[cpullvm] Pin host compiler to clang-cl-19 for Windows Builds

[pranav4330]

Pin host compiler from generic 'clang-cl' to 'clang-cl-19', resolved from the LLVM installation pre-bundled with the GitHub=hosted windows-2025/windows-11-arm runners via the System Path.

Signed-off-by: Pranav Patil pranpati@qti.qualcomm.com

[Jonathon Penix (jonathonpenix)]

Please post a link to a run of the nightlies with the Windows builds passing successfully with this change.

[Jonathon Penix (jonathonpenix)]

Two late thoughts:

• build.ps1 should also be handled as well whatever we do
• I also wonder if this should be handled closer to what was done in fe1f2ce rather than modifying the build scripts?

[Yethendra]

Yes, I agree with Jonathon's comment:

**I also wonder if this should be handled closer to what was done in fe1f2ce rather than modifying the build scripts? **

pranav4330 - If the builds are successful with "clang-cl-19" lets handle in install_dependencies ?

[pranav4330]

Yes, I can look into that Jonathon Penix (@jonathonpenix) and Yethendra, thanks for pointing it out.

[Jonathon Penix (jonathonpenix)]

The build failures should be resolved if you rebase or merge our qualcomm-software branch into yours at this point

[srilakshmi yalamaraju (sriyalamar)]

seems current runner image spec at https://github.com/actions/runner-images/blob/main/images/windows/
│ Windows2025-Readme.md showing LLVM 20.1.8 , thats why clang-19 is not found.
If we need clang-19, in install_dependencies.ps1 — we need to add, choco install llvm --version=19.1.7 -y --force
and Copy-Item "C:\Program Files\LLVM\bin\clang-cl.exe" "C:\Program Files\LLVM\bin\clang-cl-19.exe" -Force