[c++1z] Disallow deduction guides with deduced types that don't syntactically match the template being deduced.
llvm-svn: 294773
diff --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp
index 0acf91d..c12c9b2 100644
--- a/clang/lib/Sema/SemaDeclCXX.cpp
+++ b/clang/lib/Sema/SemaDeclCXX.cpp
@@ -8192,12 +8192,46 @@
diag::err_deduction_guide_no_trailing_return_type);
break;
}
+
+ // Check that the return type is written as a specialization of
+ // the template specified as the deduction-guide's name.
+ ParsedType TrailingReturnType = Chunk.Fun.getTrailingReturnType();
+ TemplateName GuidedTemplate = D.getName().TemplateName.get().get();
+ TypeSourceInfo *TSI = nullptr;
+ QualType RetTy = GetTypeFromParser(TrailingReturnType, &TSI);
+ assert(TSI && "deduction guide has valid type but invalid return type?");
+ bool AcceptableReturnType = false;
+ bool MightInstantiateToSpecialization = false;
+ if (auto RetTST =
+ TSI->getTypeLoc().getAs<TemplateSpecializationTypeLoc>()) {
+ TemplateName SpecifiedName = RetTST.getTypePtr()->getTemplateName();
+ bool TemplateMatches =
+ Context.hasSameTemplateName(SpecifiedName, GuidedTemplate);
+ if (SpecifiedName.getKind() == TemplateName::Template && TemplateMatches)
+ AcceptableReturnType = true;
+ else {
+ // This could still instantiate to the right type, unless we know it
+ // names the wrong class template.
+ auto *TD = SpecifiedName.getAsTemplateDecl();
+ MightInstantiateToSpecialization = !(TD && isa<ClassTemplateDecl>(TD) &&
+ !TemplateMatches);
+ }
+ } else if (!RetTy.hasQualifiers() && RetTy->isDependentType()) {
+ MightInstantiateToSpecialization = true;
+ }
+
+ if (!AcceptableReturnType) {
+ Diag(TSI->getTypeLoc().getLocStart(),
+ diag::err_deduction_guide_bad_trailing_return_type)
+ << GuidedTemplate << TSI->getType() << MightInstantiateToSpecialization
+ << TSI->getTypeLoc().getSourceRange();
+ }
+
+ // Keep going to check that we don't have any inner declarator pieces (we
+ // could still have a function returning a pointer to a function).
FoundFunction = true;
}
- // FIXME: Check that the return type can instantiate to a specialization of
- // the template specified as the deduction-guide's name.
-
if (D.isFunctionDefinition())
Diag(D.getIdentifierLoc(), diag::err_deduction_guide_defines_function);
}