bjoernager/rust
bjoernager/rust
1
Fork 0
Code Activity

Update query normalizer docs

Browse source
This commit is contained in:
Boxy 2025-02-28 20:27:19 +00:00
parent 60493b8973
commit a9ca11320a
1 changed files with 9 additions and 12 deletions
Download patch file Download diff file Expand all files Collapse all files

21
compiler/rustc_trait_selection/src/traits/query/normalize.rs
View file

@ -31,20 +31,19 @@ impl<'a, 'tcx> At<'a, 'tcx> {
/// normalized. If you don't care about regions, you should prefer
/// `normalize_erasing_regions`, which is more efficient.
///
/// If the normalization succeeds and is unambiguous, returns back
/// the normalized value along with various outlives relations (in
/// the form of obligations that must be discharged).
/// If the normalization succeeds, returns back the normalized
/// value along with various outlives relations (in the form of
/// obligations that must be discharged).
///
/// N.B., this will *eventually* be the main means of
/// normalizing, but for now should be used only when we actually
/// 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.
/// This normalization should *only* be used when the projection is well-formed and
/// does not have possible ambiguity (contains inference variables).
///
/// After codegen, when lifetimes do not matter, it is preferable to instead
/// 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>
where
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
// wait to fold the args.
// Wrap this in a closure so we don't accidentally return from the outer function
let res = match kind {
ty::Opaque => {
// Only normalize `impl Trait` outside of type inference, usually in codegen.