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