Add test for extra <> in dyn suggestion.

Author: m-ou-se

Diff for: src/test/ui/dyn-keyword/dyn-angle-brackets.fixed

@@ -0,0 +1,23 @@
+// See https://github.com/rust-lang/rust/issues/88508
+// run-rustfix
+// edition:2018
+#![deny(bare_trait_objects)]
+#![allow(dead_code)]
+#![allow(unused_imports)]
+
+use std::fmt;
+
+#[derive(Debug)]
+pub struct Foo;
+
+impl fmt::Display for Foo {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        <dyn fmt::Debug>::fmt(self, f)
+        //~^ ERROR trait objects without an explicit `dyn` are deprecated
+        //~| WARNING this is accepted in the current edition
+        //~| ERROR trait objects without an explicit `dyn` are deprecated
+        //~| WARNING this is accepted in the current edition
+    }
+}
+
+fn main() {}

Diff for: src/test/ui/dyn-keyword/dyn-angle-brackets.rs

@@ -0,0 +1,23 @@
+// See https://github.com/rust-lang/rust/issues/88508
+// run-rustfix
+// edition:2018
+#![deny(bare_trait_objects)]
+#![allow(dead_code)]
+#![allow(unused_imports)]
+
+use std::fmt;
+
+#[derive(Debug)]
+pub struct Foo;
+
+impl fmt::Display for Foo {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        <fmt::Debug>::fmt(self, f)
+        //~^ ERROR trait objects without an explicit `dyn` are deprecated
+        //~| WARNING this is accepted in the current edition
+        //~| ERROR trait objects without an explicit `dyn` are deprecated
+        //~| WARNING this is accepted in the current edition
+    }
+}
+
+fn main() {}

Diff for: src/test/ui/dyn-keyword/dyn-angle-brackets.stderr

@@ -0,0 +1,25 @@
+error: trait objects without an explicit `dyn` are deprecated
+  --> $DIR/dyn-angle-brackets.rs:15:10
+   |
+LL |         <fmt::Debug>::fmt(self, f)
+   |          ^^^^^^^^^^ help: use `dyn`: `dyn fmt::Debug`
+   |
+note: the lint level is defined here
+  --> $DIR/dyn-angle-brackets.rs:4:9
+   |
+LL | #![deny(bare_trait_objects)]
+   |         ^^^^^^^^^^^^^^^^^^
+   = warning: this is accepted in the current edition (Rust 2018) but is a hard error in Rust 2021!
+   = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
+
+error: trait objects without an explicit `dyn` are deprecated
+  --> $DIR/dyn-angle-brackets.rs:15:10
+   |
+LL |         <fmt::Debug>::fmt(self, f)
+   |          ^^^^^^^^^^ help: use `dyn`: `dyn fmt::Debug`
+   |
+   = warning: this is accepted in the current edition (Rust 2018) but is a hard error in Rust 2021!
+   = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
+
+error: aborting due to 2 previous errors
+