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Auto merge of #120313 - Nadrieril:graceful-error, r=compiler-errors

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pattern_analysis: Gracefully abort on type incompatibility

This leaves the option for a consumer of the crate to return `Err` instead of panicking on type error. rust-analyzer could use that (e.g. https://github.com/rust-lang/rust-analyzer/issues/15808).

Since the only use of `TypeCx::bug` is in `Constructor::is_covered_by`, it is tempting to return `false` instead of `Err()`, but that would cause "non-exhaustive match" false positives.

r? `@compiler-errors`
This commit is contained in:
bors 2024-02-05 21:36:25 +00:00
commit f067fd6084
5 changed files with 18 additions and 14 deletions
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18
compiler/rustc_pattern_analysis/src/constructor.rs
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@ -758,10 +758,12 @@ impl<Cx: TypeCx> Constructor<Cx> {
/// this checks for inclusion.
// We inline because this has a single call site in `Matrix::specialize_constructor`.
#[inline]
pub(crate) fn is_covered_by(&self, cx: &Cx, other: &Self) -> bool {
match (self, other) {
pub(crate) fn is_covered_by(&self, cx: &Cx, other: &Self) -> Result<bool, Cx::Error> {
Ok(match (self, other) {
(Wildcard, _) => {
cx.bug(format_args!("Constructor splitting should not have returned `Wildcard`"))
return Err(cx.bug(format_args!(
"Constructor splitting should not have returned `Wildcard`"
)));
}
// Wildcards cover anything
(_, Wildcard) => true,
@ -803,10 +805,12 @@ impl<Cx: TypeCx> Constructor<Cx> {
(Opaque(self_id), Opaque(other_id)) => self_id == other_id,
(Opaque(..), _) | (_, Opaque(..)) => false,
_ => cx.bug(format_args!(
"trying to compare incompatible constructors {self:?} and {other:?}"
)),
}
_ => {
return Err(cx.bug(format_args!(
"trying to compare incompatible constructors {self:?} and {other:?}"
)));
}
})
}
}