Question regarding C code generation for a compound condition

[Ian Lance Taylor]

Albert ARIBAUD <albert.aribaud@motorola.com> writes:

> Granted, the way the condition is written is not valid, as the
> evaluation will be done left to right, causing a dereference of g
> before testing it against NULL -- the right order should be "(g==NULL)
> || (g->a==0)", with short-circuit ensuring g->a is only evaluated if g
> != NULL.

Once the compiler successfully evaluates g->a == 0, it knows that g !=
NULL.  If g == NULL, then the evaluation of g->a will crash.  So there
is no need for the compiler to test g == NULL, since it will never be
true.  This is a feature, not a bug.  See -fdelete-null-pointer-checks.

Ian