68 lines
2.3 KiB
Rust
68 lines
2.3 KiB
Rust
use clippy_utils::diagnostics::span_lint_and_sugg;
|
|
use hir::{Node, PatKind};
|
|
use rustc_errors::Applicability;
|
|
use rustc_hir as hir;
|
|
use rustc_lint::{LateContext, LateLintPass};
|
|
use rustc_session::declare_lint_pass;
|
|
|
|
declare_clippy_lint! {
|
|
/// ### What it does
|
|
/// Checks for usage of `_` in patterns of type `()`.
|
|
///
|
|
/// ### Why is this bad?
|
|
/// Matching with `()` explicitly instead of `_` outlines
|
|
/// the fact that the pattern contains no data. Also it
|
|
/// would detect a type change that `_` would ignore.
|
|
///
|
|
/// ### Example
|
|
/// ```no_run
|
|
/// match std::fs::create_dir("tmp-work-dir") {
|
|
/// Ok(_) => println!("Working directory created"),
|
|
/// Err(s) => eprintln!("Could not create directory: {s}"),
|
|
/// }
|
|
/// ```
|
|
/// Use instead:
|
|
/// ```no_run
|
|
/// match std::fs::create_dir("tmp-work-dir") {
|
|
/// Ok(()) => println!("Working directory created"),
|
|
/// Err(s) => eprintln!("Could not create directory: {s}"),
|
|
/// }
|
|
/// ```
|
|
#[clippy::version = "1.73.0"]
|
|
pub IGNORED_UNIT_PATTERNS,
|
|
pedantic,
|
|
"suggest replacing `_` by `()` in patterns where appropriate"
|
|
}
|
|
declare_lint_pass!(IgnoredUnitPatterns => [IGNORED_UNIT_PATTERNS]);
|
|
|
|
impl<'tcx> LateLintPass<'tcx> for IgnoredUnitPatterns {
|
|
fn check_pat(&mut self, cx: &LateContext<'tcx>, pat: &'tcx hir::Pat<'tcx>) {
|
|
if pat.span.from_expansion() {
|
|
return;
|
|
}
|
|
|
|
match cx.tcx.hir().get_parent(pat.hir_id) {
|
|
Node::Param(param) if matches!(cx.tcx.hir().get_parent(param.hir_id), Node::Item(_)) => {
|
|
// Ignore function parameters
|
|
return;
|
|
},
|
|
Node::Local(local) if local.ty.is_some() => {
|
|
// Ignore let bindings with explicit type
|
|
return;
|
|
},
|
|
_ => {},
|
|
}
|
|
if matches!(pat.kind, PatKind::Wild) && cx.typeck_results().pat_ty(pat).peel_refs().is_unit() {
|
|
span_lint_and_sugg(
|
|
cx,
|
|
IGNORED_UNIT_PATTERNS,
|
|
pat.span,
|
|
"matching over `()` is more explicit",
|
|
"use `()` instead of `_`",
|
|
String::from("()"),
|
|
Applicability::MachineApplicable,
|
|
);
|
|
}
|
|
}
|
|
}
|