[clang] [clang] fix P3310 overload resolution flag propagation (PR #125372)

[via cfe-commits]

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@@ -1841,15 +1841,21 @@ class ClassTemplateSpecializationDecl : public CXXRecordDecl,
   LLVM_PREFERRED_TYPE(TemplateSpecializationKind)
   unsigned SpecializationKind : 3;
 
+  /// When matching the primary template, have we matched any packs on the
+  /// parameter side, versus any non-packs on the argument side, in a context
+  /// where the opposite matching is also allowed?
+  bool MatchedPackOnParmToNonPackOnArg : 1;
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cor3ntin wrote:

I know this has the same name as the one in `CheckTemplateArgumentInfo` but we should rename all of them to `MatchedNonPackArgumentWithPackParameter` or something like that (ie remove the `On`s)

https://github.com/llvm/llvm-project/pull/125372