Do not try to confirm non-dyn compatible method

Author: compiler-errors

compiler/rustc_hir_typeck/src/method/confirm.rs

@@ -291,6 +291,14 @@ impl<'a, 'tcx> ConfirmContext<'a, 'tcx> {
             probe::ObjectPick => {
                 let trait_def_id = pick.item.container_id(self.tcx);
 
+                // If the trait is not object safe (specifically, we care about when
+                // the receiver is not valid), then there's a chance that we will not
+                // actually be able to recover the object by derefing the receiver like
+                // we should if it were valid.
+                if !self.tcx.is_dyn_compatible(trait_def_id) {
+                    return ty::GenericArgs::extend_with_error(self.tcx, trait_def_id, &[]);
+                }
+
                 // This shouldn't happen for non-region error kinds, but may occur
                 // when we have error regions. Specifically, since we canonicalize
                 // during method steps, we may successfully deref when we assemble

tests/ui/async-await/dyn/mut-is-pointer-like.stderr

@@ -42,30 +42,6 @@ LL |     async fn async_dispatch(self: Pin<&mut Self>) -> Self::Output;
    = help: consider moving `async_dispatch` to another trait
    = note: required for the cast from `Pin<&mut {async block@$DIR/mut-is-pointer-like.rs:32:32: 32:37}>` to `Pin<&mut dyn AsyncTrait<Output = ()>>`
 
-error[E0277]: the trait bound `dyn AsyncTrait<Output = ()>: AsyncTrait` is not satisfied
-  --> $DIR/mut-is-pointer-like.rs:36:11
-   |
-LL |         x.async_dispatch().await;
-   |           ^^^^^^^^^^^^^^ the trait `AsyncTrait` is not implemented for `dyn AsyncTrait<Output = ()>`
-
-error[E0038]: the trait `AsyncTrait` is not dyn compatible
-  --> $DIR/mut-is-pointer-like.rs:36:9
-   |
-LL |         x.async_dispatch().await;
-   |         ^^^^^^^^^^^^^^^^^^ `AsyncTrait` is not dyn compatible
-   |
-note: for a trait to be dyn compatible it needs to allow building a vtable
-      for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>
-  --> $DIR/mut-is-pointer-like.rs:16:14
-   |
-LL | trait AsyncTrait {
-   |       ---------- this trait is not dyn compatible...
-...
-LL |     async fn async_dispatch(self: Pin<&mut Self>) -> Self::Output;
-   |              ^^^^^^^^^^^^^^ ...because method `async_dispatch` is `async`
-   = help: consider moving `async_dispatch` to another trait
-
-error: aborting due to 4 previous errors; 1 warning emitted
+error: aborting due to 2 previous errors; 1 warning emitted
 
-Some errors have detailed explanations: E0038, E0277.
-For more information about an error, try `rustc --explain E0038`.
+For more information about this error, try `rustc --explain E0038`.

tests/ui/async-await/dyn/works.stderr

@@ -42,40 +42,6 @@ LL |     async fn async_dispatch(&self);
    = help: consider moving `async_dispatch` to another trait
    = help: only type `&'static str` implements `AsyncTrait`; consider using it directly instead.
 
-error[E0038]: the trait `AsyncTrait` is not dyn compatible
-  --> $DIR/works.rs:28:11
-   |
-LL |         x.async_dispatch().await;
-   |           ^^^^^^^^^^^^^^ `AsyncTrait` is not dyn compatible
-   |
-note: for a trait to be dyn compatible it needs to allow building a vtable
-      for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>
-  --> $DIR/works.rs:14:14
-   |
-LL | trait AsyncTrait {
-   |       ---------- this trait is not dyn compatible...
-LL |     async fn async_dispatch(&self);
-   |              ^^^^^^^^^^^^^^ ...because method `async_dispatch` is `async`
-   = help: consider moving `async_dispatch` to another trait
-   = help: only type `&'static str` implements `AsyncTrait`; consider using it directly instead.
-
-error[E0038]: the trait `AsyncTrait` is not dyn compatible
-  --> $DIR/works.rs:28:9
-   |
-LL |         x.async_dispatch().await;
-   |         ^^^^^^^^^^^^^^^^^^ `AsyncTrait` is not dyn compatible
-   |
-note: for a trait to be dyn compatible it needs to allow building a vtable
-      for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>
-  --> $DIR/works.rs:14:14
-   |
-LL | trait AsyncTrait {
-   |       ---------- this trait is not dyn compatible...
-LL |     async fn async_dispatch(&self);
-   |              ^^^^^^^^^^^^^^ ...because method `async_dispatch` is `async`
-   = help: consider moving `async_dispatch` to another trait
-   = help: only type `&'static str` implements `AsyncTrait`; consider using it directly instead.
-
-error: aborting due to 4 previous errors; 1 warning emitted
+error: aborting due to 2 previous errors; 1 warning emitted
 
 For more information about this error, try `rustc --explain E0038`.

tests/ui/const-generics/generic_const_exprs/dyn-compatibility-err-ret.rs

@@ -15,7 +15,7 @@ impl Foo for () {
 }
 
 fn use_dyn(v: &dyn Foo) { //~ERROR the trait `Foo` is not dyn compatible
-    v.test(); //~ERROR the trait `Foo` is not dyn compatible
+    v.test();
 }
 
 fn main() {}

tests/ui/const-generics/generic_const_exprs/dyn-compatibility-err-ret.stderr

@@ -17,25 +17,6 @@ LL |     fn test(&self) -> [u8; bar::<Self>()];
    = help: consider moving `test` to another trait
    = help: only type `()` implements `Foo`; consider using it directly instead.
 
-error[E0038]: the trait `Foo` is not dyn compatible
-  --> $DIR/dyn-compatibility-err-ret.rs:18:5
-   |
-LL |     v.test();
-   |     ^^^^^^^^ `Foo` is not dyn compatible
-   |
-note: for a trait to be dyn compatible it needs to allow building a vtable
-      for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>
-  --> $DIR/dyn-compatibility-err-ret.rs:8:8
-   |
-LL | trait Foo {
-   |       --- this trait is not dyn compatible...
-LL |     fn test(&self) -> [u8; bar::<Self>()];
-   |        ^^^^           ^^^^^^^^^^^^^^^^^^^ ...because method `test` references the `Self` type in its return type
-   |        |
-   |        ...because method `test` references the `Self` type in its `where` clause
-   = help: consider moving `test` to another trait
-   = help: only type `()` implements `Foo`; consider using it directly instead.
-
-error: aborting due to 2 previous errors
+error: aborting due to 1 previous error
 
 For more information about this error, try `rustc --explain E0038`.

tests/ui/const-generics/generic_const_exprs/dyn-compatibility-err-where-bounds.rs

@@ -15,7 +15,6 @@ impl Foo for () {
 fn use_dyn(v: &dyn Foo) {
     //~^ ERROR the trait `Foo` is not dyn compatible
     v.test();
-    //~^ ERROR the trait `Foo` is not dyn compatible
 }
 
 fn main() {}

tests/ui/const-generics/generic_const_exprs/dyn-compatibility-err-where-bounds.stderr

@@ -15,23 +15,6 @@ LL |     fn test(&self) where [u8; bar::<Self>()]: Sized;
    = help: consider moving `test` to another trait
    = help: only type `()` implements `Foo`; consider using it directly instead.
 
-error[E0038]: the trait `Foo` is not dyn compatible
-  --> $DIR/dyn-compatibility-err-where-bounds.rs:17:5
-   |
-LL |     v.test();
-   |     ^^^^^^^^ `Foo` is not dyn compatible
-   |
-note: for a trait to be dyn compatible it needs to allow building a vtable
-      for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>
-  --> $DIR/dyn-compatibility-err-where-bounds.rs:8:8
-   |
-LL | trait Foo {
-   |       --- this trait is not dyn compatible...
-LL |     fn test(&self) where [u8; bar::<Self>()]: Sized;
-   |        ^^^^ ...because method `test` references the `Self` type in its `where` clause
-   = help: consider moving `test` to another trait
-   = help: only type `()` implements `Foo`; consider using it directly instead.
-
-error: aborting due to 2 previous errors
+error: aborting due to 1 previous error
 
 For more information about this error, try `rustc --explain E0038`.

tests/ui/dyn-compatibility/undispatchable-receiver-and-wc-references-Self.rs

@@ -25,5 +25,4 @@ pub fn foo() {
     let fetcher = fetcher();
     //~^ ERROR the trait `Fetcher` is not dyn compatible
     let _ = fetcher.get();
-    //~^ ERROR the trait `Fetcher` is not dyn compatible
 }

tests/ui/dyn-compatibility/undispatchable-receiver-and-wc-references-Self.stderr

@@ -34,24 +34,6 @@ LL | pub trait Fetcher: Send + Sync {
 LL |     fn get<'a>(self: &'a Box<Self>) -> Pin<Box<dyn Future<Output = Vec<u8>> + 'a>>
    |                      ^^^^^^^^^^^^^ ...because method `get`'s `self` parameter cannot be dispatched on
 
-error[E0038]: the trait `Fetcher` is not dyn compatible
-  --> $DIR/undispatchable-receiver-and-wc-references-Self.rs:27:13
-   |
-LL |     fn get<'a>(self: &'a Box<Self>) -> Pin<Box<dyn Future<Output = Vec<u8>> + 'a>>
-   |                      ------------- help: consider changing method `get`'s `self` parameter to be `&self`: `&Self`
-...
-LL |     let _ = fetcher.get();
-   |             ^^^^^^^^^^^^^ `Fetcher` is not dyn compatible
-   |
-note: for a trait to be dyn compatible it needs to allow building a vtable
-      for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>
-  --> $DIR/undispatchable-receiver-and-wc-references-Self.rs:11:22
-   |
-LL | pub trait Fetcher: Send + Sync {
-   |           ------- this trait is not dyn compatible...
-LL |     fn get<'a>(self: &'a Box<Self>) -> Pin<Box<dyn Future<Output = Vec<u8>> + 'a>>
-   |                      ^^^^^^^^^^^^^ ...because method `get`'s `self` parameter cannot be dispatched on
-
-error: aborting due to 3 previous errors
+error: aborting due to 2 previous errors
 
 For more information about this error, try `rustc --explain E0038`.

tests/ui/error-codes/E0038.rs

@@ -5,8 +5,6 @@ trait Trait {
 fn call_foo(x: Box<dyn Trait>) {
     //~^ ERROR E0038
     let y = x.foo();
-    //~^ ERROR E0038
-    //~| ERROR E0277
 }
 
 fn main() {