6 files changed, 32 insertions, 13 deletions
diff --git a/clang/lib/AST/ASTImporter.cpp b/clang/lib/AST/ASTImporter.cpp
index f661de5..5433b61 100644
--- a/clang/lib/AST/ASTImporter.cpp
+++ b/clang/lib/AST/ASTImporter.cpp
@@ -3997,14 +3997,16 @@ ExpectedDecl ASTNodeImporter::VisitFunctionDecl(FunctionDecl *D) {
         importExplicitSpecifier(Err, Guide->getExplicitSpecifier());
     CXXConstructorDecl *Ctor =
         importChecked(Err, Guide->getCorrespondingConstructor());
+    const CXXDeductionGuideDecl *SourceDG =
+        importChecked(Err, Guide->getSourceDeductionGuide());
     if (Err)
       return std::move(Err);
     if (GetImportedOrCreateDecl<CXXDeductionGuideDecl>(
             ToFunction, D, Importer.getToContext(), DC, ToInnerLocStart, ESpec,
-            NameInfo, T, TInfo, ToEndLoc, Ctor))
+            NameInfo, T, TInfo, ToEndLoc, Ctor,
+            Guide->getDeductionCandidateKind(), TrailingRequiresClause,
+            SourceDG, Guide->getSourceDeductionGuideKind()))
       return ToFunction;
-    cast<CXXDeductionGuideDecl>(ToFunction)
-        ->setDeductionCandidateKind(Guide->getDeductionCandidateKind());
   } else {
     if (GetImportedOrCreateDecl(
             ToFunction, D, Importer.getToContext(), DC, ToInnerLocStart,
diff --git a/clang/lib/AST/DeclCXX.cpp b/clang/lib/AST/DeclCXX.cpp
index c0a4356d..a023a9f4 100644
--- a/clang/lib/AST/DeclCXX.cpp
+++ b/clang/lib/AST/DeclCXX.cpp
@@ -2292,18 +2292,22 @@ 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(
-      C, nullptr, SourceLocation(), ExplicitSpecifier(), DeclarationNameInfo(),
-      QualType(), nullptr, SourceLocation(), nullptr,
-      DeductionCandidate::Normal, nullptr);
+      C, /*DC=*/nullptr, SourceLocation(), ExplicitSpecifier(),
+      DeclarationNameInfo(), QualType(), /*TInfo=*/nullptr, SourceLocation(),
+      /*Ctor=*/nullptr, DeductionCandidate::Normal,
+      /*TrailingRequiresClause=*/nullptr,
+      /*GeneratedFrom=*/nullptr, SourceDeductionGuideKind::None);
 }
 
 RequiresExprBodyDecl *RequiresExprBodyDecl::Create(
diff --git a/clang/lib/Sema/SemaTemplateDeductionGuide.cpp b/clang/lib/Sema/SemaTemplateDeductionGuide.cpp
index 9507833..00c5dfd3 100644
--- a/clang/lib/Sema/SemaTemplateDeductionGuide.cpp
+++ b/clang/lib/Sema/SemaTemplateDeductionGuide.cpp
@@ -1175,8 +1175,12 @@ BuildDeductionGuideForTypeAlias(Sema &SemaRef,
         GG->getTypeSourceInfo(), AliasTemplate->getBeginLoc(),
         AliasTemplate->getLocation(), AliasTemplate->getEndLoc(),
         F->isImplicit()));
-    cast<CXXDeductionGuideDecl>(Result->getTemplatedDecl())
-        ->setDeductionCandidateKind(GG->getDeductionCandidateKind());
+    auto *DGuide = cast<CXXDeductionGuideDecl>(Result->getTemplatedDecl());
+    DGuide->setDeductionCandidateKind(GG->getDeductionCandidateKind());
+    DGuide->setSourceDeductionGuide(
+        cast<CXXDeductionGuideDecl>(F->getTemplatedDecl()));
+    DGuide->setSourceDeductionGuideKind(
+        CXXDeductionGuideDecl::SourceDeductionGuideKind::Alias);
     return Result;
   }
   return nullptr;
diff --git a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
index 337262e..ebe2dd9 100644
--- a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
+++ b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
@@ -2269,7 +2269,9 @@ Decl *TemplateDeclInstantiator::VisitFunctionDecl(
         SemaRef.Context, DC, D->getInnerLocStart(),
         InstantiatedExplicitSpecifier, NameInfo, T, TInfo,
         D->getSourceRange().getEnd(), DGuide->getCorrespondingConstructor(),
-        DGuide->getDeductionCandidateKind(), TrailingRequiresClause);
+        DGuide->getDeductionCandidateKind(), TrailingRequiresClause,
+        DGuide->getSourceDeductionGuide(),
+        DGuide->getSourceDeductionGuideKind());
     Function->setAccess(D->getAccess());
   } else {
     Function = FunctionDecl::Create(
diff --git a/clang/lib/Serialization/ASTReaderDecl.cpp b/clang/lib/Serialization/ASTReaderDecl.cpp
index 0b75468..87e1931 100644
--- a/clang/lib/Serialization/ASTReaderDecl.cpp
+++ b/clang/lib/Serialization/ASTReaderDecl.cpp
@@ -2295,6 +2295,10 @@ void ASTDeclReader::VisitCXXDeductionGuideDecl(CXXDeductionGuideDecl *D) {
   VisitFunctionDecl(D);
   D->setDeductionCandidateKind(
       static_cast<DeductionCandidate>(Record.readInt()));
+  D->setSourceDeductionGuide(readDeclAs<CXXDeductionGuideDecl>());
+  D->setSourceDeductionGuideKind(
+      static_cast<CXXDeductionGuideDecl::SourceDeductionGuideKind>(
+          Record.readInt()));
 }
 
 void ASTDeclReader::VisitCXXMethodDecl(CXXMethodDecl *D) {
diff --git a/clang/lib/Serialization/ASTWriterDecl.cpp b/clang/lib/Serialization/ASTWriterDecl.cpp
index 8b9ba04..fa2294d 100644
--- a/clang/lib/Serialization/ASTWriterDecl.cpp
+++ b/clang/lib/Serialization/ASTWriterDecl.cpp
@@ -846,6 +846,9 @@ void ASTDeclWriter::VisitCXXDeductionGuideDecl(CXXDeductionGuideDecl *D) {
   Record.AddDeclRef(D->Ctor);
   VisitFunctionDecl(D);
   Record.push_back(static_cast<unsigned char>(D->getDeductionCandidateKind()));
+  Record.AddDeclRef(D->getSourceDeductionGuide());
+  Record.push_back(
+      static_cast<unsigned char>(D->getSourceDeductionGuideKind()));
   Code = serialization::DECL_CXX_DEDUCTION_GUIDE;
 }