Rollup merge of #83081 - hyd-dev:assert-message, r=m-ou-se

Fix panic message of `assert_failed_inner`

cc https://github.com/rust-lang/rust/pull/79100#discussion_r593731020

r? ``@m-ou-se``

library/core/src/panicking.rs

@@ -154,7 +154,7 @@ fn assert_failed_inner(
         Some(args) => panic!(
             r#"assertion failed: `(left {} right)`
   left: `{:?}`,
- right: `{:?}: {}`"#,
+ right: `{:?}`: {}"#,
             op, left, right, args
         ),
         None => panic!(

src/test/ui/macros/assert-eq-macro-msg.rs

@@ -0,0 +1,9 @@
+// run-fail
+// error-pattern:panicked at 'assertion failed: `(left == right)`
+// error-pattern: left: `2`
+// error-pattern:right: `3`: 1 + 1 definitely should be 3'
+// ignore-emscripten no processes
+
+fn main() {
+    assert_eq!(1 + 1, 3, "1 + 1 definitely should be 3");
+}

src/test/ui/macros/assert-matches-macro-msg.rs

@@ -0,0 +1,11 @@
+// run-fail
+// error-pattern:panicked at 'assertion failed: `(left matches right)`
+// error-pattern: left: `2`
+// error-pattern:right: `3`: 1 + 1 definitely should be 3'
+// ignore-emscripten no processes
+
+#![feature(assert_matches)]
+
+fn main() {
+    assert_matches!(1 + 1, 3, "1 + 1 definitely should be 3");
+}

src/test/ui/macros/assert-ne-macro-msg.rs

@@ -0,0 +1,9 @@
+// run-fail
+// error-pattern:panicked at 'assertion failed: `(left != right)`
+// error-pattern: left: `2`
+// error-pattern:right: `2`: 1 + 1 definitely should not be 2'
+// ignore-emscripten no processes
+
+fn main() {
+    assert_ne!(1 + 1, 2, "1 + 1 definitely should not be 2");
+}