Return `errc::no_such_file_or_directory` in `fs::access` if `GetFileAttributesW` fails (#83495)

Fixes https://github.com/llvm/llvm-project/issues/83046

There is a race condition when calling `GetFileAttributesW` that can
cause it to return `ERROR_ACCESS_DENIED` on a path which exists, which
is unexpected for callers using this function to check for file
existence by passing `AccessMode::Exist`. This was manifesting as a
compiler crash on Windows downstream in the Swift compiler when using
the `-index-store-path` flag (more information in
https://github.com/apple/llvm-project/issues/8224).

I looked for alternate APIs to avoid bringing in `shlwapi.h`, but didn't
see any good candidates. I'm not tied at all to this solution, any
feedback and alternative approaches are more than welcome.
1 file changed
tree: 115d9d164bdb92928ab43dc06cb643aebfdfc53f
  1. .ci/
  2. .github/
  3. bolt/
  4. clang/
  5. clang-tools-extra/
  6. cmake/
  7. compiler-rt/
  8. cross-project-tests/
  9. flang/
  10. libc/
  11. libclc/
  12. libcxx/
  13. libcxxabi/
  14. libunwind/
  15. lld/
  16. lldb/
  17. llvm/
  18. llvm-libgcc/
  19. mlir/
  20. openmp/
  21. polly/
  22. pstl/
  23. runtimes/
  24. third-party/
  25. utils/
  26. .clang-format
  27. .clang-tidy
  28. .git-blame-ignore-revs
  29. .gitattributes
  30. .gitignore
  31. .mailmap
  32. CODE_OF_CONDUCT.md
  33. CONTRIBUTING.md
  34. LICENSE.TXT
  35. pyproject.toml
  36. README.md
  37. SECURITY.md
README.md

The LLVM Compiler Infrastructure

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Welcome to the LLVM project!

This repository contains the source code for LLVM, a toolkit for the construction of highly optimized compilers, optimizers, and run-time environments.

The LLVM project has multiple components. The core of the project is itself called “LLVM”. This contains all of the tools, libraries, and header files needed to process intermediate representations and convert them into object files. Tools include an assembler, disassembler, bitcode analyzer, and bitcode optimizer.

C-like languages use the Clang frontend. This component compiles C, C++, Objective-C, and Objective-C++ code into LLVM bitcode -- and from there into object files, using LLVM.

Other components include: the libc++ C++ standard library, the LLD linker, and more.

Getting the Source Code and Building LLVM

Consult the Getting Started with LLVM page for information on building and running LLVM.

For information on how to contribute to the LLVM project, please take a look at the Contributing to LLVM guide.

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Join the LLVM Discourse forums, Discord chat, LLVM Office Hours or Regular sync-ups.

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