[英]Labels redefined in Macro in C
Trying to use goto labels in a C macro (running MSVC) but if the macro is called multiple times in the same caller function, C2045 label redefined errors appear.尝试在 C 宏(运行 MSVC)中使用 goto 标签,但如果在同一个调用者 function 中多次调用该宏,则会出现 C2045 ZD304BA20E96D87413411588EEABA 重新定义的错误。
I've tried using __label__ from this example: https://www.geeksforgeeks.org/local-labels-in-c/ but that label keyword is probably gcc only because MSVC reports label undefined. I've tried using __label__ from this example: https://www.geeksforgeeks.org/local-labels-in-c/ but that label keyword is probably gcc only because MSVC reports label undefined.
I understand it's really obfuscated and silly but I'm writing a transpiler to convert MASM code into C.我知道这真的很混乱和愚蠢,但我正在编写一个转译器来将 MASM 代码转换为 C。 In MASM, labels are defined locally using the LOCAL directive, __label__ is used by GCC, but what does MSVC offer as a solution?
在 MASM 中,标签是使用 LOCAL 指令在本地定义的,__label__ 由 GCC 使用,但 MSVC 提供了哪些解决方案?
#include <stdint.h>
#include <stdio.h>
#define Loopy(AA) { \
RTSZ_0:; \
if (AA >= 5) { goto RTSZ_1; } \
AA += 1; \
goto RTSZ_0; \
RTSZ_1:; \
}
int main()
{
int AA = 0;
Loopy(AA);
Loopy(AA);
return 0;
}
I was expecting the goto labels to be assigned a unique label so that when included multiple times, there would be no redefinition errors.我期望 goto 标签被分配一个唯一的 label 以便在多次包含时不会出现重新定义错误。
Is there a C keyword that can be applied to the macro or a workaround?是否有可以应用于宏的 C 关键字或解决方法? Something like:
就像是:
__Uniquelabel__ RTSZ_0; \
__Uniquelabel__ RTSZ_1; \
Any ideas?有任何想法吗? Thanks!
谢谢!
currently looking into using this code:
目前正在研究使用此代码:
#define S1(x) #x #define S2(x) S1(x) #define RTSZ "RTSZ_" S2(__LINE__) ":"
Indeed something along the above lines can be used to generate unique labels, as long as there's not more than one macro invocation per source line:实际上,只要每个源代码行不超过一个宏调用,就可以使用上述内容生成唯一标签:
#define RTSZ(i) RTSZ1(i, __LINE__)
#define RTSZ1(i, l) RTSZ2(i, l)
#define RTSZ2(i, l) RTSZ_##i##_##l
#define Loopy(AA) { \
RTSZ(0): \
if (AA >= 5) { goto RTSZ(1); } \
AA += 1; \
goto RTSZ(0); \
RTSZ(1): ; \
}
The intermediate RTSZ1()
macro serves to expand the __LINE__
macro, similar to the S2()
in your approach.中间
RTSZ1()
宏用于扩展__LINE__
宏,类似于您方法中的S2()
。
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