[all-commits] [llvm/llvm-project] 955dd8: Revert "Reland [clang] Canonicalize system headers...

[Arthur Eubanks via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 955dd8800b4745784bf6da948ec7992d5b75b4d7
      https://github.com/llvm/llvm-project/commit/955dd8800b4745784bf6da948ec7992d5b75b4d7
  Author: Arthur Eubanks <aeubanks at google.com>
  Date:   2023-11-08 (Wed, 08 Nov 2023)

  Changed paths:
    M clang/include/clang/Driver/Options.td
    M clang/include/clang/Frontend/DependencyOutputOptions.h
    M clang/include/clang/Frontend/Utils.h
    M clang/lib/Driver/ToolChains/Clang.cpp
    M clang/lib/Frontend/DependencyFile.cpp
    R clang/test/Driver/canonical-system-headers.c
    R clang/test/Preprocessor/Inputs/canonical-system-headers/a.h
    R clang/test/Preprocessor/canonical-system-headers.c

  Log Message:
  -----------
  Revert "Reland [clang] Canonicalize system headers in dependency file when -canonical-prefixes" (#71697)

This reverts commit 578a4716f549167165a2ec3bac89c86706136d4e.

This causes multiple issues. Compile time slowdown due to more path
canonicalization, and weird behavior on Windows.

Will reland under a separate flag `-f[no-]canonical-system-headers` to
match gcc in the future and further limit when it's passed by default.

Fixes #70011.