[all-commits] [llvm/llvm-project] 381a64: [Clang] Add warnings when mixing different charN_t...

[cor3ntin via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 381a649fb991eadb0c594de2d8b6166fcc11345a
      https://github.com/llvm/llvm-project/commit/381a649fb991eadb0c594de2d8b6166fcc11345a
  Author: cor3ntin <corentinjabot at gmail.com>
  Date:   2025-05-15 (Thu, 15 May 2025)

  Changed paths:
    M clang/docs/ReleaseNotes.rst
    M clang/include/clang/AST/ASTDiagnostic.h
    M clang/include/clang/AST/Type.h
    M clang/include/clang/Basic/DiagnosticGroups.td
    M clang/include/clang/Basic/DiagnosticSemaKinds.td
    M clang/lib/AST/ASTDiagnostic.cpp
    M clang/lib/AST/Type.cpp
    M clang/lib/Sema/SemaChecking.cpp
    M clang/lib/Sema/SemaExpr.cpp
    A clang/test/SemaCXX/warn-implicit-unicode-conversions.cpp
    M libcxx/include/print
    M libcxx/test/std/algorithms/alg.nonmodifying/alg.equal/equal.pass.cpp
    M libcxx/test/std/algorithms/alg.nonmodifying/alg.find/find.pass.cpp
    M libcxx/test/std/localization/codecvt_unicode.pass.cpp
    M libcxx/test/std/localization/locale.categories/category.ctype/locale.codecvt/locale.codecvt.members/char16_t_char8_t_in.pass.cpp
    M libcxx/test/std/localization/locale.categories/category.ctype/locale.codecvt/locale.codecvt.members/char16_t_char8_t_out.pass.cpp
    M libcxx/test/std/localization/locale.categories/category.ctype/locale.codecvt/locale.codecvt.members/char32_t_char8_t_in.pass.cpp
    M libcxx/test/std/localization/locale.categories/category.ctype/locale.codecvt/locale.codecvt.members/char32_t_char8_t_out.pass.cpp
    M libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/assign2.pass.cpp
    M libcxx/utils/libcxx/test/features.py
    M llvm/include/llvm/Support/ConvertUTF.h
    M llvm/lib/Support/ConvertUTFWrapper.cpp

  Log Message:
  -----------
  [Clang] Add warnings when mixing different charN_t types (#138708)

charN_t represent code units of different UTF encodings. Therefore the
values of 2 different charN_t objects do not represent the same
characters.

In order to avoid comparing apples and oranges, we add new warnings to
warn on:
  - Implicit conversions
  - Comparisons
  - Other cases involving arithmetic conversions

We only produce the warning if we cannot establish the comparison would
be safe through constant evaluation.

The new `-Wimplicit-unicode-conversion` warning is enabled by default.

Note that this PR intentionally doesn;t touches char/wchar_t, but it
would be worth considering also warning on extending the new warnings to
these types (in a follow up)

Additionally most arithmetic operations on charN_t don't really make
sense (ie what does it mean to addition code units), so we could add
warnings for that.

Fixes #138526



To unsubscribe from these emails, change your notification settings at https://github.com/llvm/llvm-project/settings/notifications