[clang] [clang] Fix CTAD not work for function-type and array-type arguments. (PR #78159)

[Haojian Wu via cfe-commits]

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@@ -2587,15 +2587,17 @@ struct ConvertConstructorToDeductionGuideTransform {
                           : ParamTy->isRValueReferenceType() ? VK_XValue
                                                              : VK_PRValue);
     }
-
-    ParmVarDecl *NewParam = ParmVarDecl::Create(SemaRef.Context, DC,
-                                                OldParam->getInnerLocStart(),
-                                                OldParam->getLocation(),
-                                                OldParam->getIdentifier(),
-                                                NewDI->getType(),
-                                                NewDI,
-                                                OldParam->getStorageClass(),
-                                                NewDefArg.get());
+    // Handle arrays and functions decay.
+    auto NewType = NewDI->getType();
+    if (NewType->isArrayType())
+      NewType = SemaRef.Context.getArrayDecayedType(NewType);
+    else if (NewType->isFunctionType())
+      NewType = SemaRef.Context.getPointerType(NewType);
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hokein wrote:

Good point, thanks. I was not aware of this API.

https://github.com/llvm/llvm-project/pull/78159