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Update query normalizer docs

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Boxy 2025-02-28 20:27:19 +00:00
parent 60493b8973
commit a9ca11320a
1 changed files with 9 additions and 12 deletions
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21
compiler/rustc_trait_selection/src/traits/query/normalize.rs
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@ -31,20 +31,19 @@ impl<'a, 'tcx> At<'a, 'tcx> {
/// normalized. If you don't care about regions, you should prefer /// normalized. If you don't care about regions, you should prefer
/// `normalize_erasing_regions`, which is more efficient. /// `normalize_erasing_regions`, which is more efficient.
/// ///
/// If the normalization succeeds and is unambiguous, returns back /// If the normalization succeeds, returns back the normalized
/// the normalized value along with various outlives relations (in /// value along with various outlives relations (in the form of
/// the form of obligations that must be discharged). /// obligations that must be discharged).
/// ///
/// N.B., this will *eventually* be the main means of /// This normalization should *only* be used when the projection is well-formed and
/// normalizing, but for now should be used only when we actually /// does not have possible ambiguity (contains inference variables).
/// know that normalization will succeed, since error reporting
/// and other details are still "under development".
///
/// This normalization should *only* be used when the projection does not
/// have possible ambiguity or may not be well-formed.
/// ///
/// After codegen, when lifetimes do not matter, it is preferable to instead /// After codegen, when lifetimes do not matter, it is preferable to instead
/// use [`TyCtxt::normalize_erasing_regions`], which wraps this procedure. /// use [`TyCtxt::normalize_erasing_regions`], which wraps this procedure.
///
/// N.B. Once the new solver is stabilized this method of normalization will
/// likely be removed as trait solver operations are already cached by the query
/// system making this redundant.
fn query_normalize<T>(self, value: T) -> Result<Normalized<'tcx, T>, NoSolution> fn query_normalize<T>(self, value: T) -> Result<Normalized<'tcx, T>, NoSolution>
where where
T: TypeFoldable<TyCtxt<'tcx>>, T: TypeFoldable<TyCtxt<'tcx>>,
@ -210,8 +209,6 @@ impl<'a, 'tcx> FallibleTypeFolder<TyCtxt<'tcx>> for QueryNormalizer<'a, 'tcx> {
// See note in `rustc_trait_selection::traits::project` about why we // See note in `rustc_trait_selection::traits::project` about why we
// wait to fold the args. // wait to fold the args.
// Wrap this in a closure so we don't accidentally return from the outer function
let res = match kind { let res = match kind {
ty::Opaque => { ty::Opaque => {
// Only normalize `impl Trait` outside of type inference, usually in codegen. // Only normalize `impl Trait` outside of type inference, usually in codegen.