我试图编译一段代码,其中包含:
#ifndef SOMEHEADER_H
#define SOMEHEADER_H
#include <stdalign.h>
#include <stdbool.h>
#include <stdint.h>
extern struct s {
_Noreturn void (*somenoreturnfunc)(bool);
} svar;
#endif
这给了我:
error: expected specifier-qualifier-list before '_Noreturn'
关于:
_Noreturn void (*somenoreturnfunc)(bool);
所以我尝试了
here
:
#ifndef SOMEHEADER_H
#define SOMEHEADER_H
#include <stdalign.h>
#include <stdbool.h>
#include <stdint.h>
#include "noreturn.h"
extern struct s {
noreturn void (*somenoreturnfunc)(bool);
} svar;
#endif
Neururn.H:
#ifndef NO_RETURN_H
#define NO_RETURN_H
#if defined(__STDC_VERSION__) && __STDC_VERSION__ >= 201112L
#define noreturn _Noreturn
#elif defined(__GNUC__)
#define noreturn __attribute__((noreturn))
#else
#define noreturn
#endif
#endif
但错误仍然会发生:
In file included from ../include/someinclude.h:8:0,
from src/main.c:17:
../include/noreturn.h:4:18: error: expected specifier-qualifier-list before '_Noreturn'
#define noreturn _Noreturn
^
../include/someinclude.h:19:5: note: in expansion of macro 'noreturn'
noreturn void (*somenoreturnfunc)(bool);
^
我很困惑,因为它是用c11编译的,所以应该可以工作:
make V=1
cc src/main.c
arm-none-eabi-gcc -mcpu=cortex-m3 -mthumb -std=c11 -Wall -pedantic -ffreestanding -static -I../libopencm3/include -I../include -DSTM32F1 -g -DDEBUG -DBUILD_STYLE=\"DEBUG\" -O0 -Iinclude -I../librt/include -MMD -MT build/main.o -MF build/main.d -o build/main.o -c src/main.c
In file included...
GCC版本为5.4.1:
arm-none-eabi-gcc --version
arm-none-eabi-gcc (15:5.4.1+svn241155-1) 5.4.1 20160919
Copyright (C) 2015 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
它应该支持所有的C11功能(_noreturn被支持
since 4.7
)
我做错了什么?如何解决此错误?
——
编辑:也许一个独立的例子可以帮助:
主要内容:
#include <stdalign.h>
#include <stdbool.h>
#include <stdint.h>
struct s {
_Noreturn void (*somenoreturnfunc)(bool);
} svar;
int main()
{
svar.somenoreturnfunc = 0;
return 0;
}
编译如下:
arm-none-eabi-gcc -mcpu=cortex-m3 -mthumb -std=c11 -Wall -pedantic -ffreestanding -static -DSTM32F1 -g -DDEBUG -DBUILD_STYLE=\"DEBUG\" -O0 -MMD -MT main.o -MF main.d -o main.o -c main.c
main.c:7:5: error: expected specifier-qualifier-list before '_Noreturn'
_Noreturn void (*somenoreturnfunc)(bool);
^
main.c:5:8: warning: struct has no members [-Wpedantic]
struct s {
^
main.c: In function 'main':
main.c:12:6: error: 'struct s' has no member named 'somenoreturnfunc'
svar.somenoreturnfunc = 0;
^
但是,当使用相同的命令行编译时
_Noreturn
编译成功。
使用编译时也会发生这种情况
gcc -std=c11 -o main main.c
:
$ gcc -std=c11 -o main main.c
main.c:7:5: error: expected specifier-qualifier-list before â_Noreturnâ
_Noreturn void (*somenoreturnfunc)(bool);
^~~~~~~~~
main.c: In function âmainâ:
main.c:12:6: error: âstruct sâ has no member named âsomenoreturnfuncâ
svar.somenoreturnfunc = 0;
^
$ gcc --version
gcc (Debian 6.3.0-18+deb9u1) 6.3.0 20170516
Copyright (C) 2016 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.