Reword E0277 default error message

```
error[E0277]: the trait `Copy` is not implemented for `X`
  --> $DIR/trait-impl-bound-suggestions.rs:14:52
   |
LL |     fn return_the_constrained_type(&self, x: X) -> ConstrainedStruct<X> {
   |                                                    ^^^^^^^^^^^^^^^^^^^^ the trait `Copy` is not implemented for `X`
```

Author: estebank

compiler/rustc_trait_selection/src/traits/error_reporting/type_err_ctxt_ext.rs

@@ -2941,7 +2941,18 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
                 }
             })
             .unwrap_or_else(|| {
-                format!("the trait bound `{trait_predicate}` is not satisfied{post_message}")
+                if let ty::ImplPolarity::Positive = trait_predicate.polarity() {
+                    format!(
+                        "the trait `{}` is not implemented for `{}`{post_message}",
+                        trait_predicate.print_modifiers_and_trait_path(),
+                        self.tcx
+                            .short_ty_string(trait_predicate.skip_binder().self_ty(), &mut None),
+                    )
+                } else {
+                    // "the trait bound `!Send: T` is not satisfied" reads better than "`!Send` is
+                    // not implemented for `T`".
+                    format!("the trait bound `{trait_predicate}` is not satisfied{post_message}")
+                }
             })
     }
 

tests/incremental/const-generics/hash-tyvid-regression-1.rs

@@ -20,8 +20,8 @@ where
 {
     use std::convert::TryFrom;
     <[T; N.get()]>::try_from(())
-    //~^ error: the trait bound
-    //~| error: the trait bound
+    //~^ ERROR the trait `From<()>` is not implemented for `[T; N.get()]`
+    //~| ERROR the trait `From<()>` is not implemented for `[T; N.get()]`
     //~| error: mismatched types
 }
 

tests/incremental/const-generics/try_unify_abstract_const_regression_tests/issue-77708-1.rs

@@ -11,7 +11,7 @@ where
     C: Delegates<FileCap<{ false }>>,
 {
     writes_to_specific_path(&cap);
-    //~^ error: the trait bound
+    //~^ ERROR the trait `Delegates<FileCap<false>>` is not implemented for `&C`
 }
 
 fn writes_to_specific_path<C>(cap: &C)

tests/incremental/const-generics/try_unify_abstract_const_regression_tests/issue-88022.rs

@@ -14,13 +14,13 @@ where
     [(); { S * 2 }]: Default;
 
 impl<'a, T, const S: usize> Iterator for BufferIter<'a, T, S> {
-    //~^ error: the trait bound
-    //~^^ error: unconstrained generic constant
+    //~^ ERROR the trait `Default` is not implemented for `[(); { S * 2 }]`
+    //~| ERROR unconstrained generic constant
     type Item = &'a T;
 
     fn next(&mut self) -> Option<Self::Item> {
-        //~^ error: the trait bound
-        //~^^ error: unconstrained generic constant
+        //~^ ERROR the trait `Default` is not implemented for `[(); { S * 2 }]`
+        //~| ERROR unconstrained generic constant
         None
     }
 }

tests/ui-fulldeps/session-diagnostic/diagnostic-derive-doc-comment-field.rs

@@ -34,7 +34,7 @@ struct Test {
     span: Span,
     /// A doc comment
     arg: NotIntoDiagnosticArg,
-    //~^ ERROR the trait bound `NotIntoDiagnosticArg: IntoDiagnosticArg` is not satisfied
+    //~^ ERROR trait `IntoDiagnosticArg` is not implemented for `NotIntoDiagnosticArg`
 }
 
 #[derive(Subdiagnostic)]
@@ -44,5 +44,5 @@ struct SubTest {
     span: Span,
     /// A doc comment
     arg: NotIntoDiagnosticArg,
-    //~^ ERROR the trait bound `NotIntoDiagnosticArg: IntoDiagnosticArg` is not satisfied
+    //~^ ERROR trait `IntoDiagnosticArg` is not implemented for `NotIntoDiagnosticArg`
 }

tests/ui-fulldeps/session-diagnostic/diagnostic-derive-doc-comment-field.stderr

@@ -1,4 +1,4 @@
-error[E0277]: the trait bound `NotIntoDiagnosticArg: IntoDiagnosticArg` is not satisfied
+error[E0277]: the trait `IntoDiagnosticArg` is not implemented for `NotIntoDiagnosticArg`
   --> $DIR/diagnostic-derive-doc-comment-field.rs:36:10
    |
 LL | #[derive(Diagnostic)]
@@ -12,7 +12,7 @@ note: required by a bound in `Diag::<'a, G>::arg`
   --> $COMPILER_DIR/rustc_errors/src/diagnostic.rs:LL:CC
    = note: this error originates in the macro `with_fn` (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error[E0277]: the trait bound `NotIntoDiagnosticArg: IntoDiagnosticArg` is not satisfied
+error[E0277]: the trait `IntoDiagnosticArg` is not implemented for `NotIntoDiagnosticArg`
   --> $DIR/diagnostic-derive-doc-comment-field.rs:46:10
    |
 LL | #[derive(Subdiagnostic)]

tests/ui-fulldeps/session-diagnostic/diagnostic-derive.rs

@@ -347,7 +347,7 @@ struct ArgFieldWithoutSkip {
     #[primary_span]
     span: Span,
     other: Hello,
-    //~^ ERROR the trait bound `Hello: IntoDiagnosticArg` is not satisfied
+    //~^ ERROR trait `IntoDiagnosticArg` is not implemented for `Hello`
 }
 
 #[derive(Diagnostic)]

tests/ui-fulldeps/session-diagnostic/diagnostic-derive.stderr

@@ -618,7 +618,7 @@ LL | #[derive(Diagnostic)]
    |
    = note: this error originates in the derive macro `Diagnostic` (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error[E0277]: the trait bound `Hello: IntoDiagnosticArg` is not satisfied
+error[E0277]: the trait `IntoDiagnosticArg` is not implemented for `Hello`
   --> $DIR/diagnostic-derive.rs:349:12
    |
 LL | #[derive(Diagnostic)]

tests/ui/allocator/not-an-allocator.stderr

@@ -1,4 +1,4 @@
-error[E0277]: the trait bound `usize: GlobalAlloc` is not satisfied
+error[E0277]: the trait `GlobalAlloc` is not implemented for `usize`
   --> $DIR/not-an-allocator.rs:2:11
    |
 LL | #[global_allocator]
@@ -9,7 +9,7 @@ LL | static A: usize = 0;
    = help: the trait `GlobalAlloc` is implemented for `System`
    = note: this error originates in the attribute macro `global_allocator` (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error[E0277]: the trait bound `usize: GlobalAlloc` is not satisfied
+error[E0277]: the trait `GlobalAlloc` is not implemented for `usize`
   --> $DIR/not-an-allocator.rs:2:11
    |
 LL | #[global_allocator]
@@ -21,7 +21,7 @@ LL | static A: usize = 0;
    = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
    = note: this error originates in the attribute macro `global_allocator` (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error[E0277]: the trait bound `usize: GlobalAlloc` is not satisfied
+error[E0277]: the trait `GlobalAlloc` is not implemented for `usize`
   --> $DIR/not-an-allocator.rs:2:11
    |
 LL | #[global_allocator]
@@ -33,7 +33,7 @@ LL | static A: usize = 0;
    = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
    = note: this error originates in the attribute macro `global_allocator` (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error[E0277]: the trait bound `usize: GlobalAlloc` is not satisfied
+error[E0277]: the trait `GlobalAlloc` is not implemented for `usize`
   --> $DIR/not-an-allocator.rs:2:11
    |
 LL | #[global_allocator]

tests/ui/array-slice-vec/repeat_empty_ok.rs

@@ -6,10 +6,10 @@ pub struct Header<'a> {
 
 pub fn test() {
     let headers = [Header{value: &[]}; 128];
-    //~^ ERROR the trait bound
+    //~^ ERROR the trait
 }
 
 pub fn test2() {
     let headers = [Header{value: &[0]}; 128];
-    //~^ ERROR the trait bound
+    //~^ ERROR the trait
 }