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Auto merge of #99860 - oli-obk:revert_97346, r=pnkfelix

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Revert "Rollup merge of #97346 - JohnTitor:remove-back-compat-hacks, …

…r=oli-obk"

This reverts commit c703d11dcc, reversing
changes made to 64eb9ab869.

it didn't apply cleanly, so now it works the same for RPIT and for TAIT instead of just working for RPIT, but we should keep those in sync anyway. It also exposed a TAIT bug (see the feature gated test that now ICEs).

r? `@pnkfelix`

fixes #99536
This commit is contained in:
bors
2022-08-18 15:41:30 +00:00
parent bb99e6fdd9 a85eb3d9df
commit 8064a49508
12 changed files with 69 additions and 67 deletions
Download Patch File Download Diff File Expand all files Collapse all files

14
compiler/rustc_infer/src/infer/opaque_types.rs
View File

@@ -40,15 +40,17 @@ pub struct OpaqueTypeDecl<'tcx> {
}
impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
pub fn replace_opaque_types_with_inference_vars(
/// This is a backwards compatibility hack to prevent breaking changes from
/// lazy TAIT around RPIT handling.
pub fn replace_opaque_types_with_inference_vars<T: TypeFoldable<'tcx>>(
&self,
ty: Ty<'tcx>,
value: T,
body_id: HirId,
span: Span,
param_env: ty::ParamEnv<'tcx>,
) -> InferOk<'tcx, Ty<'tcx>> {
if !ty.has_opaque_types() {
return InferOk { value: ty, obligations: vec![] };
) -> InferOk<'tcx, T> {
if !value.has_opaque_types() {
return InferOk { value, obligations: vec![] };
}
let mut obligations = vec![];
let replace_opaque_type = |def_id: DefId| {
@@ -56,7 +58,7 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
.as_local()
.map_or(false, |def_id| self.opaque_type_origin(def_id, span).is_some())
};
let value = ty.fold_with(&mut ty::fold::BottomUpFolder {
let value = value.fold_with(&mut ty::fold::BottomUpFolder {
tcx: self.tcx,
lt_op: |lt| lt,
ct_op: |ct| ct,

18
compiler/rustc_trait_selection/src/traits/project.rs
View File

@@ -252,10 +252,20 @@ fn project_and_unify_type<'cx, 'tcx>(
Err(InProgress) => return ProjectAndUnifyResult::Recursive,
};
debug!(?normalized, ?obligations, "project_and_unify_type result");
match infcx
.at(&obligation.cause, obligation.param_env)
.eq(normalized, obligation.predicate.term)
{
let actual = obligation.predicate.term;
// For an example where this is neccessary see src/test/ui/impl-trait/nested-return-type2.rs
// This allows users to omit re-mentioning all bounds on an associated type and just use an
// `impl Trait` for the assoc type to add more bounds.
let InferOk { value: actual, obligations: new } =
selcx.infcx().replace_opaque_types_with_inference_vars(
actual,
obligation.cause.body_id,
obligation.cause.span,
obligation.param_env,
);
obligations.extend(new);
match infcx.at(&obligation.cause, obligation.param_env).eq(normalized, actual) {
Ok(InferOk { obligations: inferred_obligations, value: () }) => {
obligations.extend(inferred_obligations);
ProjectAndUnifyResult::Holds(obligations)

9
src/test/ui/impl-trait/issues/issue-86800.rs
View File

@@ -1,6 +1,14 @@
#![feature(type_alias_impl_trait)]
// edition:2021
// unset-rustc-env:RUST_BACKTRACE
// compile-flags:-Z treat-err-as-bug=1
// error-pattern:stack backtrace:
// failure-status:101
// normalize-stderr-test "note: .*" -> ""
// normalize-stderr-test "thread 'rustc' .*" -> ""
// normalize-stderr-test " +[0-9]+:.*\n" -> ""
// normalize-stderr-test " +at .*\n" -> ""
use std::future::Future;
@@ -23,7 +31,6 @@ struct Context {
type TransactionResult<O> = Result<O, ()>;
type TransactionFuture<'__, O> = impl '__ + Future<Output = TransactionResult<O>>;
//~^ ERROR unconstrained opaque type
fn execute_transaction_fut<'f, F, O>(
f: F,

25
src/test/ui/impl-trait/issues/issue-86800.stderr
View File

@@ -1,10 +1,19 @@
error: unconstrained opaque type
--> $DIR/issue-86800.rs:25:34
|
LL | type TransactionFuture<'__, O> = impl '__ + Future<Output = TransactionResult<O>>;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: `TransactionFuture` must be used in combination with a concrete type within the same module
error: aborting due to previous error
stack backtrace:
error: internal compiler error: unexpected panic
query stack during panic:
#0 [mir_borrowck] borrow-checking `execute_transaction_fut`
#1 [type_of] computing type of `TransactionFuture::{opaque#0}`
#2 [check_mod_item_types] checking item types in top-level module
#3 [analysis] running analysis passes on this crate
end of query stack

10
src/test/ui/impl-trait/nested-return-type2-tait.rs
View File

@@ -1,5 +1,7 @@
#![feature(type_alias_impl_trait)]
// check-pass
trait Duh {}
impl Duh for i32 {}
@@ -17,13 +19,13 @@ impl<R: Duh, F: FnMut() -> R> Trait for F {
type Sendable = impl Send;
// The `Sendable` here is then later compared against the inference var
// created, causing the inference var to be set to `Sendable` instead of
// The `Sendable` here is converted to an inference var and then later compared
// against the inference var created, causing the inference var to be set to
// the hidden type of `Sendable` instead of
// the hidden type. We already have obligations registered on the inference
// var to make it uphold the `: Duh` bound on `Trait::Assoc`. The opaque
// type does not implement `Duh`, even if its hidden type does. So we error out.
// type does not implement `Duh`, but if its hidden type does.
fn foo() -> impl Trait<Assoc = Sendable> {
//~^ ERROR `Sendable: Duh` is not satisfied
|| 42
}

16
src/test/ui/impl-trait/nested-return-type2-tait.stderr
View File

@@ -1,16 +0,0 @@
error[E0277]: the trait bound `Sendable: Duh` is not satisfied
--> $DIR/nested-return-type2-tait.rs:25:13
|
LL | fn foo() -> impl Trait<Assoc = Sendable> {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `Duh` is not implemented for `Sendable`
|
= help: the trait `Duh` is implemented for `i32`
note: required because of the requirements on the impl of `Trait` for `[closure@$DIR/nested-return-type2-tait.rs:27:5: 27:7]`
--> $DIR/nested-return-type2-tait.rs:14:31
|
LL | impl<R: Duh, F: FnMut() -> R> Trait for F {
| ^^^^^ ^
error: aborting due to previous error
For more information about this error, try `rustc --explain E0277`.

2
src/test/ui/impl-trait/nested-return-type2-tait2.rs
View File

@@ -24,8 +24,8 @@ type Traitable = impl Trait<Assoc = Sendable>;
// var to make it uphold the `: Duh` bound on `Trait::Assoc`. The opaque
// type does not implement `Duh`, even if its hidden type does. So we error out.
fn foo() -> Traitable {
//~^ ERROR `Sendable: Duh` is not satisfied
|| 42
//~^ ERROR `Sendable: Duh` is not satisfied
}
fn main() {

8
src/test/ui/impl-trait/nested-return-type2-tait2.stderr
View File

@@ -1,11 +1,11 @@
error[E0277]: the trait bound `Sendable: Duh` is not satisfied
--> $DIR/nested-return-type2-tait2.rs:26:13
--> $DIR/nested-return-type2-tait2.rs:27:5
|
LL | fn foo() -> Traitable {
| ^^^^^^^^^ the trait `Duh` is not implemented for `Sendable`
LL | || 42
| ^^^^^ the trait `Duh` is not implemented for `Sendable`
|
= help: the trait `Duh` is implemented for `i32`
note: required because of the requirements on the impl of `Trait` for `[closure@$DIR/nested-return-type2-tait2.rs:28:5: 28:7]`
note: required because of the requirements on the impl of `Trait` for `[closure@$DIR/nested-return-type2-tait2.rs:27:5: 27:7]`
--> $DIR/nested-return-type2-tait2.rs:14:31
|
LL | impl<R: Duh, F: FnMut() -> R> Trait for F {

2
src/test/ui/impl-trait/nested-return-type2-tait3.rs
View File

@@ -23,8 +23,8 @@ type Traitable = impl Trait<Assoc = impl Send>;
// var to make it uphold the `: Duh` bound on `Trait::Assoc`. The opaque
// type does not implement `Duh`, even if its hidden type does. So we error out.
fn foo() -> Traitable {
//~^ ERROR `impl Send: Duh` is not satisfied
|| 42
//~^ ERROR `impl Send: Duh` is not satisfied
}
fn main() {

8
src/test/ui/impl-trait/nested-return-type2-tait3.stderr
View File

@@ -1,11 +1,11 @@
error[E0277]: the trait bound `impl Send: Duh` is not satisfied
--> $DIR/nested-return-type2-tait3.rs:25:13
--> $DIR/nested-return-type2-tait3.rs:26:5
|
LL | fn foo() -> Traitable {
| ^^^^^^^^^ the trait `Duh` is not implemented for `impl Send`
LL | || 42
| ^^^^^ the trait `Duh` is not implemented for `impl Send`
|
= help: the trait `Duh` is implemented for `i32`
note: required because of the requirements on the impl of `Trait` for `[closure@$DIR/nested-return-type2-tait3.rs:27:5: 27:7]`
note: required because of the requirements on the impl of `Trait` for `[closure@$DIR/nested-return-type2-tait3.rs:26:5: 26:7]`
--> $DIR/nested-return-type2-tait3.rs:14:31
|
LL | impl<R: Duh, F: FnMut() -> R> Trait for F {

8
src/test/ui/impl-trait/nested-return-type2.rs
View File

@@ -1,3 +1,5 @@
// check-pass
trait Duh {}
impl Duh for i32 {}
@@ -18,9 +20,11 @@ impl<R: Duh, F: FnMut() -> R> Trait for F {
// the hidden type. We already have obligations registered on the inference
// var to make it uphold the `: Duh` bound on `Trait::Assoc`. The opaque
// type does not implement `Duh`, even if its hidden type does.
// Lazy TAIT would error out, but we inserted a hack to make it work again,
// keeping backwards compatibility.
fn foo() -> impl Trait<Assoc = impl Send> {
//~^ ERROR `impl Send: Duh` is not satisfied
|| 42
}
fn main() {}
fn main() {
}

16
src/test/ui/impl-trait/nested-return-type2.stderr
View File

@@ -1,16 +0,0 @@
error[E0277]: the trait bound `impl Send: Duh` is not satisfied
--> $DIR/nested-return-type2.rs:21:13
|
LL | fn foo() -> impl Trait<Assoc = impl Send> {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `Duh` is not implemented for `impl Send`
|
= help: the trait `Duh` is implemented for `i32`
note: required because of the requirements on the impl of `Trait` for `[closure@$DIR/nested-return-type2.rs:23:5: 23:7]`
--> $DIR/nested-return-type2.rs:12:31
|
LL | impl<R: Duh, F: FnMut() -> R> Trait for F {
| ^^^^^ ^
error: aborting due to previous error
For more information about this error, try `rustc --explain E0277`.