[clang] [clang/AST] Make it possible to use SwiftAttr in type context (PR #108631)

[Gábor Horváth via cfe-commits]

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@@ -6037,13 +6038,24 @@ class AttributedType : public Type, public llvm::FoldingSetNode {
 private:
   friend class ASTContext; // ASTContext creates these
 
+  const Attr *Attribute;
+
   QualType ModifiedType;
   QualType EquivalentType;
 
   AttributedType(QualType canon, attr::Kind attrKind, QualType modified,
                  QualType equivalent)
+      : AttributedType(canon, attrKind, nullptr, modified, equivalent) {}
+
+  AttributedType(QualType canon, const Attr *attr, QualType modified,
+                 QualType equivalent);
+
+private:
+  AttributedType(QualType canon, attr::Kind attrKind, const Attr *attr,
+                 QualType modified, QualType equivalent)
       : Type(Attributed, canon, equivalent->getDependence()),
-        ModifiedType(modified), EquivalentType(equivalent) {
+        Attribute(attr), ModifiedType(modified),
+        EquivalentType(equivalent) {
     AttributedTypeBits.AttrKind = attrKind;
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Xazax-hun wrote:

I see, thanks! In that case it makes sense to me to encode this invariant in the constructor as an assertion (either `attr` is null, or it has the same kind as `attrKind`).

https://github.com/llvm/llvm-project/pull/108631