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Simplify the pattern unpeeling in lower_pattern_range_endpoint

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This commit is contained in:
Zalathar 2025-02-03 14:29:13 +11:00
parent 85f4cdc626
commit 2fb1261c21
1 changed files with 25 additions and 26 deletions
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51
compiler/rustc_mir_build/src/thir/pattern/mod.rs
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@ -161,35 +161,34 @@ impl<'a, 'tcx> PatCtxt<'a, 'tcx> {
) -> Result<Option<PatRangeBoundary<'tcx>>, ErrorGuaranteed> {
let Some(expr) = expr else { return Ok(None) };
let (kind, ascr, inline_const) = match self.lower_lit(expr) {
PatKind::ExpandedConstant { subpattern, def_id, is_inline: true } => {
(subpattern.kind, None, def_id.as_local())
}
PatKind::ExpandedConstant { subpattern, is_inline: false, .. } => {
(subpattern.kind, None, None)
}
PatKind::AscribeUserType { ascription, subpattern: box Pat { kind, .. } } => {
(kind, Some(ascription), None)
}
kind => (kind, None, None),
};
let value = match kind {
PatKind::Constant { value } => value,
PatKind::ExpandedConstant { subpattern, .. }
if let PatKind::Constant { value } = subpattern.kind =>
{
value
}
_ => {
let msg = format!(
"found bad range pattern endpoint `{expr:?}` outside of error recovery"
);
return Err(self.tcx.dcx().span_delayed_bug(expr.span, msg));
// Lower the endpoint into a temporary `PatKind` that will then be
// deconstructed to obtain the constant value and other data.
let mut kind: PatKind<'tcx> = self.lower_lit(expr);
// Unpeel any ascription or inline-const wrapper nodes.
loop {
match kind {
PatKind::AscribeUserType { ascription, subpattern } => {
ascriptions.push(ascription);
kind = subpattern.kind;
}
PatKind::ExpandedConstant { is_inline, def_id, subpattern } => {
if is_inline {
inline_consts.extend(def_id.as_local());
}
kind = subpattern.kind;
}
_ => break,
}
}
// The unpeeled kind should now be a constant, giving us the endpoint value.
let PatKind::Constant { value } = kind else {
let msg =
format!("found bad range pattern endpoint `{expr:?}` outside of error recovery");
return Err(self.tcx.dcx().span_delayed_bug(expr.span, msg));
};
ascriptions.extend(ascr);
inline_consts.extend(inline_const);
Ok(Some(PatRangeBoundary::Finite(value)))
}