On Friday, 21 February 2025 at 07:44:54 UTC, Jonathan M Davis
wrote:
I think that what it basically comes down to is that because -1
fits in int, and int implicitly converts to uint, VRP is fine
with converting the long with a value of -1 to uint. So, as
long as the value fits in 32 bits, the conversion will work
even if gets screwed up by the conversion between signed and
unsigned.
This has nothing to do with the value -1. You get the same result
even if the value of x is completely unknown:
void foo(uint) {}
void example(int x)
{
foo(x); // compiles
foo(long(x)); // compiles
foo(cast(long) x); // compiles
foo((() => cast(long) x)()); // Error: foo is not
callable [...]
}
My best guess is that when VRP looks at `long(x)` or `cast(long)
x`, it can see that x is an int, so it allows the value to be
converted *back* to int (and then from int to uint). But that
information is lost when you hide the cast expression inside a
function call.
