124 lines
4.7 KiB
Rust
124 lines
4.7 KiB
Rust
use clippy_utils::consts::constant_simple;
|
|
use clippy_utils::diagnostics::span_lint_and_sugg;
|
|
use clippy_utils::source::{indent_of, reindent_multiline, snippet_opt};
|
|
use clippy_utils::ty::is_type_diagnostic_item;
|
|
use clippy_utils::usage::contains_return_break_continue_macro;
|
|
use clippy_utils::{in_constant, is_lang_ctor, path_to_local_id, sugg};
|
|
use if_chain::if_chain;
|
|
use rustc_errors::Applicability;
|
|
use rustc_hir::LangItem::{OptionNone, OptionSome, ResultErr, ResultOk};
|
|
use rustc_hir::{Arm, Expr, ExprKind, PatKind};
|
|
use rustc_lint::LintContext;
|
|
use rustc_lint::{LateContext, LateLintPass};
|
|
use rustc_middle::lint::in_external_macro;
|
|
use rustc_session::{declare_lint_pass, declare_tool_lint};
|
|
use rustc_span::sym;
|
|
|
|
declare_clippy_lint! {
|
|
/// ### What it does
|
|
/// Finds patterns that reimplement `Option::unwrap_or` or `Result::unwrap_or`.
|
|
///
|
|
/// ### Why is this bad?
|
|
/// Concise code helps focusing on behavior instead of boilerplate.
|
|
///
|
|
/// ### Example
|
|
/// ```rust
|
|
/// let foo: Option<i32> = None;
|
|
/// match foo {
|
|
/// Some(v) => v,
|
|
/// None => 1,
|
|
/// };
|
|
/// ```
|
|
///
|
|
/// Use instead:
|
|
/// ```rust
|
|
/// let foo: Option<i32> = None;
|
|
/// foo.unwrap_or(1);
|
|
/// ```
|
|
#[clippy::version = "1.49.0"]
|
|
pub MANUAL_UNWRAP_OR,
|
|
complexity,
|
|
"finds patterns that can be encoded more concisely with `Option::unwrap_or` or `Result::unwrap_or`"
|
|
}
|
|
|
|
declare_lint_pass!(ManualUnwrapOr => [MANUAL_UNWRAP_OR]);
|
|
|
|
impl<'tcx> LateLintPass<'tcx> for ManualUnwrapOr {
|
|
fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) {
|
|
if in_external_macro(cx.sess(), expr.span) || in_constant(cx, expr.hir_id) {
|
|
return;
|
|
}
|
|
lint_manual_unwrap_or(cx, expr);
|
|
}
|
|
}
|
|
|
|
fn lint_manual_unwrap_or<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) {
|
|
fn applicable_or_arm<'a>(cx: &LateContext<'_>, arms: &'a [Arm<'a>]) -> Option<&'a Arm<'a>> {
|
|
if_chain! {
|
|
if arms.len() == 2;
|
|
if arms.iter().all(|arm| arm.guard.is_none());
|
|
if let Some((idx, or_arm)) = arms.iter().enumerate().find(|(_, arm)| {
|
|
match arm.pat.kind {
|
|
PatKind::Path(ref qpath) => is_lang_ctor(cx, qpath, OptionNone),
|
|
PatKind::TupleStruct(ref qpath, [pat], _) =>
|
|
matches!(pat.kind, PatKind::Wild) && is_lang_ctor(cx, qpath, ResultErr),
|
|
_ => false,
|
|
}
|
|
});
|
|
let unwrap_arm = &arms[1 - idx];
|
|
if let PatKind::TupleStruct(ref qpath, [unwrap_pat], _) = unwrap_arm.pat.kind;
|
|
if is_lang_ctor(cx, qpath, OptionSome) || is_lang_ctor(cx, qpath, ResultOk);
|
|
if let PatKind::Binding(_, binding_hir_id, ..) = unwrap_pat.kind;
|
|
if path_to_local_id(unwrap_arm.body, binding_hir_id);
|
|
if cx.typeck_results().expr_adjustments(unwrap_arm.body).is_empty();
|
|
if !contains_return_break_continue_macro(or_arm.body);
|
|
then {
|
|
Some(or_arm)
|
|
} else {
|
|
None
|
|
}
|
|
}
|
|
}
|
|
|
|
if_chain! {
|
|
if let ExprKind::Match(scrutinee, match_arms, _) = expr.kind;
|
|
let ty = cx.typeck_results().expr_ty(scrutinee);
|
|
if let Some(ty_name) = if is_type_diagnostic_item(cx, ty, sym::Option) {
|
|
Some("Option")
|
|
} else if is_type_diagnostic_item(cx, ty, sym::Result) {
|
|
Some("Result")
|
|
} else {
|
|
None
|
|
};
|
|
if let Some(or_arm) = applicable_or_arm(cx, match_arms);
|
|
if let Some(or_body_snippet) = snippet_opt(cx, or_arm.body.span);
|
|
if let Some(indent) = indent_of(cx, expr.span);
|
|
if constant_simple(cx, cx.typeck_results(), or_arm.body).is_some();
|
|
then {
|
|
let reindented_or_body =
|
|
reindent_multiline(or_body_snippet.into(), true, Some(indent));
|
|
|
|
let suggestion = if scrutinee.span.from_expansion() {
|
|
// we don't want parentheses around macro, e.g. `(some_macro!()).unwrap_or(0)`
|
|
sugg::Sugg::hir_with_macro_callsite(cx, scrutinee, "..")
|
|
}
|
|
else {
|
|
sugg::Sugg::hir(cx, scrutinee, "..").maybe_par()
|
|
};
|
|
|
|
span_lint_and_sugg(
|
|
cx,
|
|
MANUAL_UNWRAP_OR, expr.span,
|
|
&format!("this pattern reimplements `{}::unwrap_or`", ty_name),
|
|
"replace with",
|
|
format!(
|
|
"{}.unwrap_or({})",
|
|
suggestion,
|
|
reindented_or_body,
|
|
),
|
|
Applicability::MachineApplicable,
|
|
);
|
|
}
|
|
}
|
|
}
|