Philipp Klaus Krause schreef op 2025-02-26 11:22:
Dear SDCC users,
would an _Optional qualifier (see N3422 -
https://www.open-std.org/jtc1/sc22/wg14/www/docs/n3422.pdf for details)
be useful to you?
Basically, it would be a way for programmers to explicitly specify that
a pointer might be null.
This would allow the compiler to warn on missing null pointer checks,
e.g.:
void f(_Optional char *p)
{
*p = 0; // Warning here
}
void g(_Optional char *p)
{
if(p)
*p = 0; // No warning here
}
Since _Optional is essentially an opt-in mechanism, we would not get
any
false warnings on existing code.
Philipp
Is there also a counterpart like _Required or _NonNull to indicate that
the
pointer must already be checked to be non-null? It would have to be used
in
the prototype of course. It could climb up the calling tree to a point
where the check is performed only once.
E.g.
void f(_NonNull char *p);
{
*p = 0; // No warning here
}
void g(char *p)
{
f(p++); // Warning here
if (p)
{
f(p++); // No warning here
f(p++); // No warning here
f(p++); // No warning here
}
}
For backward compatibility the choice to warn for neither keywords can
be
done through pedantic setting.
Maarten
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