Remove unnecessary select_obligations_where_possible and redundant errors

compiler/rustc_hir_typeck/src/fn_ctxt/mod.rs

@@ -322,7 +322,6 @@ impl<'a, 'tcx> AstConv<'tcx> for FnCtxt<'a, 'tcx> {
                 ty.kind()
             {
                 self.add_required_obligations_for_hir(span, *def_id, args, hir_id);
-                self.select_obligations_where_possible(|_| {});
             }
             self.normalize(span, ty)
         } else {

tests/ui/associated-types/associated-types-invalid-trait-ref-issue-18865.rs

@@ -9,7 +9,6 @@ trait Foo<T> {
 fn f<T:Foo<isize>>(t: &T) {
     let u: <T as Foo<usize>>::Bar = t.get_bar();
     //~^ ERROR the trait bound `T: Foo<usize>` is not satisfied
-    //~| ERROR the trait bound `T: Foo<usize>` is not satisfied
 }
 
 fn main() { }

tests/ui/associated-types/associated-types-invalid-trait-ref-issue-18865.stderr

@@ -9,17 +9,6 @@ help: consider further restricting this bound
 LL | fn f<T:Foo<isize> + Foo<usize>>(t: &T) {
    |                   ++++++++++++
 
-error[E0277]: the trait bound `T: Foo<usize>` is not satisfied
+error: aborting due to previous error
-  --> $DIR/associated-types-invalid-trait-ref-issue-18865.rs:10:12
-   |
-LL |     let u: <T as Foo<usize>>::Bar = t.get_bar();
-   |            ^^^^^^^^^^^^^^^^^^^^^^ the trait `Foo<usize>` is not implemented for `T`
-   |
-help: consider further restricting this bound
-   |
-LL | fn f<T:Foo<isize> + Foo<usize>>(t: &T) {
-   |                   ++++++++++++
-
-error: aborting due to 2 previous errors
 
 For more information about this error, try `rustc --explain E0277`.

tests/ui/generic-associated-types/multiple-type-params-with-unmet-bounds.rs

@@ -7,5 +7,4 @@ impl Trait for () {
 fn main() {
     let _: <() as Trait>::P<String, String>;
     //~^ ERROR the trait bound `String: Copy` is not satisfied
-    //~| ERROR the trait bound `String: Copy` is not satisfied
 }

tests/ui/generic-associated-types/multiple-type-params-with-unmet-bounds.stderr

@@ -10,18 +10,6 @@ note: required by a bound in `Trait::P`
 LL |     type P<T: Copy, U: Copy>;
    |               ^^^^ required by this bound in `Trait::P`
 
-error[E0277]: the trait bound `String: Copy` is not satisfied
+error: aborting due to previous error
-  --> $DIR/multiple-type-params-with-unmet-bounds.rs:8:12
-   |
-LL |     let _: <() as Trait>::P<String, String>;
-   |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `Copy` is not implemented for `String`
-   |
-note: required by a bound in `Trait::P`
-  --> $DIR/multiple-type-params-with-unmet-bounds.rs:2:15
-   |
-LL |     type P<T: Copy, U: Copy>;
-   |               ^^^^ required by this bound in `Trait::P`
-
-error: aborting due to 2 previous errors
 
 For more information about this error, try `rustc --explain E0277`.

tests/ui/generic-associated-types/own-bound-span.rs

@@ -4,8 +4,6 @@ trait D {
     type P<T: Copy>;
     //~^ NOTE required by this bound in `D::P`
     //~| NOTE required by a bound in `D::P`
-    //~| NOTE required by this bound in `D::P`
-    //~| NOTE required by a bound in `D::P`
 }
 
 impl D for S {
@@ -16,6 +14,4 @@ fn main() {
     let _: <S as D>::P<String>;
     //~^ ERROR the trait bound `String: Copy` is not satisfied
     //~| NOTE the trait `Copy` is not implemented for `String`
-    //~| ERROR the trait bound `String: Copy` is not satisfied
-    //~| NOTE the trait `Copy` is not implemented for `String`
 }

tests/ui/generic-associated-types/own-bound-span.stderr

@@ -1,5 +1,5 @@
 error[E0277]: the trait bound `String: Copy` is not satisfied
-  --> $DIR/own-bound-span.rs:16:24
+  --> $DIR/own-bound-span.rs:14:24
    |
 LL |     let _: <S as D>::P<String>;
    |                        ^^^^^^ the trait `Copy` is not implemented for `String`
@@ -10,18 +10,6 @@ note: required by a bound in `D::P`
 LL |     type P<T: Copy>;
    |               ^^^^ required by this bound in `D::P`
 
-error[E0277]: the trait bound `String: Copy` is not satisfied
+error: aborting due to previous error
-  --> $DIR/own-bound-span.rs:16:12
-   |
-LL |     let _: <S as D>::P<String>;
-   |            ^^^^^^^^^^^^^^^^^^^ the trait `Copy` is not implemented for `String`
-   |
-note: required by a bound in `D::P`
-  --> $DIR/own-bound-span.rs:4:15
-   |
-LL |     type P<T: Copy>;
-   |               ^^^^ required by this bound in `D::P`
-
-error: aborting due to 2 previous errors
 
 For more information about this error, try `rustc --explain E0277`.

tests/ui/issues/issue-66353.rs

@@ -11,6 +11,5 @@ trait _A {
 fn main() {
     _Func::< <() as _A>::AssocT >::func(());
     //~^ ERROR the trait bound `(): _A` is not satisfied
-    //~| ERROR the trait bound `(): _A` is not satisfied
     //~| ERROR the trait bound `(): _Func<_>` is not satisfied
 }

tests/ui/issues/issue-66353.stderr

@@ -4,12 +4,6 @@ error[E0277]: the trait bound `(): _A` is not satisfied
 LL |     _Func::< <() as _A>::AssocT >::func(());
    |               ^^ the trait `_A` is not implemented for `()`
 
-error[E0277]: the trait bound `(): _A` is not satisfied
-  --> $DIR/issue-66353.rs:12:14
-   |
-LL |     _Func::< <() as _A>::AssocT >::func(());
-   |              ^^^^^^^^^^^^^^^^^^ the trait `_A` is not implemented for `()`
-
 error[E0277]: the trait bound `(): _Func<_>` is not satisfied
   --> $DIR/issue-66353.rs:12:41
    |
@@ -18,6 +12,6 @@ LL |     _Func::< <() as _A>::AssocT >::func(());
    |     |
    |     required by a bound introduced by this call
 
-error: aborting due to 3 previous errors
+error: aborting due to 2 previous errors
 
 For more information about this error, try `rustc --explain E0277`.

tests/ui/object-safety/assoc_type_bounds_sized_used.rs

@@ -12,7 +12,6 @@ fn bop<T: Bop + ?Sized>() {
     let _ = <T as Bop>::Bar::default();
     //~^ ERROR: trait bounds were not satisfied
     //~| ERROR: the size for values of type `T` cannot be known at compilation time
-    //~| ERROR: the size for values of type `T` cannot be known at compilation time
 }
 
 fn main() {

tests/ui/object-safety/assoc_type_bounds_sized_used.stderr

@@ -1,3 +1,17 @@
+error[E0599]: the function or associated item `default` exists for associated type `<T as Bop>::Bar`, but its trait bounds were not satisfied
+  --> $DIR/assoc_type_bounds_sized_used.rs:12:30
+   |
+LL |     let _ = <T as Bop>::Bar::default();
+   |                              ^^^^^^^ function or associated item cannot be called on `<T as Bop>::Bar` due to unsatisfied trait bounds
+   |
+   = note: the following trait bounds were not satisfied:
+           `T: Sized`
+           which is required by `<T as Bop>::Bar: Default`
+help: consider restricting the type parameter to satisfy the trait bound
+   |
+LL | fn bop<T: Bop + ?Sized>() where T: Sized {
+   |                           ++++++++++++++
+
 error[E0277]: the size for values of type `T` cannot be known at compilation time
   --> $DIR/assoc_type_bounds_sized_used.rs:12:14
    |
@@ -20,44 +34,8 @@ LL - fn bop<T: Bop + ?Sized>() {
 LL + fn bop<T: Bop>() {
    |
 
-error[E0599]: the function or associated item `default` exists for associated type `<T as Bop>::Bar`, but its trait bounds were not satisfied
-  --> $DIR/assoc_type_bounds_sized_used.rs:12:30
-   |
-LL |     let _ = <T as Bop>::Bar::default();
-   |                              ^^^^^^^ function or associated item cannot be called on `<T as Bop>::Bar` due to unsatisfied trait bounds
-   |
-   = note: the following trait bounds were not satisfied:
-           `T: Sized`
-           which is required by `<T as Bop>::Bar: Default`
-help: consider restricting the type parameter to satisfy the trait bound
-   |
-LL | fn bop<T: Bop + ?Sized>() where T: Sized {
-   |                           ++++++++++++++
-
-error[E0277]: the size for values of type `T` cannot be known at compilation time
-  --> $DIR/assoc_type_bounds_sized_used.rs:12:13
-   |
-LL | fn bop<T: Bop + ?Sized>() {
-   |        - this type parameter needs to be `Sized`
-LL |     let _ = <T as Bop>::Bar::default();
-   |             ^^^^^^^^^^^^^^^ doesn't have a size known at compile-time
-   |
-note: required by a bound in `Bop::Bar`
-  --> $DIR/assoc_type_bounds_sized_used.rs:8:15
-   |
-LL |     type Bar: Default
-   |          --- required by a bound in this associated type
-LL |     where
-LL |         Self: Sized;
-   |               ^^^^^ required by this bound in `Bop::Bar`
-help: consider removing the `?Sized` bound to make the type parameter `Sized`
-   |
-LL - fn bop<T: Bop + ?Sized>() {
-LL + fn bop<T: Bop>() {
-   |
-
 error[E0277]: the size for values of type `dyn Bop` cannot be known at compilation time
-  --> $DIR/assoc_type_bounds_sized_used.rs:19:11
+  --> $DIR/assoc_type_bounds_sized_used.rs:18:11
    |
 LL |     bop::<dyn Bop>();
    |           ^^^^^^^ doesn't have a size known at compile-time
@@ -69,7 +47,7 @@ note: required by a bound in `bop`
 LL | fn bop<T: Bop + ?Sized>() {
    |           ^^^ required by this bound in `bop`
 
-error: aborting due to 4 previous errors
+error: aborting due to 3 previous errors
 
 Some errors have detailed explanations: E0277, E0599.
 For more information about an error, try `rustc --explain E0277`.

tests/ui/rfcs/rfc-2632-const-trait-impl/assoc-type-const-bound-usage.stderr

@@ -9,17 +9,6 @@ help: consider further restricting this bound
 LL | const fn foo<T: ~const Foo + Foo>() {
    |                            +++++
 
-error[E0277]: the trait bound `T: Foo` is not satisfied
+error: aborting due to previous error
-  --> $DIR/assoc-type-const-bound-usage.rs:12:5
-   |
-LL |     <T as Foo>::Assoc::foo();
-   |     ^^^^^^^^^^^^^^^^^ the trait `Foo` is not implemented for `T`
-   |
-help: consider further restricting this bound
-   |
-LL | const fn foo<T: ~const Foo + Foo>() {
-   |                            +++++
-
-error: aborting due to 2 previous errors
 
 For more information about this error, try `rustc --explain E0277`.