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Merge pull request #2189 from gendx/pr-1590

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Start working on #1590
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Oliver Schneider 2017-11-02 10:29:30 +01:00 committed by GitHub
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4 changed files with 195 additions and 94 deletions
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1
clippy_lints/src/lib.rs
View File

@ -375,6 +375,7 @@ pub fn register_plugins(reg: &mut rustc_plugin::Registry) {
methods::FILTER_MAP,
methods::OPTION_MAP_UNWRAP_OR,
methods::OPTION_MAP_UNWRAP_OR_ELSE,
methods::RESULT_MAP_UNWRAP_OR_ELSE,
methods::OPTION_UNWRAP_USED,
methods::RESULT_UNWRAP_USED,
methods::WRONG_PUB_SELF_CONVENTION,

63
clippy_lints/src/methods.rs
View File

@ -193,6 +193,24 @@ declare_lint! {
`map_or_else(g, f)`"
}
/// **What it does:** Checks for usage of `result.map(_).unwrap_or_else(_)`.
///
/// **Why is this bad?** Readability, this can be written more concisely as
/// `result.ok().map_or_else(_, _)`.
///
/// **Known problems:** None.
///
/// **Example:**
/// ```rust
/// x.map(|a| a + 1).unwrap_or_else(some_function)
/// ```
declare_lint! {
pub RESULT_MAP_UNWRAP_OR_ELSE,
Allow,
"using `Result.map(f).unwrap_or_else(g)`, which is more succinctly expressed as \
`.ok().map_or_else(g, f)`"
}
/// **What it does:** Checks for usage of `_.map_or(None, _)`.
///
/// **Why is this bad?** Readability, this can be written more concisely as
@ -615,6 +633,7 @@ impl LintPass for Pass {
OK_EXPECT,
OPTION_MAP_UNWRAP_OR,
OPTION_MAP_UNWRAP_OR_ELSE,
RESULT_MAP_UNWRAP_OR_ELSE,
OPTION_MAP_OR_NONE,
OR_FUN_CALL,
CHARS_NEXT_CMP,
@ -1241,13 +1260,25 @@ fn lint_map_unwrap_or(cx: &LateContext, expr: &hir::Expr, map_args: &[hir::Expr]
}
}
/// lint use of `map().unwrap_or_else()` for `Option`s
fn lint_map_unwrap_or_else<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, expr: &'tcx hir::Expr, map_args: &'tcx [hir::Expr], unwrap_args: &'tcx [hir::Expr]) {
/// lint use of `map().unwrap_or_else()` for `Option`s and `Result`s
fn lint_map_unwrap_or_else<'a, 'tcx>(
cx: &LateContext<'a, 'tcx>,
expr: &'tcx hir::Expr,
map_args: &'tcx [hir::Expr],
unwrap_args: &'tcx [hir::Expr],
) {
// lint if the caller of `map()` is an `Option`
if match_type(cx, cx.tables.expr_ty(&map_args[0]), &paths::OPTION) {
let is_option = match_type(cx, cx.tables.expr_ty(&map_args[0]), &paths::OPTION);
let is_result = match_type(cx, cx.tables.expr_ty(&map_args[0]), &paths::RESULT);
if is_option || is_result {
// lint message
let msg = "called `map(f).unwrap_or_else(g)` on an Option value. This can be done more directly by calling \
`map_or_else(g, f)` instead";
let msg = if is_option {
"called `map(f).unwrap_or_else(g)` on an Option value. This can be done more directly by calling \
`map_or_else(g, f)` instead"
} else {
"called `map(f).unwrap_or_else(g)` on a Result value. This can be done more directly by calling \
`ok().map_or_else(g, f)` instead"
};
// get snippets for args to map() and unwrap_or_else()
let map_snippet = snippet(cx, map_args[1].span, "..");
let unwrap_snippet = snippet(cx, unwrap_args[1].span, "..");
@ -1258,18 +1289,32 @@ fn lint_map_unwrap_or_else<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, expr: &'tcx hir
if same_span && !multiline {
span_note_and_lint(
cx,
OPTION_MAP_UNWRAP_OR_ELSE,
if is_option {
OPTION_MAP_UNWRAP_OR_ELSE
} else {
RESULT_MAP_UNWRAP_OR_ELSE
},
expr.span,
msg,
expr.span,
&format!(
"replace `map({0}).unwrap_or_else({1})` with `map_or_else({1}, {0})`",
"replace `map({0}).unwrap_or_else({1})` with `{2}map_or_else({1}, {0})`",
map_snippet,
unwrap_snippet
unwrap_snippet,
if is_result { "ok()." } else { "" }
),
);
} else if same_span && multiline {
span_lint(cx, OPTION_MAP_UNWRAP_OR_ELSE, expr.span, msg);
span_lint(
cx,
if is_option {
OPTION_MAP_UNWRAP_OR_ELSE
} else {
RESULT_MAP_UNWRAP_OR_ELSE
},
expr.span,
msg,
);
};
}
}

23
tests/ui/methods.rs
View File

@ -149,6 +149,29 @@ fn option_methods() {
);
}
/// Checks implementation of the following lints:
/// * `RESULT_MAP_UNWRAP_OR_ELSE`
fn result_methods() {
let res: Result<i32, ()> = Ok(1);
// Check RESULT_MAP_UNWRAP_OR_ELSE
// single line case
let _ = res.map(|x| x + 1)
.unwrap_or_else(|e| 0); // should lint even though this call is on a separate line
// multi line cases
let _ = res.map(|x| {
x + 1
}
).unwrap_or_else(|e| 0);
let _ = res.map(|x| x + 1)
.unwrap_or_else(|e|
0
);
// macro case
let _ = opt_map!(res, |x| x + 1).unwrap_or_else(|e| 0); // should not lint
}
/// Struct to generate false positives for things with .iter()
#[derive(Copy, Clone)]
struct HasIter;

202
tests/ui/methods.stderr
View File

@ -220,252 +220,284 @@ help: try using and_then instead
148 | });
|
error: unnecessary structure name repetition
--> $DIR/methods.rs:173:24
error: called `map(f).unwrap_or_else(g)` on a Result value. This can be done more directly by calling `ok().map_or_else(g, f)` instead
--> $DIR/methods.rs:159:13
|
173 | fn filter(self) -> IteratorFalsePositives {
159 | let _ = res.map(|x| x + 1)
| _____________^
160 | |
161 | | .unwrap_or_else(|e| 0); // should lint even though this call is on a separate line
| |_____________________________________^
|
= note: `-D result-map-unwrap-or-else` implied by `-D warnings`
= note: replace `map(|x| x + 1).unwrap_or_else(|e| 0)` with `ok().map_or_else(|e| 0, |x| x + 1)`
error: called `map(f).unwrap_or_else(g)` on a Result value. This can be done more directly by calling `ok().map_or_else(g, f)` instead
--> $DIR/methods.rs:163:13
|
163 | let _ = res.map(|x| {
| _____________^
164 | | x + 1
165 | | }
166 | | ).unwrap_or_else(|e| 0);
| |_____________________________________^
error: called `map(f).unwrap_or_else(g)` on a Result value. This can be done more directly by calling `ok().map_or_else(g, f)` instead
--> $DIR/methods.rs:167:13
|
167 | let _ = res.map(|x| x + 1)
| _____________^
168 | | .unwrap_or_else(|e|
169 | | 0
170 | | );
| |_________________^
error: unnecessary structure name repetition
--> $DIR/methods.rs:196:24
|
196 | fn filter(self) -> IteratorFalsePositives {
| ^^^^^^^^^^^^^^^^^^^^^^ help: use the applicable keyword: `Self`
error: unnecessary structure name repetition
--> $DIR/methods.rs:177:22
--> $DIR/methods.rs:200:22
|
177 | fn next(self) -> IteratorFalsePositives {
200 | fn next(self) -> IteratorFalsePositives {
| ^^^^^^^^^^^^^^^^^^^^^^ help: use the applicable keyword: `Self`
error: unnecessary structure name repetition
--> $DIR/methods.rs:197:32
--> $DIR/methods.rs:220:32
|
197 | fn skip(self, _: usize) -> IteratorFalsePositives {
220 | fn skip(self, _: usize) -> IteratorFalsePositives {
| ^^^^^^^^^^^^^^^^^^^^^^ help: use the applicable keyword: `Self`
error: called `filter(p).next()` on an `Iterator`. This is more succinctly expressed by calling `.find(p)` instead.
--> $DIR/methods.rs:207:13
--> $DIR/methods.rs:230:13
|
207 | let _ = v.iter().filter(|&x| *x < 0).next();
230 | let _ = v.iter().filter(|&x| *x < 0).next();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: `-D filter-next` implied by `-D warnings`
= note: replace `filter(|&x| *x < 0).next()` with `find(|&x| *x < 0)`
error: called `filter(p).next()` on an `Iterator`. This is more succinctly expressed by calling `.find(p)` instead.
--> $DIR/methods.rs:210:13
--> $DIR/methods.rs:233:13
|
210 | let _ = v.iter().filter(|&x| {
233 | let _ = v.iter().filter(|&x| {
| _____________^
211 | | *x < 0
212 | | }
213 | | ).next();
234 | | *x < 0
235 | | }
236 | | ).next();
| |___________________________^
error: called `is_some()` after searching an `Iterator` with find. This is more succinctly expressed by calling `any()`.
--> $DIR/methods.rs:225:13
--> $DIR/methods.rs:248:13
|
225 | let _ = v.iter().find(|&x| *x < 0).is_some();
248 | let _ = v.iter().find(|&x| *x < 0).is_some();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: `-D search-is-some` implied by `-D warnings`
= note: replace `find(|&x| *x < 0).is_some()` with `any(|&x| *x < 0)`
error: called `is_some()` after searching an `Iterator` with find. This is more succinctly expressed by calling `any()`.
--> $DIR/methods.rs:228:13
--> $DIR/methods.rs:251:13
|
228 | let _ = v.iter().find(|&x| {
251 | let _ = v.iter().find(|&x| {
| _____________^
229 | | *x < 0
230 | | }
231 | | ).is_some();
252 | | *x < 0
253 | | }
254 | | ).is_some();
| |______________________________^
error: called `is_some()` after searching an `Iterator` with position. This is more succinctly expressed by calling `any()`.
--> $DIR/methods.rs:234:13
--> $DIR/methods.rs:257:13
|
234 | let _ = v.iter().position(|&x| x < 0).is_some();
257 | let _ = v.iter().position(|&x| x < 0).is_some();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: replace `position(|&x| x < 0).is_some()` with `any(|&x| x < 0)`
error: called `is_some()` after searching an `Iterator` with position. This is more succinctly expressed by calling `any()`.
--> $DIR/methods.rs:237:13
--> $DIR/methods.rs:260:13
|
237 | let _ = v.iter().position(|&x| {
260 | let _ = v.iter().position(|&x| {
| _____________^
238 | | x < 0
239 | | }
240 | | ).is_some();
261 | | x < 0
262 | | }
263 | | ).is_some();
| |______________________________^
error: called `is_some()` after searching an `Iterator` with rposition. This is more succinctly expressed by calling `any()`.
--> $DIR/methods.rs:243:13
--> $DIR/methods.rs:266:13
|
243 | let _ = v.iter().rposition(|&x| x < 0).is_some();
266 | let _ = v.iter().rposition(|&x| x < 0).is_some();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: replace `rposition(|&x| x < 0).is_some()` with `any(|&x| x < 0)`
error: called `is_some()` after searching an `Iterator` with rposition. This is more succinctly expressed by calling `any()`.
--> $DIR/methods.rs:246:13
--> $DIR/methods.rs:269:13
|
246 | let _ = v.iter().rposition(|&x| {
269 | let _ = v.iter().rposition(|&x| {
| _____________^
247 | | x < 0
248 | | }
249 | | ).is_some();
270 | | x < 0
271 | | }
272 | | ).is_some();
| |______________________________^
error: unnecessary structure name repetition
--> $DIR/methods.rs:263:21
--> $DIR/methods.rs:286:21
|
263 | fn new() -> Foo { Foo }
286 | fn new() -> Foo { Foo }
| ^^^ help: use the applicable keyword: `Self`
error: use of `unwrap_or` followed by a function call
--> $DIR/methods.rs:281:5
--> $DIR/methods.rs:304:5
|
281 | with_constructor.unwrap_or(make());
304 | with_constructor.unwrap_or(make());
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `with_constructor.unwrap_or_else(make)`
|
= note: `-D or-fun-call` implied by `-D warnings`
error: use of `unwrap_or` followed by a call to `new`
--> $DIR/methods.rs:284:5
--> $DIR/methods.rs:307:5
|
284 | with_new.unwrap_or(Vec::new());
307 | with_new.unwrap_or(Vec::new());
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `with_new.unwrap_or_default()`
error: use of `unwrap_or` followed by a function call
--> $DIR/methods.rs:287:5
--> $DIR/methods.rs:310:5
|
287 | with_const_args.unwrap_or(Vec::with_capacity(12));
310 | with_const_args.unwrap_or(Vec::with_capacity(12));
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `with_const_args.unwrap_or_else(|| Vec::with_capacity(12))`
error: use of `unwrap_or` followed by a function call
--> $DIR/methods.rs:290:5
--> $DIR/methods.rs:313:5
|
290 | with_err.unwrap_or(make());
313 | with_err.unwrap_or(make());
| ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `with_err.unwrap_or_else(|_| make())`
error: use of `unwrap_or` followed by a function call
--> $DIR/methods.rs:293:5
--> $DIR/methods.rs:316:5
|
293 | with_err_args.unwrap_or(Vec::with_capacity(12));
316 | with_err_args.unwrap_or(Vec::with_capacity(12));
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `with_err_args.unwrap_or_else(|_| Vec::with_capacity(12))`
error: use of `unwrap_or` followed by a call to `default`
--> $DIR/methods.rs:296:5
--> $DIR/methods.rs:319:5
|
296 | with_default_trait.unwrap_or(Default::default());
319 | with_default_trait.unwrap_or(Default::default());
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `with_default_trait.unwrap_or_default()`
error: use of `unwrap_or` followed by a call to `default`
--> $DIR/methods.rs:299:5
--> $DIR/methods.rs:322:5
|
299 | with_default_type.unwrap_or(u64::default());
322 | with_default_type.unwrap_or(u64::default());
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `with_default_type.unwrap_or_default()`
error: use of `unwrap_or` followed by a function call
--> $DIR/methods.rs:302:5
--> $DIR/methods.rs:325:5
|
302 | with_vec.unwrap_or(vec![]);
325 | with_vec.unwrap_or(vec![]);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `with_vec.unwrap_or_else(|| < [ _ ] > :: into_vec ( box [ $ ( $ x ) , * ] ))`
error: use of `unwrap_or` followed by a function call
--> $DIR/methods.rs:307:5
--> $DIR/methods.rs:330:5
|
307 | without_default.unwrap_or(Foo::new());
330 | without_default.unwrap_or(Foo::new());
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `without_default.unwrap_or_else(Foo::new)`
error: use of `or_insert` followed by a function call
--> $DIR/methods.rs:310:5
--> $DIR/methods.rs:333:5
|
310 | map.entry(42).or_insert(String::new());
333 | map.entry(42).or_insert(String::new());
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `map.entry(42).or_insert_with(String::new)`
error: use of `or_insert` followed by a function call
--> $DIR/methods.rs:313:5
--> $DIR/methods.rs:336:5
|
313 | btree.entry(42).or_insert(String::new());
336 | btree.entry(42).or_insert(String::new());
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `btree.entry(42).or_insert_with(String::new)`
error: use of `unwrap_or` followed by a function call
--> $DIR/methods.rs:316:13
--> $DIR/methods.rs:339:13
|
316 | let _ = stringy.unwrap_or("".to_owned());
339 | let _ = stringy.unwrap_or("".to_owned());
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `stringy.unwrap_or_else(|| "".to_owned())`
error: called `.iter().nth()` on a Vec. Calling `.get()` is both faster and more readable
--> $DIR/methods.rs:327:23
--> $DIR/methods.rs:350:23
|
327 | let bad_vec = some_vec.iter().nth(3);
350 | let bad_vec = some_vec.iter().nth(3);
| ^^^^^^^^^^^^^^^^^^^^^^
|
= note: `-D iter-nth` implied by `-D warnings`
error: called `.iter().nth()` on a slice. Calling `.get()` is both faster and more readable
--> $DIR/methods.rs:328:26
--> $DIR/methods.rs:351:26
|
328 | let bad_slice = &some_vec[..].iter().nth(3);
351 | let bad_slice = &some_vec[..].iter().nth(3);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^
error: called `.iter().nth()` on a slice. Calling `.get()` is both faster and more readable
--> $DIR/methods.rs:329:31
--> $DIR/methods.rs:352:31
|
329 | let bad_boxed_slice = boxed_slice.iter().nth(3);
352 | let bad_boxed_slice = boxed_slice.iter().nth(3);
| ^^^^^^^^^^^^^^^^^^^^^^^^^
error: called `.iter().nth()` on a VecDeque. Calling `.get()` is both faster and more readable
--> $DIR/methods.rs:330:29
--> $DIR/methods.rs:353:29
|
330 | let bad_vec_deque = some_vec_deque.iter().nth(3);
353 | let bad_vec_deque = some_vec_deque.iter().nth(3);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: called `.iter_mut().nth()` on a Vec. Calling `.get_mut()` is both faster and more readable
--> $DIR/methods.rs:335:23
--> $DIR/methods.rs:358:23
|
335 | let bad_vec = some_vec.iter_mut().nth(3);
358 | let bad_vec = some_vec.iter_mut().nth(3);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^
error: called `.iter_mut().nth()` on a slice. Calling `.get_mut()` is both faster and more readable
--> $DIR/methods.rs:338:26
--> $DIR/methods.rs:361:26
|
338 | let bad_slice = &some_vec[..].iter_mut().nth(3);
361 | let bad_slice = &some_vec[..].iter_mut().nth(3);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: called `.iter_mut().nth()` on a VecDeque. Calling `.get_mut()` is both faster and more readable
--> $DIR/methods.rs:341:29
--> $DIR/methods.rs:364:29
|
341 | let bad_vec_deque = some_vec_deque.iter_mut().nth(3);
364 | let bad_vec_deque = some_vec_deque.iter_mut().nth(3);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: called `skip(x).next()` on an iterator. This is more succinctly expressed by calling `nth(x)`
--> $DIR/methods.rs:353:13
--> $DIR/methods.rs:376:13
|
353 | let _ = some_vec.iter().skip(42).next();
376 | let _ = some_vec.iter().skip(42).next();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: `-D iter-skip-next` implied by `-D warnings`
error: called `skip(x).next()` on an iterator. This is more succinctly expressed by calling `nth(x)`
--> $DIR/methods.rs:354:13
--> $DIR/methods.rs:377:13
|
354 | let _ = some_vec.iter().cycle().skip(42).next();
377 | let _ = some_vec.iter().cycle().skip(42).next();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: called `skip(x).next()` on an iterator. This is more succinctly expressed by calling `nth(x)`
--> $DIR/methods.rs:355:13
--> $DIR/methods.rs:378:13
|
355 | let _ = (1..10).skip(10).next();
378 | let _ = (1..10).skip(10).next();
| ^^^^^^^^^^^^^^^^^^^^^^^
error: called `skip(x).next()` on an iterator. This is more succinctly expressed by calling `nth(x)`
--> $DIR/methods.rs:356:14
--> $DIR/methods.rs:379:14
|
356 | let _ = &some_vec[..].iter().skip(3).next();
379 | let _ = &some_vec[..].iter().skip(3).next();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: used unwrap() on an Option value. If you don't want to handle the None case gracefully, consider using expect() to provide a better panic message
--> $DIR/methods.rs:365:13
--> $DIR/methods.rs:388:13
|
365 | let _ = opt.unwrap();
388 | let _ = opt.unwrap();
| ^^^^^^^^^^^^
|
= note: `-D option-unwrap-used` implied by `-D warnings`