[clang] Extend -Wnonportable-include-path with a warning about trailing whitespace or dots (PR #96960)

[via cfe-commits]

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@@ -361,7 +361,11 @@ class NonportablePath  : Warning<
   "non-portable path to file '%0'; specified path differs in case from file"
   " name on disk">;
 def pp_nonportable_path : NonportablePath,
-  InGroup<DiagGroup<"nonportable-include-path">>;
+  InGroup<NonportablePath>;
+def pp_nonportable_path_trailing_whitespace : Warning<
+  "non-portable path to file '%0'; specified path contains trailing"
+  "whitespace or dots">,
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zmodem wrote:

Unless it would complicate the code too much, could we use `%select{whitespace|dots}` here to make the diagnostic specific to whether it's a trailing space or dot?

https://github.com/llvm/llvm-project/pull/96960