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Rollup merge of #102382 - cuviper:defid-order, r=fee1-dead

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Manually order `DefId` on 64-bit big-endian

`DefId` uses different field orders on 64-bit big-endian vs. others, in
order to optimize its `Hash` implementation. However, that also made it
derive different lexical ordering for `PartialOrd` and `Ord`. That
caused spurious differences wherever `DefId`s are sorted, like the
candidate sources list in `report_method_error`.

Now we manually implement `PartialOrd` and `Ord` on 64-bit big-endian to
match the same lexical ordering as other targets, fixing at least one
test, `src/test/ui/methods/method-ambig-two-traits-cross-crate.rs`.
This commit is contained in:
Matthias Krüger 2022-09-30 19:06:05 +02:00 committed by GitHub
commit e2bc6b8172
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1 changed files with 19 additions and 1 deletions
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20
compiler/rustc_span/src/def_id.rs
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@ -218,7 +218,9 @@ impl<D: Decoder> Decodable<D> for DefIndex {
/// index and a def index.
///
/// You can create a `DefId` from a `LocalDefId` using `local_def_id.to_def_id()`.
#[derive(Clone, PartialEq, Eq, PartialOrd, Ord, Copy)]
#[derive(Clone, PartialEq, Eq, Copy)]
// Don't derive order on 64-bit big-endian, so we can be consistent regardless of field order.
#[cfg_attr(not(all(target_pointer_width = "64", target_endian = "big")), derive(PartialOrd, Ord))]
// On below-64 bit systems we can simply use the derived `Hash` impl
#[cfg_attr(not(target_pointer_width = "64"), derive(Hash))]
#[repr(C)]
@ -260,6 +262,22 @@ impl Hash for DefId {
}
}
// Implement the same comparison as derived with the other field order.
#[cfg(all(target_pointer_width = "64", target_endian = "big"))]
impl Ord for DefId {
#[inline]
fn cmp(&self, other: &DefId) -> std::cmp::Ordering {
Ord::cmp(&(self.index, self.krate), &(other.index, other.krate))
}
}
#[cfg(all(target_pointer_width = "64", target_endian = "big"))]
impl PartialOrd for DefId {
#[inline]
fn partial_cmp(&self, other: &DefId) -> Option<std::cmp::Ordering> {
Some(Ord::cmp(self, other))
}
}
impl DefId {
/// Makes a local `DefId` from the given `DefIndex`.
#[inline]