Pin clang to version 17 in sanitizer CI jobs

[hanxizh9910]

Analysis

The daily CI sanitizer jobs with clang are failing during the build step.

The ubuntu-latest runner now has clang 18, but the LLVM gold plugin
is still version 17. When the static Lua module is built with -flto,
the .o files contain LLVM 18 bitcode that the gold plugin (v17) cannot
read:
bfd plugin: LLVM gold plugin has failed to create LTO module: Unknown attribute kind (91) (Producer: 'LLVM18.1.3' Reader: 'LLVM 17.0.6')
Example failure: https://github.com/valkey-io/valkey/actions/runs/24753491944/job/72421581512

Fix

Pin the sanitizer jobs to clang-17 so the compiler and gold plugin
versions match.
Tested(successfully built): https://github.com/hanxizh9910/valkey/actions/runs/24859845008

Note

If clang-17 is removed from the ubuntu-latest image in the future,
we may need to either add an explicit install step

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 76.37%. Comparing base (03c2d4c) to head (bde9dbc).
⚠️ Report is 7 commits behind head on unstable.

Additional details and impacted files

@@             Coverage Diff              @@
##           unstable    #3546      +/-   ##
============================================
+ Coverage     76.21%   76.37%   +0.16%     
============================================
  Files           159      159              
  Lines         81672    80045    -1627     
============================================
- Hits          62243    61132    -1111     
+ Misses        19429    18913     -516     

see 126 files with indirect coverage changes

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[Nikhil-Manglore]

I realized we don't run the sanitizer tests for the run-extra-tests label, but it looks like the local tests Hanxi ran passed

[sarthakaggarwal97]

I think this would work fine. Another option is trying out if we can pin it to clang-17 for the sanitizer jobs. That is probably less invasive than a makefile change since it only changes daily.yml file

something like this?

      matrix:
        compiler: [gcc, clang-17]

[hpatro]

@eifrah-aws Could you also take a look?

[hpatro]

Would this degrade performance?

[hanxizh9910]

Related commit: 0327c27

[hpatro]

@hanxizh9910 curious why did we choose clang 17 instead of 18?

[roshkhatri]

I think we can remove the LTO flag and it shouldn't affect the performance as the Lua module is compiled into a static archive and then it's linked into valkey-server using --whole-archive. So we are anyway taking every object in this lua archive and including it directly. LTO is optimizing across file boundaries at link time, but the module and valkey has a good boundary and are interacting with the valkey server with limited calls. So there's very little for LTO to optimize across that seam. The hot path is inside the Lua interpreter itself, and that still gets full -O2/-O3 optimization. I think there will be no meaningful performance impact.

[hanxizh9910]

@hanxizh9910 curious why did we choose clang 17 instead of 18?

Hi, because the LLVM gold plugin on the runner is version 17. We need the compiler to match the gold plugin. Pinning to clang-18 wouldn't help

[roshkhatri]

@hanxizh9910 curious why did we choose clang 17 instead of 18?

The reader, bfd plugin shipped with ubuntu latest is still on 17 and does not support reading LLVM 18 bitcode
Either we upgrade bfd plugin on the runners while setting up env. which is extra effort.
Or just select clang 17 for now

[sarthakaggarwal97]

FYI: The current tests failures in CI should get fixes with #3545

[hpatro]

Started failing after #3392 merge. Merging it for now to help stabilize the daily. However, take a look @eifrah-aws once you get time.

[hanxizh9910]

failed to make again: https://github.com/valkey-io/valkey/actions/runs/24865821147/job/72801509679. Will make a new PR using the old way to fix it