Brandon Chinn pushed to branch wip/interpolated-strings-refactor at Glasgow Haskell Compiler / GHC

Commits:

• 4e9297ea
  by Simon Jakobi at 2026-09-11T08:32:45-04:00

  ci: Actually pass --ignore-perf-failures to the testsuite driver
  
  684c0018d9 changed the IGNORE_PERF_FAILURES handling to append to
  RUNTEST_ARGS with bash array syntax, but the three use sites still
  expand RUNTEST_ARGS as a scalar, which yields only the first array
  element. The appended flag was therefore dropped in every job, so
  perf improvements kept failing Marge Bot batches and master pipelines,
  contrary to #19562.
  
  Append as a string instead, matching the existing --force-colors
  append in test_hadrian.
  
  Fixes #27563.
  
  Assisted-by: Claude Fable 5.1
  

• 4f78dfdf
  by Simon Jakobi at 2026-09-11T08:33:24-04:00

  testsuite: Give T26537 a 1.5x compile timeout
  
  Its -fregs-graph compile step tends to time out in unoptimized builds
  (#27188, #27776).
  
  Assisted-by: Claude Fable 5.1
  

• 130286e3
  by Alan Zimmerman at 2026-09-11T08:34:08-04:00

  EPA: Remove ListBanana / ListParens from AnnListBrackets
  
  This is a step towards making AnnList only represent
  lists of items which can have either braces or layout.
  

• a9827d13
  by Simon Jakobi at 2026-09-11T18:53:32-04:00

  Reject ~, UNPACK and multiplicity annotations on type data fields
  
  Only `!` was rejected so far. `~`, UNPACK and multiplicity annotations
  were silently accepted. None of them make sense at the type level, so
  restriction (R3) of Note [Type data declarations] now covers all of
  them.
  
  Fixes #27732.
  
  Assisted-by: Claude Fable 5.1
  

• c71d5e23
  by Alan Zimmerman at 2026-09-11T18:54:11-04:00

  EPA: Add a Note for the exact print main loop
  

• 2f525215
  by Brandon Chinn at 2026-09-11T19:38:46-07:00

  Reorganize processChars functions
  
  Move functions around, no code changes
  

• 74fadf63
  by Brandon Chinn at 2026-09-11T19:38:46-07:00

  Always use processCharsSingle to get StringLexError
  

• 3783dc88
  by Brandon Chinn at 2026-09-11T19:38:46-07:00

  Add pprHsStringMulti, unify string ppr functions
  

• d8b024b3
  by Brandon Chinn at 2026-09-11T23:52:58-07:00

  Break out Language.Haskell.Syntax.StringMeta
  

40 changed files:

• .gitlab/ci.sh
• + changelog.d/27732
• compiler/GHC/Hs/Expr.hs
• compiler/GHC/Hs/Pat.hs
• compiler/GHC/Parser.y
• compiler/GHC/Parser/Annotation.hs
• compiler/GHC/Parser/Lexer.x
• compiler/GHC/Parser/PostProcess.hs
• compiler/GHC/Parser/String.hs
• compiler/GHC/Rename/Module.hs
• compiler/GHC/Tc/Errors/Types.hs
• compiler/GHC/Utils/Outputable.hs
• + compiler/Language/Haskell/Syntax/StringMeta.hs
• compiler/ghc.cabal.in
• docs/users_guide/exts/type_data.rst
• libraries/base/src/GHC/Show.hs
• libraries/ghc-internal/src/GHC/Internal/Show.hs
• testsuite/tests/codeGen/should_run/all.T
• testsuite/tests/count-deps/CountDepsParser.stdout
• testsuite/tests/ghc-api/T25121_status.stdout
• 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/type-data/should_fail/T27732a.hs
• + testsuite/tests/type-data/should_fail/T27732a.stderr
• + testsuite/tests/type-data/should_fail/T27732b.hs
• + testsuite/tests/type-data/should_fail/T27732b.stderr
• + testsuite/tests/type-data/should_fail/T27732c.hs
• + testsuite/tests/type-data/should_fail/T27732c.stderr
• + testsuite/tests/type-data/should_fail/T27732d.hs
• + testsuite/tests/type-data/should_fail/T27732d.stderr
• + testsuite/tests/type-data/should_fail/T27732e.hs
• + testsuite/tests/type-data/should_fail/T27732e.stderr
• + testsuite/tests/type-data/should_fail/T27732f.hs
• + testsuite/tests/type-data/should_fail/T27732f.stderr
• testsuite/tests/type-data/should_fail/TDStrictnessGADT.stderr
• testsuite/tests/type-data/should_fail/TDStrictnessH98.stderr
• testsuite/tests/type-data/should_fail/all.T
• utils/check-exact/ExactPrint.hs
• utils/check-exact/Utils.hs

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