1 use clippy_utils::diagnostics::span_lint_and_then;
2 use clippy_utils::{match_def_path, paths};
3 use if_chain::if_chain;
4 use rustc_ast::LitKind;
5 use rustc_errors::Applicability;
7 use rustc_hir::{Expr, ExprKind};
8 use rustc_lint::{LateContext, LateLintPass};
9 use rustc_session::{declare_lint_pass, declare_tool_lint};
10 use rustc_span::source_map::Spanned;
12 declare_clippy_lint! {
13 /// **What it does:** Finds occurrences of `Vec::resize(0, an_int)`
15 /// **Why is this bad?** This is probably an argument inversion mistake.
17 /// **Known problems:** None.
21 /// vec!(1, 2, 3, 4, 5).resize(0, 5)
23 pub VEC_RESIZE_TO_ZERO,
25 "emptying a vector with `resize(0, an_int)` instead of `clear()` is probably an argument inversion mistake"
28 declare_lint_pass!(VecResizeToZero => [VEC_RESIZE_TO_ZERO]);
30 impl<'tcx> LateLintPass<'tcx> for VecResizeToZero {
31 fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
33 if let hir::ExprKind::MethodCall(path_segment, _, ref args, _) = expr.kind;
34 if let Some(method_def_id) = cx.typeck_results().type_dependent_def_id(expr.hir_id);
35 if match_def_path(cx, method_def_id, &paths::VEC_RESIZE) && args.len() == 3;
36 if let ExprKind::Lit(Spanned { node: LitKind::Int(0, _), .. }) = args[1].kind;
37 if let ExprKind::Lit(Spanned { node: LitKind::Int(..), .. }) = args[2].kind;
39 let method_call_span = expr.span.with_lo(path_segment.ident.span.lo());
44 "emptying a vector with `resize`",
46 db.help("the arguments may be inverted...");
49 "...or you can empty the vector with",
50 "clear()".to_string(),
51 Applicability::MaybeIncorrect,