[clang] Move the aggreate deduction guide cache login to

SemaTemplate.cpp, NFC.

this is a NFC refactoring change, which is needed for the upcoming fix
for alias templates.

Author: hokein

clang/lib/Sema/SemaInit.cpp

@@ -10930,32 +10930,15 @@ QualType Sema::DeduceTemplateSpecializationFromInitializer(
                   Context.getLValueReferenceType(ElementTypes[I].withConst());
           }
 
-        llvm::FoldingSetNodeID ID;
-        ID.AddPointer(Template);
-        for (auto &T : ElementTypes)
-          T.getCanonicalType().Profile(ID);
-        unsigned Hash = ID.ComputeHash();
-        if (AggregateDeductionCandidates.count(Hash) == 0) {
-          if (FunctionTemplateDecl *TD =
-                  DeclareImplicitDeductionGuideFromInitList(
-                      Template, ElementTypes,
-                      TSInfo->getTypeLoc().getEndLoc())) {
-            auto *GD = cast<CXXDeductionGuideDecl>(TD->getTemplatedDecl());
-            GD->setDeductionCandidateKind(DeductionCandidate::Aggregate);
-            AggregateDeductionCandidates[Hash] = GD;
-            addDeductionCandidate(TD, GD, DeclAccessPair::make(TD, AS_public),
-                                  OnlyListConstructors,
-                                  /*AllowAggregateDeductionCandidate=*/true);
-          }
-        } else {
-          CXXDeductionGuideDecl *GD = AggregateDeductionCandidates[Hash];
-          FunctionTemplateDecl *TD = GD->getDescribedFunctionTemplate();
-          assert(TD && "aggregate deduction candidate is function template");
+        if (FunctionTemplateDecl *TD =
+                DeclareImplicitDeductionGuideFromInitList(
+                    Template, ElementTypes, TSInfo->getTypeLoc().getEndLoc())) {
+          auto *GD = cast<CXXDeductionGuideDecl>(TD->getTemplatedDecl());
           addDeductionCandidate(TD, GD, DeclAccessPair::make(TD, AS_public),
                                 OnlyListConstructors,
                                 /*AllowAggregateDeductionCandidate=*/true);
+          HasAnyDeductionGuide = true;
         }
-        HasAnyDeductionGuide = true;
       }
     };
 

clang/lib/Sema/SemaTemplate.cpp

@@ -3018,6 +3018,23 @@ void DeclareImplicitDeductionGuidesForTypeAlias(
 FunctionTemplateDecl *Sema::DeclareImplicitDeductionGuideFromInitList(
     TemplateDecl *Template, MutableArrayRef<QualType> ParamTypes,
     SourceLocation Loc) {
+  llvm::FoldingSetNodeID ID;
+  ID.AddPointer(Template);
+  for (auto &T : ParamTypes)
+    T.getCanonicalType().Profile(ID);
+  unsigned Hash = ID.ComputeHash();
+  
+  auto Found = AggregateDeductionCandidates.find(Hash);
+  if (Found != AggregateDeductionCandidates.end()) {
+    CXXDeductionGuideDecl *GD = Found->getSecond();
+    return GD->getDescribedFunctionTemplate();
+  }
+  
+  // if (auto *AliasTemplate = llvm::dyn_cast<TypeAliasTemplateDecl>(Template)) {
+  //   DeclareImplicitDeductionGuidesForTypeAlias(*this, AliasTemplate, Loc);
+  //   return;
+  // }
+
   if (CXXRecordDecl *DefRecord =
           cast<CXXRecordDecl>(Template->getTemplatedDecl())->getDefinition()) {
     if (TemplateDecl *DescribedTemplate =
@@ -3050,10 +3067,13 @@ FunctionTemplateDecl *Sema::DeclareImplicitDeductionGuideFromInitList(
       Transform.NestedPattern ? Transform.NestedPattern : Transform.Template;
   ContextRAII SavedContext(*this, Pattern->getTemplatedDecl());
 
-  auto *DG = cast<FunctionTemplateDecl>(
+  auto *FTD = cast<FunctionTemplateDecl>(
       Transform.buildSimpleDeductionGuide(ParamTypes));
   SavedContext.pop();
-  return DG;
+  auto *GD = cast<CXXDeductionGuideDecl>(FTD->getTemplatedDecl());
+  GD->setDeductionCandidateKind(DeductionCandidate::Aggregate);
+  AggregateDeductionCandidates[Hash] = GD;
+  return FTD;
 }
 
 void Sema::DeclareImplicitDeductionGuides(TemplateDecl *Template,