================
@@ -10598,10 +10598,38 @@ QualType
Sema::DeduceTemplateSpecializationFromInitializer(
if (TemplateName.isDependent())
return SubstAutoTypeDependent(TSInfo->getType());
- // We can only perform deduction for class templates.
+ // We can only perform deduction for class templates or alias templates.
auto *Template =
dyn_cast_or_null<ClassTemplateDecl>(TemplateName.getAsTemplateDecl());
+ TemplateDecl* LookupTemplateDecl = Template;
if (!Template) {
+ if (auto *AliasTemplate = dyn_cast_or_null<TypeAliasTemplateDecl>(
+ TemplateName.getAsTemplateDecl())) {
+ Diag(Kind.getLocation(),
+ diag::warn_cxx17_compat_ctad_for_alias_templates);
+ LookupTemplateDecl = AliasTemplate;
+ auto UnderlyingType = AliasTemplate->getTemplatedDecl()
+ ->getUnderlyingType()
+ .getCanonicalType();
+ // C++ [over.match.class.deduct#3]: ..., the defining-type-id of A must
be
+ // of the form
+ // [typename] [nested-name-specifier] [template] simple-template-id
+ if (const auto *TST =
+ UnderlyingType->getAs<TemplateSpecializationType>()) {
+ Template = dyn_cast_or_null<ClassTemplateDecl>(
+ TST->getTemplateName().getAsTemplateDecl());
+ } else if (const auto *RT = UnderlyingType->getAs<RecordType>()) {
+ // Cases where template arguments in the RHS of the alias are not
+ // dependent. e.g.
+ // using AliasFoo = Foo<bool>;
+ if (const auto *CTSD = llvm::dyn_cast<ClassTemplateSpecializationDecl>(
+ RT->getAsCXXRecordDecl()))
+ Template = CTSD->getSpecializedTemplate();
+ }
+ }
+ }
+ if (!Template) {
+ // FIXME: update the diagnostic message to include C++20 alias templates
----------------
cor3ntin wrote:
There is a FIXME here
https://github.com/llvm/llvm-project/pull/77890
_______________________________________________
cfe-commits mailing list
cfe-commits@lists.llvm.org
https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
