[libcxx] [llvm] [libc++] Optionally support filecheck-based tests (PR #165769)

[Nikolas Klauser via llvm-commits]

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@@ -355,6 +355,14 @@ def _mingwSupportsModules(cfg):
         name="has-no-zdump",
         when=lambda cfg: runScriptExitCode(cfg, ["zdump --version"]) != 0,
     ),
+    # Whether the `filecheck` executable is available. Note that this corresponds to
+    # a Python port of LLVM's FileCheck, not LLVM's actual FileCheck program, since
+    # that one requires building parts of LLVM that we don't want to build when merely
+    # testing libc++.
+    Feature(
+        name="has-filecheck",
+        when=lambda cfg: runScriptExitCode(cfg, ["filecheck --version"]) == 0,
+    ),
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philnik777 wrote:

I think allowing the external version is very reasonable, but IMO we should also look for `FileCheck`, since folks may very well have that already on their system (e.g. I do).

https://github.com/llvm/llvm-project/pull/165769