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clang-p2996/clang/test/SemaTemplate/ms-lookup-template-base-classes.cpp
Krystian Stasiowski fd87d765c0 [Clang][Sema] Don't build CXXDependentScopeMemberExprs for potentially implicit class member access expressions (#92318) 
According to [expr.prim.id.general] p2:
> If an _id-expression_ `E` denotes a non-static non-type member of some
class `C` at a point where the current class is `X` and
> - `E` is potentially evaluated or `C` is `X` or a base class of `X`,
and
> - `E` is not the _id-expression_ of a class member access expression,
and
> - if `E` is a _qualified-id_, `E` is not the un-parenthesized operand
of the unary `&` operator,
>
> the _id-expression_ is transformed into a class member access
expression using `(*this)` as the object expression.

Consider the following:
```
struct A
{
    void f0();

    template<typename T>
    void f1();
};

template<typename T>
struct B : T
{
    auto g0() -> decltype(T::f0()); // ok

    auto g1() -> decltype(T::template f1<int>()); // error: call to non-static member function without an object argument
};

template struct B<A>;
```

Clang incorrectly rejects the call to `f1` in the _trailing-return-type_
of `g1`. Furthermore, the following snippet results in a crash during
codegen:
```
struct A
{
    void f();
};

template<typename T>
struct B : T
{
    template<typename U>
    static void g();
    
    template<>
    void g<int>()
    {
        return T::f(); // crash here
    }
};

template struct B<A>;
```
This happens because we unconditionally build a
`CXXDependentScopeMemberExpr` (with an implicit object expression) for
`T::f` when parsing the template definition, even though we don't know
whether `g` is an implicit object member function yet.

This patch fixes these issues by instead building
`DependentScopeDeclRefExpr`s for such expressions, and only transforming
them into implicit class member access expressions during instantiation.
Since we implemented the MS "unqualified lookup into dependent bases"
extension by building an implicit class member access (and relying on
the first component name of the _nested-name-specifier_ to be looked up
in the context of the object expression during instantiation), we
instead pre-append a fake _nested-name-specifier_ that refers to the
injected-class-name of the enclosing class. This patch also refactors
`Sema::BuildQualifiedDeclarationNameExpr` and
`Sema::BuildQualifiedTemplateIdExpr`, streamlining their implementation
and removing any redundant checks.
2024-05-20 13:55:01 -04:00

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// RUN: %clang_cc1 -fcxx-exceptions -fexceptions -std=c++1y -fms-compatibility -fno-spell-checking -fsyntax-only -verify %s
// RUN: %clang_cc1 -fcxx-exceptions -fexceptions -std=c++20 -fms-compatibility -fno-spell-checking -fsyntax-only -verify %s
template <class T>
class A {
public:
void f(T a) { }// expected-note 2{{must qualify identifier to find this declaration in dependent base class}}
void g();// expected-note 2{{must qualify identifier to find this declaration in dependent base class}}
};
template <class T>
class B : public A<T> {
public:
void z(T a)
{
f(a); // expected-warning 2{{use of member 'f' found via unqualified lookup into dependent bases of class templates is a Microsoft extension}}
g(); // expected-warning 2{{use of member 'g' found via unqualified lookup into dependent bases of class templates is a Microsoft extension}}
}
};
template class B<int>; // expected-note {{requested here}}
template class B<char>; // expected-note {{requested here}}
void test()
{
B<int> b;
b.z(3);
}
struct A2 {
template<class T> void f(T) {
XX; //expected-error {{use of undeclared identifier 'XX'}}
A2::XX; //expected-error {{no member named 'XX' in 'A2'}}
}
};
template void A2::f(int);
template<class T0>
struct A3 {
template<class T1> void f(T1) {
XX; //expected-error {{use of undeclared identifier 'XX'}}
}
};
template void A3<int>::f(int);
template<class T0>
struct A4 {
void f(char) {
XX; //expected-error {{use of undeclared identifier 'XX'}}
}
};
template class A4<int>;
namespace lookup_dependent_bases_id_expr {
template<class T> class A {
public:
int var;
};
template<class T>
class B : public A<T> {
public:
void f() {
var = 3; // expected-warning {{use of undeclared identifier 'var'; unqualified lookup into dependent bases of class template 'B' is a Microsoft extension}}
}
};
template class B<int>;
template<typename T> struct C;
// Test lookup with incomplete lookup context
template<typename T>
auto C<T>::f() -> decltype(x) { } // expected-error {{use of undeclared identifier 'x'}}
// expected-error@-1 {{out-of-line definition of 'f' from class 'C<T>' without definition}}
}
namespace lookup_dependent_base_class_static_function {
template <class T>
class A {
public:
static void static_func();// expected-note {{must qualify identifier to find this declaration in dependent base class}}
void func();// expected-note {{must qualify identifier to find this declaration in dependent base class}}
};
template <class T>
class B : public A<T> {
public:
static void z2(){
static_func(); // expected-warning {{use of member 'static_func' found via unqualified lookup into dependent bases of class templates is a Microsoft extension}}
func(); // expected-warning {{use of member 'func' found via unqualified lookup into dependent bases of class templates is a Microsoft extension}} expected-error {{call to non-static member function without an object argument}}
}
};
template class B<int>; // expected-note {{requested here}}
}
namespace lookup_dependent_base_class_default_argument {
template<class T>
class A {
public:
static int f1(); // expected-note {{must qualify identifier to find this declaration in dependent base class}}
int f2(); // expected-note {{must qualify identifier to find this declaration in dependent base class}}
};
template<class T>
class B : public A<T> {
public:
void g1(int p = f1());// expected-warning {{use of member 'f1' found via unqualified lookup into dependent bases of class templates is a Microsoft extension}}
void g2(int p = f2());// expected-warning {{use of member 'f2' found via unqualified lookup into dependent bases of class templates is a Microsoft extension}} expected-error {{call to non-static member function without an object argument}}
};
void foo()
{
B<int> b;
b.g1(); // expected-note {{required here}}
b.g2(); // expected-note {{required here}}
}
}
namespace lookup_dependent_base_class_friend {
template <class T>
class B {
public:
static void g(); // expected-note {{must qualify identifier to find this declaration in dependent base class}}
};
template <class T>
class A : public B<T> {
public:
friend void foo(A<T> p){
g(); // expected-warning {{use of member 'g' found via unqualified lookup into dependent bases of class templates is a Microsoft extension}}
}
};
int main2()
{
A<int> a;
foo(a); // expected-note {{requested here}}
}
}
namespace lookup_dependent_base_no_typo_correction {
class C {
public:
int m_hWnd;
};
template <class T>
class A : public T {
public:
void f(int hWnd) {
m_hWnd = 1; // expected-warning {{use of undeclared identifier 'm_hWnd'; unqualified lookup into dependent bases of class template 'A' is a Microsoft extension}}
}
};
template class A<C>;
}
namespace PR12701 {
class A {};
class B {};
template <class T>
class Base {
public:
bool base_fun(void* p) { return false; } // expected-note {{must qualify identifier to find this declaration in dependent base class}}
operator T*() const { return 0; }
};
template <class T>
class Container : public Base<T> {
public:
template <typename S>
bool operator=(const Container<S>& rhs) {
return base_fun(rhs); // expected-warning {{use of member 'base_fun' found via unqualified lookup into dependent bases of class templates is a Microsoft extension}}
}
};
void f() {
Container<A> text_provider;
Container<B> text_provider2;
text_provider2 = text_provider; // expected-note {{in instantiation of function template specialization}}
}
} // namespace PR12701
namespace PR16014 {
struct A {
int a;
static int sa;
};
template <typename T> struct B : T {
int foo() { return a; } // expected-warning {{lookup into dependent bases}}
int *bar() { return &a; } // expected-warning {{lookup into dependent bases}}
int baz() { return T::a; }
int T::*qux() { return &T::a; }
static int T::*stuff() { return &T::a; }
static int stuff1() { return T::sa; }
static int *stuff2() { return &T::sa; }
static int stuff3() { return sa; } // expected-warning {{lookup into dependent bases}}
static int *stuff4() { return &sa; } // expected-warning {{lookup into dependent bases}}
};
template <typename T> struct C : T {
int foo() { return b; } // expected-error {{no member named 'b' in 'PR16014::C<A>'}} expected-warning {{lookup into dependent bases}}
int *bar() { return &b; } // expected-error {{no member named 'b' in 'PR16014::C<A>'}} expected-warning {{lookup into dependent bases}}
int baz() { return T::b; } // expected-error {{no member named 'b' in 'PR16014::A'}}
int T::*qux() { return &T::b; } // expected-error {{no member named 'b' in 'PR16014::A'}}
int T::*fuz() { return &U::a; } // expected-error {{no member named 'U' in 'PR16014::C<A>'}} \
// expected-warning {{unqualified lookup into dependent bases of class template 'C'}}
};
template struct B<A>;
template struct C<A>; // expected-note-re 1+ {{in instantiation of member function 'PR16014::C<PR16014::A>::{{.*}}' requested here}}
template <typename T> struct D : T {
struct Inner {
int foo() {
// FIXME: MSVC can find this in D's base T! Even worse, if ::sa exists,
// clang will use it instead.
return sa; // expected-error {{use of undeclared identifier 'sa'}}
}
};
};
template struct D<A>;
}
namespace PR19233 {
template <class T>
struct A : T {
void foo() {
::undef(); // expected-error {{no member named 'undef' in the global namespace}}
}
void bar() {
::UndefClass::undef(); // expected-error {{no member named 'UndefClass' in the global namespace}}
}
void baz() {
B::qux(); // expected-error {{no member named 'B' in 'PR19233::A<D>'}} \
// expected-warning {{unqualified lookup into dependent bases of class template 'A'}}
}
};
struct B { void qux(); };
struct C : B { };
template struct A<C>; // No error! B is a base of A<C>, and qux is available.
struct D { };
template struct A<D>; // expected-note {{in instantiation of member function 'PR19233::A<PR19233::D>::baz' requested here}}
}
namespace nonmethod_missing_this {
template <typename T> struct Base { int y = 42; };
template <typename T> struct Derived : Base<T> {
int x = y; // expected-warning {{lookup into dependent bases}}
auto foo(int j) -> decltype(y * j) { // expected-warning {{lookup into dependent bases}}
return y * j; // expected-warning {{lookup into dependent bases}}
}
int bar() {
return [&] { return y; }(); // expected-warning {{lookup into dependent bases}}
}
};
template struct Derived<int>;
}
namespace typedef_in_base {
template <typename T> struct A { typedef T NameFromBase; };
template <typename T> struct B : A<T> {
NameFromBase m; // expected-warning {{found via unqualified lookup into dependent bases}}
};
static_assert(sizeof(B<int>) == 4, "");
}
namespace struct_in_base {
template <typename T> struct A { struct NameFromBase {}; };
template <typename T> struct B : A<T> {
NameFromBase m; // expected-warning {{found via unqualified lookup into dependent bases}}
};
static_assert(sizeof(B<int>) == 1, "");
}
namespace enum_in_base {
template <typename T> struct A { enum NameFromBase { X }; };
template <typename T> struct B : A<T> {
NameFromBase m; // expected-warning {{found via unqualified lookup into dependent bases}}
};
static_assert(sizeof(B<int>) == sizeof(A<int>::NameFromBase), "");
}
namespace two_types_in_base {
template <typename T> struct A { typedef T NameFromBase; }; // expected-note {{member type 'int' found by ambiguous name lookup}}
template <typename T> struct B { struct NameFromBase { T m; }; }; // expected-note {{member type 'two_types_in_base::B<int>::NameFromBase' found by ambiguous name lookup}}
template <typename T> struct C : A<T>, B<T> {
NameFromBase m; // expected-error {{member 'NameFromBase' found in multiple base classes of different types}} expected-warning {{use of member 'NameFromBase' found via unqualified lookup into dependent bases of class templates is a Microsoft extension}}
};
static_assert(sizeof(C<int>) != 0, ""); // expected-note {{in instantiation of template class 'two_types_in_base::C<int>' requested here}}
}
namespace type_and_decl_in_base {
template <typename T> struct A { typedef T NameFromBase; };
template <typename T> struct B { static const T NameFromBase = 42; };
template <typename T> struct C : A<T>, B<T> {
NameFromBase m; // expected-error {{unknown type name 'NameFromBase'}}
};
}
namespace classify_type_from_base {
template <typename T> struct A { struct NameFromBase {}; };
template <typename T> struct B : A<T> {
A<NameFromBase> m; // expected-warning {{found via unqualified lookup into dependent bases}}
};
}
namespace classify_nontype_from_base {
// MSVC does not do lookup of non-type declarations from dependent template base
// classes. The extra lookup only applies to types.
template <typename T> struct A { void NameFromBase() {} };
template <void (*F)()> struct B { };
template <typename T> struct C : A<T> {
B<C::NameFromBase> a; // correct
B<NameFromBase> b; // expected-error {{use of undeclared identifier 'NameFromBase'}}
};
}
namespace template_in_base {
template <typename T> struct A {
template <typename U> struct NameFromBase { U x; };
};
template <typename T> struct B : A<T> {
// Correct form.
typename B::template NameFromBase<T> m;
};
template <typename T> struct C : A<T> {
// Incorrect form.
NameFromBase<T> m; // expected-error {{no template named 'NameFromBase'}}
};
}
namespace type_in_inner_class_in_base {
template <typename T>
struct A {
struct B { typedef T NameFromBase; };
};
template <typename T>
struct C : A<T>::B { NameFromBase m; }; // expected-error {{unknown type name 'NameFromBase'}}
}
namespace type_in_inner_template_class_in_base {
template <typename T>
struct A {
template <typename U> struct B { typedef U InnerType; };
};
template <typename T>
struct C : A<T>::template B<T> {
NameFromBase m; // expected-error {{unknown type name 'NameFromBase'}}
};
}
namespace have_nondependent_base {
template <typename T>
struct A {
// Nothing, lookup should fail.
};
template <typename T>
struct B : A<T> { NameFromBase m; }; // expected-error {{unknown type name 'NameFromBase'}}
struct C : A<int> { NameFromBase m; }; // expected-error {{unknown type name 'NameFromBase'}}
}
namespace type_in_base_of_dependent_base {
struct A { typedef int NameFromBase; };
template <typename T>
struct B : A {};
template <typename T>
struct C : B<T> { NameFromBase m; }; // expected-warning {{use of member 'NameFromBase' found via unqualified lookup into dependent bases of class templates is a Microsoft extension}}
}
namespace type_in_second_dependent_base {
template <typename T>
struct A {};
template<typename T>
struct B { typedef T NameFromBase; };
template <typename T>
struct D : A<T>, B<T> { NameFromBase m; }; // expected-warning {{use of member 'NameFromBase' found via unqualified lookup into dependent bases of class templates is a Microsoft extension}}
}
namespace type_in_second_non_dependent_base {
struct A {};
struct B { typedef int NameFromBase; };
template<typename T>
struct C : A, B {};
template <typename T>
struct D : C<T> { NameFromBase m; }; // expected-warning {{use of member 'NameFromBase' found via unqualified lookup into dependent bases of class templates is a Microsoft extension}}
}
namespace type_in_virtual_base_of_dependent_base {
template <typename T>
struct A { typedef T NameFromBase; };
template <typename T>
struct B : virtual A<T> {};
template <typename T>
struct C : B<T>, virtual A<T> { NameFromBase m; }; // expected-warning {{use of member 'NameFromBase' found via unqualified lookup into dependent bases of class templates is a Microsoft extension}}
C<int> c;
}
namespace type_in_base_of_multiple_dependent_bases {
template <typename T>
struct A { typedef T NameFromBase; };
template <typename T>
struct B : public A<T> {};
template <typename T>
struct C : B<T>, public A<T> { NameFromBase m; }; // expected-warning {{use of member 'NameFromBase' found via unqualified lookup into dependent bases of class templates is a Microsoft extension}} expected-warning {{direct base 'A<int>' is inaccessible due to ambiguity:}}
C<int> c; // expected-note {{in instantiation of template class 'type_in_base_of_multiple_dependent_bases::C<int>' requested here}}
}
namespace type_in_dependent_base_of_non_dependent_type {
template<typename T> struct A { typedef int NameFromBase; };
template<typename T> struct B : A<T> {
struct C;
template<typename TT>
struct D : C {
NameFromBase m; // expected-warning {{use of member 'NameFromBase' found via unqualified lookup into dependent bases of class templates is a Microsoft extension}}
};
struct E : C {
NameFromBase m; // expected-warning {{use of member 'NameFromBase' found via unqualified lookup into dependent bases of class templates is a Microsoft extension}}
};
};
template<typename T> struct B<T>::C : B {
NameFromBase m; // expected-warning {{use of member 'NameFromBase' found via unqualified lookup into dependent bases of class templates is a Microsoft extension}}
};
template<typename T> struct F : B<T>::C {
NameFromBase m; // expected-error {{unknown type name 'NameFromBase'}}
};
}
namespace lookup_in_function_contexts {
template <typename T> struct A { typedef T NameFromBase; };
template <typename T>
struct B : A<T> {
// expected-warning@+1 {{lookup into dependent bases}}
static auto lateSpecifiedFunc() -> decltype(NameFromBase()) {
return {};
}
static void memberFunc() {
NameFromBase x; // expected-warning {{lookup into dependent bases}}
}
static void funcLocalClass() {
struct X {
NameFromBase x; // expected-warning {{lookup into dependent bases}}
} y;
}
void localClassMethod() {
struct X {
void bar() {
NameFromBase m; // expected-warning {{lookup into dependent bases}}
}
} x;
x.bar();
}
static void funcLambda() {
auto l = []() {
NameFromBase x; // expected-warning {{lookup into dependent bases}}
};
l();
}
static constexpr int constexprFunc() {
NameFromBase x = {}; // expected-warning {{lookup into dependent bases}}
return sizeof(x);
}
static auto autoFunc() {
NameFromBase x; // expected-warning {{lookup into dependent bases}}
return x;
}
};
// Force us to parse the methods.
template struct B<int>;
}
namespace function_template_deduction {
// Overloaded function templates.
template <int N> int f() { return N; }
template <typename T> int f() { return sizeof(T); }
// Dependent base class with type.
template <typename T>
struct A { typedef T NameFromBase; };
template <typename T>
struct B : A<T> {
// expected-warning@+1 {{found via unqualified lookup into dependent bases}}
int x = f<NameFromBase>();
};
// Dependent base class with enum.
template <typename T> struct C { enum { NameFromBase = 4 }; };
template <typename T> struct D : C<T> {
// expected-warning@+1 {{use of undeclared identifier 'NameFromBase'; unqualified lookup into dependent bases}}
int x = f<NameFromBase>();
};
}
namespace function_template_undef_impl {
template<class T>
void f() {
Undef::staticMethod(); // expected-error {{use of undeclared identifier 'Undef'}}
UndefVar.method(); // expected-error {{use of undeclared identifier 'UndefVar'}}
}
}
namespace PR20716 {
template <template <typename T> class A>
struct B : A<int>
{
XXX x; // expected-error {{unknown type name}}
};
template <typename T>
struct C {};
template <typename T>
using D = C<T>;
template <typename T>
struct E : D<T>
{
XXX x; // expected-error {{unknown type name}}
};
}
namespace PR23810 {
void f(int);
struct Base {
void f(); // expected-note{{must qualify identifier to find this declaration in dependent base class}}
};
template <typename T> struct Template : T {
void member() {
f(); // expected-warning {{found via unqualified lookup into dependent bases}}
}
};
void test() {
Template<Base> x;
x.member(); // expected-note{{requested here}}
};
}
namespace PR23823 {
// Don't delay lookup in SFINAE context.
template <typename T> decltype(g(T())) check(); // expected-note{{candidate template ignored: substitution failure [with T = int]: use of undeclared identifier 'g'}}
decltype(check<int>()) x; // expected-error{{no matching function for call to 'check'}}
void h();
template <typename T> decltype(h(T())) check2(); // expected-note{{candidate template ignored: substitution failure [with T = int]: no matching function for call to 'h'}}
decltype(check2<int>()) y; // expected-error{{no matching function for call to 'check2'}}
}
// We also allow unqualified lookup into bases in contexts where the we know the
// undeclared identifier *must* be a type, such as a new expression or catch
// parameter type.
template <typename T>
struct UseUnqualifiedTypeNames : T {
void foo() {
void *P = new TheType; // expected-warning {{unqualified lookup}} expected-error {{no type}}
size_t x = __builtin_offsetof(TheType, f2); // expected-warning {{unqualified lookup}} expected-error {{no type}}
try {
} catch (TheType) { // expected-warning {{unqualified lookup}} expected-error {{no type}}
}
enum E : IntegerType { E0 = 42 }; // expected-warning {{unqualified lookup}} expected-error {{no type}}
_Atomic(TheType) a; // expected-warning {{unqualified lookup}} expected-error {{no type}}
}
void out_of_line();
};
template <typename T>
void UseUnqualifiedTypeNames<T>::out_of_line() {
void *p = new TheType; // expected-warning {{unqualified lookup}} expected-error {{no type}}
}
struct Base {
typedef int IntegerType;
struct TheType {
int f1, f2;
};
};
template struct UseUnqualifiedTypeNames<Base>;
struct BadBase { };
template struct UseUnqualifiedTypeNames<BadBase>; // expected-note-re 2 {{in instantiation {{.*}} requested here}}
namespace partial_template_lookup {
class Bar;
class Spare;
template <class T, class X = Bar>
class FooTemplated;
class FooBase {
public:
typedef int BaseTypedef;
};
// Partial template spec (unused)
template <class T>
class FooTemplated<T, Spare> {};
// Partial template spec (used)
template <class T>
class FooTemplated<T, Bar> : public FooBase {};
// Full template spec
template <class T, class X>
class FooTemplated : public FooTemplated<T, Bar> {
public:
BaseTypedef Member; // expected-warning {{unqualified lookup}}
};
}
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