[Tinycc-devel] semantic of postincrement

[Dr.-Ing. Torsten Finke]

Dear TCC-Developers, 
 
running some tests on tcc-0.9.25 I found an interesting behaviour concerning
postincrement. 

Please consider the following little program: 

#--------------------------------------------------
#include <stdio.h>
int main()
{
    int i = 0, a[] = { -1, -1 };
    a[i++] = i; 
    printf("%d %d\n", a[0], a[1]);
    return 0;
}
#--------------------------------------------------

running it I expected the output to be: 

0 -1

but indeed it is:

1 -1

Trying to understand the ANSI-C Standard, the evaluation sequence of the
assignment statement should be:
1. evaluate right side (since assignment is right associative) -> i = 0
2. calculate indix to "a" -> 0
3. assign 0 to a[0]
4. increment i

Am I wrong? 

BTW: GCC, VC++, cc(HP-UX) do as I had expected; TCC and LCC do not, but do the
same. 


TCC seems to be very nice. Thanks for your great work. 


Best regards 


Torsten Finke



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