Auto merge of #54694 - csmoe:self_this, r=estebank

Suggest to use self for fake-self from other languages

Closes https://github.com/rust-lang/rust/issues/54019
r? @estebank

src/test/ui/self/suggest-self.rs

@@ -0,0 +1,52 @@
+// Copyright 2018 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+struct Foo {
+    x: i32,
+}
+
+impl Foo {
+    fn this1(&self) -> i32 {
+        let this = self;
+        let a = 1;
+        this.x
+    }
+
+    fn this2(&self) -> i32 {
+        let a = Foo {
+            x: 2
+        };
+        let this = a;
+        this.x
+    }
+
+    fn foo(&self) -> i32 {
+        this.x
+        //~^ ERROR cannot find value `this` in this scope
+    }
+
+    fn bar(&self) -> i32 {
+        this.foo()
+        //~^ ERROR cannot find value `this` in this scope
+    }
+
+    fn baz(&self) -> i32 {
+        my.bar()
+        //~^ ERROR cannot find value `my` in this scope
+    }
+}
+
+fn main() {
+    let this = vec![1, 2, 3];
+    let my = vec![1, 2, 3];
+    let len = this.len();
+    let len = my.len();
+}
+

src/test/ui/self/suggest-self.stderr

@@ -0,0 +1,30 @@
+error[E0425]: cannot find value `this` in this scope
+  --> $DIR/suggest-self.rs:31:9
+   |
+LL |         this.x
+   |         ^^^^
+   |         |
+   |         not found in this scope
+   |         help: did you mean: `self`
+
+error[E0425]: cannot find value `this` in this scope
+  --> $DIR/suggest-self.rs:36:9
+   |
+LL |         this.foo()
+   |         ^^^^
+   |         |
+   |         not found in this scope
+   |         help: did you mean: `self`
+
+error[E0425]: cannot find value `my` in this scope
+  --> $DIR/suggest-self.rs:41:9
+   |
+LL |         my.bar()
+   |         ^^
+   |         |
+   |         not found in this scope
+   |         help: did you mean: `self`
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0425`.