Re: [Tinycc-devel] Integer constant expression bug

[grischka]

Elijah Stone wrote:
> Actually, the problem is with the CEXPR_EH macro; it always returns 1.
>
> If I replace the definition with '#define CEXPR_EH
> __builtin_constant_p', all of your tests pass.
>
> I guess the problem is that the behaviour of this clause (from 6.5.15p6)
> is not correctly implemented:
>
> > if one operand is a null pointer constant, the result has the type of
> > the other operand

The clause is correctly implemented, it's just that for tcc there is no
difference between 0 and the optimized result of X*0.

-- gr

>  -E
>
> On Thu, 20 May 2021, Petr Skocik wrote:
>
> > Hi.
> >
> > Not sure if this is news but tinycc treats certain values which are
> > definitely not integer constant expressions as if they were.
> >
> > Examples:
> >
> > #define CEXPR_EH(X) _Generic((1? (void *) ((!!(X))*0ll) : (int *) 0),
> > int*: 1, void*: 0)
> > //ok
> > void should_be_ok1(void) { enum{x=0};  _Static_assert(CEXPR_EH(x),"");  }
> >
> > //each of these fails on tinycc
> > void should_be_ok2(void) {  extern int x;
> > _Static_assert(!CEXPR_EH(x),"");  }
> > void should_be_ok3(void) {  int x=0;  _Static_assert(!CEXPR_EH(x),"");  }
> > void should_be_ok4(int x) {  _Static_assert(!CEXPR_EH(x),"");  }
> > void should_be_ok5(void) {  double x=0;
> > _Static_assert(!CEXPR_EH(x),"");  }
> > void should_be_ok6(void) {  extern double y;
> > _Static_assert(!CEXPR_EH(y),"");  }
> > void should_be_ok7(void) {  char *x=0 ;
> > _Static_assert(!CEXPR_EH(x),"");  }
> > void should_be_ok8(char *x) { _Static_assert(!CEXPR_EH(x),"");  }
> >
> > Regards,
> >
> > Petr S.
> >
> >
> > _______________________________________________
> > Tinycc-devel mailing list
> > Tinycc-devel@nongnu.org
> > https://lists.nongnu.org/mailman/listinfo/tinycc-devel
>
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