mirror of
https://github.com/rust-lang/rust.git
synced 2025-06-05 03:38:29 +00:00
Rollup merge of #98013 - compiler-errors:guide-inference-2, r=lcnr
Subtype FRU fields first in `type_changing_struct_update` So this fixes a subtle bug that `type_changing_struct_update` introduced, where it'll no longer coerce the base expr correctly. I actually think this code is easier to understand now, too. r? `@lcnr` since you reviewed the last one
This commit is contained in:
Dylan DPC
GitHub
commit
4793397f11
@ -1561,73 +1561,70 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
|
|||||||
// FIXME: We are currently creating two branches here in order to maintain
|
// FIXME: We are currently creating two branches here in order to maintain
|
||||||
// consistency. But they should be merged as much as possible.
|
// consistency. But they should be merged as much as possible.
|
||||||
let fru_tys = if self.tcx.features().type_changing_struct_update {
|
let fru_tys = if self.tcx.features().type_changing_struct_update {
|
||||||
if let ty::Adt(adt, substs) = adt_ty.kind() && adt.is_struct() {
|
if adt.is_struct() {
|
||||||
// Make an ADT with fresh inference substitutions. This
|
// Make some fresh substitutions for our ADT type.
|
||||||
// will allow us to guide inference along so that, e.g.
|
|
||||||
// ```
|
|
||||||
// let x = MyStruct<'a, B, const C: usize> {
|
|
||||||
// f: 1,
|
|
||||||
// ..Default::default()
|
|
||||||
// };
|
|
||||||
// ```
|
|
||||||
// will have the default base expression constrained to
|
|
||||||
// `MyStruct<'_, _, _>`, as opposed to just `_`... This
|
|
||||||
// will allow us to then do a subtyping relation on all
|
|
||||||
// of the `remaining_fields` below, per the RFC.
|
|
||||||
let fresh_substs = self.fresh_substs_for_item(base_expr.span, adt.did());
|
let fresh_substs = self.fresh_substs_for_item(base_expr.span, adt.did());
|
||||||
let fresh_base_ty = self.tcx.mk_adt(*adt, fresh_substs);
|
// We do subtyping on the FRU fields first, so we can
|
||||||
let base_ty = self.check_expr_has_type_or_error(
|
// learn exactly what types we expect the base expr
|
||||||
base_expr,
|
// needs constrained to be compatible with the struct
|
||||||
fresh_base_ty,
|
// type we expect from the expectation value.
|
||||||
|_| {
|
let fru_tys = variant
|
||||||
error_happened = true;
|
.fields
|
||||||
},
|
.iter()
|
||||||
);
|
.map(|f| {
|
||||||
let base_ty = self.shallow_resolve(base_ty);
|
let fru_ty = self.normalize_associated_types_in(
|
||||||
if let ty::Adt(base_adt, base_substs) = base_ty.kind() && adt == base_adt {
|
expr_span,
|
||||||
variant
|
self.field_ty(base_expr.span, f, fresh_substs),
|
||||||
.fields
|
);
|
||||||
.iter()
|
let ident = self.tcx.adjust_ident(f.ident(self.tcx), variant.def_id);
|
||||||
.map(|f| {
|
if let Some(_) = remaining_fields.remove(&ident) {
|
||||||
let fru_ty = self.normalize_associated_types_in(
|
let target_ty = self.field_ty(base_expr.span, f, substs);
|
||||||
expr_span,
|
let cause = self.misc(base_expr.span);
|
||||||
self.field_ty(base_expr.span, f, base_substs),
|
match self.at(&cause, self.param_env).sup(target_ty, fru_ty) {
|
||||||
);
|
Ok(InferOk { obligations, value: () }) => {
|
||||||
let ident = self
|
self.register_predicates(obligations)
|
||||||
.tcx
|
}
|
||||||
.adjust_ident(f.ident(self.tcx), variant.def_id);
|
Err(_) => {
|
||||||
if let Some(_) = remaining_fields.remove(&ident) {
|
// This should never happen, since we're just subtyping the
|
||||||
let target_ty =
|
// remaining_fields, but it's fine to emit this, I guess.
|
||||||
self.field_ty(base_expr.span, f, substs);
|
self.report_mismatched_types(
|
||||||
let cause = self.misc(base_expr.span);
|
&cause,
|
||||||
match self
|
target_ty,
|
||||||
.at(&cause, self.param_env)
|
fru_ty,
|
||||||
.sup(target_ty, fru_ty)
|
FieldMisMatch(variant.name, ident.name),
|
||||||
{
|
)
|
||||||
Ok(InferOk { obligations, value: () }) => {
|
.emit();
|
||||||
self.register_predicates(obligations)
|
|
||||||
}
|
|
||||||
// FIXME: Need better diagnostics for `FieldMisMatch` error
|
|
||||||
Err(_) => {
|
|
||||||
self.report_mismatched_types(
|
|
||||||
&cause,
|
|
||||||
target_ty,
|
|
||||||
fru_ty,
|
|
||||||
FieldMisMatch(variant.name, ident.name),
|
|
||||||
)
|
|
||||||
.emit();
|
|
||||||
}
|
|
||||||
}
|
}
|
||||||
}
|
}
|
||||||
self.resolve_vars_if_possible(fru_ty)
|
}
|
||||||
})
|
self.resolve_vars_if_possible(fru_ty)
|
||||||
.collect()
|
})
|
||||||
} else {
|
.collect();
|
||||||
if !error_happened && !base_ty.references_error() {
|
// The use of fresh substs that we have subtyped against
|
||||||
span_bug!(base_expr.span, "expected an error to have been reported in `check_expr_has_type_or_error`");
|
// our base ADT type's fields allows us to guide inference
|
||||||
}
|
// along so that, e.g.
|
||||||
return;
|
// ```
|
||||||
}
|
// MyStruct<'a, F1, F2, const C: usize> {
|
||||||
|
// f: F1,
|
||||||
|
// // Other fields that reference `'a`, `F2`, and `C`
|
||||||
|
// }
|
||||||
|
//
|
||||||
|
// let x = MyStruct {
|
||||||
|
// f: 1usize,
|
||||||
|
// ..other_struct
|
||||||
|
// };
|
||||||
|
// ```
|
||||||
|
// will have the `other_struct` expression constrained to
|
||||||
|
// `MyStruct<'a, _, F2, C>`, as opposed to just `_`...
|
||||||
|
// This is important to allow coercions to happen in
|
||||||
|
// `other_struct` itself. See `coerce-in-base-expr.rs`.
|
||||||
|
let fresh_base_ty = self.tcx.mk_adt(*adt, fresh_substs);
|
||||||
|
self.check_expr_has_type_or_error(
|
||||||
|
base_expr,
|
||||||
|
self.resolve_vars_if_possible(fresh_base_ty),
|
||||||
|
|_| {},
|
||||||
|
);
|
||||||
|
fru_tys
|
||||||
} else {
|
} else {
|
||||||
// Check the base_expr, regardless of a bad expected adt_ty, so we can get
|
// Check the base_expr, regardless of a bad expected adt_ty, so we can get
|
||||||
// type errors on that expression, too.
|
// type errors on that expression, too.
|
||||||
|
|||||||
@ -0,0 +1,28 @@
|
|||||||
|
// check-pass
|
||||||
|
|
||||||
|
#![feature(type_changing_struct_update)]
|
||||||
|
#![allow(incomplete_features)]
|
||||||
|
|
||||||
|
use std::any::Any;
|
||||||
|
|
||||||
|
struct Foo<A, B: ?Sized, C: ?Sized> {
|
||||||
|
a: A,
|
||||||
|
b: Box<B>,
|
||||||
|
c: Box<C>,
|
||||||
|
}
|
||||||
|
|
||||||
|
struct B;
|
||||||
|
struct C;
|
||||||
|
|
||||||
|
fn main() {
|
||||||
|
let y = Foo::<usize, dyn Any, dyn Any> {
|
||||||
|
a: 0,
|
||||||
|
b: Box::new(B),
|
||||||
|
..Foo {
|
||||||
|
a: 0,
|
||||||
|
b: Box::new(B),
|
||||||
|
// C needs to be told to coerce to `Box<dyn Any>`
|
||||||
|
c: Box::new(C),
|
||||||
|
}
|
||||||
|
};
|
||||||
|
}
|
||||||
@ -50,7 +50,6 @@ fn fail_update() {
|
|||||||
let m3 = Machine::<i32, i32> {
|
let m3 = Machine::<i32, i32> {
|
||||||
..m1
|
..m1
|
||||||
//~^ ERROR mismatched types [E0308]
|
//~^ ERROR mismatched types [E0308]
|
||||||
//~| ERROR mismatched types [E0308]
|
|
||||||
};
|
};
|
||||||
}
|
}
|
||||||
|
|
||||||
|
|||||||
@ -2,29 +2,20 @@ error[E0308]: mismatched types
|
|||||||
--> $DIR/type-generic-update.rs:46:11
|
--> $DIR/type-generic-update.rs:46:11
|
||||||
|
|
|
|
||||||
LL | ..m1
|
LL | ..m1
|
||||||
| ^^ field type mismatch: Machine.state
|
| ^^ expected `i32`, found `f64`
|
||||||
|
|
|
|
||||||
= note: expected type `i32`
|
= note: expected struct `Machine<'_, i32, _>`
|
||||||
found type `f64`
|
found struct `Machine<'_, f64, _>`
|
||||||
|
|
||||||
error[E0308]: mismatched types
|
error[E0308]: mismatched types
|
||||||
--> $DIR/type-generic-update.rs:51:11
|
--> $DIR/type-generic-update.rs:51:11
|
||||||
|
|
|
|
||||||
LL | ..m1
|
LL | ..m1
|
||||||
| ^^ field type mismatch: Machine.state
|
| ^^ expected `i32`, found `f64`
|
||||||
|
|
|
|
||||||
= note: expected type `i32`
|
= note: expected struct `Machine<'_, i32, i32>`
|
||||||
found type `f64`
|
found struct `Machine<'_, f64, f64>`
|
||||||
|
|
||||||
error[E0308]: mismatched types
|
error: aborting due to 2 previous errors
|
||||||
--> $DIR/type-generic-update.rs:51:11
|
|
||||||
|
|
|
||||||
LL | ..m1
|
|
||||||
| ^^ field type mismatch: Machine.message
|
|
||||||
|
|
|
||||||
= note: expected type `i32`
|
|
||||||
found type `f64`
|
|
||||||
|
|
||||||
error: aborting due to 3 previous errors
|
|
||||||
|
|
||||||
For more information about this error, try `rustc --explain E0308`.
|
For more information about this error, try `rustc --explain E0308`.
|
||||||
|
|||||||
Loading…
Reference in New Issue
Block a user