| use crate::consts::{constant, Constant}; |
| use crate::utils::paths; |
| use crate::utils::{is_direct_expn_of, is_expn_of, match_function_call, snippet_opt, span_lint_and_help}; |
| use if_chain::if_chain; |
| use rustc_ast::ast::LitKind; |
| use rustc_hir::{Expr, ExprKind, PatKind, UnOp}; |
| use rustc_lint::{LateContext, LateLintPass}; |
| use rustc_session::{declare_lint_pass, declare_tool_lint}; |
| |
| declare_clippy_lint! { |
| /// **What it does:** Checks for `assert!(true)` and `assert!(false)` calls. |
| /// |
| /// **Why is this bad?** Will be optimized out by the compiler or should probably be replaced by a |
| /// panic!() or unreachable!() |
| /// |
| /// **Known problems:** None |
| /// |
| /// **Example:** |
| /// ```rust,ignore |
| /// assert!(false) |
| /// // or |
| /// assert!(true) |
| /// // or |
| /// const B: bool = false; |
| /// assert!(B) |
| /// ``` |
| pub ASSERTIONS_ON_CONSTANTS, |
| style, |
| "`assert!(true)` / `assert!(false)` will be optimized out by the compiler, and should probably be replaced by a `panic!()` or `unreachable!()`" |
| } |
| |
| declare_lint_pass!(AssertionsOnConstants => [ASSERTIONS_ON_CONSTANTS]); |
| |
| impl<'a, 'tcx> LateLintPass<'a, 'tcx> for AssertionsOnConstants { |
| fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, e: &'tcx Expr<'_>) { |
| let lint_true = |is_debug: bool| { |
| span_lint_and_help( |
| cx, |
| ASSERTIONS_ON_CONSTANTS, |
| e.span, |
| if is_debug { |
| "`debug_assert!(true)` will be optimized out by the compiler" |
| } else { |
| "`assert!(true)` will be optimized out by the compiler" |
| }, |
| "remove it", |
| ); |
| }; |
| let lint_false_without_message = || { |
| span_lint_and_help( |
| cx, |
| ASSERTIONS_ON_CONSTANTS, |
| e.span, |
| "`assert!(false)` should probably be replaced", |
| "use `panic!()` or `unreachable!()`", |
| ); |
| }; |
| let lint_false_with_message = |panic_message: String| { |
| span_lint_and_help( |
| cx, |
| ASSERTIONS_ON_CONSTANTS, |
| e.span, |
| &format!("`assert!(false, {})` should probably be replaced", panic_message), |
| &format!("use `panic!({})` or `unreachable!({})`", panic_message, panic_message), |
| ) |
| }; |
| |
| if let Some(debug_assert_span) = is_expn_of(e.span, "debug_assert") { |
| if debug_assert_span.from_expansion() { |
| return; |
| } |
| if_chain! { |
| if let ExprKind::Unary(_, ref lit) = e.kind; |
| if let Some((Constant::Bool(is_true), _)) = constant(cx, cx.tables, lit); |
| if is_true; |
| then { |
| lint_true(true); |
| } |
| }; |
| } else if let Some(assert_span) = is_direct_expn_of(e.span, "assert") { |
| if assert_span.from_expansion() { |
| return; |
| } |
| if let Some(assert_match) = match_assert_with_message(&cx, e) { |
| match assert_match { |
| // matched assert but not message |
| AssertKind::WithoutMessage(false) => lint_false_without_message(), |
| AssertKind::WithoutMessage(true) | AssertKind::WithMessage(_, true) => lint_true(false), |
| AssertKind::WithMessage(panic_message, false) => lint_false_with_message(panic_message), |
| }; |
| } |
| } |
| } |
| } |
| |
| /// Result of calling `match_assert_with_message`. |
| enum AssertKind { |
| WithMessage(String, bool), |
| WithoutMessage(bool), |
| } |
| |
| /// Check if the expression matches |
| /// |
| /// ```rust,ignore |
| /// match { let _t = !c; _t } { |
| /// true => { |
| /// { |
| /// ::std::rt::begin_panic(message, _) |
| /// } |
| /// } |
| /// _ => { } |
| /// }; |
| /// ``` |
| /// |
| /// where `message` is any expression and `c` is a constant bool. |
| fn match_assert_with_message<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr<'_>) -> Option<AssertKind> { |
| if_chain! { |
| if let ExprKind::Match(ref expr, ref arms, _) = expr.kind; |
| // matches { let _t = expr; _t } |
| if let ExprKind::DropTemps(ref expr) = expr.kind; |
| if let ExprKind::Unary(UnOp::UnNot, ref expr) = expr.kind; |
| // bind the first argument of the `assert!` macro |
| if let Some((Constant::Bool(is_true), _)) = constant(cx, cx.tables, expr); |
| // arm 1 pattern |
| if let PatKind::Lit(ref lit_expr) = arms[0].pat.kind; |
| if let ExprKind::Lit(ref lit) = lit_expr.kind; |
| if let LitKind::Bool(true) = lit.node; |
| // arm 1 block |
| if let ExprKind::Block(ref block, _) = arms[0].body.kind; |
| if block.stmts.is_empty(); |
| if let Some(block_expr) = &block.expr; |
| if let ExprKind::Block(ref inner_block, _) = block_expr.kind; |
| if let Some(begin_panic_call) = &inner_block.expr; |
| // function call |
| if let Some(args) = match_function_call(cx, begin_panic_call, &paths::BEGIN_PANIC); |
| if args.len() == 1; |
| // bind the second argument of the `assert!` macro if it exists |
| if let panic_message = snippet_opt(cx, args[0].span); |
| // second argument of begin_panic is irrelevant |
| // as is the second match arm |
| then { |
| // an empty message occurs when it was generated by the macro |
| // (and not passed by the user) |
| return panic_message |
| .filter(|msg| !msg.is_empty()) |
| .map(|msg| AssertKind::WithMessage(msg, is_true)) |
| .or(Some(AssertKind::WithoutMessage(is_true))); |
| } |
| } |
| None |
| } |