[CMake] Fix config when static zstd libraries are not found

[uditagarwal97]

Fixes: #113583

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[uditagarwal97]

Ping

[uditagarwal97]

Ping

[mgorny]

LGTM. To be honest, I hate the growing complexity of this code, but I understand that it's causing issues currently and it makes sense to fix that. I can't judge how good the fix is, but at least I can tell that it doesn't seem likely to break anything.

[sarnex]

@uditagarwal97 You can ping me to merge once CI passes

[aaronpuchert]

If you emit an error, it seems like you can leave LLVM_ENABLE_ZSTD as it is.

[aaronpuchert]

But I don't see why this is not in this if. We should probably not care about LLVM_USE_STATIC_ZSTD if LLVM_ENABLE_ZSTD is off. As for the LLVM_USE_SANITIZER MATCHES "Memory.*" case, I guess that is acceptable.

[uditagarwal97]

That's a fair point. I've moved it inside the parent if in c698368

[aaronpuchert]

Looks good to me. I share @mgorny's concerns about complexity, but I don't see an easy way out.

[uditagarwal97]

@sarnex can you please merge this?

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[llvm-ci]

LLVM Buildbot has detected a new failure on builder clang-ppc64-aix running on aix-ppc64 while building llvm at step 6 "test-build-unified-tree-check-all".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/64/builds/3888

Here is the relevant piece of the build log for the reference

Step 6 (test-build-unified-tree-check-all) failure: test (failure)
******************** TEST 'lit :: timeout-hang.py' FAILED ********************
Exit Code: 1

Command Output (stdout):
--
# RUN: at line 13
not env -u FILECHECK_OPTS "/home/llvm/llvm-external-buildbots/workers/env/bin/python3.11" /home/llvm/llvm-external-buildbots/workers/aix-ppc64/clang-ppc64-aix/llvm-project/llvm/utils/lit/lit.py -j1 --order=lexical Inputs/timeout-hang/run-nonexistent.txt  --timeout=1 --param external=0 | "/home/llvm/llvm-external-buildbots/workers/env/bin/python3.11" /home/llvm/llvm-external-buildbots/workers/aix-ppc64/clang-ppc64-aix/build/utils/lit/tests/timeout-hang.py 1
# executed command: not env -u FILECHECK_OPTS /home/llvm/llvm-external-buildbots/workers/env/bin/python3.11 /home/llvm/llvm-external-buildbots/workers/aix-ppc64/clang-ppc64-aix/llvm-project/llvm/utils/lit/lit.py -j1 --order=lexical Inputs/timeout-hang/run-nonexistent.txt --timeout=1 --param external=0
# .---command stderr------------
# | lit.py: /home/llvm/llvm-external-buildbots/workers/aix-ppc64/clang-ppc64-aix/llvm-project/llvm/utils/lit/lit/main.py:72: note: The test suite configuration requested an individual test timeout of 0 seconds but a timeout of 1 seconds was requested on the command line. Forcing timeout to be 1 seconds.
# `-----------------------------
# executed command: /home/llvm/llvm-external-buildbots/workers/env/bin/python3.11 /home/llvm/llvm-external-buildbots/workers/aix-ppc64/clang-ppc64-aix/build/utils/lit/tests/timeout-hang.py 1
# .---command stdout------------
# | Testing took as long or longer than timeout
# `-----------------------------
# error: command failed with exit status: 1

--

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