[libcxx] [llvm] [libc++][modules] Adds module testing. (PR #76246)

[Mark de Wever via llvm-commits]

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@@ -223,6 +280,12 @@ class CxxStandardLibraryTest(lit.formats.FileBasedTest):
             allows adding special compilation flags without having to use a
             .sh.cpp test, which would be more powerful but perhaps overkill.
 
+        // MODULE: std std.compat
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mordante wrote:

This comment and the one on line 250 need to move after #73136 has landed

https://github.com/llvm/llvm-project/pull/76246