Re: [Tinycc-devel] What C version tcc is supposed to implement?

[Michael Matz]

Hello Christian,

Am 16.02.2013 12:04, schrieb Christian Jullien:
>      tcc_define_symbol(s, "__STDC_VERSION__", "199901L");
>
> This define pretends it is ISO/IEC 9899:1999 (E)

Strictly speaking that's optimistic, because it also depends on the C 
library on which tcc has no influence (some embedded C libs can be 
configured to not support wchar for instance).  But in your case it's 
simply an error on your part.

> Because __STDC_VERSION__ is set to 199901L
> This code should be legal:

It's legal, but doesn't do what you want:

> int main()
> {

When a program is started stdout/err/in have no orientation yet.  The 
first input/output operation determines which orientation it gets ...

> #if defined(__STDC_VERSION__) && (__STDC_VERSION__ >= 199901L)
>          wchar_t* s = L"ABCDEFGHIJKLMNOPQRSTUVWXYZ";
>          char* p = (char*)s;
>          printf("%x %x %x %x\n", p[0],p[1],p[2],p[3]);

... and printf is byte-oriented, so stdout will from now on be 
byte-oriented, and the string is output...

>          printf("%x %x %x %x\n", p[4],p[5],p[6],p[7]);

... stdout is byte-oriented, printf is byte-oriented, so the string is 
output ...

>          wprintf(L"Hello World\n");

... and this doesn't work, because stdout is byte-oriented, but wprintf 
requires a stream that isn't byte-oriented.  If you had checked for 
errors you would have seen one.  Once a stream has an orientation it 
can't be switched anymore.  Remove the printf's and leave only wprintf 
and it works.  Alternatively if you want to output wide characters on a 
byte-oriented stream use printf and %ls.  For the whole background see 
fwide(3) and wprintf(3).


Ciao,
Michael.