60 lines
2.2 KiB
Rust
60 lines
2.2 KiB
Rust
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use crate::utils::span_lint_and_then;
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use if_chain::if_chain;
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use rustc_errors::Applicability;
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use rustc_hir::{Expr, ExprKind};
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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::source_map::Spanned;
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use crate::utils::{match_def_path, paths};
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use rustc_ast::ast::LitKind;
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use rustc_hir as hir;
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declare_clippy_lint! {
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/// **What it does:** Finds occurences of `Vec::resize(0, an_int)`
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///
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/// **Why is this bad?** This is probably an argument inversion mistake.
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///
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/// **Known problems:** None.
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///
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/// **Example:**
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/// ```rust
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/// vec!(1, 2, 3, 4, 5).resize(0, 5)
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/// ```
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pub VEC_RESIZE_TO_ZERO,
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correctness,
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"emptying a vector with `resize(0, an_int)` instead of `clear()` is probably an argument inversion mistake"
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}
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declare_lint_pass!(VecResizeToZero => [VEC_RESIZE_TO_ZERO]);
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impl<'a, 'tcx> LateLintPass<'a, 'tcx> for VecResizeToZero {
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fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr<'_>) {
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if_chain! {
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if let hir::ExprKind::MethodCall(path_segment, _, ref args) = expr.kind;
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if let Some(method_def_id) = cx.tables.type_dependent_def_id(expr.hir_id);
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if match_def_path(cx, method_def_id, &paths::VEC_RESIZE) && args.len() == 3;
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if let ExprKind::Lit(Spanned { node: LitKind::Int(0, _), .. }) = args[1].kind;
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if let ExprKind::Lit(Spanned { node: LitKind::Int(..), .. }) = args[2].kind;
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then {
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let method_call_span = expr.span.with_lo(path_segment.ident.span.lo());
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span_lint_and_then(
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cx,
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VEC_RESIZE_TO_ZERO,
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expr.span,
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"emptying a vector with `resize`",
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|db| {
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db.help("the arguments may be inverted...");
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db.span_suggestion(
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method_call_span,
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"...or you can empty the vector with",
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"clear()".to_string(),
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Applicability::MaybeIncorrect,
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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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}
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