Parse A::template B as an identifier rather than as a template-id with no

template arguments.

This fixes some cases where we'd incorrectly accept "A::template B" when B is a
kind of template that requires template arguments (in particular, a variable
template or a concept).


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@331013 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 14 insertions, 11 deletions

diff --git a/lib/Sema/SemaExpr.cpp b/lib/Sema/SemaExpr.cpp
index 6f2800ea27..b1ecbfad4c 100644
--- a/lib/Sema/SemaExpr.cpp
+++ b/lib/Sema/SemaExpr.cpp
@@ -2080,7 +2080,7 @@ Sema::ActOnIdExpression(Scope *S, CXXScopeSpec &SS,
                  (Id.getKind() == UnqualifiedIdKind::IK_ImplicitSelfParam)
                      ? LookupObjCImplicitSelfParam
                      : LookupOrdinaryName);
-  if (TemplateArgs) {
+  if (TemplateKWLoc.isValid() || TemplateArgs) {
     // Lookup the template name again to correctly establish the context in
     // which it was found. This is really unfortunate as we already did the
     // lookup to determine that it was a template name in the first place. If
@@ -2089,7 +2089,7 @@ Sema::ActOnIdExpression(Scope *S, CXXScopeSpec &SS,
     bool MemberOfUnknownSpecialization;
     LookupTemplateName(R, S, SS, QualType(), /*EnteringContext=*/false,
                        MemberOfUnknownSpecialization);
-    
+
     if (MemberOfUnknownSpecialization ||
         (R.getResultKind() == LookupResult::NotFoundInCurrentInstantiation))
       return ActOnDependentIdExpression(SS, TemplateKWLoc, NameInfo,
@@ -2155,6 +2155,9 @@ Sema::ActOnIdExpression(Scope *S, CXXScopeSpec &SS,
       if (SS.isValid())
         CCC->setTypoNNS(SS.getScopeRep());
     }
+    // FIXME: DiagnoseEmptyLookup produces bad diagnostics if we're looking for
+    // a template name, but we happen to have always already looked up the name
+    // before we get here if it must be a template name.
     if (DiagnoseEmptyLookup(S, SS, R,
                             CCC ? std::move(CCC) : std::move(DefaultValidator),
                             nullptr, None, &TE)) {
diff --git a/lib/Sema/SemaExprMember.cpp b/lib/Sema/SemaExprMember.cpp
index 775008ea80..e03f143bcb 100644
--- a/lib/Sema/SemaExprMember.cpp
+++ b/lib/Sema/SemaExprMember.cpp
@@ -759,9 +759,9 @@ Sema::BuildMemberReferenceExpr(Expr *Base, QualType BaseType,
     TypoExpr *TE = nullptr;
     QualType RecordTy = BaseType;
     if (IsArrow) RecordTy = RecordTy->getAs<PointerType>()->getPointeeType();
-    if (LookupMemberExprInRecord(*this, R, nullptr,
-                                 RecordTy->getAs<RecordType>(), OpLoc, IsArrow,
-                                 SS, TemplateArgs != nullptr, TE))
+    if (LookupMemberExprInRecord(
+            *this, R, nullptr, RecordTy->getAs<RecordType>(), OpLoc, IsArrow,
+            SS, TemplateKWLoc.isValid() || TemplateArgs != nullptr, TE))
       return ExprError();
     if (TE)
       return TE;
@@ -769,10 +769,10 @@ Sema::BuildMemberReferenceExpr(Expr *Base, QualType BaseType,
   // Explicit member accesses.
   } else {
     ExprResult BaseResult = Base;
-    ExprResult Result = LookupMemberExpr(
-        *this, R, BaseResult, IsArrow, OpLoc, SS,
-        ExtraArgs ? ExtraArgs->ObjCImpDecl : nullptr,
-        TemplateArgs != nullptr);
+    ExprResult Result =
+        LookupMemberExpr(*this, R, BaseResult, IsArrow, OpLoc, SS,
+                         ExtraArgs ? ExtraArgs->ObjCImpDecl : nullptr,
+                         TemplateKWLoc.isValid() || TemplateArgs != nullptr);
 
     if (BaseResult.isInvalid())
       return ExprError();
diff --git a/lib/Sema/SemaTemplate.cpp b/lib/Sema/SemaTemplate.cpp
index 788eaca674..d98176ad2e 100644
--- a/lib/Sema/SemaTemplate.cpp
+++ b/lib/Sema/SemaTemplate.cpp
@@ -158,7 +158,7 @@ bool Sema::hasAnyAcceptableTemplateNames(LookupResult &R,
 TemplateNameKind Sema::isTemplateName(Scope *S,
                                       CXXScopeSpec &SS,
                                       bool hasTemplateKeyword,
-                                      UnqualifiedId &Name,
+                                      const UnqualifiedId &Name,
                                       ParsedType ObjectTypePtr,
                                       bool EnteringContext,
                                       TemplateTy &TemplateResult,
@@ -4102,7 +4102,7 @@ Sema::BuildQualifiedTemplateIdExpr(CXXScopeSpec &SS,
 TemplateNameKind Sema::ActOnDependentTemplateName(Scope *S,
                                                   CXXScopeSpec &SS,
                                                   SourceLocation TemplateKWLoc,
-                                                  UnqualifiedId &Name,
+                                                  const UnqualifiedId &Name,
                                                   ParsedType ObjectType,
                                                   bool EnteringContext,
                                                   TemplateTy &Result,