[clang] [clang][ptrauth] Warn about the use of a weak signing schema (PR #157779)

[Martin Balao Alonso via cfe-commits]

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@@ -8357,6 +8357,16 @@ NamedDecl *Sema::ActOnVariableDeclarator(
                                    D.isFunctionDefinition());
   }
 
+  // Warn about the use of a weak pointer authentication schema on a variable
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martinuy wrote:

Sounds good, but I have a question. My understanding is that you are thinking of moving both the condition we check and the `Diag` call into a separate function. Considering that no action such as invalidating the declaration would be taken on the caller side -at least for now-, shouldn't the return type of the separate function be `void` (similar to `void Sema::DiagnoseUniqueObjectDuplication(const VarDecl *)` or `void Sema::DiagnoseAutoDeductionFailure(const VarDecl *, const Expr *)`?

https://github.com/llvm/llvm-project/pull/157779