72 lines
2.8 KiB
Rust
72 lines
2.8 KiB
Rust
use clippy_utils::diagnostics::span_lint_and_sugg;
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use clippy_utils::macros::{root_macro_call, FormatArgsExpn};
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use clippy_utils::source::snippet_with_applicability;
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use clippy_utils::{peel_blocks_with_stmt, sugg};
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use rustc_errors::Applicability;
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use rustc_hir::{Expr, ExprKind, UnOp};
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use rustc_lint::{LateContext, LateLintPass};
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use rustc_session::{declare_lint_pass, declare_tool_lint};
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use rustc_span::sym;
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declare_clippy_lint! {
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/// ### What it does
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/// Detects `if`-then-`panic!` that can be replaced with `assert!`.
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///
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/// ### Why is this bad?
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/// `assert!` is simpler than `if`-then-`panic!`.
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///
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/// ### Example
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/// ```rust
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/// let sad_people: Vec<&str> = vec![];
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/// if !sad_people.is_empty() {
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/// panic!("there are sad people: {:?}", sad_people);
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/// }
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/// ```
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/// Use instead:
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/// ```rust
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/// let sad_people: Vec<&str> = vec![];
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/// assert!(sad_people.is_empty(), "there are sad people: {:?}", sad_people);
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/// ```
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#[clippy::version = "1.57.0"]
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pub MANUAL_ASSERT,
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pedantic,
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"`panic!` and only a `panic!` in `if`-then statement"
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}
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declare_lint_pass!(ManualAssert => [MANUAL_ASSERT]);
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impl<'tcx> LateLintPass<'tcx> for ManualAssert {
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fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &Expr<'tcx>) {
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if_chain! {
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if let ExprKind::If(cond, then, None) = expr.kind;
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if !matches!(cond.kind, ExprKind::Let(_));
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if !expr.span.from_expansion();
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let then = peel_blocks_with_stmt(then);
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if let Some(macro_call) = root_macro_call(then.span);
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if cx.tcx.item_name(macro_call.def_id) == sym::panic;
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if !cx.tcx.sess.source_map().is_multiline(cond.span);
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if let Some(format_args) = FormatArgsExpn::find_nested(cx, then, macro_call.expn);
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then {
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let mut applicability = Applicability::MachineApplicable;
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let format_args_snip = snippet_with_applicability(cx, format_args.inputs_span(), "..", &mut applicability);
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let cond = cond.peel_drop_temps();
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let (cond, not) = match cond.kind {
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ExprKind::Unary(UnOp::Not, e) => (e, ""),
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_ => (cond, "!"),
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};
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let cond_sugg = sugg::Sugg::hir_with_applicability(cx, cond, "..", &mut applicability).maybe_par();
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let sugg = format!("assert!({not}{cond_sugg}, {format_args_snip});");
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span_lint_and_sugg(
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cx,
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MANUAL_ASSERT,
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expr.span,
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"only a `panic!` in `if`-then statement",
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"try",
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sugg,
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Applicability::MachineApplicable,
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);
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}
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}
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}
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}
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