Revert "[SemaTemplate] Stop passing insertion position around during VarTemplate instantiation"

This reverts commit 8ac709578067f77a7036fe50610277516fa36d50.

This commit changes the public API of clang, so it needs to be reworked.

5 files changed, 16 insertions, 20 deletions

diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
index 7a7722559397..6f7ad8076718 100644
--- a/clang/include/clang/Sema/Sema.h
+++ b/clang/include/clang/Sema/Sema.h
@@ -9123,7 +9123,7 @@ public:
       const TemplateArgumentList &TemplateArgList,
       const TemplateArgumentListInfo &TemplateArgsInfo,
       SmallVectorImpl<TemplateArgument> &Converted,
-      SourceLocation PointOfInstantiation,
+      SourceLocation PointOfInstantiation, void *InsertPos,
       LateInstantiatedAttrVec *LateAttrs = nullptr,
       LocalInstantiationScope *StartingScope = nullptr);
   VarTemplateSpecializationDecl *CompleteVarTemplateSpecializationDecl(
diff --git a/clang/include/clang/Sema/Template.h b/clang/include/clang/Sema/Template.h
index 0dcaf565591b..91d175fdd050 100644
--- a/clang/include/clang/Sema/Template.h
+++ b/clang/include/clang/Sema/Template.h
@@ -600,7 +600,7 @@ enum class TemplateSubstitutionKind : char {
                         TagDecl *NewDecl);
 
     Decl *VisitVarTemplateSpecializationDecl(
-        VarTemplateDecl *VarTemplate, VarDecl *FromVar,
+        VarTemplateDecl *VarTemplate, VarDecl *FromVar, void *InsertPos,
         const TemplateArgumentListInfo &TemplateArgsInfo,
         ArrayRef<TemplateArgument> Converted,
         VarTemplateSpecializationDecl *PrevDecl = nullptr);
diff --git a/clang/lib/Sema/SemaTemplate.cpp b/clang/lib/Sema/SemaTemplate.cpp
index ddae944a48f3..c05ed0b14e3e 100644
--- a/clang/lib/Sema/SemaTemplate.cpp
+++ b/clang/lib/Sema/SemaTemplate.cpp
@@ -4471,7 +4471,7 @@ Sema::CheckVarTemplateId(VarTemplateDecl *Template, SourceLocation TemplateLoc,
   // FIXME: LateAttrs et al.?
   VarTemplateSpecializationDecl *Decl = BuildVarTemplateInstantiation(
       Template, InstantiationPattern, *InstantiationArgs, TemplateArgs,
-      Converted, TemplateNameLoc /*, LateAttrs, StartingScope*/);
+      Converted, TemplateNameLoc, InsertPos /*, LateAttrs, StartingScope*/);
   if (!Decl)
     return true;
 
diff --git a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
index 903785a2be42..baec13ba627c 100644
--- a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
+++ b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
@@ -3602,11 +3602,11 @@ Decl *TemplateDeclInstantiator::VisitVarTemplateSpecializationDecl(
     return nullptr;
 
   return VisitVarTemplateSpecializationDecl(
-      InstVarTemplate, D, VarTemplateArgsInfo, Converted, PrevDecl);
+      InstVarTemplate, D, InsertPos, VarTemplateArgsInfo, Converted, PrevDecl);
 }
 
 Decl *TemplateDeclInstantiator::VisitVarTemplateSpecializationDecl(
-    VarTemplateDecl *VarTemplate, VarDecl *D,
+    VarTemplateDecl *VarTemplate, VarDecl *D, void *InsertPos,
     const TemplateArgumentListInfo &TemplateArgsInfo,
     ArrayRef<TemplateArgument> Converted,
     VarTemplateSpecializationDecl *PrevDecl) {
@@ -3629,11 +3629,8 @@ Decl *TemplateDeclInstantiator::VisitVarTemplateSpecializationDecl(
       SemaRef.Context, Owner, D->getInnerLocStart(), D->getLocation(),
       VarTemplate, DI->getType(), DI, D->getStorageClass(), Converted);
   Var->setTemplateArgsInfo(TemplateArgsInfo);
-  if (!PrevDecl) {
-    void *InsertPos = nullptr;
-    VarTemplate->findSpecialization(Converted, InsertPos);
+  if (InsertPos)
     VarTemplate->AddSpecialization(Var, InsertPos);
-  }
 
   if (SemaRef.getLangOpts().OpenCL)
     SemaRef.deduceOpenCLAddressSpace(Var);
@@ -4842,7 +4839,7 @@ VarTemplateSpecializationDecl *Sema::BuildVarTemplateInstantiation(
     const TemplateArgumentList &TemplateArgList,
     const TemplateArgumentListInfo &TemplateArgsInfo,
     SmallVectorImpl<TemplateArgument> &Converted,
-    SourceLocation PointOfInstantiation,
+    SourceLocation PointOfInstantiation, void *InsertPos,
     LateInstantiatedAttrVec *LateAttrs,
     LocalInstantiationScope *StartingScope) {
   if (FromVar->isInvalidDecl())
@@ -4881,7 +4878,7 @@ VarTemplateSpecializationDecl *Sema::BuildVarTemplateInstantiation(
 
   return cast_or_null<VarTemplateSpecializationDecl>(
       Instantiator.VisitVarTemplateSpecializationDecl(
-          VarTemplate, FromVar, TemplateArgsInfo, Converted));
+          VarTemplate, FromVar, InsertPos, TemplateArgsInfo, Converted));
 }
 
 /// Instantiates a variable template specialization by completing it
@@ -5313,8 +5310,8 @@ void Sema::InstantiateVariableDefinition(SourceLocation PointOfInstantiation,
     TemplateDeclInstantiator Instantiator(*this, Var->getDeclContext(),
                                           TemplateArgs);
     Var = cast_or_null<VarDecl>(Instantiator.VisitVarTemplateSpecializationDecl(
-        VarSpec->getSpecializedTemplate(), Def, VarSpec->getTemplateArgsInfo(),
-        VarSpec->getTemplateArgs().asArray(), VarSpec));
+        VarSpec->getSpecializedTemplate(), Def, nullptr,
+        VarSpec->getTemplateArgsInfo(), VarSpec->getTemplateArgs().asArray()));
     if (Var) {
       llvm::PointerUnion<VarTemplateDecl *,
                          VarTemplatePartialSpecializationDecl *> PatternPtr =
@@ -5324,6 +5321,12 @@ void Sema::InstantiateVariableDefinition(SourceLocation PointOfInstantiation,
         cast<VarTemplateSpecializationDecl>(Var)->setInstantiationOf(
             Partial, &VarSpec->getTemplateInstantiationArgs());
 
+      // Merge the definition with the declaration.
+      LookupResult R(*this, Var->getDeclName(), Var->getLocation(),
+                     LookupOrdinaryName, forRedeclarationInCurContext());
+      R.addDecl(OldVar);
+      MergeVarDecl(Var, R);
+
       // Attach the initializer.
       InstantiateVariableInitializer(Var, Def, TemplateArgs);
     }
diff --git a/clang/test/SemaTemplate/instantiate-var-template.cpp b/clang/test/SemaTemplate/instantiate-var-template.cpp
index a24b205da596..b7b83e4afdd5 100644
--- a/clang/test/SemaTemplate/instantiate-var-template.cpp
+++ b/clang/test/SemaTemplate/instantiate-var-template.cpp
@@ -40,10 +40,3 @@ namespace PR24483 {
   template<typename... T> A<T...> models;
   template<> struct B models<>; // expected-error {{incomplete type 'struct B'}} expected-note {{forward declaration}}
 }
-
-namespace InvalidInsertPos {
-  template<typename T, int N> T v;
-  template<int N> decltype(v<int, N-1>) v<int, N>;
-  template<> int v<int, 0>;
-  int k = v<int, 500>;
-}