[clang] cffb0dd - [SemaTemplate] Stop passing insertion position around during VarTemplate instantiation

[Bruno Cardoso Lopes via cfe-commits]

Author: Bruno Cardoso Lopes
Date: 2020-10-12T16:48:50-07:00
New Revision: cffb0dd54d41d8e249d2009467c4beb5b681ba26

URL: https://github.com/llvm/llvm-project/commit/cffb0dd54d41d8e249d2009467c4beb5b681ba26
DIFF: https://github.com/llvm/llvm-project/commit/cffb0dd54d41d8e249d2009467c4beb5b681ba26.diff

LOG: [SemaTemplate] Stop passing insertion position around during VarTemplate instantiation

They can get stale at use time because of updates from other recursive
specializations. Instead, rely on the existence of previous declarations to add
the specialization.

Differential Revision: https://reviews.llvm.org/D87853

Added: 
    

Modified: 
    clang/include/clang/Sema/Sema.h
    clang/include/clang/Sema/Template.h
    clang/lib/Sema/SemaTemplate.cpp
    clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
    clang/test/SemaTemplate/instantiate-var-template.cpp

Removed: 
    


################################################################################
diff  --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
index ca1f87cfdb2b..b5f0c08300bf 100644
--- a/clang/include/clang/Sema/Sema.h
+++ b/clang/include/clang/Sema/Sema.h
@@ -9171,7 +9171,7 @@ class Sema final {
       const TemplateArgumentList &TemplateArgList,
       const TemplateArgumentListInfo &TemplateArgsInfo,
       SmallVectorImpl<TemplateArgument> &Converted,
-      SourceLocation PointOfInstantiation, void *InsertPos,
+      SourceLocation PointOfInstantiation,
       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 91d175fdd050..0dcaf565591b 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, void *InsertPos,
+        VarTemplateDecl *VarTemplate, VarDecl *FromVar,
         const TemplateArgumentListInfo &TemplateArgsInfo,
         ArrayRef<TemplateArgument> Converted,
         VarTemplateSpecializationDecl *PrevDecl = nullptr);

diff  --git a/clang/lib/Sema/SemaTemplate.cpp b/clang/lib/Sema/SemaTemplate.cpp
index 8baf5b96fbf8..4ecae8faad66 100644
--- a/clang/lib/Sema/SemaTemplate.cpp
+++ b/clang/lib/Sema/SemaTemplate.cpp
@@ -4584,7 +4584,7 @@ Sema::CheckVarTemplateId(VarTemplateDecl *Template, SourceLocation TemplateLoc,
   // FIXME: LateAttrs et al.?
   VarTemplateSpecializationDecl *Decl = BuildVarTemplateInstantiation(
       Template, InstantiationPattern, *InstantiationArgs, TemplateArgs,
-      Converted, TemplateNameLoc, InsertPos /*, LateAttrs, StartingScope*/);
+      Converted, TemplateNameLoc /*, LateAttrs, StartingScope*/);
   if (!Decl)
     return true;
 

diff  --git a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
index 9420bd04b7a9..7200dc72825d 100644
--- a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
+++ b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
@@ -3628,11 +3628,11 @@ Decl *TemplateDeclInstantiator::VisitVarTemplateSpecializationDecl(
     return nullptr;
 
   return VisitVarTemplateSpecializationDecl(
-      InstVarTemplate, D, InsertPos, VarTemplateArgsInfo, Converted, PrevDecl);
+      InstVarTemplate, D, VarTemplateArgsInfo, Converted, PrevDecl);
 }
 
 Decl *TemplateDeclInstantiator::VisitVarTemplateSpecializationDecl(
-    VarTemplateDecl *VarTemplate, VarDecl *D, void *InsertPos,
+    VarTemplateDecl *VarTemplate, VarDecl *D,
     const TemplateArgumentListInfo &TemplateArgsInfo,
     ArrayRef<TemplateArgument> Converted,
     VarTemplateSpecializationDecl *PrevDecl) {
@@ -3655,8 +3655,11 @@ Decl *TemplateDeclInstantiator::VisitVarTemplateSpecializationDecl(
       SemaRef.Context, Owner, D->getInnerLocStart(), D->getLocation(),
       VarTemplate, DI->getType(), DI, D->getStorageClass(), Converted);
   Var->setTemplateArgsInfo(TemplateArgsInfo);
-  if (InsertPos)
+  if (!PrevDecl) {
+    void *InsertPos = nullptr;
+    VarTemplate->findSpecialization(Converted, InsertPos);
     VarTemplate->AddSpecialization(Var, InsertPos);
+  }
 
   if (SemaRef.getLangOpts().OpenCL)
     SemaRef.deduceOpenCLAddressSpace(Var);
@@ -4865,7 +4868,7 @@ VarTemplateSpecializationDecl *Sema::BuildVarTemplateInstantiation(
     const TemplateArgumentList &TemplateArgList,
     const TemplateArgumentListInfo &TemplateArgsInfo,
     SmallVectorImpl<TemplateArgument> &Converted,
-    SourceLocation PointOfInstantiation, void *InsertPos,
+    SourceLocation PointOfInstantiation,
     LateInstantiatedAttrVec *LateAttrs,
     LocalInstantiationScope *StartingScope) {
   if (FromVar->isInvalidDecl())
@@ -4904,7 +4907,7 @@ VarTemplateSpecializationDecl *Sema::BuildVarTemplateInstantiation(
 
   return cast_or_null<VarTemplateSpecializationDecl>(
       Instantiator.VisitVarTemplateSpecializationDecl(
-          VarTemplate, FromVar, InsertPos, TemplateArgsInfo, Converted));
+          VarTemplate, FromVar, TemplateArgsInfo, Converted));
 }
 
 /// Instantiates a variable template specialization by completing it
@@ -5327,8 +5330,8 @@ void Sema::InstantiateVariableDefinition(SourceLocation PointOfInstantiation,
     TemplateDeclInstantiator Instantiator(*this, Var->getDeclContext(),
                                           TemplateArgs);
     Var = cast_or_null<VarDecl>(Instantiator.VisitVarTemplateSpecializationDecl(
-        VarSpec->getSpecializedTemplate(), Def, nullptr,
-        VarSpec->getTemplateArgsInfo(), VarSpec->getTemplateArgs().asArray()));
+        VarSpec->getSpecializedTemplate(), Def, VarSpec->getTemplateArgsInfo(),
+        VarSpec->getTemplateArgs().asArray(), VarSpec));
     if (Var) {
       llvm::PointerUnion<VarTemplateDecl *,
                          VarTemplatePartialSpecializationDecl *> PatternPtr =
@@ -5338,12 +5341,6 @@ 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 b7b83e4afdd5..a24b205da596 100644
--- a/clang/test/SemaTemplate/instantiate-var-template.cpp
+++ b/clang/test/SemaTemplate/instantiate-var-template.cpp
@@ -40,3 +40,10 @@ 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>;
+}