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Auto merge of #3978 - phansch:rustfix_len_zero, r=flip1995
Add run-rustfix for len_zero lint * Extracts len_without_is_empty into separate file * Adds `// run-rustfix` to `tests/ui/len_zero.rs` cc #3630
2 parents c6e43b1 + bae7d29 commit 77fbdb6

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5 files changed

+367
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‎tests/ui/len_without_is_empty.rs

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#![warn(clippy::len_without_is_empty)]
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#![allow(dead_code, unused)]
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pub struct PubOne;
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impl PubOne {
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pub fn len(self: &Self) -> isize {
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1
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}
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}
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impl PubOne {
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// A second impl for this struct -- the error span shouldn't mention this.
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pub fn irrelevant(self: &Self) -> bool {
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false
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}
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}
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// Identical to `PubOne`, but with an `allow` attribute on the impl complaining `len`.
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pub struct PubAllowed;
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#[allow(clippy::len_without_is_empty)]
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impl PubAllowed {
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pub fn len(self: &Self) -> isize {
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1
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}
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}
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// No `allow` attribute on this impl block, but that doesn't matter -- we only require one on the
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// impl containing `len`.
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impl PubAllowed {
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pub fn irrelevant(self: &Self) -> bool {
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false
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}
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}
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pub trait PubTraitsToo {
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fn len(self: &Self) -> isize;
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}
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impl PubTraitsToo for One {
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fn len(self: &Self) -> isize {
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0
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}
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}
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pub struct HasIsEmpty;
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impl HasIsEmpty {
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pub fn len(self: &Self) -> isize {
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1
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}
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fn is_empty(self: &Self) -> bool {
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false
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}
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}
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pub struct HasWrongIsEmpty;
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impl HasWrongIsEmpty {
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pub fn len(self: &Self) -> isize {
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1
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}
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pub fn is_empty(self: &Self, x: u32) -> bool {
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false
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}
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}
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struct NotPubOne;
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impl NotPubOne {
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pub fn len(self: &Self) -> isize {
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// No error; `len` is pub but `NotPubOne` is not exported anyway.
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1
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}
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}
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struct One;
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impl One {
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fn len(self: &Self) -> isize {
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// No error; `len` is private; see issue #1085.
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1
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}
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}
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trait TraitsToo {
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fn len(self: &Self) -> isize;
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// No error; `len` is private; see issue #1085.
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}
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impl TraitsToo for One {
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fn len(self: &Self) -> isize {
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0
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}
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}
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struct HasPrivateIsEmpty;
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impl HasPrivateIsEmpty {
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pub fn len(self: &Self) -> isize {
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1
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}
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fn is_empty(self: &Self) -> bool {
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false
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}
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}
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struct Wither;
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pub trait WithIsEmpty {
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fn len(self: &Self) -> isize;
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fn is_empty(self: &Self) -> bool;
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}
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impl WithIsEmpty for Wither {
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fn len(self: &Self) -> isize {
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1
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}
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fn is_empty(self: &Self) -> bool {
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false
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}
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}
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pub trait Empty {
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fn is_empty(&self) -> bool;
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}
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pub trait InheritingEmpty: Empty {
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// Must not trigger `LEN_WITHOUT_IS_EMPTY`.
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fn len(&self) -> isize;
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}
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// This used to ICE.
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pub trait Foo: Sized {}
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pub trait DependsOnFoo: Foo {
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fn len(&mut self) -> usize;
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}
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fn main() {}

‎tests/ui/len_without_is_empty.stderr

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error: item `PubOne` has a public `len` method but no corresponding `is_empty` method
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--> $DIR/len_without_is_empty.rs:6:1
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|
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LL | / impl PubOne {
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LL | | pub fn len(self: &Self) -> isize {
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LL | | 1
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LL | | }
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LL | | }
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| |_^
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|
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= note: `-D clippy::len-without-is-empty` implied by `-D warnings`
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error: trait `PubTraitsToo` has a `len` method but no (possibly inherited) `is_empty` method
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--> $DIR/len_without_is_empty.rs:37:1
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|
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LL | / pub trait PubTraitsToo {
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LL | | fn len(self: &Self) -> isize;
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LL | | }
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| |_^
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error: item `HasIsEmpty` has a public `len` method but a private `is_empty` method
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--> $DIR/len_without_is_empty.rs:49:1
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|
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LL | / impl HasIsEmpty {
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LL | | pub fn len(self: &Self) -> isize {
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LL | | 1
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LL | | }
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... |
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LL | | }
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LL | | }
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| |_^
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error: item `HasWrongIsEmpty` has a public `len` method but no corresponding `is_empty` method
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--> $DIR/len_without_is_empty.rs:61:1
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|
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LL | / impl HasWrongIsEmpty {
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LL | | pub fn len(self: &Self) -> isize {
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LL | | 1
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LL | | }
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... |
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LL | | }
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LL | | }
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| |_^
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error: trait `DependsOnFoo` has a `len` method but no (possibly inherited) `is_empty` method
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--> $DIR/len_without_is_empty.rs:141:1
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|
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LL | / pub trait DependsOnFoo: Foo {
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LL | | fn len(&mut self) -> usize;
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LL | | }
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| |_^
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error: aborting due to 5 previous errors
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‎tests/ui/len_zero.fixed

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// run-rustfix
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#![warn(clippy::len_zero)]
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#![allow(dead_code, unused, clippy::len_without_is_empty)]
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pub struct One;
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struct Wither;
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trait TraitsToo {
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fn len(self: &Self) -> isize;
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// No error; `len` is private; see issue #1085.
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}
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impl TraitsToo for One {
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fn len(self: &Self) -> isize {
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0
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}
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}
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pub struct HasIsEmpty;
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impl HasIsEmpty {
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pub fn len(self: &Self) -> isize {
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1
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}
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fn is_empty(self: &Self) -> bool {
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false
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}
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}
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pub struct HasWrongIsEmpty;
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impl HasWrongIsEmpty {
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pub fn len(self: &Self) -> isize {
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1
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}
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pub fn is_empty(self: &Self, x: u32) -> bool {
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false
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}
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}
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pub trait WithIsEmpty {
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fn len(self: &Self) -> isize;
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fn is_empty(self: &Self) -> bool;
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}
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impl WithIsEmpty for Wither {
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fn len(self: &Self) -> isize {
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1
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}
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fn is_empty(self: &Self) -> bool {
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false
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}
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}
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fn main() {
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let x = [1, 2];
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if x.is_empty() {
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println!("This should not happen!");
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}
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if "".is_empty() {}
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let y = One;
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if y.len() == 0 {
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// No error; `One` does not have `.is_empty()`.
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println!("This should not happen either!");
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}
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let z: &TraitsToo = &y;
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if z.len() > 0 {
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// No error; `TraitsToo` has no `.is_empty()` method.
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println!("Nor should this!");
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}
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let has_is_empty = HasIsEmpty;
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if has_is_empty.is_empty() {
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println!("Or this!");
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}
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if !has_is_empty.is_empty() {
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println!("Or this!");
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}
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if !has_is_empty.is_empty() {
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println!("Or this!");
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}
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if has_is_empty.is_empty() {
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println!("Or this!");
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}
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if !has_is_empty.is_empty() {
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println!("Or this!");
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}
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if has_is_empty.len() > 1 {
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// No error.
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println!("This can happen.");
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}
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if has_is_empty.len() <= 1 {
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// No error.
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println!("This can happen.");
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}
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if has_is_empty.is_empty() {
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println!("Or this!");
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}
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if !has_is_empty.is_empty() {
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println!("Or this!");
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}
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if !has_is_empty.is_empty() {
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println!("Or this!");
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}
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if !has_is_empty.is_empty() {
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println!("Or this!");
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}
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if has_is_empty.is_empty() {
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println!("Or this!");
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}
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if 1 < has_is_empty.len() {
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// No error.
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println!("This can happen.");
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}
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if 1 >= has_is_empty.len() {
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// No error.
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println!("This can happen.");
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}
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assert!(!has_is_empty.is_empty());
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let with_is_empty: &WithIsEmpty = &Wither;
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if with_is_empty.is_empty() {
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println!("Or this!");
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}
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assert!(!with_is_empty.is_empty());
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let has_wrong_is_empty = HasWrongIsEmpty;
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if has_wrong_is_empty.len() == 0 {
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// No error; `HasWrongIsEmpty` does not have `.is_empty()`.
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println!("Or this!");
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}
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}
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fn test_slice(b: &[u8]) {
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if !b.is_empty() {}
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}

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