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Merge pull request #3281 from CYBAI/redundant-match

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Add lint for redundant pattern matching for explicit return boolean
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Philipp Hansch 2018-10-17 07:31:09 +02:00 committed by GitHub
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10 changed files with 369 additions and 145 deletions
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1
CHANGELOG.md
View file

@ -816,6 +816,7 @@ All notable changes to this project will be documented in this file.
[`redundant_closure_call`]: https://rust-lang-nursery.github.io/rust-clippy/master/index.html#redundant_closure_call
[`redundant_field_names`]: https://rust-lang-nursery.github.io/rust-clippy/master/index.html#redundant_field_names
[`redundant_pattern`]: https://rust-lang-nursery.github.io/rust-clippy/master/index.html#redundant_pattern
[`redundant_pattern_matching`]: https://rust-lang-nursery.github.io/rust-clippy/master/index.html#redundant_pattern_matching
[`ref_in_deref`]: https://rust-lang-nursery.github.io/rust-clippy/master/index.html#ref_in_deref
[`regex_macro`]: https://rust-lang-nursery.github.io/rust-clippy/master/index.html#regex_macro
[`replace_consts`]: https://rust-lang-nursery.github.io/rust-clippy/master/index.html#replace_consts

12
clippy_lints/src/deprecated_lints.rs
View file

@ -16,7 +16,7 @@ macro_rules! declare_deprecated_lint {
/// **What it does:** Nothing. This lint has been deprecated.
///
/// **Deprecation reason:** This used to check for `assert!(a == b)` and recommend
/// **Deprecation reason:** This used to check for `assert!(a == b)` and recommend
/// replacement with `assert_eq!(a, b)`, but this is no longer needed after RFC 2011.
declare_deprecated_lint! {
pub SHOULD_ASSERT_EQ,
@ -102,3 +102,13 @@ declare_deprecated_lint! {
pub ASSIGN_OPS,
"using compound assignment operators (e.g. `+=`) is harmless"
}
/// **What it does:** Nothing. This lint has been deprecated.
///
/// **Deprecation reason:** The original rule will only lint for `if let`. After
/// making it support to lint `match`, naming as `if let` is not suitable for it.
/// So, this lint is deprecated.
declare_deprecated_lint! {
pub IF_LET_REDUNDANT_PATTERN_MATCHING,
"this lint has been changed to redundant_pattern_matching"
}

103
clippy_lints/src/if_let_redundant_pattern_matching.rs
View file

@ -1,103 +0,0 @@
// Copyright 2014-2018 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
use crate::rustc::lint::{LateContext, LateLintPass, LintArray, LintPass};
use crate::rustc::{declare_tool_lint, lint_array};
use crate::rustc::hir::*;
use crate::utils::{match_qpath, paths, snippet, span_lint_and_then};
use crate::rustc_errors::Applicability;
/// **What it does:** Lint for redundant pattern matching over `Result` or
/// `Option`
///
/// **Why is this bad?** It's more concise and clear to just use the proper
/// utility function
///
/// **Known problems:** None.
///
/// **Example:**
///
/// ```rust
/// if let Ok(_) = Ok::<i32, i32>(42) {}
/// if let Err(_) = Err::<i32, i32>(42) {}
/// if let None = None::<()> {}
/// if let Some(_) = Some(42) {}
/// ```
///
/// The more idiomatic use would be:
///
/// ```rust
/// if Ok::<i32, i32>(42).is_ok() {}
/// if Err::<i32, i32>(42).is_err() {}
/// if None::<()>.is_none() {}
/// if Some(42).is_some() {}
/// ```
///
declare_clippy_lint! {
pub IF_LET_REDUNDANT_PATTERN_MATCHING,
style,
"use the proper utility function avoiding an `if let`"
}
#[derive(Copy, Clone)]
pub struct Pass;
impl LintPass for Pass {
fn get_lints(&self) -> LintArray {
lint_array!(IF_LET_REDUNDANT_PATTERN_MATCHING)
}
}
impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Pass {
#[allow(clippy::similar_names)]
fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) {
if let ExprKind::Match(ref op, ref arms, MatchSource::IfLetDesugar { .. }) = expr.node {
if arms[0].pats.len() == 1 {
let good_method = match arms[0].pats[0].node {
PatKind::TupleStruct(ref path, ref pats, _) if pats.len() == 1 => {
if let PatKind::Wild = pats[0].node {
if match_qpath(path, &paths::RESULT_OK) {
"is_ok()"
} else if match_qpath(path, &paths::RESULT_ERR) {
"is_err()"
} else if match_qpath(path, &paths::OPTION_SOME) {
"is_some()"
} else {
return;
}
} else {
return;
}
},
PatKind::Path(ref path) if match_qpath(path, &paths::OPTION_NONE) => "is_none()",
_ => return,
};
span_lint_and_then(
cx,
IF_LET_REDUNDANT_PATTERN_MATCHING,
arms[0].pats[0].span,
&format!("redundant pattern matching, consider using `{}`", good_method),
|db| {
let span = expr.span.to(op.span);
db.span_suggestion_with_applicability(
span,
"try this",
format!("if {}.{}", snippet(cx, op.span, "_"), good_method),
Applicability::MachineApplicable, // snippet
);
},
);
}
}
}
}

12
clippy_lints/src/lib.rs
View file

@ -126,7 +126,6 @@ pub mod formatting;
pub mod functions;
pub mod identity_conversion;
pub mod identity_op;
pub mod if_let_redundant_pattern_matching;
pub mod if_not_else;
pub mod indexing_slicing;
pub mod infallible_destructuring_match;
@ -180,6 +179,7 @@ pub mod ptr_offset_with_cast;
pub mod question_mark;
pub mod ranges;
pub mod redundant_field_names;
pub mod redundant_pattern_matching;
pub mod reference;
pub mod regex;
pub mod replace_consts;
@ -303,6 +303,10 @@ pub fn register_plugins(reg: &mut rustc_plugin::Registry<'_>, conf: &Conf) {
"assign_ops",
"using compound assignment operators (e.g. `+=`) is harmless",
);
store.register_removed(
"if_let_redundant_pattern_matching",
"this lint has been changed to redundant_pattern_matching",
);
// end deprecated lints, do not remove this comment, it’s used in `update_lints`
reg.register_late_lint_pass(box serde_api::Serde);
@ -402,7 +406,7 @@ pub fn register_plugins(reg: &mut rustc_plugin::Registry<'_>, conf: &Conf) {
reg.register_late_lint_pass(box missing_doc::MissingDoc::new());
reg.register_late_lint_pass(box missing_inline::MissingInline);
reg.register_late_lint_pass(box ok_if_let::Pass);
reg.register_late_lint_pass(box if_let_redundant_pattern_matching::Pass);
reg.register_late_lint_pass(box redundant_pattern_matching::Pass);
reg.register_late_lint_pass(box partialeq_ne_impl::Pass);
reg.register_early_lint_pass(box reference::Pass);
reg.register_early_lint_pass(box reference::DerefPass);
@ -565,7 +569,6 @@ pub fn register_plugins(reg: &mut rustc_plugin::Registry<'_>, conf: &Conf) {
functions::TOO_MANY_ARGUMENTS,
identity_conversion::IDENTITY_CONVERSION,
identity_op::IDENTITY_OP,
if_let_redundant_pattern_matching::IF_LET_REDUNDANT_PATTERN_MATCHING,
indexing_slicing::OUT_OF_BOUNDS_INDEXING,
infallible_destructuring_match::INFALLIBLE_DESTRUCTURING_MATCH,
infinite_iter::INFINITE_ITER,
@ -680,6 +683,7 @@ pub fn register_plugins(reg: &mut rustc_plugin::Registry<'_>, conf: &Conf) {
ranges::RANGE_PLUS_ONE,
ranges::RANGE_ZIP_WITH_LEN,
redundant_field_names::REDUNDANT_FIELD_NAMES,
redundant_pattern_matching::REDUNDANT_PATTERN_MATCHING,
reference::DEREF_ADDROF,
reference::REF_IN_DEREF,
regex::INVALID_REGEX,
@ -749,7 +753,6 @@ pub fn register_plugins(reg: &mut rustc_plugin::Registry<'_>, conf: &Conf) {
excessive_precision::EXCESSIVE_PRECISION,
formatting::SUSPICIOUS_ASSIGNMENT_FORMATTING,
formatting::SUSPICIOUS_ELSE_FORMATTING,
if_let_redundant_pattern_matching::IF_LET_REDUNDANT_PATTERN_MATCHING,
infallible_destructuring_match::INFALLIBLE_DESTRUCTURING_MATCH,
len_zero::LEN_WITHOUT_IS_EMPTY,
len_zero::LEN_ZERO,
@ -800,6 +803,7 @@ pub fn register_plugins(reg: &mut rustc_plugin::Registry<'_>, conf: &Conf) {
ptr::PTR_ARG,
question_mark::QUESTION_MARK,
redundant_field_names::REDUNDANT_FIELD_NAMES,
redundant_pattern_matching::REDUNDANT_PATTERN_MATCHING,
regex::REGEX_MACRO,
regex::TRIVIAL_REGEX,
returns::LET_AND_RETURN,

228
clippy_lints/src/redundant_pattern_matching.rs Normal file
View file

@ -0,0 +1,228 @@
// Copyright 2014-2018 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
use crate::rustc::lint::{LateContext, LateLintPass, LintArray, LintPass};
use crate::rustc::{declare_tool_lint, lint_array};
use crate::rustc::hir::*;
use crate::syntax::ptr::P;
use crate::syntax::ast::LitKind;
use crate::utils::{match_qpath, paths, snippet, span_lint_and_then};
use crate::rustc_errors::Applicability;
/// **What it does:** Lint for redundant pattern matching over `Result` or
/// `Option`
///
/// **Why is this bad?** It's more concise and clear to just use the proper
/// utility function
///
/// **Known problems:** None.
///
/// **Example:**
///
/// ```rust
/// if let Ok(_) = Ok::<i32, i32>(42) {}
/// if let Err(_) = Err::<i32, i32>(42) {}
/// if let None = None::<()> {}
/// if let Some(_) = Some(42) {}
/// match Ok::<i32, i32>(42) {
/// Ok(_) => true,
/// Err(_) => false,
/// };
/// ```
///
/// The more idiomatic use would be:
///
/// ```rust
/// if Ok::<i32, i32>(42).is_ok() {}
/// if Err::<i32, i32>(42).is_err() {}
/// if None::<()>.is_none() {}
/// if Some(42).is_some() {}
/// Ok::<i32, i32>(42).is_ok();
/// ```
///
declare_clippy_lint! {
pub REDUNDANT_PATTERN_MATCHING,
style,
"use the proper utility function avoiding an `if let`"
}
#[derive(Copy, Clone)]
pub struct Pass;
impl LintPass for Pass {
fn get_lints(&self) -> LintArray {
lint_array!(REDUNDANT_PATTERN_MATCHING)
}
}
impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Pass {
#[allow(clippy::similar_names)]
fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) {
if let ExprKind::Match(ref op, ref arms, ref match_source) = expr.node {
match match_source {
MatchSource::Normal => find_sugg_for_match(cx, expr, op, arms),
MatchSource::IfLetDesugar { .. } => find_sugg_for_if_let(cx, expr, op, arms),
_ => return,
}
}
}
}
fn find_sugg_for_if_let<'a, 'tcx>(
cx: &LateContext<'a, 'tcx>,
expr: &'tcx Expr,
op: &P<Expr>,
arms: &HirVec<Arm>
) {
if arms[0].pats.len() == 1 {
let good_method = match arms[0].pats[0].node {
PatKind::TupleStruct(ref path, ref pats, _) if pats.len() == 1 => {
if let PatKind::Wild = pats[0].node {
if match_qpath(path, &paths::RESULT_OK) {
"is_ok()"
} else if match_qpath(path, &paths::RESULT_ERR) {
"is_err()"
} else if match_qpath(path, &paths::OPTION_SOME) {
"is_some()"
} else {
return;
}
} else {
return;
}
},
PatKind::Path(ref path) if match_qpath(path, &paths::OPTION_NONE) => "is_none()",
_ => return,
};
span_lint_and_then(
cx,
REDUNDANT_PATTERN_MATCHING,
arms[0].pats[0].span,
&format!("redundant pattern matching, consider using `{}`", good_method),
|db| {
let span = expr.span.to(op.span);
db.span_suggestion_with_applicability(
span,
"try this",
format!("if {}.{}", snippet(cx, op.span, "_"), good_method),
Applicability::MachineApplicable, // snippet
);
},
);
} else {
return;
}
}
fn find_sugg_for_match<'a, 'tcx>(
cx: &LateContext<'a, 'tcx>,
expr: &'tcx Expr,
op: &P<Expr>,
arms: &HirVec<Arm>
) {
if arms.len() == 2 {
let node_pair = (&arms[0].pats[0].node, &arms[1].pats[0].node);
let found_good_method = match node_pair {
(
PatKind::TupleStruct(ref path_left, ref pats_left, _),
PatKind::TupleStruct(ref path_right, ref pats_right, _)
) if pats_left.len() == 1 && pats_right.len() == 1 => {
if let (PatKind::Wild, PatKind::Wild) = (&pats_left[0].node, &pats_right[0].node) {
find_good_method_for_match(
arms,
path_left,
path_right,
&paths::RESULT_OK,
&paths::RESULT_ERR,
"is_ok()",
"is_err()"
)
} else {
None
}
},
(
PatKind::TupleStruct(ref path_left, ref pats, _),
PatKind::Path(ref path_right)
) | (
PatKind::Path(ref path_left),
PatKind::TupleStruct(ref path_right, ref pats, _)
) if pats.len() == 1 => {
if let PatKind::Wild = pats[0].node {
find_good_method_for_match(
arms,
path_left,
path_right,
&paths::OPTION_SOME,
&paths::OPTION_NONE,
"is_some()",
"is_none()"
)
} else {
None
}
},
_ => None,
};
if let Some(good_method) = found_good_method {
span_lint_and_then(
cx,
REDUNDANT_PATTERN_MATCHING,
expr.span,
&format!("redundant pattern matching, consider using `{}`", good_method),
|db| {
let span = expr.span.to(op.span);
db.span_suggestion_with_applicability(
span,
"try this",
format!("{}.{}", snippet(cx, op.span, "_"), good_method),
Applicability::MachineApplicable, // snippet
);
},
);
}
} else {
return;
}
}
fn find_good_method_for_match<'a>(
arms: &HirVec<Arm>,
path_left: &QPath,
path_right: &QPath,
expected_left: &[&str],
expected_right: &[&str],
should_be_left: &'a str,
should_be_right: &'a str
) -> Option<&'a str> {
let body_node_pair = if match_qpath(path_left, expected_left) && match_qpath(path_right, expected_right) {
(&(*arms[0].body).node, &(*arms[1].body).node)
} else if match_qpath(path_right, expected_left) && match_qpath(path_left, expected_right) {
(&(*arms[1].body).node, &(*arms[0].body).node)
} else {
return None;
};
match body_node_pair {
(ExprKind::Lit(ref lit_left), ExprKind::Lit(ref lit_right)) => {
match (&lit_left.node, &lit_right.node) {
(LitKind::Bool(true), LitKind::Bool(false)) => Some(should_be_left),
(LitKind::Bool(false), LitKind::Bool(true)) => Some(should_be_right),
_ => None,
}
},
_ => None,
}
}

34
tests/ui/if_let_redundant_pattern_matching.stderr
View file

@ -1,34 +0,0 @@
error: redundant pattern matching, consider using `is_ok()`
--> $DIR/if_let_redundant_pattern_matching.rs:19:12
|
19 | if let Ok(_) = Ok::<i32, i32>(42) {}
| -------^^^^^------------------------ help: try this: `if Ok::<i32, i32>(42).is_ok()`
|
= note: `-D clippy::if-let-redundant-pattern-matching` implied by `-D warnings`
error: redundant pattern matching, consider using `is_err()`
--> $DIR/if_let_redundant_pattern_matching.rs:21:12
|
21 | if let Err(_) = Err::<i32, i32>(42) {
| _____- ^^^^^^
22 | | }
| |_____- help: try this: `if Err::<i32, i32>(42).is_err()`
error: redundant pattern matching, consider using `is_none()`
--> $DIR/if_let_redundant_pattern_matching.rs:24:12
|
24 | if let None = None::<()> {
| _____- ^^^^
25 | | }
| |_____- help: try this: `if None::<()>.is_none()`
error: redundant pattern matching, consider using `is_some()`
--> $DIR/if_let_redundant_pattern_matching.rs:27:12
|
27 | if let Some(_) = Some(42) {
| _____- ^^^^^^^
28 | | }
| |_____- help: try this: `if Some(42).is_some()`
error: aborting due to 4 previous errors

2
tests/ui/matches.rs
View file

@ -13,7 +13,7 @@
#![warn(clippy::all)]
#![allow(unused, clippy::if_let_redundant_pattern_matching)]
#![allow(unused, clippy::redundant_pattern_matching)]
#![warn(clippy::single_match_else, clippy::match_same_arms)]
enum ExprNode {

2
tests/ui/needless_pass_by_value.rs
View file

@ -11,7 +11,7 @@
#![warn(clippy::needless_pass_by_value)]
#![allow(dead_code, clippy::single_match, clippy::if_let_redundant_pattern_matching, clippy::many_single_char_names, clippy::option_option)]
#![allow(dead_code, clippy::single_match, clippy::redundant_pattern_matching, clippy::many_single_char_names, clippy::option_option)]
use std::borrow::Borrow;
use std::convert::AsRef;

32
tests/ui/if_let_redundant_pattern_matching.rs → tests/ui/redundant_pattern_matching.rs
View file

@ -12,7 +12,7 @@
#![warn(clippy::all)]
#![warn(clippy::if_let_redundant_pattern_matching)]
#![warn(clippy::redundant_pattern_matching)]
fn main() {
@ -42,4 +42,34 @@ fn main() {
if let Ok(x) = Ok::<i32,i32>(42) {
println!("{}", x);
}
match Ok::<i32, i32>(42) {
Ok(_) => true,
Err(_) => false,
};
match Ok::<i32, i32>(42) {
Ok(_) => false,
Err(_) => true,
};
match Err::<i32, i32>(42) {
Ok(_) => false,
Err(_) => true,
};
match Err::<i32, i32>(42) {
Ok(_) => true,
Err(_) => false,
};
match Some(42) {
Some(_) => true,
None => false,
};
match None::<()> {
Some(_) => false,
None => true,
};
}

88
tests/ui/redundant_pattern_matching.stderr Normal file
View file

@ -0,0 +1,88 @@
error: redundant pattern matching, consider using `is_ok()`
--> $DIR/redundant_pattern_matching.rs:19:12
|
19 | if let Ok(_) = Ok::<i32, i32>(42) {}
| -------^^^^^------------------------ help: try this: `if Ok::<i32, i32>(42).is_ok()`
|
= note: `-D clippy::redundant-pattern-matching` implied by `-D warnings`
error: redundant pattern matching, consider using `is_err()`
--> $DIR/redundant_pattern_matching.rs:21:12
|
21 | if let Err(_) = Err::<i32, i32>(42) {
| _____- ^^^^^^
22 | | }
| |_____- help: try this: `if Err::<i32, i32>(42).is_err()`
error: redundant pattern matching, consider using `is_none()`
--> $DIR/redundant_pattern_matching.rs:24:12
|
24 | if let None = None::<()> {
| _____- ^^^^
25 | | }
| |_____- help: try this: `if None::<()>.is_none()`
error: redundant pattern matching, consider using `is_some()`
--> $DIR/redundant_pattern_matching.rs:27:12
|
27 | if let Some(_) = Some(42) {
| _____- ^^^^^^^
28 | | }
| |_____- help: try this: `if Some(42).is_some()`
error: redundant pattern matching, consider using `is_ok()`
--> $DIR/redundant_pattern_matching.rs:46:5
|
46 | / match Ok::<i32, i32>(42) {
47 | | Ok(_) => true,
48 | | Err(_) => false,
49 | | };
| |_____^ help: try this: `Ok::<i32, i32>(42).is_ok()`
error: redundant pattern matching, consider using `is_err()`
--> $DIR/redundant_pattern_matching.rs:51:5
|
51 | / match Ok::<i32, i32>(42) {
52 | | Ok(_) => false,
53 | | Err(_) => true,
54 | | };
| |_____^ help: try this: `Ok::<i32, i32>(42).is_err()`
error: redundant pattern matching, consider using `is_err()`
--> $DIR/redundant_pattern_matching.rs:56:5
|
56 | / match Err::<i32, i32>(42) {
57 | | Ok(_) => false,
58 | | Err(_) => true,
59 | | };
| |_____^ help: try this: `Err::<i32, i32>(42).is_err()`
error: redundant pattern matching, consider using `is_ok()`
--> $DIR/redundant_pattern_matching.rs:61:5
|
61 | / match Err::<i32, i32>(42) {
62 | | Ok(_) => true,
63 | | Err(_) => false,
64 | | };
| |_____^ help: try this: `Err::<i32, i32>(42).is_ok()`
error: redundant pattern matching, consider using `is_some()`
--> $DIR/redundant_pattern_matching.rs:66:5
|
66 | / match Some(42) {
67 | | Some(_) => true,
68 | | None => false,
69 | | };
| |_____^ help: try this: `Some(42).is_some()`
error: redundant pattern matching, consider using `is_none()`
--> $DIR/redundant_pattern_matching.rs:71:5
|
71 | / match None::<()> {
72 | | Some(_) => false,
73 | | None => true,
74 | | };
| |_____^ help: try this: `None::<()>.is_none()`
error: aborting due to 10 previous errors