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Also suggest as_mut for match_as_ref

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This commit is contained in:
Wilco Kusee 2017-12-20 10:39:48 +01:00
parent 919601bc51
commit a6ccc6fe3d
3 changed files with 29 additions and 22 deletions
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27
clippy_lints/src/matches.rs
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@ -148,7 +148,7 @@ declare_lint! {
/// **What it does:** Checks for match which is used to add a reference to an
/// `Option` value.
///
/// **Why is this bad?** Using `as_ref()` instead is shorter.
/// **Why is this bad?** Using `as_ref()` or `as_mut()` instead is shorter.
///
/// **Known problems:** None.
///
@ -163,7 +163,7 @@ declare_lint! {
declare_lint! {
pub MATCH_AS_REF,
Warn,
"a match on an Option value instead of using `as_ref()`"
"a match on an Option value instead of using `as_ref()` or `as_mut`"
}
#[allow(missing_copy_implementations)]
@ -438,15 +438,22 @@ fn check_match_as_ref(cx: &LateContext, ex: &Expr, arms: &[Arm], expr: &Expr) {
if arms.len() == 2 &&
arms[0].pats.len() == 1 && arms[0].guard.is_none() &&
arms[1].pats.len() == 1 && arms[1].guard.is_none() {
if (is_ref_some_arm(&arms[0]) && is_none_arm(&arms[1])) ||
(is_ref_some_arm(&arms[1]) && is_none_arm(&arms[0])) {
let arm_ref: Option<BindingAnnotation> = if is_none_arm(&arms[0]) {
is_ref_some_arm(&arms[1])
} else if is_none_arm(&arms[1]) {
is_ref_some_arm(&arms[0])
} else {
None
};
if let Some(rb) = arm_ref {
let suggestion = if rb == BindingAnnotation::Ref { "as_ref" } else { "as_mut" };
span_lint_and_sugg(
cx,
MATCH_AS_REF,
expr.span,
"use as_ref() instead",
&format!("use {}() instead", suggestion),
"try this",
format!("{}.as_ref()", snippet(cx, ex.span, "_"))
format!("{}.{}()", snippet(cx, ex.span, "_"), suggestion)
)
}
}
@ -574,7 +581,7 @@ fn is_none_arm(arm: &Arm) -> bool {
}
// Checks if arm has the form `Some(ref v) => Some(v)` (checks for `ref` and `ref mut`)
fn is_ref_some_arm(arm: &Arm) -> bool {
fn is_ref_some_arm(arm: &Arm) -> Option<BindingAnnotation> {
if_chain! {
if let PatKind::TupleStruct(ref path, ref pats, _) = arm.pats[0].node;
if pats.len() == 1 && match_qpath(path, &paths::OPTION_SOME);
@ -585,12 +592,12 @@ fn is_ref_some_arm(arm: &Arm) -> bool {
if match_qpath(some_path, &paths::OPTION_SOME) && args.len() == 1;
if let ExprPath(ref qpath) = args[0].node;
if let &QPath::Resolved(_, ref path2) = qpath;
if path2.segments.len() == 1;
if path2.segments.len() == 1 && ident.node == path2.segments[0].name;
then {
return ident.node == path2.segments[0].name
return Some(rb)
}
}
false
None
}
fn has_only_ref_pats(arms: &[Arm]) -> bool {