mikros/rust
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Always check predicates in can_coerce

Browse Source 
This only changed two tests and I consider both changes an improvement.
This commit is contained in:
Tyler Mandry 2021-09-30 01:22:17 +00:00
parent 5c14433c00
commit 485ae9f2c0
4 changed files with 11 additions and 27 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

16
compiler/rustc_typeck/src/check/coercion.rs
View File

@ -934,20 +934,10 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
}
/// Same as `try_coerce()`, but without side-effects.
///
/// Returns false if the coercion creates any obligations that result in
/// errors.
pub fn can_coerce(&self, expr_ty: Ty<'tcx>, target: Ty<'tcx>) -> bool {
let source = self.resolve_vars_with_obligations(expr_ty);
debug!("coercion::can({:?} -> {:?})", source, target);
let cause = self.cause(rustc_span::DUMMY_SP, ObligationCauseCode::ExprAssignable);
// We don't ever need two-phase here since we throw out the result of the coercion
let coerce = Coerce::new(self, cause, AllowTwoPhase::No);
self.probe(|_| coerce.coerce(source, target)).is_ok()
}
/// Same as `try_coerce()`, but without side-effects and attempts to select
/// all predicates created by the coercion. This is useful for e.g. checking
/// that associated types are correct.
pub fn can_coerce_and_satisfy_predicates(&self, expr_ty: Ty<'tcx>, target: Ty<'tcx>) -> bool {
let source = self.resolve_vars_with_obligations(expr_ty);
debug!("coercion::can_with_predicates({:?} -> {:?})", source, target);

4
compiler/rustc_typeck/src/check/fn_ctxt/suggestions.rs
View File

@ -373,7 +373,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
let box_found = self.tcx.mk_box(found);
let pin_box_found = self.tcx.mk_lang_item(box_found, LangItem::Pin).unwrap();
let pin_found = self.tcx.mk_lang_item(found, LangItem::Pin).unwrap();
if self.can_coerce_and_satisfy_predicates(pin_box_found, expected) {
if self.can_coerce(pin_box_found, expected) {
debug!("can coerce {:?} to {:?}, suggesting Box::pin", pin_box_found, expected);
match found.kind() {
ty::Adt(def, _) if def.is_box() => {
@ -391,7 +391,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
}
}
true
} else if self.can_coerce_and_satisfy_predicates(pin_found, expected) {
} else if self.can_coerce(pin_found, expected) {
match found.kind() {
ty::Adt(def, _) if def.is_box() => {
err.help("use `Box::pin`");

6
src/test/ui/cross/cross-borrow-trait.stderr
View File

@ -2,10 +2,8 @@ error[E0308]: mismatched types
--> $DIR/cross-borrow-trait.rs:10:26
|
LL | let _y: &dyn Trait = x;
| ---------- ^
| | |
| | expected `&dyn Trait`, found struct `Box`
| | help: consider borrowing here: `&x`
| ---------- ^ expected `&dyn Trait`, found struct `Box`
| |
| expected due to this
|
= note: expected reference `&dyn Trait`

12
src/test/ui/dst/dst-bad-coercions.stderr
View File

@ -13,10 +13,8 @@ error[E0308]: mismatched types
--> $DIR/dst-bad-coercions.rs:15:21
|
LL | let y: &dyn T = x;
| ------ ^
| | |
| | expected `&dyn T`, found *-ptr
| | help: consider borrowing here: `&x`
| ------ ^ expected `&dyn T`, found *-ptr
| |
| expected due to this
|
= note: expected reference `&dyn T`
@ -37,10 +35,8 @@ error[E0308]: mismatched types
--> $DIR/dst-bad-coercions.rs:20:21
|
LL | let y: &dyn T = x;
| ------ ^
| | |
| | expected `&dyn T`, found *-ptr
| | help: consider borrowing here: `&x`
| ------ ^ expected `&dyn T`, found *-ptr
| |
| expected due to this
|
= note: expected reference `&dyn T`