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fix redundant_pattern_matching lint 

- now it handles `while let` case
- better suggestions in `if let` case
This commit is contained in:
Aleksei Latyshev 2020-04-17 13:53:13 +03:00
parent f1fb815603
commit 092c4595fe
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GPG Key ID: 46FDD62F9CC114DB
4 changed files with 153 additions and 51 deletions
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30
clippy_lints/src/redundant_pattern_matching.rs
View File

@ -1,4 +1,5 @@
use crate::utils::{match_qpath, paths, snippet, span_lint_and_then};
use crate::utils::{match_qpath, match_trait_method, paths, snippet, span_lint_and_then};
use if_chain::if_chain;
use rustc_ast::ast::LitKind;
use rustc_errors::Applicability;
use rustc_hir::{Arm, Expr, ExprKind, MatchSource, PatKind, QPath};
@ -48,9 +49,8 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for RedundantPatternMatching {
if let ExprKind::Match(op, arms, ref match_source) = &expr.kind {
match match_source {
MatchSource::Normal => find_sugg_for_match(cx, expr, op, arms),
MatchSource::IfLetDesugar { contains_else_clause } => {
find_sugg_for_if_let(cx, expr, op, arms, *contains_else_clause)
},
MatchSource::IfLetDesugar { .. } => find_sugg_for_if_let(cx, expr, op, arms, "if"),
MatchSource::WhileLetDesugar => find_sugg_for_if_let(cx, expr, op, arms, "while"),
_ => return,
}
}
@ -62,7 +62,7 @@ fn find_sugg_for_if_let<'a, 'tcx>(
expr: &'tcx Expr<'_>,
op: &Expr<'_>,
arms: &[Arm<'_>],
has_else: bool,
keyword: &'static str,
) {
let good_method = match arms[0].pat.kind {
PatKind::TupleStruct(ref path, ref patterns, _) if patterns.len() == 1 => {
@ -86,7 +86,16 @@ fn find_sugg_for_if_let<'a, 'tcx>(
_ => return,
};
let maybe_semi = if has_else { "" } else { ";" };
// check that `while_let_on_iterator` lint does not trigger
if_chain! {
if keyword == "while";
if let ExprKind::MethodCall(method_path, _, _) = op.kind;
if method_path.ident.name == sym!(next);
if match_trait_method(cx, op, &paths::ITERATOR);
then {
return;
}
}
span_lint_and_then(
cx,
@ -94,12 +103,15 @@ fn find_sugg_for_if_let<'a, 'tcx>(
arms[0].pat.span,
&format!("redundant pattern matching, consider using `{}`", good_method),
|diag| {
let span = expr.span.to(op.span);
// in the case of WhileLetDesugar expr.span == op.span incorrectly.
// this is a workaround to restore true value of expr.span
let expr_span = expr.span.to(arms[1].span);
let span = expr_span.until(op.span.shrink_to_hi());
diag.span_suggestion(
span,
"try this",
format!("{}.{}{}", snippet(cx, op.span, "_"), good_method, maybe_semi),
Applicability::MaybeIncorrect, // snippet
format!("{} {}.{}", keyword, snippet(cx, op.span, "_"), good_method),
Applicability::MachineApplicable, // snippet
);
},
);

51
tests/ui/redundant_pattern_matching.fixed
View File

@ -2,16 +2,37 @@
#![warn(clippy::all)]
#![warn(clippy::redundant_pattern_matching)]
#![allow(clippy::unit_arg, unused_must_use)]
#![allow(clippy::unit_arg, unused_must_use, clippy::needless_bool)]
fn main() {
Ok::<i32, i32>(42).is_ok();
if Ok::<i32, i32>(42).is_ok() {}
Err::<i32, i32>(42).is_err();
if Err::<i32, i32>(42).is_err() {}
None::<()>.is_none();
if None::<()>.is_none() {}
Some(42).is_some();
if Some(42).is_some() {}
if Some(42).is_some() {
foo();
} else {
bar();
}
while Some(42).is_some() {}
while Some(42).is_none() {}
while None::<()>.is_none() {}
while Ok::<i32, i32>(10).is_ok() {}
while Ok::<i32, i32>(10).is_err() {}
let mut v = vec![1, 2, 3];
while v.pop().is_some() {
foo();
}
if Ok::<i32, i32>(42).is_ok() {}
@ -39,22 +60,34 @@ fn main() {
let _ = None::<()>.is_none();
let _ = Ok::<usize, ()>(4).is_ok();
let _ = if Ok::<usize, ()>(4).is_ok() { true } else { false };
let _ = does_something();
let _ = returns_unit();
let opt = Some(false);
let x = opt.is_some();
let x = if opt.is_some() { true } else { false };
takes_bool(x);
}
fn takes_bool(_: bool) {}
fn foo() {}
fn bar() {}
fn does_something() -> bool {
Ok::<i32, i32>(4).is_ok()
if Ok::<i32, i32>(4).is_ok() {
true
} else {
false
}
}
fn returns_unit() {
Ok::<i32, i32>(4).is_ok();
if Ok::<i32, i32>(4).is_ok() {
true
} else {
false
};
}

27
tests/ui/redundant_pattern_matching.rs
View File

@ -2,7 +2,7 @@
#![warn(clippy::all)]
#![warn(clippy::redundant_pattern_matching)]
#![allow(clippy::unit_arg, unused_must_use)]
#![allow(clippy::unit_arg, unused_must_use, clippy::needless_bool)]
fn main() {
if let Ok(_) = Ok::<i32, i32>(42) {}
@ -13,6 +13,27 @@ fn main() {
if let Some(_) = Some(42) {}
if let Some(_) = Some(42) {
foo();
} else {
bar();
}
while let Some(_) = Some(42) {}
while let None = Some(42) {}
while let None = None::<()> {}
while let Ok(_) = Ok::<i32, i32>(10) {}
while let Err(_) = Ok::<i32, i32>(10) {}
let mut v = vec![1, 2, 3];
while let Some(_) = v.pop() {
foo();
}
if Ok::<i32, i32>(42).is_ok() {}
if Err::<i32, i32>(42).is_err() {}
@ -72,6 +93,10 @@ fn main() {
fn takes_bool(_: bool) {}
fn foo() {}
fn bar() {}
fn does_something() -> bool {
if let Ok(_) = Ok::<i32, i32>(4) {
true

96
tests/ui/redundant_pattern_matching.stderr
View File

@ -2,7 +2,7 @@ error: redundant pattern matching, consider using `is_ok()`
--> $DIR/redundant_pattern_matching.rs:8:12
|
LL | if let Ok(_) = Ok::<i32, i32>(42) {}
| -------^^^^^------------------------ help: try this: `Ok::<i32, i32>(42).is_ok();`
| -------^^^^^--------------------- help: try this: `if Ok::<i32, i32>(42).is_ok()`
|
= note: `-D clippy::redundant-pattern-matching` implied by `-D warnings`
@ -10,22 +10,64 @@ error: redundant pattern matching, consider using `is_err()`
--> $DIR/redundant_pattern_matching.rs:10:12
|
LL | if let Err(_) = Err::<i32, i32>(42) {}
| -------^^^^^^------------------------- help: try this: `Err::<i32, i32>(42).is_err();`
| -------^^^^^^---------------------- help: try this: `if Err::<i32, i32>(42).is_err()`
error: redundant pattern matching, consider using `is_none()`
--> $DIR/redundant_pattern_matching.rs:12:12
|
LL | if let None = None::<()> {}
| -------^^^^---------------- help: try this: `None::<()>.is_none();`
| -------^^^^------------- help: try this: `if None::<()>.is_none()`
error: redundant pattern matching, consider using `is_some()`
--> $DIR/redundant_pattern_matching.rs:14:12
|
LL | if let Some(_) = Some(42) {}
| -------^^^^^^^-------------- help: try this: `Some(42).is_some();`
| -------^^^^^^^----------- help: try this: `if Some(42).is_some()`
error: redundant pattern matching, consider using `is_some()`
--> $DIR/redundant_pattern_matching.rs:16:12
|
LL | if let Some(_) = Some(42) {
| -------^^^^^^^----------- help: try this: `if Some(42).is_some()`
error: redundant pattern matching, consider using `is_some()`
--> $DIR/redundant_pattern_matching.rs:22:15
|
LL | while let Some(_) = Some(42) {}
| ----------^^^^^^^----------- help: try this: `while Some(42).is_some()`
error: redundant pattern matching, consider using `is_none()`
--> $DIR/redundant_pattern_matching.rs:24:15
|
LL | while let None = Some(42) {}
| ----------^^^^----------- help: try this: `while Some(42).is_none()`
error: redundant pattern matching, consider using `is_none()`
--> $DIR/redundant_pattern_matching.rs:26:15
|
LL | while let None = None::<()> {}
| ----------^^^^------------- help: try this: `while None::<()>.is_none()`
error: redundant pattern matching, consider using `is_ok()`
--> $DIR/redundant_pattern_matching.rs:28:5
--> $DIR/redundant_pattern_matching.rs:28:15
|
LL | while let Ok(_) = Ok::<i32, i32>(10) {}
| ----------^^^^^--------------------- help: try this: `while Ok::<i32, i32>(10).is_ok()`
error: redundant pattern matching, consider using `is_err()`
--> $DIR/redundant_pattern_matching.rs:30:15
|
LL | while let Err(_) = Ok::<i32, i32>(10) {}
| ----------^^^^^^--------------------- help: try this: `while Ok::<i32, i32>(10).is_err()`
error: redundant pattern matching, consider using `is_some()`
--> $DIR/redundant_pattern_matching.rs:33:15
|
LL | while let Some(_) = v.pop() {
| ----------^^^^^^^---------- help: try this: `while v.pop().is_some()`
error: redundant pattern matching, consider using `is_ok()`
--> $DIR/redundant_pattern_matching.rs:49:5
|
LL | / match Ok::<i32, i32>(42) {
LL | | Ok(_) => true,
@ -34,7 +76,7 @@ LL | | };
| |_____^ help: try this: `Ok::<i32, i32>(42).is_ok()`
error: redundant pattern matching, consider using `is_err()`
--> $DIR/redundant_pattern_matching.rs:33:5
--> $DIR/redundant_pattern_matching.rs:54:5
|
LL | / match Ok::<i32, i32>(42) {
LL | | Ok(_) => false,
@ -43,7 +85,7 @@ LL | | };
| |_____^ help: try this: `Ok::<i32, i32>(42).is_err()`
error: redundant pattern matching, consider using `is_err()`
--> $DIR/redundant_pattern_matching.rs:38:5
--> $DIR/redundant_pattern_matching.rs:59:5
|
LL | / match Err::<i32, i32>(42) {
LL | | Ok(_) => false,
@ -52,7 +94,7 @@ LL | | };
| |_____^ help: try this: `Err::<i32, i32>(42).is_err()`
error: redundant pattern matching, consider using `is_ok()`
--> $DIR/redundant_pattern_matching.rs:43:5
--> $DIR/redundant_pattern_matching.rs:64:5
|
LL | / match Err::<i32, i32>(42) {
LL | | Ok(_) => true,
@ -61,7 +103,7 @@ LL | | };
| |_____^ help: try this: `Err::<i32, i32>(42).is_ok()`
error: redundant pattern matching, consider using `is_some()`
--> $DIR/redundant_pattern_matching.rs:48:5
--> $DIR/redundant_pattern_matching.rs:69:5
|
LL | / match Some(42) {
LL | | Some(_) => true,
@ -70,7 +112,7 @@ LL | | };
| |_____^ help: try this: `Some(42).is_some()`
error: redundant pattern matching, consider using `is_none()`
--> $DIR/redundant_pattern_matching.rs:53:5
--> $DIR/redundant_pattern_matching.rs:74:5
|
LL | / match None::<()> {
LL | | Some(_) => false,
@ -79,7 +121,7 @@ LL | | };
| |_____^ help: try this: `None::<()>.is_none()`
error: redundant pattern matching, consider using `is_none()`
--> $DIR/redundant_pattern_matching.rs:58:13
--> $DIR/redundant_pattern_matching.rs:79:13
|
LL | let _ = match None::<()> {
| _____________^
@ -89,38 +131,28 @@ LL | | };
| |_____^ help: try this: `None::<()>.is_none()`
error: redundant pattern matching, consider using `is_ok()`
--> $DIR/redundant_pattern_matching.rs:63:20
--> $DIR/redundant_pattern_matching.rs:84:20
|
LL | let _ = if let Ok(_) = Ok::<usize, ()>(4) { true } else { false };
| -------^^^^^--------------------------------------------- help: try this: `Ok::<usize, ()>(4).is_ok()`
| -------^^^^^--------------------- help: try this: `if Ok::<usize, ()>(4).is_ok()`
error: redundant pattern matching, consider using `is_some()`
--> $DIR/redundant_pattern_matching.rs:69:20
--> $DIR/redundant_pattern_matching.rs:90:20
|
LL | let x = if let Some(_) = opt { true } else { false };
| -------^^^^^^^------------------------------ help: try this: `opt.is_some()`
| -------^^^^^^^------ help: try this: `if opt.is_some()`
error: redundant pattern matching, consider using `is_ok()`
--> $DIR/redundant_pattern_matching.rs:76:12
--> $DIR/redundant_pattern_matching.rs:101:12
|
LL | if let Ok(_) = Ok::<i32, i32>(4) {
| _____- ^^^^^
LL | | true
LL | | } else {
LL | | false
LL | | }
| |_____- help: try this: `Ok::<i32, i32>(4).is_ok()`
LL | if let Ok(_) = Ok::<i32, i32>(4) {
| -------^^^^^-------------------- help: try this: `if Ok::<i32, i32>(4).is_ok()`
error: redundant pattern matching, consider using `is_ok()`
--> $DIR/redundant_pattern_matching.rs:84:12
--> $DIR/redundant_pattern_matching.rs:109:12
|
LL | if let Ok(_) = Ok::<i32, i32>(4) {
| _____- ^^^^^
LL | | true
LL | | } else {
LL | | false
LL | | };
| |_____- help: try this: `Ok::<i32, i32>(4).is_ok()`
LL | if let Ok(_) = Ok::<i32, i32>(4) {
| -------^^^^^-------------------- help: try this: `if Ok::<i32, i32>(4).is_ok()`
error: aborting due to 15 previous errors
error: aborting due to 22 previous errors