2019-10-05 09:45:02 -05:00
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use crate::consts::{constant, Constant};
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2020-11-17 14:16:15 -06:00
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use crate::utils::{is_direct_expn_of, is_expn_of, match_panic_call, snippet_opt, span_lint_and_help};
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2019-10-05 09:45:02 -05:00
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use if_chain::if_chain;
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2020-02-29 21:23:33 -06:00
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use rustc_ast::ast::LitKind;
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2020-02-21 02:39:38 -06:00
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use rustc_hir::{Expr, ExprKind, PatKind, UnOp};
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2020-01-12 00:08:41 -06:00
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use rustc_lint::{LateContext, LateLintPass};
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2020-01-11 05:37:08 -06:00
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use rustc_session::{declare_lint_pass, declare_tool_lint};
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2018-12-25 16:29:03 -06:00
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declare_clippy_lint! {
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2019-01-30 19:15:29 -06:00
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/// **What it does:** Checks for `assert!(true)` and `assert!(false)` calls.
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2019-03-05 10:50:33 -06:00
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///
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/// **Why is this bad?** Will be optimized out by the compiler or should probably be replaced by a
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2020-03-17 20:50:39 -05:00
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/// `panic!()` or `unreachable!()`
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2019-03-05 10:50:33 -06:00
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///
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/// **Known problems:** None
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///
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/// **Example:**
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2019-03-10 17:01:56 -05:00
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/// ```rust,ignore
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2019-01-30 19:15:29 -06:00
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/// assert!(false)
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/// assert!(true)
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2019-03-05 10:50:33 -06:00
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/// const B: bool = false;
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2019-01-30 19:15:29 -06:00
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/// assert!(B)
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2019-03-05 10:50:33 -06:00
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/// ```
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2019-01-09 04:38:38 -06:00
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pub ASSERTIONS_ON_CONSTANTS,
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style,
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2019-03-10 12:19:47 -05:00
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"`assert!(true)` / `assert!(false)` will be optimized out by the compiler, and should probably be replaced by a `panic!()` or `unreachable!()`"
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2018-12-25 16:29:03 -06:00
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}
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2019-04-08 15:43:55 -05:00
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declare_lint_pass!(AssertionsOnConstants => [ASSERTIONS_ON_CONSTANTS]);
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2018-12-25 16:29:03 -06:00
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2020-06-25 15:41:36 -05:00
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impl<'tcx> LateLintPass<'tcx> for AssertionsOnConstants {
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fn check_expr(&mut self, cx: &LateContext<'tcx>, e: &'tcx Expr<'_>) {
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2020-01-19 20:52:58 -06:00
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let lint_true = |is_debug: bool| {
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2020-01-26 19:56:22 -06:00
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span_lint_and_help(
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2019-10-07 15:08:00 -05:00
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cx,
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ASSERTIONS_ON_CONSTANTS,
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e.span,
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2020-01-19 20:52:58 -06:00
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if is_debug {
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"`debug_assert!(true)` will be optimized out by the compiler"
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} else {
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"`assert!(true)` will be optimized out by the compiler"
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},
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2020-04-18 05:28:29 -05:00
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None,
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2019-10-07 15:08:00 -05:00
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"remove it",
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);
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};
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let lint_false_without_message = || {
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2020-01-26 19:56:22 -06:00
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span_lint_and_help(
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2019-10-07 15:08:00 -05:00
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cx,
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ASSERTIONS_ON_CONSTANTS,
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e.span,
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"`assert!(false)` should probably be replaced",
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2020-04-18 05:28:29 -05:00
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None,
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2019-10-07 15:08:00 -05:00
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"use `panic!()` or `unreachable!()`",
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);
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2019-08-17 13:46:44 -05:00
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};
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2019-10-07 15:08:00 -05:00
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let lint_false_with_message = |panic_message: String| {
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2020-01-26 19:56:22 -06:00
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span_lint_and_help(
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2019-10-07 15:08:00 -05:00
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cx,
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ASSERTIONS_ON_CONSTANTS,
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e.span,
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&format!("`assert!(false, {})` should probably be replaced", panic_message),
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2020-04-18 05:28:29 -05:00
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None,
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2019-10-07 15:08:00 -05:00
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&format!("use `panic!({})` or `unreachable!({})`", panic_message, panic_message),
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)
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};
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2019-08-17 13:46:44 -05:00
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if let Some(debug_assert_span) = is_expn_of(e.span, "debug_assert") {
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2019-08-19 11:30:32 -05:00
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if debug_assert_span.from_expansion() {
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2019-08-17 13:46:44 -05:00
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return;
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}
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2019-10-07 15:08:00 -05:00
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if_chain! {
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if let ExprKind::Unary(_, ref lit) = e.kind;
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2020-07-17 03:47:04 -05:00
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if let Some((Constant::Bool(is_true), _)) = constant(cx, cx.typeck_results(), lit);
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2019-10-07 15:08:00 -05:00
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if is_true;
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then {
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2020-01-19 20:52:58 -06:00
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lint_true(true);
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2019-10-07 15:08:00 -05:00
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}
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};
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2019-08-17 13:46:44 -05:00
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} else if let Some(assert_span) = is_direct_expn_of(e.span, "assert") {
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2019-08-19 11:30:32 -05:00
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if assert_span.from_expansion() {
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2019-08-17 13:46:44 -05:00
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return;
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}
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2019-10-07 15:08:00 -05:00
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if let Some(assert_match) = match_assert_with_message(&cx, e) {
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match assert_match {
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// matched assert but not message
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AssertKind::WithoutMessage(false) => lint_false_without_message(),
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2020-01-19 20:52:58 -06:00
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AssertKind::WithoutMessage(true) | AssertKind::WithMessage(_, true) => lint_true(false),
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2019-10-07 15:08:00 -05:00
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AssertKind::WithMessage(panic_message, false) => lint_false_with_message(panic_message),
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};
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2019-10-05 09:45:02 -05:00
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}
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}
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}
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}
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2019-10-07 15:08:00 -05:00
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/// Result of calling `match_assert_with_message`.
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enum AssertKind {
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WithMessage(String, bool),
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WithoutMessage(bool),
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}
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2019-10-06 13:10:30 -05:00
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/// Check if the expression matches
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///
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/// ```rust,ignore
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/// match { let _t = !c; _t } {
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/// true => {
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/// {
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/// ::std::rt::begin_panic(message, _)
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/// }
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/// }
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/// _ => { }
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/// };
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/// ```
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///
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2019-10-07 15:08:00 -05:00
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/// where `message` is any expression and `c` is a constant bool.
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2020-06-25 15:41:36 -05:00
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fn match_assert_with_message<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) -> Option<AssertKind> {
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2019-10-05 09:45:02 -05:00
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if_chain! {
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2019-10-06 13:10:30 -05:00
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if let ExprKind::Match(ref expr, ref arms, _) = expr.kind;
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// matches { let _t = expr; _t }
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2019-10-05 09:45:02 -05:00
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if let ExprKind::DropTemps(ref expr) = expr.kind;
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if let ExprKind::Unary(UnOp::UnNot, ref expr) = expr.kind;
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2019-10-06 13:10:30 -05:00
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// bind the first argument of the `assert!` macro
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2020-07-17 03:47:04 -05:00
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if let Some((Constant::Bool(is_true), _)) = constant(cx, cx.typeck_results(), expr);
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2019-10-05 09:45:02 -05:00
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// arm 1 pattern
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if let PatKind::Lit(ref lit_expr) = arms[0].pat.kind;
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if let ExprKind::Lit(ref lit) = lit_expr.kind;
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if let LitKind::Bool(true) = lit.node;
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// arm 1 block
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2019-10-06 13:10:30 -05:00
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if let ExprKind::Block(ref block, _) = arms[0].body.kind;
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2019-12-27 01:12:26 -06:00
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if block.stmts.is_empty();
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2019-10-06 13:10:30 -05:00
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if let Some(block_expr) = &block.expr;
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if let ExprKind::Block(ref inner_block, _) = block_expr.kind;
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if let Some(begin_panic_call) = &inner_block.expr;
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2019-10-05 09:45:02 -05:00
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// function call
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2020-11-17 14:16:15 -06:00
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if let Some(args) = match_panic_call(cx, begin_panic_call);
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2020-01-05 00:43:41 -06:00
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if args.len() == 1;
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2019-10-07 15:08:00 -05:00
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// bind the second argument of the `assert!` macro if it exists
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if let panic_message = snippet_opt(cx, args[0].span);
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2019-10-06 13:10:30 -05:00
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// second argument of begin_panic is irrelevant
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// as is the second match arm
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2019-10-05 09:45:02 -05:00
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then {
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2019-10-07 15:08:00 -05:00
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// an empty message occurs when it was generated by the macro
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// (and not passed by the user)
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return panic_message
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.filter(|msg| !msg.is_empty())
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.map(|msg| AssertKind::WithMessage(msg, is_true))
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.or(Some(AssertKind::WithoutMessage(is_true)));
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2018-12-25 16:29:03 -06:00
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}
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}
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2019-10-06 13:10:30 -05:00
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None
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}
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