4 files changed, 18 insertions, 22 deletions
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index 1bcc9329e4c..0c412d373cb 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -724,13 +724,7 @@ void Sema::DiagnoseUnknownTypeName(IdentifierInfo *&II,
     if (isTemplateName(S, SS ? *SS : EmptySS, /*hasTemplateKeyword=*/false,
                        Name, nullptr, true, TemplateResult,
                        MemberOfUnknownSpecialization) == TNK_Type_template) {
-      TemplateName TplName = TemplateResult.get();
-      Diag(IILoc, diag::err_template_missing_args)
-        << (int)getTemplateNameKindForDiagnostics(TplName) << TplName;
-      if (TemplateDecl *TplDecl = TplName.getAsTemplateDecl()) {
-        Diag(TplDecl->getLocation(), diag::note_template_decl_here)
-          << TplDecl->getTemplateParameters()->getSourceRange();
-      }
+      diagnoseMissingTemplateArguments(TemplateResult.get(), IILoc);
       return;
     }
   }
@@ -1167,6 +1161,8 @@ Sema::getTemplateNameKindForDiagnostics(TemplateName Name) {
     return TemplateNameKindForDiagnostics::AliasTemplate;
   if (isa<TemplateTemplateParmDecl>(TD))
     return TemplateNameKindForDiagnostics::TemplateTemplateParam;
+  if (isa<ConceptDecl>(TD))
+    return TemplateNameKindForDiagnostics::Concept;
   return TemplateNameKindForDiagnostics::DependentTemplate;
 }
 
diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index b4d1eb0e0ce..6f2800ea27d 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -2776,9 +2776,7 @@ ExprResult Sema::BuildDeclarationNameExpr(
   if (TemplateDecl *Template = dyn_cast<TemplateDecl>(D)) {
     // Specifically diagnose references to class templates that are missing
     // a template argument list.
-    Diag(Loc, diag::err_template_decl_ref) << (isa<VarTemplateDecl>(D) ? 1 : 0)
-                                           << Template << SS.getRange();
-    Diag(Template->getLocation(), diag::note_template_decl_here);
+    diagnoseMissingTemplateArguments(TemplateName(Template), Loc);
     return ExprError();
   }
 
diff --git a/clang/lib/Sema/SemaExprMember.cpp b/clang/lib/Sema/SemaExprMember.cpp
index 01a13c4b357..775008ea807 100644
--- a/clang/lib/Sema/SemaExprMember.cpp
+++ b/clang/lib/Sema/SemaExprMember.cpp
@@ -920,16 +920,12 @@ getVarTemplateSpecialization(Sema &S, VarTemplateDecl *VarTempl,
                       const TemplateArgumentListInfo *TemplateArgs,
                       const DeclarationNameInfo &MemberNameInfo,
                       SourceLocation TemplateKWLoc) {
-
   if (!TemplateArgs) {
-    S.Diag(MemberNameInfo.getBeginLoc(), diag::err_template_decl_ref)
-        << /*Variable template*/ 1 << MemberNameInfo.getName()
-        << MemberNameInfo.getSourceRange();
-
-    S.Diag(VarTempl->getLocation(), diag::note_template_decl_here);
-
+    S.diagnoseMissingTemplateArguments(TemplateName(VarTempl),
+                                       MemberNameInfo.getBeginLoc());
     return nullptr;
   }
+
   DeclResult VDecl = S.CheckVarTemplateId(
       VarTempl, TemplateKWLoc, MemberNameInfo.getLoc(), *TemplateArgs);
   if (VDecl.isInvalid())
diff --git a/clang/lib/Sema/SemaTemplate.cpp b/clang/lib/Sema/SemaTemplate.cpp
index 239f3617ca9..442a8ec6805 100644
--- a/clang/lib/Sema/SemaTemplate.cpp
+++ b/clang/lib/Sema/SemaTemplate.cpp
@@ -3988,6 +3988,16 @@ Sema::CheckVarTemplateId(const CXXScopeSpec &SS,
                                   /*FoundD=*/nullptr, TemplateArgs);
 }
 
+void Sema::diagnoseMissingTemplateArguments(TemplateName Name,
+                                            SourceLocation Loc) {
+  Diag(Loc, diag::err_template_missing_args)
+    << (int)getTemplateNameKindForDiagnostics(Name) << Name;
+  if (TemplateDecl *TD = Name.getAsTemplateDecl()) {
+    Diag(TD->getLocation(), diag::note_template_decl_here)
+      << TD->getTemplateParameters()->getSourceRange();
+  }
+}
+
 ExprResult Sema::BuildTemplateIdExpr(const CXXScopeSpec &SS,
                                      SourceLocation TemplateKWLoc,
                                      LookupResult &R,
@@ -4208,11 +4218,7 @@ bool Sema::CheckTemplateTypeArgument(TemplateTypeParmDecl *Param,
     // is a template without any arguments.
     SourceRange SR = AL.getSourceRange();
     TemplateName Name = Arg.getAsTemplateOrTemplatePattern();
-    Diag(SR.getBegin(), diag::err_template_missing_args)
-      << (int)getTemplateNameKindForDiagnostics(Name) << Name << SR;
-    if (TemplateDecl *Decl = Name.getAsTemplateDecl())
-      Diag(Decl->getLocation(), diag::note_template_decl_here);
-
+    diagnoseMissingTemplateArguments(Name, SR.getEnd());
     return true;
   }
   case TemplateArgument::Expression: {