[clang] [PAC] Re-sign a pointer to a noexcept member function when it is converted to a pointer to a member function without noexcept (PR #109056)

[Akira Hatanaka via cfe-commits]

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@@ -2419,8 +2419,13 @@ Value *ScalarExprEmitter::VisitCastExpr(CastExpr *CE) {
     return Visit(const_cast<Expr*>(E));
 
   case CK_NoOp: {
-    return CE->changesVolatileQualification() ? EmitLoadOfLValue(CE)
-                                              : Visit(const_cast<Expr *>(E));
+    if (CE->changesVolatileQualification())
+      return EmitLoadOfLValue(CE);
+    auto V = Visit(const_cast<Expr *>(E));
+    if (CGF.CGM.getCodeGenOpts().PointerAuth.CXXMemberFunctionPointers &&
+        CE->getType()->isMemberFunctionPointerType())
+      V = CGF.CGM.getCXXABI().EmitMemberPointerConversion(CGF, CE, V);
+    return V;
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ahatanak wrote:

Depending on the kind of casts in the source code, `CStyleCastExpr` or `CXXReinterpretCastExpr` (or possibly another cast kind) is used when casting to a completely different function pointer type.

But those are explicit casts. I'm not sure there's another cast operation other than `CK_NoOp` in `clang/AST/OperationKinds.def` that we can use for that purpose.

https://github.com/llvm/llvm-project/pull/109056