Marge Bot pushed to branch wip/marge_bot_batch_merge_job at Glasgow Haskell Compiler / GHC

Commits:

• 7c96a1ac
  by Sylvain Henry at 2026-07-29T01:27:43-04:00

  RTS: correctly mark slop bytes when shrinking large arrays (#19048)
  
  Correctly mark slop bytes even when profiling is off so that heap census
  doesn't traverse garbage-collected closures.
  

• 5e409971
  by Simon Jakobi at 2026-07-29T01:27:46-04:00

  Add -XLazyFieldAnnotations (GHC proposal 752)
  
  Unbundle the prefix `~` lazy field annotation syntax from StrictData. The
  new LazyFieldAnnotations extension controls whether `~` is accepted on
  constructor fields. StrictData (and Strict, transitively) imply the new
  extension.
  
  See https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0752-lazy-field-annotations.rst.
  
  Closes #24455.
  
  Assisted-by: Claude Opus 4.8
  

• 40fe4203
  by Simon Jakobi at 2026-07-29T01:27:47-04:00

  testsuite: Relax T24471 residency tolerance
  
  T24471 peak residency fluctuates enough on i386 to cause spurious
  failures. Use the standard residency tolerance while retaining the
  existing allocation threshold.
  
  See https://gitlab.haskell.org/ghc/ghc/-/work_items/24471#note_682303.
  
  Assisted-by: gpt-5.6-sol via Codex CLI
  

• 33758a3d
  by Cheng Shao at 2026-07-29T01:27:49-04:00

  compiler: fix missing top-level procedure labels in cmm dumps
  
  This patch fixes missing top-level procedure labels in some
  intermediate Cmm pass dumps. Fixes #27553.
  
  Co-authored-by: Codex <codex@openai.com>
  

• dbc4c438
  by sheaf at 2026-07-29T01:28:07-04:00

  Add some type-family-heavy performance tests
  
  FamAppCachePerf stress-tests the performance of lookups in the
  type family application cache.
  
  T27336 is a minimisation extracted from the reported reproducer.
  
  SimplCastPerf is a measure of coercion growth due to the simplifier
  calling mkTransCo without re-optimising the result.
  

41 changed files:

• + changelog.d/fix-cmm-dump-labels
• + changelog.d/fix-heap-census-large-arrays-19048
• + changelog.d/lazy-field-annotations
• compiler/GHC/Cmm/Pipeline.hs
• compiler/GHC/Driver/Flags.hs
• compiler/GHC/Tc/Errors/Ppr.hs
• compiler/GHC/Tc/Errors/Types.hs
• compiler/GHC/Tc/TyCl.hs
• docs/users_guide/exts/strict.rst
• libraries/ghc-internal/src/GHC/Internal/LanguageExtensions.hs
• rts/Apply.cmm
• rts/ZeroSlop.c → rts/MarkSlop.c
• rts/PrimOps.cmm
• rts/Printer.c
• rts/ProfHeap.c
• rts/RtsFlags.c
• rts/ThreadPaused.c
• rts/include/Cmm.h
• rts/include/rts/storage/ClosureMacros.h
• rts/rts.cabal
• rts/sm/NonMovingMark.c
• rts/sm/Sanity.c
• rts/sm/Storage.c
• + testsuite/tests/deSugar/should_run/LazyFieldAnnotationsSemantics.hs
• + testsuite/tests/deSugar/should_run/LazyFieldAnnotationsSemantics.stdout
• testsuite/tests/deSugar/should_run/all.T
• testsuite/tests/driver/T4437.hs
• testsuite/tests/interface-stability/template-haskell-exports.stdout
• + testsuite/tests/perf/compiler/FamAppCachePerf.hs
• + testsuite/tests/perf/compiler/SimplCastPerf.hs
• + testsuite/tests/perf/compiler/T27336.hs
• testsuite/tests/perf/compiler/all.T
• + testsuite/tests/rts/T19048.hs
• + testsuite/tests/rts/T19048.stdout
• testsuite/tests/rts/all.T
• + testsuite/tests/typecheck/should_compile/LazyFieldAnnotations.hs
• testsuite/tests/typecheck/should_compile/all.T
• testsuite/tests/typecheck/should_fail/LazyFieldsDisabled.stderr
• + testsuite/tests/typecheck/should_fail/LazyFieldsDisabledStrictData.hs
• + testsuite/tests/typecheck/should_fail/LazyFieldsDisabledStrictData.stderr
• testsuite/tests/typecheck/should_fail/all.T

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