[clang] [clang] Implement P2582R1: CTAD from inherited constructors (PR #98788)

[Erich Keane via cfe-commits]

================
@@ -2246,18 +2246,21 @@ CXXDeductionGuideDecl *CXXDeductionGuideDecl::Create(
     ASTContext &C, DeclContext *DC, SourceLocation StartLoc,
     ExplicitSpecifier ES, const DeclarationNameInfo &NameInfo, QualType T,
     TypeSourceInfo *TInfo, SourceLocation EndLocation, CXXConstructorDecl *Ctor,
-    DeductionCandidate Kind, Expr *TrailingRequiresClause) {
-  return new (C, DC)
-      CXXDeductionGuideDecl(C, DC, StartLoc, ES, NameInfo, T, TInfo,
-                            EndLocation, Ctor, Kind, TrailingRequiresClause);
+    DeductionCandidate Kind, Expr *TrailingRequiresClause,
+    const CXXDeductionGuideDecl *GeneratedFrom,
+    SourceDeductionGuideKind SourceKind) {
+  return new (C, DC) CXXDeductionGuideDecl(
+      C, DC, StartLoc, ES, NameInfo, T, TInfo, EndLocation, Ctor, Kind,
+      TrailingRequiresClause, GeneratedFrom, SourceKind);
 }
 
 CXXDeductionGuideDecl *
 CXXDeductionGuideDecl::CreateDeserialized(ASTContext &C, GlobalDeclID ID) {
   return new (C, ID) CXXDeductionGuideDecl(
----------------
erichkeane wrote:

For `Expr`s we usually have a `CreateEmpty` that has an `empty`/`empty-ish` private constructor associated with it. or something like that.... this is very much making me wish we had the same for this one.

https://github.com/llvm/llvm-project/pull/98788