rust/clippy_lints/src/methods/unwrap_or_else_default.rs
2021-12-23 22:12:08 -08:00

47 lines
1.5 KiB
Rust

//! Lint for `some_result_or_option.unwrap_or_else(Default::default)`
use super::UNWRAP_OR_ELSE_DEFAULT;
use clippy_utils::{
diagnostics::span_lint_and_sugg, is_default_equivalent_call, source::snippet_with_applicability,
ty::is_type_diagnostic_item,
};
use rustc_errors::Applicability;
use rustc_hir as hir;
use rustc_lint::LateContext;
use rustc_span::sym;
pub(super) fn check<'tcx>(
cx: &LateContext<'tcx>,
expr: &'tcx hir::Expr<'_>,
recv: &'tcx hir::Expr<'_>,
u_arg: &'tcx hir::Expr<'_>,
) {
// something.unwrap_or_else(Default::default)
// ^^^^^^^^^- recv ^^^^^^^^^^^^^^^^- u_arg
// ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^- expr
let recv_ty = cx.typeck_results().expr_ty(recv);
let is_option = is_type_diagnostic_item(cx, recv_ty, sym::Option);
let is_result = is_type_diagnostic_item(cx, recv_ty, sym::Result);
if_chain! {
if is_option || is_result;
if is_default_equivalent_call(cx, u_arg);
then {
let mut applicability = Applicability::MachineApplicable;
span_lint_and_sugg(
cx,
UNWRAP_OR_ELSE_DEFAULT,
expr.span,
"use of `.unwrap_or_else(..)` to construct default value",
"try",
format!(
"{}.unwrap_or_default()",
snippet_with_applicability(cx, recv.span, "..", &mut applicability)
),
applicability,
);
}
}
}