100 lines
3.8 KiB
Rust
100 lines
3.8 KiB
Rust
use clippy_utils::diagnostics::span_lint_and_sugg;
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use clippy_utils::higher::PanicExpn;
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use clippy_utils::source::snippet_with_applicability;
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use clippy_utils::{is_expn_of, sugg};
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use rustc_errors::Applicability;
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use rustc_hir::{Block, Expr, ExprKind, StmtKind, 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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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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pub IF_THEN_PANIC,
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style,
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"`panic!` and only a `panic!` in `if`-then statement"
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}
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declare_lint_pass!(IfThenPanic => [IF_THEN_PANIC]);
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impl LateLintPass<'_> for IfThenPanic {
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fn check_expr(&mut self, cx: &LateContext<'_>, expr: &Expr<'_>) {
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if_chain! {
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if let Expr {
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kind: ExprKind:: If(cond, Expr {
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kind: ExprKind::Block(
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Block {
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stmts: [stmt],
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..
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},
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_),
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..
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}, None),
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..
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} = &expr;
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if is_expn_of(stmt.span, "panic").is_some();
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if !matches!(cond.kind, ExprKind::Let(_, _, _));
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if let StmtKind::Semi(semi) = stmt.kind;
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if !cx.tcx.sess.source_map().is_multiline(cond.span);
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then {
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let span = if let Some(panic_expn) = PanicExpn::parse(semi) {
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match *panic_expn.format_args.value_args {
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[] => panic_expn.format_args.format_string_span,
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[.., last] => panic_expn.format_args.format_string_span.to(last.span),
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}
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} else {
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if_chain! {
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if let ExprKind::Block(block, _) = semi.kind;
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if let Some(init) = block.expr;
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if let ExprKind::Call(_, [format_args]) = init.kind;
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then {
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format_args.span
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} else {
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return
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}
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}
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};
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let mut applicability = Applicability::MachineApplicable;
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let sugg = snippet_with_applicability(cx, span, "..", &mut applicability);
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let cond_sugg = if let ExprKind::DropTemps(e, ..) = cond.kind {
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if let Expr{kind: ExprKind::Unary(UnOp::Not, not_expr), ..} = e {
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sugg::Sugg::hir_with_applicability(cx, not_expr, "..", &mut applicability).maybe_par().to_string()
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} else {
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format!("!{}", sugg::Sugg::hir_with_applicability(cx, e, "..", &mut applicability).maybe_par())
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}
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} else {
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format!("!{}", sugg::Sugg::hir_with_applicability(cx, cond, "..", &mut applicability).maybe_par())
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};
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span_lint_and_sugg(
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cx,
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IF_THEN_PANIC,
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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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format!("assert!({}, {});", cond_sugg, 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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