[libcxx] [llvm] [RFC][libc++][test] Improves C++ Standard filtering. (PR #89499)

[Louis Dionne via llvm-commits]

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@@ -165,11 +165,28 @@ def getSuitableClangTidy(cfg):
         default=lambda cfg: next(
             s for s in reversed(_allStandards) if getStdFlag(cfg, s)
         ),
-        actions=lambda std: [
+        actions=lambda std: filter(None, [
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ldionne wrote:

I think we should add Lit support for arithmetic expressions instead. @jdenny-ornl do you have thoughts on this?

https://github.com/llvm/llvm-project/pull/89499