Add ui tests for panic![123] and panic!{123}.

src/test/ui/non-fmt-panic.rs

@@ -37,6 +37,9 @@ fn main() {
 
     panic!(format!("{}", 1)); //~ WARN panic message is not a string literal
 
+    panic![123]; //~ WARN panic message is not a string literal
+    panic!{123}; //~ WARN panic message is not a string literal
+
     // Check that the lint only triggers for std::panic and core::panic,
     // not any panic macro:
     macro_rules! panic {

src/test/ui/non-fmt-panic.stderr

@@ -212,5 +212,37 @@ help: remove the `format!(..)` macro call
 LL |     panic!("{}", 1);
    |           --     --
 
-warning: 16 warnings emitted
+warning: panic message is not a string literal
+  --> $DIR/non-fmt-panic.rs:40:12
+   |
+LL |     panic![123];
+   |            ^^^
+   |
+   = note: this is no longer accepted in Rust 2021
+help: add a "{}" format string to Display the message
+   |
+LL |     panic!["{}", 123];
+   |            ^^^^^
+help: or use std::panic::panic_any instead
+   |
+LL |     std::panic::panic_any(123);
+   |     ^^^^^^^^^^^^^^^^^^^^^^   ^
+
+warning: panic message is not a string literal
+  --> $DIR/non-fmt-panic.rs:41:12
+   |
+LL |     panic!{123};
+   |            ^^^
+   |
+   = note: this is no longer accepted in Rust 2021
+help: add a "{}" format string to Display the message
+   |
+LL |     panic!{"{}", 123};
+   |            ^^^^^
+help: or use std::panic::panic_any instead
+   |
+LL |     std::panic::panic_any(123);
+   |     ^^^^^^^^^^^^^^^^^^^^^^   ^
+
+warning: 18 warnings emitted