https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106981
--- Comment #7 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
(In reply to Tobias Burnus from comment #6)
> (In reply to Jakub Jelinek from comment #5)
>
> > The fix could be either partially backport what C++ FE did in
> > --- gcc/c/c-typeck.cc.jj 2022-09-23 09:02:56.525318361 +0200
> > +++ gcc/c/c-typeck.cc 2022-09-23 10:33:06.596467788 +0200
>
> > + if (CONSTANT_CLASS_P (t1) && !comptypes (TREE_TYPE (t1), TREE_TYPE (t2)))
> > + return false;
>
> Maybe. Though I think we still need something like my:
>
> + if (n > TREE_OPERAND_LENGTH (t2))
> + return false;
>
> (With ">" not ">=" as I accidentally had.)
> Given that
> if (!c_tree_equal (TREE_OPERAND (t1, i), TREE_OPERAND (t2, i)))
> does not make sense when exceeding the operand length!
I don't understand.
We have there:
int i, n = TREE_OPERAND_LENGTH (t1);
switch (code1)
{
case PREINCREMENT_EXPR:
case PREDECREMENT_EXPR:
case POSTINCREMENT_EXPR:
case POSTDECREMENT_EXPR:
n = 1;
break;
case ARRAY_REF:
n = 2;
break;
default:
break;
}
if (TREE_CODE_CLASS (code1) == tcc_vl_exp
&& n != TREE_OPERAND_LENGTH (t2))
return false;
and know that code1 == code2. So, except for tcc_vl_exp like CALL_EXPR,
TREE_OPERAND_LENGTH (t1) == TREE_OPERAND_LENGTH (t2) and n is in most
cases equal to that too, except for the pre/post in/decrements (which have
length 2) and ARRAY_REF which has length 4 and we use a smaller number.
