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Detect also a non-reversed comparison

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This commit is contained in:
JarredAllen 2020-05-24 19:45:41 -07:00
parent 955a25ee7d
commit 059e8edd15
6 changed files with 94 additions and 52 deletions
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10
clippy_lints/src/lib.rs
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@ -304,7 +304,7 @@ macro_rules! declare_clippy_lint {
mod shadow;
mod single_component_path_imports;
mod slow_vector_initialization;
mod sort_by_key_reverse;
mod sort_by_key;
mod strings;
mod suspicious_trait_impl;
mod swap;
@ -780,7 +780,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
&shadow::SHADOW_UNRELATED,
&single_component_path_imports::SINGLE_COMPONENT_PATH_IMPORTS,
&slow_vector_initialization::SLOW_VECTOR_INITIALIZATION,
&sort_by_key_reverse::SORT_BY_KEY_REVERSE,
&sort_by_key::SORT_BY_KEY,
&strings::STRING_ADD,
&strings::STRING_ADD_ASSIGN,
&strings::STRING_LIT_AS_BYTES,
@ -998,7 +998,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
store.register_late_pass(|| box ptr_offset_with_cast::PtrOffsetWithCast);
store.register_late_pass(|| box redundant_clone::RedundantClone);
store.register_late_pass(|| box slow_vector_initialization::SlowVectorInit);
store.register_late_pass(|| box sort_by_key_reverse::SortByKeyReverse);
store.register_late_pass(|| box sort_by_key::SortByKey);
store.register_late_pass(|| box types::RefToMut);
store.register_late_pass(|| box assertions_on_constants::AssertionsOnConstants);
store.register_late_pass(|| box missing_const_for_fn::MissingConstForFn);
@ -1394,7 +1394,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
LintId::of(&serde_api::SERDE_API_MISUSE),
LintId::of(&single_component_path_imports::SINGLE_COMPONENT_PATH_IMPORTS),
LintId::of(&slow_vector_initialization::SLOW_VECTOR_INITIALIZATION),
LintId::of(&sort_by_key_reverse::SORT_BY_KEY_REVERSE),
LintId::of(&sort_by_key::SORT_BY_KEY),
LintId::of(&strings::STRING_LIT_AS_BYTES),
LintId::of(&suspicious_trait_impl::SUSPICIOUS_ARITHMETIC_IMPL),
LintId::of(&suspicious_trait_impl::SUSPICIOUS_OP_ASSIGN_IMPL),
@ -1596,7 +1596,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
LintId::of(&ranges::RANGE_ZIP_WITH_LEN),
LintId::of(&reference::DEREF_ADDROF),
LintId::of(&reference::REF_IN_DEREF),
LintId::of(&sort_by_key_reverse::SORT_BY_KEY_REVERSE),
LintId::of(&sort_by_key::SORT_BY_KEY),
LintId::of(&swap::MANUAL_SWAP),
LintId::of(&temporary_assignment::TEMPORARY_ASSIGNMENT),
LintId::of(&transmute::CROSSPOINTER_TRANSMUTE),

52
clippy_lints/src/sort_by_key_reverse.rs → clippy_lints/src/sort_by_key.rs
View File

@ -11,33 +11,35 @@
declare_clippy_lint! {
/// **What it does:**
/// Detects when people use `Vec::sort_by` and pass in a function
/// which compares the second argument to the first.
/// which compares the two arguments, either directly or indirectly.
///
/// **Why is this bad?**
/// It is more clear to use `Vec::sort_by_key` and `std::cmp::Reverse`
/// It is more clear to use `Vec::sort_by_key` (or
/// `Vec::sort_by_key` and `std::cmp::Reverse` if necessary) than
/// using
///
/// **Known problems:** None.
///
/// **Example:**
///
/// ```rust
/// vec.sort_by(|a, b| b.foo().cmp(&a.foo()));
/// vec.sort_by(|a, b| a.foo().cmp(b.foo()));
/// ```
/// Use instead:
/// ```rust
/// vec.sort_by_key(|e| Reverse(e.foo()));
/// vec.sort_by_key(|a| a.foo());
/// ```
pub SORT_BY_KEY_REVERSE,
pub SORT_BY_KEY,
complexity,
"Use of `Vec::sort_by` when `Vec::sort_by_key` would be clearer"
}
declare_lint_pass!(SortByKeyReverse => [SORT_BY_KEY_REVERSE]);
declare_lint_pass!(SortByKey => [SORT_BY_KEY]);
struct LintTrigger {
vec_name: String,
closure_arg: String,
closure_reverse_body: String,
closure_body: String,
unstable: bool,
}
@ -154,43 +156,49 @@ fn detect_lint(cx: &LateContext<'_, '_>, expr: &Expr<'_>) -> Option<LintTrigger>
if utils::match_type(cx, &cx.tables.expr_ty(vec), &paths::VEC);
if let closure_body = cx.tcx.hir().body(*closure_body_id);
if let &[
Param { pat: Pat { kind: PatKind::Binding(_, _, a_ident, _), .. }, ..},
Param { pat: Pat { kind: PatKind::Binding(_, _, b_ident, _), .. }, .. }
Param { pat: Pat { kind: PatKind::Binding(_, _, left_ident, _), .. }, ..},
Param { pat: Pat { kind: PatKind::Binding(_, _, right_ident, _), .. }, .. }
] = &closure_body.params;
if let ExprKind::MethodCall(method_path, _, [ref b_expr, ref a_expr]) = &closure_body.value.kind;
if let ExprKind::MethodCall(method_path, _, [ref left_expr, ref right_expr]) = &closure_body.value.kind;
if method_path.ident.name.to_ident_string() == "cmp";
if mirrored_exprs(&cx, &a_expr, &a_ident, &b_expr, &b_ident);
then {
let (closure_body, closure_arg) = if mirrored_exprs(
&cx,
&left_expr,
&left_ident,
&right_expr,
&right_ident
) {
(Sugg::hir(cx, &left_expr, "..").to_string(), left_ident.name.to_string())
} else if mirrored_exprs(&cx, &left_expr, &right_ident, &right_expr, &left_ident) {
(format!("Reverse({})", Sugg::hir(cx, &left_expr, "..").to_string()), right_ident.name.to_string())
} else {
return None;
};
let vec_name = Sugg::hir(cx, &args[0], "..").to_string();
let unstable = name == "sort_unstable_by";
let closure_arg = format!("&{}", b_ident.name.to_ident_string());
let closure_reverse_body = Sugg::hir(cx, &b_expr, "..").to_string();
// Get rid of parentheses, because they aren't needed anymore
// while closure_reverse_body.chars().next() == Some('(') && closure_reverse_body.chars().last() == Some(')') {
// closure_reverse_body = String::from(&closure_reverse_body[1..closure_reverse_body.len()-1]);
// }
Some(LintTrigger { vec_name, unstable, closure_arg, closure_reverse_body })
Some(LintTrigger { vec_name, unstable, closure_arg, closure_body })
} else {
None
}
}
}
impl LateLintPass<'_, '_> for SortByKeyReverse {
impl LateLintPass<'_, '_> for SortByKey {
fn check_expr(&mut self, cx: &LateContext<'_, '_>, expr: &Expr<'_>) {
if let Some(trigger) = detect_lint(cx, expr) {
utils::span_lint_and_sugg(
cx,
SORT_BY_KEY_REVERSE,
SORT_BY_KEY,
expr.span,
"use Vec::sort_by_key here instead",
"try",
format!(
"{}.sort{}_by_key(|{}| Reverse({}))",
"{}.sort{}_by_key(|&{}| {})",
trigger.vec_name,
if trigger.unstable { "_unstable" } else { "" },
trigger.closure_arg,
trigger.closure_reverse_body,
trigger.closure_body,
),
Applicability::MachineApplicable,
);

8
tests/ui/sort_by_key_reverse.fixed → tests/ui/sort_by_key.fixed
View File

@ -1,5 +1,5 @@
// run-rustfix
#![warn(clippy::sort_by_key_reverse)]
#![warn(clippy::sort_by_key)]
use std::cmp::Reverse;
@ -9,6 +9,11 @@ fn id(x: isize) -> isize {
fn main() {
let mut vec: Vec<isize> = vec![3, 6, 1, 2, 5];
// Forward examples
vec.sort_by_key(|&a| a);
vec.sort_by_key(|&a| (a + 5).abs());
vec.sort_by_key(|&a| id(-a));
// Reverse examples
vec.sort_by_key(|&b| Reverse(b));
vec.sort_by_key(|&b| Reverse((b + 5).abs()));
vec.sort_by_key(|&b| Reverse(id(-b)));
@ -18,5 +23,4 @@ fn main() {
vec.sort_by(|_, b| b.cmp(&5));
vec.sort_by(|_, b| b.cmp(c));
vec.sort_by(|a, _| a.cmp(c));
vec.sort_by(|a, b| a.cmp(b));
}

6
tests/ui/sort_by_key_reverse.rs → tests/ui/sort_by_key.rs
View File

@ -9,6 +9,11 @@ fn id(x: isize) -> isize {
fn main() {
let mut vec: Vec<isize> = vec![3, 6, 1, 2, 5];
// Forward examples
vec.sort_by(|a, b| a.cmp(b));
vec.sort_by(|a, b| (a + 5).abs().cmp(&(b + 5).abs()));
vec.sort_by(|a, b| id(-a).cmp(&id(-b)));
// Reverse examples
vec.sort_by(|a, b| b.cmp(a));
vec.sort_by(|a, b| (b + 5).abs().cmp(&(a + 5).abs()));
vec.sort_by(|a, b| id(-b).cmp(&id(-a)));
@ -18,5 +23,4 @@ fn main() {
vec.sort_by(|_, b| b.cmp(&5));
vec.sort_by(|_, b| b.cmp(c));
vec.sort_by(|a, _| a.cmp(c));
vec.sort_by(|a, b| a.cmp(b));
}

48
tests/ui/sort_by_key.stderr Normal file
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@ -0,0 +1,48 @@
error: use Vec::sort_by_key here instead
--> $DIR/sort_by_key.rs:13:5
|
LL | vec.sort_by(|a, b| a.cmp(b));
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `vec.sort_by_key(|&a| a)`
|
= note: `-D clippy::sort-by-key` implied by `-D warnings`
error: use Vec::sort_by_key here instead
--> $DIR/sort_by_key.rs:14:5
|
LL | vec.sort_by(|a, b| (a + 5).abs().cmp(&(b + 5).abs()));
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `vec.sort_by_key(|&a| (a + 5).abs())`
error: use Vec::sort_by_key here instead
--> $DIR/sort_by_key.rs:15:5
|
LL | vec.sort_by(|a, b| id(-a).cmp(&id(-b)));
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `vec.sort_by_key(|&a| id(-a))`
error: use Vec::sort_by_key here instead
--> $DIR/sort_by_key.rs:17:5
|
LL | vec.sort_by(|a, b| b.cmp(a));
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `vec.sort_by_key(|&b| Reverse(b))`
error: use Vec::sort_by_key here instead
--> $DIR/sort_by_key.rs:18:5
|
LL | vec.sort_by(|a, b| (b + 5).abs().cmp(&(a + 5).abs()));
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `vec.sort_by_key(|&b| Reverse((b + 5).abs()))`
error: use Vec::sort_by_key here instead
--> $DIR/sort_by_key.rs:19:5
|
LL | vec.sort_by(|a, b| id(-b).cmp(&id(-a)));
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `vec.sort_by_key(|&b| Reverse(id(-b)))`
error: unknown clippy lint: clippy::sort_by_key_reverse
--> $DIR/sort_by_key.rs:2:9
|
LL | #![warn(clippy::sort_by_key_reverse)]
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: did you mean: `clippy::sort_by_key`
|
= note: `-D clippy::unknown-clippy-lints` implied by `-D warnings`
error: aborting due to 7 previous errors

22
tests/ui/sort_by_key_reverse.stderr
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@ -1,22 +0,0 @@
error: use Vec::sort_by_key here instead
--> $DIR/sort_by_key_reverse.rs:12:5
|
LL | vec.sort_by(|a, b| b.cmp(a));
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `vec.sort_by_key(|&b| Reverse(b))`
|
= note: `-D clippy::sort-by-key-reverse` implied by `-D warnings`
error: use Vec::sort_by_key here instead
--> $DIR/sort_by_key_reverse.rs:13:5
|
LL | vec.sort_by(|a, b| (b + 5).abs().cmp(&(a + 5).abs()));
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `vec.sort_by_key(|&b| Reverse((b + 5).abs()))`
error: use Vec::sort_by_key here instead
--> $DIR/sort_by_key_reverse.rs:14:5
|
LL | vec.sort_by(|a, b| id(-b).cmp(&id(-a)));
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `vec.sort_by_key(|&b| Reverse(id(-b)))`
error: aborting due to 3 previous errors