rust: assertions: Support index field wrapped in BqlCell

Currently, if the `num` field of a varray is not a numeric type, such as
being placed in a wrapper, the array variant of assert_field_type will
fail the check.

HPET currently wraps num_timers in BqlCell<>. Although BqlCell<> is not
necessary from strictly speaking, it makes sense for vmstate to respect
BqlCell.

The failure of assert_field_type is because it cannot convert BqlCell<T>
into usize for use as the index.  Use a constant 0 instead for the index,
by avoiding $(...)? and extracting the common parts of
assert_field_type! into an internal case.

Commit message based on a patch by Zhao Liu <zhao1.liu@intel.com>.

Link: https://lore.kernel.org/r/20250414144943.1112885-3-zhao1.liu@intel.com
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Paolo Bonzini 2025-05-02 10:56:06 +02:00
parent 756ea88fff
commit fff99a88be

View file

@ -78,33 +78,26 @@ macro_rules! assert_same_type {
/// ```
#[macro_export]
macro_rules! assert_field_type {
($t:ty, $i:tt, $ti:ty) => {
(@internal $param_name:ident, $ti:ty, $t:ty, $($field:tt)*) => {
const _: () = {
#[allow(unused)]
fn assert_field_type(v: $t) {
fn types_must_be_equal<T, U>(_: T)
fn assert_field_type($param_name: &$t) {
fn types_must_be_equal<T, U>(_: &T)
where
T: $crate::assertions::EqType<Itself = U>,
{
}
types_must_be_equal::<_, $ti>(v.$i);
types_must_be_equal::<_, $ti>(&$($field)*);
}
};
};
($t:ty, $i:tt, $ti:ty) => {
$crate::assert_field_type!(@internal v, $ti, $t, v.$i);
};
($t:ty, $i:tt, $ti:ty, num = $num:ident) => {
const _: () = {
#[allow(unused)]
fn assert_field_type(v: $t) {
fn types_must_be_equal<T, U>(_: T)
where
T: $crate::assertions::EqType<Itself = U>,
{
}
let index: usize = v.$num.try_into().unwrap();
types_must_be_equal::<_, &$ti>(&v.$i[index]);
}
};
$crate::assert_field_type!(@internal v, $ti, $t, v.$i[0]);
};
}