Compiler projects using llvm
// RUN: %clang_cc1 -verify=all,c2x -std=c2x -fsyntax-only %s
// RUN: %clang_cc1 -verify=all -std=c17 -fdouble-square-bracket-attributes -fsyntax-only %s
// RUN: %clang_cc1 -verify=none -Wno-deprecated-attributes -D_CLANG_DISABLE_CRT_DEPRECATION_WARNINGS -std=c2x -fsyntax-only %s
// RUN: %clang_cc1 -verify=none -Wno-deprecated-attributes -D_CLANG_DISABLE_CRT_DEPRECATION_WARNINGS -std=c17 -fdouble-square-bracket-attributes -fsyntax-only %s
// none-no-diagnostics

// Test preprocessor functionality.
#if !__has_c_attribute(noreturn)
#error "No noreturn attribute support?"
#endif

#if !__has_c_attribute(_Noreturn)
#error "No _Noreturn attribute support?"
#endif

#if __has_c_attribute(noreturn) != __has_c_attribute(_Noreturn) || \
    __has_c_attribute(noreturn) != 202202L
#error "Wrong value for __has_c_attribute(noreturn)"
#endif

// If we're testings with deprecations disabled, we don't care about testing
// the scenarios that trigger errors because we're only interested in the
// deprecation warning behaviors.
#ifndef _CLANG_DISABLE_CRT_DEPRECATION_WARNINGS
// Test that the attribute accepts no args, applies to the correct subject, etc.
[[noreturn(12)]] void func4(void); // all-error {{attribute 'noreturn' cannot have an argument list}}
[[noreturn]] int not_a_func; // all-error {{'noreturn' attribute only applies to functions}}
void func5(void) [[noreturn]]; // all-error {{'noreturn' attribute cannot be applied to types}}
#endif

_Noreturn void func1(void); // ok, using the function specifier
[[noreturn]] void func2(void);

// This is deprecated because it's only for compatibility with inclusion of the
// <stdnoreturn.h> header where the noreturn macro expands to _Noreturn.
[[_Noreturn]] void func3(void); // all-warning {{the '[[_Noreturn]]' attribute spelling is deprecated in C2x; use '[[noreturn]]' instead}}

// Test the behavior of including <stdnoreturn.h>
#include <stdnoreturn.h>

[[noreturn]] void func6(void);

void func7 [[noreturn]] (void);

noreturn void func8(void);

// Ensure the function specifier form still works.
void noreturn func9(void);

// Ensure that spelling the deprecated form of the attribute is still diagnosed.
[[_Noreturn]] void func10(void); // all-warning {{the '[[_Noreturn]]' attribute spelling is deprecated in C2x; use '[[noreturn]]' instead}}

// Test preprocessor functionality after including <stdnoreturn.h>.
#if !__has_c_attribute(noreturn)
#error "No noreturn attribute support?"
#endif

#if !__has_c_attribute(_Noreturn)
#error "No _Noreturn attribute support?"
#endif

// Test that a macro which expands to _Noreturn is still diagnosed when it
// doesn't come from a system header.
#define NORETURN _Noreturn
[[NORETURN]] void func11(void); // all-warning {{the '[[_Noreturn]]' attribute spelling is deprecated in C2x; use '[[noreturn]]' instead}}