[clang] [RFC] Initial implementation of P2719 (PR #113510)

[Oliver Hunt via cfe-commits]

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@@ -4749,6 +4753,15 @@ class Sema final : public SemaBase {
 
   CXXRecordDecl *getStdBadAlloc() const;
   EnumDecl *getStdAlignValT() const;
+  ClassTemplateDecl *getStdTypeIdentity() const;
+  std::optional<QualType> InstantiateSpecializedTypeIdentity(QualType Subject);
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ojhunt wrote:

What is the correct coding style? Over time I've been told upper case, whereas other times lower - in this particular case I followed lower case for the `get` for consistency with the neighboring `get` methods, and upper case for the new one because it didn't have a "consistency with similar methods" rationale and the feedback on other patches seemed to imply that functions are _meant_ to have upper case first letter (I think I actually intentionally capitalized this function before pushing the PR \o/)

I'd prefer lower case start, but I just want to know which it is actually meant to be :D

https://github.com/llvm/llvm-project/pull/113510