker/Linker.hs - compiler/GHC/Tc/Deriv/Generics.hs - compiler/GHC/Tc/Errors/Types.hs - compiler/GHC/Tc/Gen/Export.hs - compiler/GHC/Tc/Module.hs - compiler/GHC/Tc/Types.hs - compiler/GHC/Tc/Types/ErrCtxt.hs - compiler/GHC/ThToHs.hs - compiler/GHC/Types/Unique.hs - compiler/GHC/Types/UnresolvedImport.hs - compiler/GHC/Unit/Home.hs - compiler/GHC/Unit/Module.hs - compiler/GHC/Unit/Module/Env.hs - + compiler/GHC/Unit/Module/Name.hs - compiler/GHC/Unit/Parser.hs - compiler/GHC/Unit/Types.hs - compiler/GHC/Unit/Types.hs-boot - compiler/GHC/Utils/Binary.hs - compiler/GHC/Utils/Outputable.hs - compiler/Language/Haskell/Syntax.hs - compiler/Language/Haskell/Syntax/Expr.hs - compiler/Language/Haskell/Syntax/ImpExp.hs - compiler/Language/Haskell/Syntax/Lit.hs - compiler/Language/Haskell/Syntax/Module/Name.hs - compiler/Language/Haskell/Syntax/Text.hs - compiler/ghc.cabal.in - ghc/GHCi/UI.hs - ghc/GHCi/UI/Info.hs - libraries/base/base.cabal.in - libraries/base/changelog.md - libraries/base/src/Control/Concurrent/Chan.hs - + libraries/base/src/Control/Concurrent/Chan/Strict.hs - libraries/base/src/Control/Concurrent/MVar.hs - + libraries/base/src/Control/Concurrent/MVar/Strict.hs - libraries/base/src/Data/IORef.hs - + libraries/base/src/Data/IORef/Strict.hs - linters/lint-codes/LintCodes/Static.hs - testsuite/tests/count-deps/CountDepsAst.stdout - testsuite/tests/count-deps/CountDepsParser.stdout - testsuite/tests/ghc-api/downsweep/IncrementalDownsweep.hs - testsuite/tests/ghc-api/exactprint/T22919.stderr - testsuite/tests/ghc-api/exactprint/Test20239.stderr - testsuite/tests/ghc-api/exactprint/ZeroWidthSemi.stderr - testsuite/tests/haddock/should_compile_flag_haddock/T17544.stderr - testsuite/tests/haddock/should_compile_flag_haddock/T17544_kw.stderr - testsuite/tests/haddock/should_compile_flag_haddock/T24221.stderr - testsuite/tests/hiefile/should_run/T24544.hs - testsuite/tests/interface-stability/base-exports.stdout - testsuite/tests/interface-stability/base-exports.stdout-javascript-unknown-ghcjs - testsuite/tests/interface-stability/base-exports.stdout-mingw32 - testsuite/tests/module/mod185.stderr - testsuite/tests/parser/should_compile/DumpParsedAst.stderr - testsuite/tests/parser/should_compile/DumpParsedAstComments.stderr - testsuite/tests/parser/should_compile/DumpRenamedAst.stderr - testsuite/tests/parser/should_compile/DumpSemis.stderr - testsuite/tests/parser/should_compile/KindSigs.stderr - testsuite/tests/parser/should_compile/T14189.stderr - testsuite/tests/parser/should_compile/T15323.stderr - testsuite/tests/parser/should_compile/T20452.stderr - testsuite/tests/parser/should_compile/T20718.stderr - testsuite/tests/parser/should_compile/T20718b.stderr - testsuite/tests/parser/should_compile/T20846.stderr - testsuite/tests/parser/should_compile/T23315/T23315.stderr - testsuite/tests/printer/AnnotationNoListTuplePuns.stdout - testsuite/tests/printer/T18791.stderr - testsuite/tests/printer/Test20297.stdout - testsuite/tests/printer/Test24533.stdout - testsuite/tests/profiling/should_run/caller-cc/CallerCcParser.hs - utils/check-exact/ExactPrint.hs - utils/haddock/haddock-api/src/Haddock/Backends/Hyperlinker/Renderer.hs The diff was not included because it is too large. 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