如何在Watcom C中定义NORETURN宏

Question

是否可以使用Open Watcom C编译器(而不是C++)来执行#define NORETURN(x)宏？

基于the fine manual，我有这个文件test.c

#include <stdlib.h>

#ifdef __GNUC__
#define STATIC_NORETURN(sig) static void sig __attribute__((__noreturn__))
#define EXTERN_NORETURN(sig) extern void sig __attribute__((__noreturn__))
#endif

#ifdef __WATCOMC__
#pragma aux noreturn aborts;
#define STATIC_NORETURN(sig) static void __pragma("noreturn") sig
#define EXTERN_NORETURN(sig) extern void __pragma("noreturn") sig
#endif

STATIC_NORETURN(my_static_example(void));
EXTERN_NORETURN(my_extern_example(void));

static void my_static_example(void) {
    exit(0);
}

void my_extern_example(void) {
    my_static_example();
}

它使用GCC编译，没有任何错误或警告：

$ gcc -Wall -Wextra -pedantic -std=gnu99 -c test.c

但不使用Open Watcom 1.9：

$ wine wcc386 -q -wx test.c
test.c(14): Error! E1009: Expecting ')' but found 'noreturn'
test.c(14): Error! E1026: Invalid declarator
test.c(14): Error! E1009: Expecting ',' but found 'noreturn'
test.c(14): Error! E1026: Invalid declarator
test.c(14): Error! E1009: Expecting ',' but found ')'
test.c(14): Error! E1024: Declared symbol 'my_static_example' is not in parameter list
test.c(15): Error! E1023: Storage class of parameter must be register or unspecified
test.c(15): Error! E1009: Expecting ')' but found 'noreturn'
test.c(15): Error! E1024: Declared symbol '__pragma' is not in parameter list
test.c(15): Error! E1009: Expecting ',' but found 'noreturn'
test.c(15): Error! E1026: Invalid declarator
test.c(15): Error! E1009: Expecting ',' but found ')'
test.c(15): Error! E1024: Declared symbol 'my_extern_example' is not in parameter list
test.c(17): Error! E1023: Storage class of parameter must be register or unspecified
test.c(17): Error! E1024: Declared symbol 'my_static_example' is not in parameter list
test.c(17): Error! E1076: Missing semicolon at end of declaration
test.c(22): Warning! W131: No prototype found for function 'my_static_example'
test.c(14): Warning! W202: Symbol '__pragma' has been defined, but not referenced

仔细阅读后，我认为手册上说，由于某种原因，__pragma只能在C++代码中工作。但我不确定我是否理解正确。对于C语言，有没有不需要在每个函数定义的地方使用#pragma的等价物？我尽量避免使用ifdefs，所以最好在一个中心位置定义一个可移植的NORETURN宏。

Answer 1

阅读https://open-watcom.github.io/open-watcom-v2-wikidocs/cguide.html：

__declspec( noreturn )
    indicates to the C/C++ compiler that function does not return.
    Example:
    ...

要兼容stdnoreturn.h，不要想出你自己的风格。执行以下操作：

// possibly in some noreturn.h
// maybe even name it stdnoreturn.h
#if __STDC_VERSION__ >= 201110L
#include <stdnoreturn.h>
#elif defined(__WATCOMC__)
#define noreturn __declspec(noreturn)
#else
#error
#endif

#include <stdlib.h>

static noreturn void my_static_example(void) {
    exit(0);
}

noreturn void my_extern_example(void) {
    my_static_example();
}

在使用Version 2.0的wcc386 -q -wx test.c上编译正常。