Add missing_assert_message lint

Co-authored-by: Weihang Lo <me@weihanglo.tw>

tests/ui/filter_map_next_fixable.fixed

@@ -1,7 +1,7 @@
 // run-rustfix
 
 #![warn(clippy::all, clippy::pedantic)]
-#![allow(unused)]
+#![allow(unused, clippy::missing_assert_message)]
 
 fn main() {
     let a = ["1", "lol", "3", "NaN", "5"];

tests/ui/filter_map_next_fixable.rs

@@ -1,7 +1,7 @@
 // run-rustfix
 
 #![warn(clippy::all, clippy::pedantic)]
-#![allow(unused)]
+#![allow(unused, clippy::missing_assert_message)]
 
 fn main() {
     let a = ["1", "lol", "3", "NaN", "5"];

tests/ui/missing_assert_message.rs

@@ -0,0 +1,84 @@
+#![allow(unused)]
+#![warn(clippy::missing_assert_message)]
+
+macro_rules! bar {
+    ($( $x:expr ),*) => {
+        foo()
+    };
+}
+
+fn main() {}
+
+// Should trigger warning
+fn asserts_without_message() {
+    assert!(foo());
+    assert_eq!(foo(), foo());
+    assert_ne!(foo(), foo());
+    debug_assert!(foo());
+    debug_assert_eq!(foo(), foo());
+    debug_assert_ne!(foo(), foo());
+}
+
+// Should trigger warning
+fn asserts_without_message_but_with_macro_calls() {
+    assert!(bar!(true));
+    assert!(bar!(true, false));
+    assert_eq!(bar!(true), foo());
+    assert_ne!(bar!(true, true), bar!(true));
+}
+
+// Should trigger warning
+fn asserts_with_trailing_commas() {
+    assert!(foo(),);
+    assert_eq!(foo(), foo(),);
+    assert_ne!(foo(), foo(),);
+    debug_assert!(foo(),);
+    debug_assert_eq!(foo(), foo(),);
+    debug_assert_ne!(foo(), foo(),);
+}
+
+// Should not trigger warning
+fn asserts_with_message_and_with_macro_calls() {
+    assert!(bar!(true), "msg");
+    assert!(bar!(true, false), "msg");
+    assert_eq!(bar!(true), foo(), "msg");
+    assert_ne!(bar!(true, true), bar!(true), "msg");
+}
+
+// Should not trigger warning
+fn asserts_with_message() {
+    assert!(foo(), "msg");
+    assert_eq!(foo(), foo(), "msg");
+    assert_ne!(foo(), foo(), "msg");
+    debug_assert!(foo(), "msg");
+    debug_assert_eq!(foo(), foo(), "msg");
+    debug_assert_ne!(foo(), foo(), "msg");
+}
+
+// Should not trigger warning
+#[test]
+fn asserts_without_message_but_inside_a_test_function() {
+    assert!(foo());
+    assert_eq!(foo(), foo());
+    assert_ne!(foo(), foo());
+    debug_assert!(foo());
+    debug_assert_eq!(foo(), foo());
+    debug_assert_ne!(foo(), foo());
+}
+
+// Should not trigger warning
+#[cfg(test)]
+mod tests {
+    fn asserts_without_message_but_inside_a_test_module() {
+        assert!(foo());
+        assert_eq!(foo(), foo());
+        assert_ne!(foo(), foo());
+        debug_assert!(foo());
+        debug_assert_eq!(foo(), foo());
+        debug_assert_ne!(foo(), foo());
+    }
+}
+
+fn foo() -> bool {
+    true
+}

tests/ui/missing_assert_message.stderr

@@ -0,0 +1,100 @@
+error: assert without any message
+  --> $DIR/missing_assert_message.rs:14:5
+   |
+LL |     assert!(foo());
+   |     ^^^^^^^^^^^^^^
+   |
+   = note: `-D clippy::missing-assert-message` implied by `-D warnings`
+
+error: assert without any message
+  --> $DIR/missing_assert_message.rs:15:5
+   |
+LL |     assert_eq!(foo(), foo());
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: assert without any message
+  --> $DIR/missing_assert_message.rs:16:5
+   |
+LL |     assert_ne!(foo(), foo());
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: assert without any message
+  --> $DIR/missing_assert_message.rs:17:5
+   |
+LL |     debug_assert!(foo());
+   |     ^^^^^^^^^^^^^^^^^^^^
+
+error: assert without any message
+  --> $DIR/missing_assert_message.rs:18:5
+   |
+LL |     debug_assert_eq!(foo(), foo());
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: assert without any message
+  --> $DIR/missing_assert_message.rs:19:5
+   |
+LL |     debug_assert_ne!(foo(), foo());
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: assert without any message
+  --> $DIR/missing_assert_message.rs:24:5
+   |
+LL |     assert!(bar!(true));
+   |     ^^^^^^^^^^^^^^^^^^^
+
+error: assert without any message
+  --> $DIR/missing_assert_message.rs:25:5
+   |
+LL |     assert!(bar!(true, false));
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: assert without any message
+  --> $DIR/missing_assert_message.rs:26:5
+   |
+LL |     assert_eq!(bar!(true), foo());
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: assert without any message
+  --> $DIR/missing_assert_message.rs:27:5
+   |
+LL |     assert_ne!(bar!(true, true), bar!(true));
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: assert without any message
+  --> $DIR/missing_assert_message.rs:32:5
+   |
+LL |     assert!(foo(),);
+   |     ^^^^^^^^^^^^^^^
+
+error: assert without any message
+  --> $DIR/missing_assert_message.rs:33:5
+   |
+LL |     assert_eq!(foo(), foo(),);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: assert without any message
+  --> $DIR/missing_assert_message.rs:34:5
+   |
+LL |     assert_ne!(foo(), foo(),);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: assert without any message
+  --> $DIR/missing_assert_message.rs:35:5
+   |
+LL |     debug_assert!(foo(),);
+   |     ^^^^^^^^^^^^^^^^^^^^^
+
+error: assert without any message
+  --> $DIR/missing_assert_message.rs:36:5
+   |
+LL |     debug_assert_eq!(foo(), foo(),);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: assert without any message
+  --> $DIR/missing_assert_message.rs:37:5
+   |
+LL |     debug_assert_ne!(foo(), foo(),);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 16 previous errors
+