Marge Bot pushed to branch wip/marge_bot_batch_merge_job at Glasgow Haskell Compiler / GHC Commits: 4354218f by Adam Gundry at 2026-03-19T08:23:57-04:00 ghci: Mention active language edition in startup banner Per GHC proposal 632, this makes the GHCi startup banner include the active language edition, plus an indication of whether this was the default (as opposed to being explicitly selected via an option such as `-XGHC2024`). For example: ``` $ ghci GHCi, version 9.14.1: https://www.haskell.org/ghc/ :? for help Using default language edition: GHC2024 ghci> ``` Fixes #26037. - - - - - 04895566 by Sylvain Henry at 2026-03-19T08:24:26-04:00 Check that shift values are valid In GHC's codebase in non-DEBUG builds we silently substitute shiftL/R with unsafeShiftL/R for performance reasons. However we were not checking that the shift value was valid for unsafeShiftL/R, leading to wrong computations, but only in non-DEBUG builds. This patch adds the necessary checks and reports an error when a wrong shift value is passed. - - - - - 2b5a4872 by Sylvain Henry at 2026-03-19T08:24:26-04:00 Implement basic value range analysis (#25718) Perform basic value range analysis to try to determine at compile time the result of the application of some comparison primops (ltWord#, etc.). This subsumes the built-in rewrite rules used previously to check if one of the comparison argument was a bound (e.g. (x :: Word8) <= 255 is always True). Our analysis is more powerful and handles type conversions: e.g. word8ToWord x <= 255 is now detected as always True too. We also use value range analysis to filter unreachable alternatives in case-expressions. To support this, we had to allow case-expressions for primitive types to not have a DEFAULT alternative (as was assumed before and checked in Core lint). - - - - - 26e6a745 by sheaf at 2026-03-19T08:24:43-04:00 Improve incomplete record selector warnings This commit stops GHC from emitting spurious incomplete record selector warnings for bare selectors/projections such as .fld There are two places we currently emit incomplete record selector warnings: 1. In the desugarer, when we see a record selector or an occurrence of 'getField'. Here, we can use pattern matching information to ensure we don't give false positives. 2. In the typechecker, which might sometimes give false positives but can emit warnings in cases that the pattern match checker would otherwise miss. This is explained in Note [Detecting incomplete record selectors] in GHC.HsToCore.Pmc. Now, we obviously don't want to emit the same error twice, and generally we prefer (1), as those messages contain fewer false positives. So we suppress (2) when we are sure we are going to emit (1); the logic for doing so is in GHC.Tc.Instance.Class.warnIncompleteRecSel, and works by looking at the CtOrigin. Now, the issue was that this logic handled explicit record selectors as well as overloaded record field selectors such as "x.r" (which turns into a simple GetFieldOrigin CtOrigin), but it didn't properly handle record projectors like ".fld" or ".fld1.fld2" (which result in other CtOrigins such as 'RecordFieldProjectionOrigin'). To solve this problem, we re-use the 'isHasFieldOrigin' introduced in fbdc623a (slightly adjusted). On the way, we also had to update the desugarer with special handling for the 'ExpandedThingTc' case in 'ds_app', to make sure that 'ds_app_var' sees all the type arguments to 'getField' in order for it to indeed emit warnings like in (1). Fixes #26686 - - - - - 6ead1bbf by Cheng Shao at 2026-03-19T08:24:45-04:00 rts: opportunistically grow the MutableByteArray# in-place in resizeMutableByteArray# Following !15234, this patch improves `resizeMutableByteArray#` memory efficiency by growing the `MutableByteArray#` in-place if possible, addressing an old todo comment here. Also adds a new test case `resizeMutableByteArrayInPlace` that stresses this behavior. - - - - - 4b1ff14e by Zubin Duggal at 2026-03-19T08:24:46-04:00 compiler/ffi: Collapse void pointer chains in capi wrappers New gcc/clang treat -Wincompatible-pointer-types as an error by default. Since C only allows implicit conversion from void*, not void**, capi wrappers for functions taking e.g. abstract** would fail to compile when the Haskell type Ptr (Ptr Abstract) was naively translated to void**. Collapse nested void pointers to a single void* when the pointee type has no known C representation. Fixes #26852 - - - - - c0b5e874 by Teo Camarasu at 2026-03-19T08:24:47-04:00 ghc-internal: Float Generics to near top of module graph We remove GHC.Internal.Generics from the critical path of the `ghc-internal` module graph. GHC.Internal.Generics used to be in the middle of the module graph, but now it is nearer the top (built later). This change thins out the module graph and allows us to get rid of the ByteOrder hs-boot file. We implement this by moving Generics instances from the module where the datatype is defined to the GHC.Internal.Generics module. This trades off increasing the compiled size of GHC.Internal.Generics with reducing the dependency footprint of datatype modules. Not all instances are moved to GHC.Internal.Generics. For instance, `GHC.Internal.Control.Monad.Fix` keeps its instance as it is one of the very last modules compiled in `ghc-internal` and so inverting the relationship here would risk adding GHC.Internal.Generics back onto the critical path. We also don't change modules that are re-exported from the `template-haskell` or `ghc-heap`. This is done to make it easy to eventually move `Generics` to `base` once something like #26657 is implemented. Resolves #26930 Metric Decrease: T21839c - - - - - 511afa7e by Luite Stegeman at 2026-03-19T08:25:01-04:00 Move some functions related to pointer tagging to a separate module - - - - - 316ec094 by Luite Stegeman at 2026-03-19T08:25:01-04:00 Branchless unpacking for enumeration types Change unpacking for enumeration types to go to Word8#/Word16#/Word# directly instead of going through an intermediate unboxed sum. This allows us to do a branchless conversion using DataToTag and TagToEnum. Fixes #26970 - - - - - 14aad09b by Luite Stegeman at 2026-03-19T08:25:06-04:00 bytecode: Carefully SLIDE off the end of a stack chunk The SLIDE bytecode instruction was not checking for stack chunk boundaries and could corrupt the stack underflow frame, leading to crashes. We add a check to use safe writes if we cross the chunk boundary and also handle stack underflow if Sp is advanced past the underflow frame. fix #27001 - - - - - e1e03d27 by Cheng Shao at 2026-03-19T08:25:07-04:00 ghci: serialize BCOByteArray buffer directly when possible This patch changes the `Binary` instances of `BCOByteArray` to directly serialize the underlying buffer when possible, while also taking into account the issue of host-dependent `Word` width. See added comments and amended `Note [BCOByteArray serialization]` for detailed explanation. Closes #27020. - - - - - eaa9beaa by Matthew Pickering at 2026-03-19T08:25:15-04:00 Use OsPath rather than FilePath in Downsweep cache This gets us one step closure to uniformly using `OsPath` in the compiler. - - - - - 93de2b51 by Cheng Shao at 2026-03-19T08:25:17-04:00 hadrian: fix ghc-in-ghci flavour stage0 shared libraries This patch fixes missing stage0 shared libraries in hadrian ghc-in-ghci flavour, which was accidentally dropped in 669d09f950a6e88b903d9fd8a7571531774d4d5d and resulted in a regression in HLS support on linux/macos. Fixes #27057. - - - - - fea35103 by Cheng Shao at 2026-03-19T08:25:17-04:00 ghc-internal: fix unused imports again Fixes #27059. - - - - - 54456a53 by Sylvain Henry at 2026-03-19T08:25:23-04:00 JS: install rts/Types.h header file (#27033) It was an omission, making HsFFI.h not usable with GHC using the JS backend. - - - - - b9918009 by Cheng Shao at 2026-03-19T08:25:25-04:00 hadrian: don't compile RTS with -Winline This patch removes `-Winline` from cflags when compiling the RTS, given that: 1. It generates a huge pile of spam and hurts developer experience 2. Whether inlining happens is highly dependent on toolchains, flavours, etc, and it's not really an issue to fix if inlining doesn't happen; it's a hint to the C compiler anyway. Fixes #27060. - - - - - f55d53f3 by Cheng Shao at 2026-03-19T08:25:25-04:00 hadrian: compile libffi-clib with -Wno-deprecated-declarations This patch adds `-Wno-deprecated-declarations` to cflags of `libffi-clib`, given that it produces noise at compile-time that aren't really our issue to fix anyway, it's from vendored libffi source code. - - - - - 93 changed files: - compiler/GHC/Cmm/Utils.hs - compiler/GHC/Core.hs - compiler/GHC/Core/Lint.hs - compiler/GHC/Core/Opt/ConstantFold.hs - + compiler/GHC/Core/Opt/Range.hs - compiler/GHC/Core/Opt/Simplify/Iteration.hs - compiler/GHC/Driver/Downsweep.hs - compiler/GHC/HsToCore/Expr.hs - compiler/GHC/HsToCore/Foreign/C.hs - compiler/GHC/HsToCore/Pmc.hs - + compiler/GHC/Platform/Tag.hs - compiler/GHC/Prelude/Basic.hs - compiler/GHC/StgToCmm/Closure.hs - compiler/GHC/StgToCmm/Expr.hs - compiler/GHC/StgToCmm/Utils.hs - compiler/GHC/Tc/Errors.hs - compiler/GHC/Tc/Instance/Class.hs - compiler/GHC/Tc/TyCl/Build.hs - compiler/GHC/Tc/Types/Origin.hs - compiler/GHC/Types/Id/Make.hs - compiler/GHC/Types/RepType.hs - compiler/ghc.cabal.in - ghc/GHCi/UI.hs - ghc/Main.hs - hadrian/src/Settings/Flavours/GhcInGhci.hs - hadrian/src/Settings/Packages.hs - libraries/ghc-internal/src/GHC/Internal/ByteOrder.hs - − libraries/ghc-internal/src/GHC/Internal/ByteOrder.hs-boot - libraries/ghc-internal/src/GHC/Internal/Char.hs - libraries/ghc-internal/src/GHC/Internal/Conc/IO.hs - libraries/ghc-internal/src/GHC/Internal/Data/Foldable.hs - libraries/ghc-internal/src/GHC/Internal/Data/Functor/Const.hs - libraries/ghc-internal/src/GHC/Internal/Data/Functor/Identity.hs - libraries/ghc-internal/src/GHC/Internal/Data/Monoid.hs - libraries/ghc-internal/src/GHC/Internal/Data/Semigroup/Internal.hs - libraries/ghc-internal/src/GHC/Internal/Data/Traversable.hs - libraries/ghc-internal/src/GHC/Internal/Data/Version.hs - libraries/ghc-internal/src/GHC/Internal/Event/Control.hs - libraries/ghc-internal/src/GHC/Internal/Functor/ZipList.hs - libraries/ghc-internal/src/GHC/Internal/Generics.hs - libraries/ghc-internal/src/GHC/Internal/IO/Exception.hs - libraries/ghc-internal/src/GHC/Internal/RTS/Flags.hsc - libraries/ghc-internal/src/GHC/Internal/RTS/Flags/Test.hsc - libraries/ghc-internal/src/GHC/Internal/Read.hs - libraries/ghc-internal/src/GHC/Internal/System/Posix/Internals.hs - libraries/ghc-internal/src/GHC/Internal/TopHandler.hs - libraries/ghc-internal/src/GHC/Internal/Unicode/Bits.hs - libraries/ghci/GHCi/ResolvedBCO.hs - rts/Interpreter.c - rts/PrimOps.cmm - rts/rts.cabal - + testsuite/tests/bytecode/T27001.hs - + testsuite/tests/bytecode/T27001.stdout - testsuite/tests/bytecode/all.T - testsuite/tests/count-deps/CountDepsAst.stdout - testsuite/tests/count-deps/CountDepsParser.stdout - + testsuite/tests/ffi/should_compile/T26852.h - + testsuite/tests/ffi/should_compile/T26852.hs - + testsuite/tests/ffi/should_compile/T26852.stderr - testsuite/tests/ffi/should_compile/all.T - testsuite/tests/ghci/scripts/ListTuplePunsPpr.stdout - testsuite/tests/ghci/scripts/T10963.stderr - testsuite/tests/ghci/scripts/ghci064.stdout - testsuite/tests/ghci/should_run/BinaryArray.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/interface-stability/base-exports.stdout-ws-32 - + testsuite/tests/javascript/js-c-sources/T27033.hs - + testsuite/tests/javascript/js-c-sources/T27033.stdout - + testsuite/tests/javascript/js-c-sources/T27033_c.c - + testsuite/tests/javascript/js-c-sources/T27033_js.js - testsuite/tests/javascript/js-c-sources/all.T - + testsuite/tests/overloadedrecflds/should_compile/T26686.hs - + testsuite/tests/overloadedrecflds/should_compile/T26686.stderr - testsuite/tests/overloadedrecflds/should_compile/all.T - testsuite/tests/rts/all.T - + testsuite/tests/rts/resizeMutableByteArrayInPlace.hs - + testsuite/tests/simplCore/should_compile/T19166.hs - + testsuite/tests/simplCore/should_compile/T19166.stderr - + testsuite/tests/simplCore/should_compile/T25718.hs - + testsuite/tests/simplCore/should_compile/T25718.stderr - + testsuite/tests/simplCore/should_compile/T25718a.hs - + testsuite/tests/simplCore/should_compile/T25718a.stderr - + testsuite/tests/simplCore/should_compile/T25718b.hs - + testsuite/tests/simplCore/should_compile/T25718b.stderr - + testsuite/tests/simplCore/should_compile/T25718c.hs - + testsuite/tests/simplCore/should_compile/T25718c.stderr-ws-32 - + testsuite/tests/simplCore/should_compile/T25718c.stderr-ws-64 - testsuite/tests/simplCore/should_compile/all.T - testsuite/tests/simplStg/should_run/all.T - + testsuite/tests/simplStg/should_run/unpack_enum.hs - + testsuite/tests/simplStg/should_run/unpack_enum.stdout The diff was not included because it is too large. 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