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use valid_range_exclusive for correct overflow handling

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This commit is contained in:
Ralf Jung 2019-11-09 12:19:44 +01:00
parent 6fd909b2b1
commit d78c4aa62e
1 changed files with 7 additions and 4 deletions
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11
src/librustc_target/abi/mod.rs
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@ -1051,17 +1051,20 @@ impl<'a, Ty> TyLayout<'a, Ty> {
where
Self: Copy,
Ty: TyLayoutMethods<'a, C>,
C: LayoutOf<Ty = Ty, TyLayout: MaybeResult<Self, Error = E>>
C: LayoutOf<Ty = Ty, TyLayout: MaybeResult<Self, Error = E>> + HasDataLayout
{
let scalar_allows_raw_init = move |s: &Scalar| -> bool {
let range = &s.valid_range;
if zero {
let range = &s.valid_range;
// The range must contain 0.
range.contains(&0) ||
(*range.start() > *range.end()) // wrap-around allows 0
} else {
// The range must include all values.
*range.start() == range.end().wrapping_add(1)
// The range must include all values. `valid_range_exclusive` handles
// the wrap-around using target arithmetic; with wrap-around then the full
// range is one where `start == end`.
let range = s.valid_range_exclusive(cx);
range.start == range.end
}
};