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).

llvm-svn: 331013

1 files changed, 5 insertions, 2 deletions

diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index 6f2800ea27d..b1ecbfad4c3 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/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)) {