1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
|
use clippy_utils::diagnostics::span_lint_and_then;
use clippy_utils::{match_def_path, paths};
use if_chain::if_chain;
use rustc_ast::LitKind;
use rustc_errors::Applicability;
use rustc_hir as hir;
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;
declare_clippy_lint! {
/// ### What it does
/// Finds occurrences of `Vec::resize(0, an_int)`
///
/// ### Why is this bad?
/// This is probably an argument inversion mistake.
///
/// ### Example
/// ```rust
/// vec!(1, 2, 3, 4, 5).resize(0, 5)
/// ```
///
/// Use instead:
/// ```rust
/// vec!(1, 2, 3, 4, 5).clear()
/// ```
#[clippy::version = "1.46.0"]
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, args, _) = expr.kind;
if let Some(method_def_id) = cx.typeck_results().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,
);
},
);
}
}
}
}
|
