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Reject wrapping ranges of pattern types

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This commit is contained in:
Oli Scherer 2025-01-30 08:41:20 +00:00
parent f38819ce17
commit 916f9552e9
3 changed files with 41 additions and 106 deletions
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28
compiler/rustc_ty_utils/src/layout.rs
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@ -220,6 +220,34 @@ fn layout_of_uncached<'tcx>(
.try_to_bits(tcx, cx.typing_env)
.ok_or_else(|| error(cx, LayoutError::Unknown(ty)))?;
// FIXME(pattern_types): create implied bounds from pattern types in signatures
// that require that the range end is >= the range start so that we can't hit
// this error anymore without first having hit a trait solver error.
// Very fuzzy on the details here, but pattern types are an internal impl detail,
// so we can just go with this for now
if scalar.is_signed() {
let range = scalar.valid_range_mut();
let start = layout.size.sign_extend(range.start);
let end = layout.size.sign_extend(range.end);
if end < start {
let guar = tcx.dcx().err(format!(
"pattern type ranges cannot wrap: {start}..={end}"
));
return Err(error(cx, LayoutError::ReferencesError(guar)));
}
} else {
let range = scalar.valid_range_mut();
if range.end < range.start {
let guar = tcx.dcx().err(format!(
"pattern type ranges cannot wrap: {}..={}",
range.start, range.end
));
return Err(error(cx, LayoutError::ReferencesError(guar)));
}
};
let niche = Niche {
offset: Size::ZERO,
value: scalar.primitive(),