llvm-project/clang/test/SemaCXX/cxx2a-initializer-aggregate...

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// RUN: %clang_cc1 -std=c++20 %s -verify=cxx20,expected,pedantic,override,reorder -pedantic-errors
// RUN: %clang_cc1 -std=c++17 %s -verify=expected,pedantic,override,reorder -Wno-c++20-designator -pedantic-errors
// RUN: %clang_cc1 -std=c++20 %s -verify=cxx20,expected,pedantic -Werror=c99-designator -Wno-reorder-init-list -Wno-initializer-overrides
// RUN: %clang_cc1 -std=c++20 %s -verify=cxx20,expected,reorder -Wno-c99-designator -Werror=reorder-init-list -Wno-initializer-overrides
// RUN: %clang_cc1 -std=c++20 %s -verify=cxx20,expected,override -Wno-c99-designator -Wno-reorder-init-list -Werror=initializer-overrides
// RUN: %clang_cc1 -std=c++20 %s -verify=cxx20,expected -Wno-c99-designator -Wno-reorder-init-list -Wno-initializer-overrides
[c++20] Implement semantic restrictions for C++20 designated initializers. This has some interesting interactions with our existing extensions to support C99 designated initializers as an extension in C++. Those are resolved as follows: * We continue to permit the full breadth of C99 designated initializers in C++, with the exception that we disallow a partial overwrite of an initializer with a non-trivially-destructible type. (Full overwrite is OK, because we won't run the first initializer at all.) * The C99 extensions are disallowed in SFINAE contexts and during overload resolution, where they could change the meaning of valid programs. * C++20 disallows reordering of initializers. We only check for that for the simple cases that the C++20 rules permit (designators of the form '.field_name =' and continue to allow reordering in other cases). It would be nice to improve this behavior in future. * All C99 designated initializer extensions produce a warning by default in C++20 mode. People are going to learn the C++ rules based on what Clang diagnoses, so it's important we diagnose these properly by default. * In C++ <= 17, we apply the C++20 rules rather than the C99 rules, and so still diagnose C99 extensions as described above. We continue to accept designated C++20-compatible initializers in C++ <= 17 silently by default (but naturally still reject under -pedantic-errors). This is not a complete implementation of P0329R4. In particular, that paper introduces new non-C99-compatible syntax { .field { init } }, and we do not support that yet. This is based on a previous patch by Don Hinton, though I've made substantial changes when addressing the above interactions. Differential Revision: https://reviews.llvm.org/D59754 llvm-svn: 370544
2019-08-31 06:52:55 +08:00
namespace class_with_ctor {
struct A { // cxx20-note 6{{candidate}}
A() = default; // cxx20-note 3{{candidate}}
int x;
int y;
};
A a = {1, 2}; // cxx20-error {{no matching constructor}}
struct B {
int x;
int y;
};
B b1 = B(); // trigger declaration of implicit ctors
B b2 = {1, 2}; // ok
struct C : A {
A a;
};
C c1 = {{}, {}}; // ok, call default ctor twice
C c2 = {{1, 2}, {3, 4}}; // cxx20-error 2{{no matching constructor}}
}
[c++20] Implement semantic restrictions for C++20 designated initializers. This has some interesting interactions with our existing extensions to support C99 designated initializers as an extension in C++. Those are resolved as follows: * We continue to permit the full breadth of C99 designated initializers in C++, with the exception that we disallow a partial overwrite of an initializer with a non-trivially-destructible type. (Full overwrite is OK, because we won't run the first initializer at all.) * The C99 extensions are disallowed in SFINAE contexts and during overload resolution, where they could change the meaning of valid programs. * C++20 disallows reordering of initializers. We only check for that for the simple cases that the C++20 rules permit (designators of the form '.field_name =' and continue to allow reordering in other cases). It would be nice to improve this behavior in future. * All C99 designated initializer extensions produce a warning by default in C++20 mode. People are going to learn the C++ rules based on what Clang diagnoses, so it's important we diagnose these properly by default. * In C++ <= 17, we apply the C++20 rules rather than the C99 rules, and so still diagnose C99 extensions as described above. We continue to accept designated C++20-compatible initializers in C++ <= 17 silently by default (but naturally still reject under -pedantic-errors). This is not a complete implementation of P0329R4. In particular, that paper introduces new non-C99-compatible syntax { .field { init } }, and we do not support that yet. This is based on a previous patch by Don Hinton, though I've made substantial changes when addressing the above interactions. Differential Revision: https://reviews.llvm.org/D59754 llvm-svn: 370544
2019-08-31 06:52:55 +08:00
namespace designator {
struct A { int x, y; };
struct B { A a; };
A a1 = {
.y = 1, // reorder-note {{previous initialization for field 'y' is here}}
.x = 2 // reorder-error {{ISO C++ requires field designators to be specified in declaration order; field 'y' will be initialized after field 'x'}}
};
int arr[3] = {[1] = 5}; // pedantic-error {{array designators are a C99 extension}}
B b = {.a.x = 0}; // pedantic-error {{nested designators are a C99 extension}}
A a2 = {
.x = 1, // pedantic-error {{mixture of designated and non-designated initializers in the same initializer list is a C99 extension}}
2 // pedantic-note {{first non-designated initializer is here}}
};
A a3 = {
1, // pedantic-note {{first non-designated initializer is here}}
.y = 2 // pedantic-error {{mixture of designated and non-designated initializers in the same initializer list is a C99 extension}}
};
A a4 = {
.x = 1, // override-note {{previous}}
.x = 1 // override-error {{overrides prior initialization}}
};
A a5 = {
.y = 1, // override-note {{previous}}
.y = 1 // override-error {{overrides prior initialization}}
};
struct C { int :0, x, :0, y, :0; };
C c = {
.x = 1, // override-note {{previous}}
.x = 1, // override-error {{overrides prior initialization}} override-note {{previous}}
.y = 1, // override-note {{previous}}
.y = 1, // override-error {{overrides prior initialization}}
.x = 1, // reorder-error {{declaration order}} override-error {{overrides prior initialization}} override-note {{previous}}
.x = 1, // override-error {{overrides prior initialization}}
};
}
namespace base_class {
struct base {
int x;
};
struct derived : base {
int y;
};
derived d = {.x = 1, .y = 2}; // expected-error {{'x' does not refer to any field}}
}
namespace union_ {
union U { int a, b; };
U u = {
.a = 1, // override-note {{here}}
.b = 2, // override-error {{overrides prior}}
};
}
namespace overload_resolution {
struct A { int x, y; };
union B { int x, y; };
void f(A a);
void f(B b) = delete;
void g() { f({.x = 1, .y = 2}); } // ok, calls non-union overload
// As an extension of the union case, overload resolution won't pick any
// candidate where a field initializer would be overridden.
struct A2 { int x, other, y; };
int f(A2);
void g2() { int k = f({.x = 1, 2, .y = 3}); (void)k; } // pedantic-error {{mixture of designated and non-designated}} pedantic-note {{here}}
struct C { int x; };
void h(A a); // expected-note {{candidate}}
void h(C c); // expected-note {{candidate}}
void i() {
h({.x = 1, .y = 2});
h({.y = 1, .x = 2}); // reorder-error {{declaration order}} reorder-note {{previous}}
h({.x = 1}); // expected-error {{ambiguous}}
}
struct D { int y, x; };
void j(A a); // expected-note {{candidate}}
void j(D d); // expected-note {{candidate}}
void k() {
j({.x = 1, .y = 2}); // expected-error {{ambiguous}}
}
}
namespace deduction {
struct A { int x, y; };
union B { int x, y; };
template<typename T, typename U> void f(decltype(T{.x = 1, .y = 2}) = {});
template<typename T, typename U> void f(decltype(U{.x = 1, .y = 2}) = {}) = delete;
void g() { f<A, B>(); } // ok, calls non-union overload
struct C { int y, x; };
template<typename T, typename U> void h(decltype(T{.y = 1, .x = 2}) = {}) = delete;
template<typename T, typename U> void h(decltype(U{.y = 1, .x = 2}) = {});
void i() {
h<A, C>(); // ok, selects C overload by SFINAE
}
}