https://github.com/sdkrystian updated
https://github.com/llvm/llvm-project/pull/80842
>From 13abf4ca1003f4cc04926881ce74c5f4818a761c Mon Sep 17 00:00:00 2001
From: Krystian Stasiowski <sdkryst...@gmail.com>
Date: Tue, 6 Feb 2024 09:14:42 -0500
Subject: [PATCH] [Clang][Sema] Diagnose declarative nested-name-specifiers
naming alias templates
---
.../clang/Basic/DiagnosticSemaKinds.td | 3 ++
clang/lib/Sema/SemaDecl.cpp | 36 +++++++++++++------
.../expr.prim.id/expr.prim.id.qual/p3.cpp | 29 +++++++++++++++
.../temp.res/temp.dep/temp.dep.type/p1.cpp | 2 +-
4 files changed, 59 insertions(+), 11 deletions(-)
create mode 100644
clang/test/CXX/expr/expr.prim/expr.prim.id/expr.prim.id.qual/p3.cpp
diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td
b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index f76e7a3392183e..d02fddd0693413 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -8250,6 +8250,9 @@ def err_not_tag_in_scope : Error<
def ext_template_after_declarative_nns : ExtWarn<
"'template' cannot be used after a declarative nested name specifier">,
InGroup<DiagGroup<"template-in-declaration-name">>;
+def ext_alias_template_in_declarative_nns : ExtWarn<
+ "a declarative nested name specifier cannot name an alias template">,
+ InGroup<DiagGroup<"alias-template-in-declaration-name">>;
def err_no_typeid_with_fno_rtti : Error<
"use of typeid requires -frtti">;
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index 481d952d2389bb..9d4f757caf9ca3 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -6207,6 +6207,8 @@ bool Sema::diagnoseQualifiedDeclaration(CXXScopeSpec &SS,
DeclContext *DC,
SourceLocation Loc,
TemplateIdAnnotation *TemplateId,
bool IsMemberSpecialization) {
+ assert(SS.isValid() && "diagnoseQualifiedDeclaration called for declaration "
+ "without nested-name-specifier");
DeclContext *Cur = CurContext;
while (isa<LinkageSpecDecl>(Cur) || isa<CapturedDecl>(Cur))
Cur = Cur->getParent();
@@ -6295,22 +6297,36 @@ bool Sema::diagnoseQualifiedDeclaration(CXXScopeSpec
&SS, DeclContext *DC,
<< FixItHint::CreateRemoval(TemplateId->TemplateKWLoc);
NestedNameSpecifierLoc SpecLoc(SS.getScopeRep(), SS.location_data());
- while (SpecLoc.getPrefix()) {
+ do {
if (SpecLoc.getNestedNameSpecifier()->getKind() ==
NestedNameSpecifier::TypeSpecWithTemplate)
Diag(Loc, diag::ext_template_after_declarative_nns)
<< FixItHint::CreateRemoval(
SpecLoc.getTypeLoc().getTemplateKeywordLoc());
- SpecLoc = SpecLoc.getPrefix();
- }
- // C++11 [dcl.meaning]p1:
- // [...] "The nested-name-specifier of the qualified declarator-id shall
- // not begin with a decltype-specifer"
- if (isa_and_nonnull<DecltypeType>(
- SpecLoc.getNestedNameSpecifier()->getAsType()))
- Diag(Loc, diag::err_decltype_in_declarator)
- << SpecLoc.getTypeLoc().getSourceRange();
+ if (const Type *T = SpecLoc.getNestedNameSpecifier()->getAsType()) {
+ if (const auto *TST = T->getAsAdjusted<TemplateSpecializationType>()) {
+ // C++23 [expr.prim.id.qual]p3:
+ // [...] If a nested-name-specifier N is declarative and has a
+ // simple-template-id with a template argument list A that involves a
+ // template parameter, let T be the template nominated by N without
A.
+ // T shall be a class template.
+ if (TST->isDependentType() && TST->isTypeAlias())
+ Diag(Loc, diag::ext_alias_template_in_declarative_nns)
+ << SpecLoc.getLocalSourceRange();
+ } else if (T->isDecltypeType()) {
+ // C++23 [expr.prim.id.qual]p2:
+ // [...] A declarative nested-name-specifier shall not have a
+ // decltype-specifier.
+ //
+ // FIXME: This wording appears to be defective as it does not forbid
+ // declarative nested-name-specifiers with pack-index-specifiers.
+ // See https://github.com/cplusplus/CWG/issues/499.
+ Diag(Loc, diag::err_decltype_in_declarator)
+ << SpecLoc.getTypeLoc().getSourceRange();
+ }
+ }
+ } while ((SpecLoc = SpecLoc.getPrefix()));
return false;
}
diff --git
a/clang/test/CXX/expr/expr.prim/expr.prim.id/expr.prim.id.qual/p3.cpp
b/clang/test/CXX/expr/expr.prim/expr.prim.id/expr.prim.id.qual/p3.cpp
new file mode 100644
index 00000000000000..c73ffa55a26a31
--- /dev/null
+++ b/clang/test/CXX/expr/expr.prim/expr.prim.id/expr.prim.id.qual/p3.cpp
@@ -0,0 +1,29 @@
+// RUN: %clang_cc1 -verify %s
+
+template<typename T>
+struct A {
+ void f();
+};
+
+template<typename T>
+using B = A<T>;
+
+template<typename T>
+void B<T>::f() { } // expected-warning {{a declarative nested name specifier
cannot name an alias template}}
+
+template<>
+void B<int>::f() { } // ok, template argument list of simple-template-id
doesn't involve template parameters
+
+namespace N {
+
+ template<typename T>
+ struct D {
+ void f();
+ };
+
+ template<typename T>
+ using E = D<T>;
+}
+
+template<typename T>
+void N::E<T>::f() { } // expected-warning {{a declarative nested name
specifier cannot name an alias template}}
diff --git a/clang/test/CXX/temp/temp.res/temp.dep/temp.dep.type/p1.cpp
b/clang/test/CXX/temp/temp.res/temp.dep/temp.dep.type/p1.cpp
index 82983f05fe8782..910dab11ee5e18 100644
--- a/clang/test/CXX/temp/temp.res/temp.dep/temp.dep.type/p1.cpp
+++ b/clang/test/CXX/temp/temp.res/temp.dep/temp.dep.type/p1.cpp
@@ -26,5 +26,5 @@ namespace Example2 {
void g();
};
template<class T> using B = A<T>;
- template<class T> void B<T>::g() {} // ok.
+ template<class T> void B<T>::g() {} // // expected-warning {{a declarative
nested name specifier cannot name an alias template}}
}
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