[Clang][Sema] Don't say "is declared here" for invalid template locat…

…ions If a template is defined via an external AST source, it won't have a location. When we emit warnings about misusing such templates we shouldn't emit a "template is declared here" warning with no location, as that's just confusing. Reviewers: llvm-beanz, erichkeane, AaronBallman Reviewed By: erichkeane, AaronBallman Pull Request: #71264
llvm · Dec 6, 2023 · 0cd308a · 0cd308a
1 parent 62b11e1
commit 0cd308a
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Showing 9 changed files with 91 additions and 61 deletions.
diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -4933,6 +4933,8 @@ def err_template_param_shadow : Error<
 def ext_template_param_shadow : ExtWarn<
   err_template_param_shadow.Summary>, InGroup<MicrosoftTemplateShadow>;
 def note_template_param_here : Note<"template parameter is declared here">;
+def note_template_param_external : Note<
+  "template parameter from hidden source: %0">;
 def warn_template_export_unsupported : Warning<
   "exported templates are unsupported">;
 def err_template_outside_namespace_or_class_scope : Error<
@@ -5061,6 +5063,8 @@ def err_template_arg_list_different_arity : Error<
   "%select{class template|function template|variable template|alias template|"
   "template template parameter|concept|template}1 %2">;
 def note_template_decl_here : Note<"template is declared here">;
+def note_template_decl_external : Note<
+  "template declaration from hidden source: %0">;
 def err_template_arg_must_be_type : Error<
   "template argument for template type parameter must be a type">;
 def err_template_arg_must_be_type_suggest : Error<

diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
@@ -8561,6 +8561,10 @@ class Sema final {
                                      TemplateParameterList *Params,
                                      TemplateArgumentLoc &Arg);
 
+  void NoteTemplateLocation(const NamedDecl &Decl,
+                            std::optional<SourceRange> ParamRange = {});
+  void NoteTemplateParameterLocation(const NamedDecl &Decl);
+
   ExprResult
   BuildExpressionFromDeclTemplateArgument(const TemplateArgument &Arg,
                                           QualType ParamType,

diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
@@ -5971,7 +5971,7 @@ Sema::GetNameFromUnqualifiedId(const UnqualifiedId &Name) {
            diag::err_deduction_guide_name_not_class_template)
         << (int)getTemplateNameKindForDiagnostics(TN) << TN;
       if (Template)
-        Diag(Template->getLocation(), diag::note_template_decl_here);
+        NoteTemplateLocation(*Template);
       return DeclarationNameInfo();
     }
 

diff --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp
@@ -11462,7 +11462,7 @@ bool Sema::CheckDeductionGuideDeclarator(Declarator &D, QualType &R,
           GuidedTemplateDecl->getDeclContext()->getRedeclContext())) {
     Diag(D.getIdentifierLoc(), diag::err_deduction_guide_wrong_scope)
       << GuidedTemplateDecl;
-    Diag(GuidedTemplateDecl->getLocation(), diag::note_template_decl_here);
+    NoteTemplateLocation(*GuidedTemplateDecl);
   }
 
   auto &DS = D.getMutableDeclSpec();

diff --git a/clang/lib/Sema/SemaInit.cpp b/clang/lib/Sema/SemaInit.cpp
@@ -10573,7 +10573,7 @@ QualType Sema::DeduceTemplateSpecializationFromInitializer(
          diag::err_deduced_non_class_template_specialization_type)
       << (int)getTemplateNameKindForDiagnostics(TemplateName) << TemplateName;
     if (auto *TD = TemplateName.getAsTemplateDecl())
-      Diag(TD->getLocation(), diag::note_template_decl_here);
+      NoteTemplateLocation(*TD);
     return QualType();
   }
 

diff --git a/clang/lib/Sema/SemaLambda.cpp b/clang/lib/Sema/SemaLambda.cpp
@@ -1444,7 +1444,7 @@ void Sema::ActOnStartOfLambdaDefinition(LambdaIntroducer &Intro,
       for (const auto &Capture : Intro.Captures) {
         if (Capture.Id == TP->getIdentifier()) {
           Diag(Capture.Loc, diag::err_template_param_shadow) << Capture.Id;
-          Diag(TP->getLocation(), diag::note_template_param_here);
+          NoteTemplateParameterLocation(*TP);
         }
       }
     }