X-Git-Url: https://git.lizzy.rs/?a=blobdiff_plain;f=clippy_lints%2Fsrc%2Fassertions_on_constants.rs;h=874fff1f0814fb8a963123b23fcfc338e8f4809f;hb=e5a5b0a0774625eebbe7b29c67b49dc6431544d1;hp=36ed835e2581536f194a3a27ba8a0d99f56f1b9c;hpb=fc1c2f5f1aad73d58673fc64952fc144e3e50bf7;p=rust.git diff --git a/clippy_lints/src/assertions_on_constants.rs b/clippy_lints/src/assertions_on_constants.rs index 36ed835e258..874fff1f081 100644 --- a/clippy_lints/src/assertions_on_constants.rs +++ b/clippy_lints/src/assertions_on_constants.rs @@ -1,11 +1,12 @@ +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_help_and_lint}; use if_chain::if_chain; -use rustc::hir::{Expr, ExprKind}; +use rustc::declare_lint_pass; +use rustc::hir::*; use rustc::lint::{LateContext, LateLintPass, LintArray, LintPass}; -use rustc::{declare_lint_pass, declare_tool_lint}; -use syntax_pos::Span; - -use crate::consts::{constant, Constant}; -use crate::utils::{in_macro, is_direct_expn_of, span_help_and_lint}; +use rustc_session::declare_tool_lint; +use syntax::ast::LitKind; declare_clippy_lint! { /// **What it does:** Checks for `assert!(true)` and `assert!(false)` calls. @@ -33,42 +34,115 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for AssertionsOnConstants { fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, e: &'tcx Expr) { - let mut is_debug_assert = false; - let debug_assert_not_in_macro = |span: Span| { - is_debug_assert = true; - // Check that `debug_assert!` itself is not inside a macro - !in_macro(span) + let lint_true = || { + span_help_and_lint( + cx, + ASSERTIONS_ON_CONSTANTS, + e.span, + "`assert!(true)` will be optimized out by the compiler", + "remove it", + ); + }; + let lint_false_without_message = || { + span_help_and_lint( + cx, + ASSERTIONS_ON_CONSTANTS, + e.span, + "`assert!(false)` should probably be replaced", + "use `panic!()` or `unreachable!()`", + ); }; - if_chain! { - if let Some(assert_span) = is_direct_expn_of(e.span, "assert"); - if !in_macro(assert_span) - || is_direct_expn_of(assert_span, "debug_assert") - .map_or(false, debug_assert_not_in_macro); - if let ExprKind::Unary(_, ref lit) = e.node; - if let Some(bool_const) = constant(cx, cx.tables, lit); - then { - match bool_const.0 { - Constant::Bool(true) => { - span_help_and_lint( - cx, - ASSERTIONS_ON_CONSTANTS, - e.span, - "`assert!(true)` will be optimized out by the compiler", - "remove it" - ); - }, - Constant::Bool(false) if !is_debug_assert => { - span_help_and_lint( - 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_help_and_lint( + 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(); } + }; + } 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(), + 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 { + 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.len() == 0; + 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() == 2; + // 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 }