Re: [Tinycc-devel] __LINE__ and #line undelying type

[Elijah Stone]

On Fri, 16 Apr 2021, Christian Jullien wrote:

> C standard says:
> _ _LINE_ _ The presumed line number (within the current source file) of the 
> current
> source line (an integer constant).
>
> So, it should be a signed integer (same as int on your running architecture 
> which is internally either int32_t or int64_t depending on how int is 
> represented).
> For type safety, it is important that __LINE__ is an int because a lot of code 
> uses this type to call functions as below:
>
> void debug(const char* file, int line, const char* msg) {
>  printf("%s(%d) %s\n", file, line msg);
> }
>
> gcc, clang and tcc all use an int as you can see below, so tcc looks right to 
> me:

You are not testing the right thing.  It is an int literal in any case, 
but tcc allows it to overflow.
Here is a better test:

$ cat tt.c
#line 2147483644
#include <stdio.h>
#define STR2(x) #x
#define STR(x) STR2(x)
int main(void) {
        puts(STR(__LINE__));
}
$ gcc -o tt tt.c && ./tt
2147483648
$ tcc -o tt tt.c && ./tt
-2147483648

 -E