[clang-tools-extra] fix usr rhs (PR #68329)

[Sam McCall via cfe-commits]

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@@ -1070,6 +1063,24 @@ void USRGenerator::VisitMSGuidDecl(const MSGuidDecl *D) {
   D->NamedDecl::printName(Out);
 }
 
+void USRGenerator::VisitBaseUsingDecl(const BaseUsingDecl *D) {
+  // Add the filename when needed to disambiguate using decls from different
+  // files.
+  if (ShouldGenerateLocation(D) && GenLoc(D, /*IncludeOffset=*/false))
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sam-mccall wrote:

as discussed offline, ShouldGenerateLocation doesn't seem like the right check here:
 - we definitely want to include the filename for *.cpp
 - we may want to include the filename for *.h
 - we probably should exclude system headers
 - for using decls inside functions, we need to include the filename if the **function** is not externally visible (though it's probably fine to include it always)

https://github.com/llvm/llvm-project/pull/68329