Re: [Tinycc-devel] Divisions by zero in dead branches cause compiler errors

[Michael Matz]

Hello,

On Wed, 15 Jan 2020, Petr Skočík wrote:

> I've just noticed `_Static_assert( !0 || 1/0, "");` fails to compile on
> tinycc.

Thanks for the report, that shows that unevaluated sub-expressions of 
const expressions were mishandled.  We also diagnosed (incorrectly)

  static int i = 2 || 1 / 0;

(which even is literally written down in the standard).

> It seems to me like simply commenting out the
>
>                if (const_wanted)
>                    tcc_error("division by zero in constant");
>
> at tccgen.c:2090 could do the trick.
>
> Then we get a less specific "constant expression expected" instead of
> "division by zero in constant" for  "enum { a = 1/0 };", but perhaps
> fancy diagnostics are best left to big compilers.

Yeah, I've chosen a more complete solution, so that the latter is still 
diagnosed, but the former isn't.


Ciao,
Michael.