Merge commit '3c06e0b1ce' into clippyup

clippy_lints/src/missing_assert_message.rs

@@ -0,0 +1,82 @@
+use clippy_utils::diagnostics::span_lint_and_help;
+use clippy_utils::macros::{find_assert_args, find_assert_eq_args, root_macro_call_first_node, PanicExpn};
+use clippy_utils::{is_in_cfg_test, is_in_test_function};
+use rustc_hir::Expr;
+use rustc_lint::{LateContext, LateLintPass};
+use rustc_session::{declare_lint_pass, declare_tool_lint};
+use rustc_span::sym;
+
+declare_clippy_lint! {
+    /// ### What it does
+    /// Checks assertions without a custom panic message.
+    ///
+    /// ### Why is this bad?
+    /// Without a good custom message, it'd be hard to understand what went wrong when the assertion fails.
+    /// A good custom message should be more about why the failure of the assertion is problematic
+    /// and not what is failed because the assertion already conveys that.
+    ///
+    /// ### Known problems
+    /// This lint cannot check the quality of the custom panic messages.
+    /// Hence, you can suppress this lint simply by adding placeholder messages
+    /// like "assertion failed". However, we recommend coming up with good messages
+    /// that provide useful information instead of placeholder messages that
+    /// don't provide any extra information.
+    ///
+    /// ### Example
+    /// ```rust
+    /// # struct Service { ready: bool }
+    /// fn call(service: Service) {
+    ///     assert!(service.ready);
+    /// }
+    /// ```
+    /// Use instead:
+    /// ```rust
+    /// # struct Service { ready: bool }
+    /// fn call(service: Service) {
+    ///     assert!(service.ready, "`service.poll_ready()` must be called first to ensure that service is ready to receive requests");
+    /// }
+    /// ```
+    #[clippy::version = "1.69.0"]
+    pub MISSING_ASSERT_MESSAGE,
+    restriction,
+    "checks assertions without a custom panic message"
+}
+
+declare_lint_pass!(MissingAssertMessage => [MISSING_ASSERT_MESSAGE]);
+
+impl<'tcx> LateLintPass<'tcx> for MissingAssertMessage {
+    fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
+        let Some(macro_call) = root_macro_call_first_node(cx, expr) else { return };
+        let single_argument = match cx.tcx.get_diagnostic_name(macro_call.def_id) {
+            Some(sym::assert_macro | sym::debug_assert_macro) => true,
+            Some(
+                sym::assert_eq_macro | sym::assert_ne_macro | sym::debug_assert_eq_macro | sym::debug_assert_ne_macro,
+            ) => false,
+            _ => return,
+        };
+
+        // This lint would be very noisy in tests, so just ignore if we're in test context
+        if is_in_test_function(cx.tcx, expr.hir_id) || is_in_cfg_test(cx.tcx, expr.hir_id) {
+            return;
+        }
+
+        let panic_expn = if single_argument {
+            let Some((_, panic_expn)) = find_assert_args(cx, expr, macro_call.expn) else { return };
+            panic_expn
+        } else {
+            let Some((_, _, panic_expn)) = find_assert_eq_args(cx, expr, macro_call.expn) else { return };
+            panic_expn
+        };
+
+        if let PanicExpn::Empty = panic_expn {
+            span_lint_and_help(
+                cx,
+                MISSING_ASSERT_MESSAGE,
+                macro_call.span,
+                "assert without any message",
+                None,
+                "consider describing why the failing assert is problematic",
+            );
+        }
+    }
+}