Do not fail method_autoderef_steps on infer types. Let method resolution handle it

Author: oli-obk

compiler/rustc_hir_typeck/src/method/probe.rs

@@ -556,6 +556,7 @@ fn method_autoderef_steps<'tcx>(
 
     let final_ty = autoderef.final_ty(true);
     let opt_bad_ty = match final_ty.kind() {
+        ty::Infer(ty::TyVar(_)) if !reached_raw_pointer => None,
         ty::Infer(ty::TyVar(_)) | ty::Error(_) => Some(MethodAutoderefBadTy {
             reached_raw_pointer,
             ty: infcx.make_query_response_ignoring_pending_obligations(inference_vars, final_ty),

tests/crashes/121613-2.rs

@@ -1,8 +1,14 @@
-//@ known-bug: #121613
+//! This test used to ICE #121613
+//! Using a generic parameter where there are none expected
+//! caused an ICE, hiding the important later errors.
+
+#![feature(more_qualified_paths)]
+
 fn main() {
     let _ = <Foo as A>::Assoc { br: 2 };
 
     let <E>::V(..) = E::V(|a, b| a.cmp(b));
+    //~^ ERROR: multiple applicable items in scope
 }
 
 struct StructStruct {

tests/crashes/121613.rs tests/ui/associated-types/param_mismatch_on_associatedtype_constructor.rs

@@ -0,0 +1,22 @@
+error[E0034]: multiple applicable items in scope
+  --> $DIR/param_mismatch_on_associatedtype_constructor.rs:10:36
+   |
+LL |     let <E>::V(..) = E::V(|a, b| a.cmp(b));
+   |                                    ^^^ multiple `cmp` found
+   |
+note: candidate #1 is defined in the trait `Iterator`
+  --> $SRC_DIR/core/src/iter/traits/iterator.rs:LL:COL
+note: candidate #2 is defined in the trait `Ord`
+  --> $SRC_DIR/core/src/cmp.rs:LL:COL
+help: disambiguate the method for candidate #1
+   |
+LL |     let <E>::V(..) = E::V(|a, b| Iterator::cmp(a, b));
+   |                                  ~~~~~~~~~~~~~~~~~~~
+help: disambiguate the method for candidate #2
+   |
+LL |     let <E>::V(..) = E::V(|a, b| Ord::cmp(&a, b));
+   |                                  ~~~~~~~~~~~~~~~
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0034`.

tests/ui/associated-types/param_mismatch_on_associatedtype_constructor.stderr

@@ -29,12 +29,12 @@ impl<F> Deref for Value<Rc<F>> {
 
 fn main() {
     let var_fn = Value::wrap();
-    //~^ ERROR type annotations needed for `Value<Rc<_>>`
 
     // The combination of `Value: Wrap` obligation plus the autoderef steps
     // (caused by the `Deref` impl above) actually means that the self type
     // of the method fn below is constrained to be `Value<Rc<dyn Fn(?0, ?1) -> ?2>>`.
     // However, that's only known to us on the error path -- we still need
     // to emit an ambiguity error, though.
     let _ = var_fn.clone();
+    //~^ ERROR: the size for values of type `dyn Fn(_, _) -> _` cannot be known
 }

tests/ui/autoref-autoderef/deref-ambiguity-becomes-nonambiguous.rs

@@ -1,17 +1,18 @@
-error[E0282]: type annotations needed for `Value<Rc<_>>`
-  --> $DIR/deref-ambiguity-becomes-nonambiguous.rs:31:9
+error[E0277]: the size for values of type `dyn Fn(_, _) -> _` cannot be known at compilation time
+  --> $DIR/deref-ambiguity-becomes-nonambiguous.rs:38:13
    |
-LL |     let var_fn = Value::wrap();
-   |         ^^^^^^
-...
 LL |     let _ = var_fn.clone();
-   |                    ----- type must be known at this point
+   |             ^^^^^^^^^^^^^^ doesn't have a size known at compile-time
    |
-help: consider giving `var_fn` an explicit type, where the placeholders `_` are specified
+   = help: the trait `Sized` is not implemented for `dyn Fn(_, _) -> _`, which is required by `Value<Rc<_>>: Deref`
+note: required for `Value<Rc<dyn Fn(_, _) -> _>>` to implement `Deref`
+  --> $DIR/deref-ambiguity-becomes-nonambiguous.rs:22:9
    |
-LL |     let var_fn: Value<Rc<_>> = Value::wrap();
-   |               ++++++++++++++
+LL | impl<F> Deref for Value<Rc<F>> {
+   |      -  ^^^^^     ^^^^^^^^^^^^
+   |      |
+   |      unsatisfied trait bound introduced here
 
 error: aborting due to 1 previous error
 
-For more information about this error, try `rustc --explain E0282`.
+For more information about this error, try `rustc --explain E0277`.

tests/ui/autoref-autoderef/deref-ambiguity-becomes-nonambiguous.stderr

@@ -5,7 +5,7 @@ LL |     needs_foo(|x| {
    |                ^
 ...
 LL |         x.to_string();
-   |           --------- type must be known at this point
+   |         ------------- type must be known at this point
    |
 help: consider giving this closure parameter an explicit type
    |

tests/ui/closures/deduce-signature/obligation-with-leaking-placeholders.next.stderr

@@ -5,7 +5,7 @@ LL |         let mut iter = foo(n - 1, m);
    |             ^^^^^^^^
 LL |
 LL |         assert_eq!(iter.get(), 1);
-   |                         --- type must be known at this point
+   |                    ---------- type must be known at this point
    |
 help: consider giving `iter` an explicit type
    |

tests/ui/impl-trait/call_method_ambiguous.next.stderr

@@ -5,7 +5,7 @@ LL |         let x = my_foo();
    |             ^
 LL |
 LL |         x.my_debug();
-   |           -------- type must be known at this point
+   |         ------------ type must be known at this point
    |
 help: consider giving `x` an explicit type
    |

tests/ui/impl-trait/call_method_on_inherent_impl.next.stderr

@@ -4,7 +4,7 @@ error[E0282]: type annotations needed for `&_`
 LL |         let x = &my_foo();
    |             ^
 LL |         x.my_debug();
-   |           -------- type must be known at this point
+   |         ------------ type must be known at this point
    |
 help: consider giving `x` an explicit type, where the placeholders `_` are specified
    |

tests/ui/impl-trait/call_method_on_inherent_impl_on_rigid_type.next.stderr

@@ -5,7 +5,7 @@ LL |         let x = my_foo();
    |             ^
 LL |
 LL |         x.my_debug();
-   |           -------- type must be known at this point
+   |         ------------ type must be known at this point
    |
 help: consider giving `x` an explicit type
    |
@@ -19,7 +19,7 @@ LL |         let x = &my_bar();
    |             ^
 LL |
 LL |         x.my_debug();
-   |           -------- type must be known at this point
+   |         ------------ type must be known at this point
    |
 help: consider giving `x` an explicit type, where the placeholders `_` are specified
    |

tests/ui/impl-trait/call_method_on_inherent_impl_ref.next.stderr

@@ -1,31 +1,15 @@
-error[E0282]: type annotations needed
-  --> $DIR/hidden-type-is-opaque-2.rs:10:17
+error[E0599]: no method named `reify_as` found for type `_` in the current scope
+  --> $DIR/hidden-type-is-opaque-2.rs:11:14
    |
-LL |     Thunk::new(|mut cont| {
-   |                 ^^^^^^^^
-LL |
 LL |         cont.reify_as();
-   |              -------- type must be known at this point
-   |
-help: consider giving this closure parameter an explicit type
-   |
-LL |     Thunk::new(|mut cont: /* Type */| {
-   |                         ++++++++++++
+   |              ^^^^^^^^ method not found in `_`
 
-error[E0282]: type annotations needed
-  --> $DIR/hidden-type-is-opaque-2.rs:20:17
+error[E0599]: no method named `reify_as` found for type `_` in the current scope
+  --> $DIR/hidden-type-is-opaque-2.rs:21:14
    |
-LL |     Thunk::new(|mut cont| {
-   |                 ^^^^^^^^
-LL |
 LL |         cont.reify_as();
-   |              -------- type must be known at this point
-   |
-help: consider giving this closure parameter an explicit type
-   |
-LL |     Thunk::new(|mut cont: /* Type */| {
-   |                         ++++++++++++
+   |              ^^^^^^^^ method not found in `_`
 
 error: aborting due to 2 previous errors
 
-For more information about this error, try `rustc --explain E0282`.
+For more information about this error, try `rustc --explain E0599`.

tests/ui/impl-trait/hidden-type-is-opaque-2.default.stderr

@@ -1,31 +1,15 @@
-error[E0282]: type annotations needed
-  --> $DIR/hidden-type-is-opaque-2.rs:10:17
+error[E0599]: no method named `reify_as` found for type `_` in the current scope
+  --> $DIR/hidden-type-is-opaque-2.rs:11:14
    |
-LL |     Thunk::new(|mut cont| {
-   |                 ^^^^^^^^
-LL |
 LL |         cont.reify_as();
-   |              -------- type must be known at this point
-   |
-help: consider giving this closure parameter an explicit type
-   |
-LL |     Thunk::new(|mut cont: /* Type */| {
-   |                         ++++++++++++
+   |              ^^^^^^^^ method not found in `_`
 
-error[E0282]: type annotations needed
-  --> $DIR/hidden-type-is-opaque-2.rs:20:17
+error[E0599]: no method named `reify_as` found for type `_` in the current scope
+  --> $DIR/hidden-type-is-opaque-2.rs:21:14
    |
-LL |     Thunk::new(|mut cont| {
-   |                 ^^^^^^^^
-LL |
 LL |         cont.reify_as();
-   |              -------- type must be known at this point
-   |
-help: consider giving this closure parameter an explicit type
-   |
-LL |     Thunk::new(|mut cont: /* Type */| {
-   |                         ++++++++++++
+   |              ^^^^^^^^ method not found in `_`
 
 error: aborting due to 2 previous errors
 
-For more information about this error, try `rustc --explain E0282`.
+For more information about this error, try `rustc --explain E0599`.

tests/ui/impl-trait/hidden-type-is-opaque-2.next.stderr

@@ -8,8 +8,8 @@
 
 fn reify_as() -> Thunk<impl FnOnce(Continuation) -> Continuation> {
     Thunk::new(|mut cont| {
-        //~^ ERROR type annotations needed
         cont.reify_as();
+        //~^ ERROR: no method named `reify_as` found for type `_`
         cont
     })
 }
@@ -18,8 +18,8 @@ type Tait = impl FnOnce(Continuation) -> Continuation;
 
 fn reify_as_tait() -> Thunk<Tait> {
     Thunk::new(|mut cont| {
-        //~^ ERROR type annotations needed
         cont.reify_as();
+        //~^ ERROR: no method named `reify_as` found for type `_`
         cont
     })
 }

tests/ui/impl-trait/hidden-type-is-opaque-2.rs

@@ -1,8 +1,8 @@
 error[E0282]: type annotations needed
-  --> $DIR/method-resolution4.rs:13:20
+  --> $DIR/method-resolution4.rs:13:9
    |
 LL |         foo(false).next().unwrap();
-   |                    ^^^^ cannot infer type
+   |         ^^^^^^^^^^^^^^^^^ cannot infer type
 
 error[E0308]: mismatched types
   --> $DIR/method-resolution4.rs:16:5

tests/ui/impl-trait/method-resolution4.next.stderr

@@ -1,8 +1,8 @@
 error[E0282]: type annotations needed
-  --> $DIR/recursive-bound-eval.rs:18:28
+  --> $DIR/recursive-bound-eval.rs:19:13
    |
 LL |     move || recursive_fn().parse()
-   |                            ^^^^^ cannot infer type
+   |             ^^^^^^^^^^^^^^^^^^^^^^ cannot infer type
 
 error: aborting due to 1 previous error
 

tests/ui/impl-trait/recursive-bound-eval.current.stderr

@@ -3,6 +3,7 @@
 
 //@revisions: next current
 //@[next] compile-flags: -Znext-solver
+//@[current] check-pass
 
 pub trait Parser<E> {
     fn parse(&self) -> E;
@@ -16,8 +17,7 @@ impl<E, T: Fn() -> E> Parser<E> for T {
 
 pub fn recursive_fn<E>() -> impl Parser<E> {
     move || recursive_fn().parse()
-    //~^ ERROR: type annotations needed
-    //[current]~^^ ERROR: no method named `parse` found for opaque type
+    //[next]~^ ERROR: type annotations needed
 }
 
 fn main() {}

tests/ui/impl-trait/recursive-bound-eval.next.stderr

@@ -1,19 +1,15 @@
 //@ revisions: current next
 //@ ignore-compare-mode-next-solver (explicit revisions)
-//@[current] check-pass
+//@ check-pass
 //@[next] compile-flags: -Znext-solver
 #![feature(coroutines, coroutine_trait)]
 
 use std::ops::{Coroutine, CoroutineState};
 
 fn foo() -> impl Coroutine<Yield = (), Return = ()> {
-    // FIXME(-Znext-solver): this fails with a mismatched types as the
-    // hidden type of the opaque ends up as {type error}. We should not
-    // emit errors for such goals.
 
-    #[coroutine] || { //[next]~ ERROR mismatched types
+    #[coroutine] || {
         let mut gen = Box::pin(foo());
-        //[next]~^ ERROR type annotations needed
         let mut r = gen.as_mut().resume(());
         while let CoroutineState::Yielded(v) = r {
             yield v;