mirror of
https://github.com/rust-lang/rust-clippy
synced 2024-12-23 11:33:19 +00:00
72 lines
3 KiB
Rust
72 lines
3 KiB
Rust
use crate::utils::{is_type_diagnostic_item, method_chain_args, snippet_with_applicability, span_lint_and_sugg};
|
|
use if_chain::if_chain;
|
|
use rustc_errors::Applicability;
|
|
use rustc_hir::{Expr, ExprKind, MatchSource, PatKind, QPath};
|
|
use rustc_lint::{LateContext, LateLintPass};
|
|
use rustc_session::{declare_lint_pass, declare_tool_lint};
|
|
|
|
declare_clippy_lint! {
|
|
/// **What it does:*** Checks for unnecessary `ok()` in if let.
|
|
///
|
|
/// **Why is this bad?** Calling `ok()` in if let is unnecessary, instead match
|
|
/// on `Ok(pat)`
|
|
///
|
|
/// **Known problems:** None.
|
|
///
|
|
/// **Example:**
|
|
/// ```ignore
|
|
/// for i in iter {
|
|
/// if let Some(value) = i.parse().ok() {
|
|
/// vec.push(value)
|
|
/// }
|
|
/// }
|
|
/// ```
|
|
/// Could be written:
|
|
///
|
|
/// ```ignore
|
|
/// for i in iter {
|
|
/// if let Ok(value) = i.parse() {
|
|
/// vec.push(value)
|
|
/// }
|
|
/// }
|
|
/// ```
|
|
pub IF_LET_SOME_RESULT,
|
|
style,
|
|
"usage of `ok()` in `if let Some(pat)` statements is unnecessary, match on `Ok(pat)` instead"
|
|
}
|
|
|
|
declare_lint_pass!(OkIfLet => [IF_LET_SOME_RESULT]);
|
|
|
|
impl<'tcx> LateLintPass<'tcx> for OkIfLet {
|
|
fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
|
|
if_chain! { //begin checking variables
|
|
if let ExprKind::Match(ref op, ref body, source) = expr.kind; //test if expr is a match
|
|
if let MatchSource::IfLetDesugar { .. } = source; //test if it is an If Let
|
|
if let ExprKind::MethodCall(_, ok_span, ref result_types, _) = op.kind; //check is expr.ok() has type Result<T,E>.ok(, _)
|
|
if let PatKind::TupleStruct(QPath::Resolved(_, ref x), ref y, _) = body[0].pat.kind; //get operation
|
|
if method_chain_args(op, &["ok"]).is_some(); //test to see if using ok() methoduse std::marker::Sized;
|
|
if is_type_diagnostic_item(cx, cx.tables().expr_ty(&result_types[0]), sym!(result_type));
|
|
if rustc_hir_pretty::to_string(rustc_hir_pretty::NO_ANN, |s| s.print_path(x, false)) == "Some";
|
|
|
|
then {
|
|
let mut applicability = Applicability::MachineApplicable;
|
|
let some_expr_string = snippet_with_applicability(cx, y[0].span, "", &mut applicability);
|
|
let trimmed_ok = snippet_with_applicability(cx, op.span.until(ok_span), "", &mut applicability);
|
|
let sugg = format!(
|
|
"if let Ok({}) = {}",
|
|
some_expr_string,
|
|
trimmed_ok.trim().trim_end_matches('.'),
|
|
);
|
|
span_lint_and_sugg(
|
|
cx,
|
|
IF_LET_SOME_RESULT,
|
|
expr.span.with_hi(op.span.hi()),
|
|
"Matching on `Some` with `ok()` is redundant",
|
|
&format!("Consider matching on `Ok({})` and removing the call to `ok` instead", some_expr_string),
|
|
sugg,
|
|
applicability,
|
|
);
|
|
}
|
|
}
|
|
}
|
|
}
|