[clang] [clang][modules] Minor improvements to diagnosing `out of date` errors (PR #136612)

[Cyndy Ishida via cfe-commits]

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@@ -0,0 +1,62 @@
+/// This tests the expected error case when there is a mismatch between the pcm dependencies passed in 
+/// the command line with `fmodule-file` and whats encoded in the pcm. 
+
+/// The steps are: 
+/// 1. Build module (A-1) with no dependencies.
+/// 2. Build the same module with files that resolve from different search paths. (A-2).
+/// 3. Build module (B) that depends on the earlier module (A-1).
+/// 4. Build client that depends on both modules (A & B) but depends on a different version (A-2).
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cyndyishida wrote:

Updated, let me know if it still reads confusingly. 

https://github.com/llvm/llvm-project/pull/136612