Only download prebuilt DXC releases on Windows

[Bernhard M. Wiedemann (bmwiedemann)]

The DXIL backward compatibility section downloads four release archives from github and then uses them exclusively from inside an if(WIN32) block, because what it wants out of them is bin//dxil.dll -- a Windows binary that has no equivalent, and no consumer, on other platforms.

The download itself was outside that guard, and ExternalProject_Add adds its download target to ALL, so every Linux and macOS build fetched all four archives for nothing. It also makes an ordinary build depend on network access, which breaks offline and distribution builds.

Move the add_released_dxc() call inside the existing if(WIN32), matching what taef_exec/DownloadWarp.cmake already does for the WARP package.

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[Copilot]

Pull request overview

Note

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Updates the Clang test CMake configuration to only register released DXC binaries on Windows hosts.

Changes:

• Moves add_released_dxc(${name} ${version}) under a WIN32 guard.

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[Copilot]

Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated no new comments.

Suppressed comments (1)

tools/clang/test/CMakeLists.txt:145

• loop_end becomes -1 when DXC_RELEASES is empty (or DXC_RELEASES_LENGTH is 0), which can cause an invalid foreach(RANGE ...) in some CMake versions/configurations. Add a guard before computing loop_end/entering the loop (e.g., only run the foreach when num_pairs is greater than 0) to make this robust.

  list(LENGTH DXC_RELEASES DXC_RELEASES_LENGTH)
  math(EXPR num_pairs "${DXC_RELEASES_LENGTH} / 2")
  math(EXPR loop_end "${num_pairs} - 1")
  foreach(i RANGE 0 ${loop_end})

[Bernhard M. Wiedemann (bmwiedemann)]

@microsoft-github-policy-service agree

[Copilot]

Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated no new comments.

Suppressed comments (2)

tools/clang/test/CMakeLists.txt:150

• The loop assumes DXC_RELEASES contains at least one complete (name, version) pair and that its length is even. If DXC_RELEASES is empty (or accidentally edited to an odd length), loop_end can become negative and/or list(GET ...) can go out of range, failing CMake configuration. Consider guarding with a if(num_pairs GREATER 0) (or if(DXC_RELEASES_LENGTH GREATER_EQUAL 2)) and optionally emitting a clear message(FATAL_ERROR ...) when DXC_RELEASES_LENGTH is odd.

  list(LENGTH DXC_RELEASES DXC_RELEASES_LENGTH)
  math(EXPR num_pairs "${DXC_RELEASES_LENGTH} / 2")
  math(EXPR loop_end "${num_pairs} - 1")
  foreach(i RANGE 0 ${loop_end})
    math(EXPR idx_name "${i}*2")
    math(EXPR idx_version "${i}*2 + 1")

    list(GET DXC_RELEASES ${idx_name} name)
    list(GET DXC_RELEASES ${idx_version} version)

tools/clang/test/CMakeLists.txt:152

• Using very generic variable names like name and version in directory scope can be confusing and increases the risk of unintended reuse elsewhere in the file. Consider renaming these loop variables to something more specific (e.g., dxc_release_name / dxc_release_version) to improve clarity.

    list(GET DXC_RELEASES ${idx_name} name)
    list(GET DXC_RELEASES ${idx_version} version)

    add_released_dxc(${name} ${version})

[Damyan Pepper (damyanp)]

/azp run

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[Damyan Pepper (damyanp)]

Bernhard M. Wiedemann (@bmwiedemann) - thank you for your contribution!