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llvm / llvm-project / ab60910e01eaa8bcf993cdb59a95f882b3859fd1
commitab60910e01eaa8bcf993cdb59a95f882b3859fd1[log] [tgz]
authorA. Jiang <de34@live.cn>Tue May 13 04:49:25 2025 +0800
committerGitHub <noreply@github.com>Mon May 12 16:49:25 2025 -0400
tree836029e7523ea2d6d08a67f0e255c00e6990c435
parentfa985b5f1e3db76e5f52dec41c2100cb354c771a [diff]
[libc++][format] Discard contents since null-terminator in character arrays in formatting (#116571)

Currently, built-in `char`/`wchar_t` arrays are assumed to be
null-terminated sequence with the terminator being the last element in
formatting. This doesn't conform to [format.arg]/6.9.

> otherwise, if `decay_t<TD>` is `char_type*` or `const char_type*`,
> initializes value with `static_cast<const char_type*>(v)`;

The standard wording specifies that character arrays are decayed to
pointers. When the null terminator is not the last element or there's no
null terminator (the latter case is UB), libc++ currently produces
different results.

Also fixes and hardens `formatter<CharT[N], CharT>::format` in
`<__format/formatter_string.h>`. These specializations are rarely used.

Fixes #115935. Also checks the preconditions in this case, which fixes
#116570.
5 files changed
tree: 836029e7523ea2d6d08a67f0e255c00e6990c435
  1. .ci/
  2. .github/
  3. bolt/
  4. clang/
  5. clang-tools-extra/
  6. cmake/
  7. compiler-rt/
  8. cross-project-tests/
  9. flang/
  10. flang-rt/
  11. libc/
  12. libclc/
  13. libcxx/
  14. libcxxabi/
  15. libunwind/
  16. lld/
  17. lldb/
  18. llvm/
  19. llvm-libgcc/
  20. mlir/
  21. offload/
  22. openmp/
  23. polly/
  24. pstl/
  25. runtimes/
  26. third-party/
  27. utils/
  28. .clang-format
  29. .clang-format-ignore
  30. .clang-tidy
  31. .git-blame-ignore-revs
  32. .gitattributes
  33. .gitignore
  34. .mailmap
  35. CODE_OF_CONDUCT.md
  36. CONTRIBUTING.md
  37. LICENSE.TXT
  38. pyproject.toml
  39. README.md
  40. SECURITY.md
README.md

The LLVM Compiler Infrastructure

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