Add version mismatch help message for unimplemented trait

Issue #22750
The error reporting for E0277 (the trait `X` is not implemented for `Foo`)
now checks whether `Foo` implements a trait with the same path as `X`,
which probably means that the programmer wanted to actually use only one
version of the trait `X` instead of the two.

src/test/ui/traits/auxiliary/crate_a1.rs

@@ -2,10 +2,4 @@ pub struct Foo;
 
 pub trait Bar{}
 
-pub fn bar() -> Box<Bar> {
-    unimplemented!()
-}
-
-
-pub fn try_foo(x: Foo){}
-pub fn try_bar(x: Box<Bar>){}
+pub fn try_foo(x: impl Bar){}

src/test/ui/traits/auxiliary/crate_a2.rs

@@ -0,0 +1,5 @@
+pub struct Foo;
+
+pub trait Bar{}
+
+impl Bar for Foo {}

src/test/ui/traits/trait-bounds-same-crate-name.rs

@@ -0,0 +1,21 @@
+// aux-build:crate_a1.rs
+// aux-build:crate_a2.rs
+
+// Issue 22750
+// This tests the extra help message reported when a trait bound
+// is not met but the struct implements a trait with the same path.
+
+fn main() {
+    let foo2 = {
+        extern crate crate_a2 as a;
+        a::Foo
+    };
+
+    {
+        extern crate crate_a1 as a;
+        a::try_foo(foo2);
+        //~^ ERROR E0277
+        //~| Trait impl with same name found
+        //~| Perhaps two different versions of crate `crate_a2`
+    }
+}

src/test/ui/traits/trait-bounds-same-crate-name.stderr

@@ -0,0 +1,21 @@
+error[E0277]: the trait bound `main::a::Foo: main::a::Bar` is not satisfied
+  --> $DIR/trait-bounds-same-crate-name.rs:16:20
+   |
+LL |         a::try_foo(foo2);
+   |                    ^^^^ the trait `main::a::Bar` is not implemented for `main::a::Foo`
+   | 
+  ::: $DIR/auxiliary/crate_a1.rs:5:24
+   |
+LL | pub fn try_foo(x: impl Bar){}
+   |                        --- required by this bound in `main::a::try_foo`
+   |
+help: Trait impl with same name found
+  --> $DIR/auxiliary/crate_a2.rs:5:1
+   |
+LL | impl Bar for Foo {}
+   | ^^^^^^^^^^^^^^^^^^^
+   = note: Perhaps two different versions of crate `crate_a2` are being used?
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0277`.