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Auto merge of #3666 - detrumi:map-or-on-non-copy, r=flip1995

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Only suggest map_or for copy types

Fixes #2686
This commit is contained in:
bors 2019-02-27 08:28:48 +00:00
commit ff2798840c
4 changed files with 173 additions and 77 deletions
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45
clippy_lints/src/methods/mod.rs
View File

@ -22,6 +22,7 @@ use syntax::ast;
use syntax::source_map::{BytePos, Span};
use syntax::symbol::LocalInternedString;
mod option_map_unwrap_or;
mod unnecessary_filter_map;
#[derive(Clone)]
@ -836,7 +837,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Pass {
["unwrap", "get_mut"] => lint_get_unwrap(cx, expr, arg_lists[1], true),
["unwrap", ..] => lint_unwrap(cx, expr, arg_lists[0]),
["expect", "ok"] => lint_ok_expect(cx, expr, arg_lists[1]),
["unwrap_or", "map"] => lint_map_unwrap_or(cx, expr, arg_lists[1], arg_lists[0]),
["unwrap_or", "map"] => option_map_unwrap_or::lint(cx, expr, arg_lists[1], arg_lists[0]),
["unwrap_or_else", "map"] => lint_map_unwrap_or_else(cx, expr, arg_lists[1], arg_lists[0]),
["map_or", ..] => lint_map_or_none(cx, expr, arg_lists[0]),
["next", "filter"] => lint_filter_next(cx, expr, arg_lists[1]),
@ -1769,48 +1770,6 @@ fn lint_ok_expect(cx: &LateContext<'_, '_>, expr: &hir::Expr, ok_args: &[hir::Ex
}
}
/// lint use of `map().unwrap_or()` for `Option`s
fn lint_map_unwrap_or(cx: &LateContext<'_, '_>, expr: &hir::Expr, map_args: &[hir::Expr], unwrap_args: &[hir::Expr]) {
// lint if the caller of `map()` is an `Option`
if match_type(cx, cx.tables.expr_ty(&map_args[0]), &paths::OPTION) {
// get snippets for args to map() and unwrap_or()
let map_snippet = snippet(cx, map_args[1].span, "..");
let unwrap_snippet = snippet(cx, unwrap_args[1].span, "..");
// lint message
// comparing the snippet from source to raw text ("None") below is safe
// because we already have checked the type.
let arg = if unwrap_snippet == "None" { "None" } else { "a" };
let suggest = if unwrap_snippet == "None" {
"and_then(f)"
} else {
"map_or(a, f)"
};
let msg = &format!(
"called `map(f).unwrap_or({})` on an Option value. \
This can be done more directly by calling `{}` instead",
arg, suggest
);
// lint, with note if neither arg is > 1 line and both map() and
// unwrap_or() have the same span
let multiline = map_snippet.lines().count() > 1 || unwrap_snippet.lines().count() > 1;
let same_span = map_args[1].span.ctxt() == unwrap_args[1].span.ctxt();
if same_span && !multiline {
let suggest = if unwrap_snippet == "None" {
format!("and_then({})", map_snippet)
} else {
format!("map_or({}, {})", unwrap_snippet, map_snippet)
};
let note = format!(
"replace `map({}).unwrap_or({})` with `{}`",
map_snippet, unwrap_snippet, suggest
);
span_note_and_lint(cx, OPTION_MAP_UNWRAP_OR, expr.span, msg, expr.span, &note);
} else if same_span && multiline {
span_lint(cx, OPTION_MAP_UNWRAP_OR, expr.span, msg);
};
}
}
/// lint use of `map().flatten()` for `Iterators`
fn lint_map_flatten<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, expr: &'tcx hir::Expr, map_args: &'tcx [hir::Expr]) {
// lint if caller of `.map().flatten()` is an Iterator

122
clippy_lints/src/methods/option_map_unwrap_or.rs Normal file
View File

@ -0,0 +1,122 @@
use crate::utils::paths;
use crate::utils::{is_copy, match_type, snippet, span_lint, span_note_and_lint};
use rustc::hir::intravisit::{walk_path, NestedVisitorMap, Visitor};
use rustc::hir::{self, *};
use rustc::lint::LateContext;
use rustc_data_structures::fx::FxHashSet;
use syntax::symbol::Symbol;
use super::OPTION_MAP_UNWRAP_OR;
/// lint use of `map().unwrap_or()` for `Option`s
pub(super) fn lint<'a, 'tcx>(
cx: &LateContext<'a, 'tcx>,
expr: &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) {
if !is_copy(cx, cx.tables.expr_ty(&unwrap_args[1])) {
// Do not lint if the `map` argument uses identifiers in the `map`
// argument that are also used in the `unwrap_or` argument
let mut unwrap_visitor = UnwrapVisitor {
cx,
identifiers: FxHashSet::default(),
};
unwrap_visitor.visit_expr(&unwrap_args[1]);
let mut map_expr_visitor = MapExprVisitor {
cx,
identifiers: unwrap_visitor.identifiers,
found_identifier: false,
};
map_expr_visitor.visit_expr(&map_args[1]);
if map_expr_visitor.found_identifier {
return;
}
}
// get snippets for args to map() and unwrap_or()
let map_snippet = snippet(cx, map_args[1].span, "..");
let unwrap_snippet = snippet(cx, unwrap_args[1].span, "..");
// lint message
// comparing the snippet from source to raw text ("None") below is safe
// because we already have checked the type.
let arg = if unwrap_snippet == "None" { "None" } else { "a" };
let suggest = if unwrap_snippet == "None" {
"and_then(f)"
} else {
"map_or(a, f)"
};
let msg = &format!(
"called `map(f).unwrap_or({})` on an Option value. \
This can be done more directly by calling `{}` instead",
arg, suggest
);
// lint, with note if neither arg is > 1 line and both map() and
// unwrap_or() have the same span
let multiline = map_snippet.lines().count() > 1 || unwrap_snippet.lines().count() > 1;
let same_span = map_args[1].span.ctxt() == unwrap_args[1].span.ctxt();
if same_span && !multiline {
let suggest = if unwrap_snippet == "None" {
format!("and_then({})", map_snippet)
} else {
format!("map_or({}, {})", unwrap_snippet, map_snippet)
};
let note = format!(
"replace `map({}).unwrap_or({})` with `{}`",
map_snippet, unwrap_snippet, suggest
);
span_note_and_lint(cx, OPTION_MAP_UNWRAP_OR, expr.span, msg, expr.span, &note);
} else if same_span && multiline {
span_lint(cx, OPTION_MAP_UNWRAP_OR, expr.span, msg);
};
}
}
struct UnwrapVisitor<'a, 'tcx: 'a> {
cx: &'a LateContext<'a, 'tcx>,
identifiers: FxHashSet<Symbol>,
}
impl<'a, 'tcx: 'a> Visitor<'tcx> for UnwrapVisitor<'a, 'tcx> {
fn visit_path(&mut self, path: &'tcx Path, _id: HirId) {
self.identifiers.insert(ident(path));
walk_path(self, path);
}
fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
NestedVisitorMap::All(&self.cx.tcx.hir())
}
}
struct MapExprVisitor<'a, 'tcx: 'a> {
cx: &'a LateContext<'a, 'tcx>,
identifiers: FxHashSet<Symbol>,
found_identifier: bool,
}
impl<'a, 'tcx: 'a> Visitor<'tcx> for MapExprVisitor<'a, 'tcx> {
fn visit_path(&mut self, path: &'tcx Path, _id: HirId) {
if self.identifiers.contains(&ident(path)) {
self.found_identifier = true;
return;
}
walk_path(self, path);
}
fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
NestedVisitorMap::All(&self.cx.tcx.hir())
}
}
fn ident(path: &Path) -> Symbol {
path.segments
.last()
.expect("segments should be composed of at least 1 element")
.ident
.name
}

7
tests/ui/methods.rs
View File

@ -179,6 +179,13 @@ fn option_methods() {
// macro case
let _ = opt_map!(opt, |x| x + 1).unwrap_or(0); // should not lint
// Should not lint if not copyable
let id: String = "identifier".to_string();
let _ = Some("prefix").map(|p| format!("{}.{}", p, id)).unwrap_or(id);
// ...but DO lint if the `unwrap_or` argument is not used in the `map`
let id: String = "identifier".to_string();
let _ = Some("prefix").map(|p| format!("{}.", p)).unwrap_or(id);
// Check OPTION_MAP_UNWRAP_OR_ELSE
// single line case
let _ = opt.map(|x| x + 1)

76
tests/ui/methods.stderr
View File

@ -89,8 +89,16 @@ LL | | .unwrap_or(None);
|
= note: replace `map(|x| Some(x + 1)).unwrap_or(None)` with `and_then(|x| Some(x + 1))`
error: called `map(f).unwrap_or(a)` on an Option value. This can be done more directly by calling `map_or(a, f)` instead
--> $DIR/methods.rs:187:13
|
LL | let _ = Some("prefix").map(|p| format!("{}.", p)).unwrap_or(id);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: replace `map(|p| format!("{}.", p)).unwrap_or(id)` with `map_or(id, |p| format!("{}.", p))`
error: 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
--> $DIR/methods.rs:184:13
--> $DIR/methods.rs:191:13
|
LL | let _ = opt.map(|x| x + 1)
| _____________^
@ -102,7 +110,7 @@ LL | | .unwrap_or_else(|| 0); // should lint even though this cal
= note: replace `map(|x| x + 1).unwrap_or_else(|| 0)` with `map_or_else(|| 0, |x| x + 1)`
error: 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
--> $DIR/methods.rs:188:13
--> $DIR/methods.rs:195:13
|
LL | let _ = opt.map(|x| {
| _____________^
@ -112,7 +120,7 @@ LL | | ).unwrap_or_else(|| 0);
| |____________________________________^
error: 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
--> $DIR/methods.rs:192:13
--> $DIR/methods.rs:199:13
|
LL | let _ = opt.map(|x| x + 1)
| _____________^
@ -122,7 +130,7 @@ LL | | );
| |_________________^
error: called `map_or(None, f)` on an Option value. This can be done more directly by calling `and_then(f)` instead
--> $DIR/methods.rs:201:13
--> $DIR/methods.rs:208:13
|
LL | let _ = opt.map_or(None, |x| Some(x + 1));
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try using and_then instead: `opt.and_then(|x| Some(x + 1))`
@ -130,7 +138,7 @@ LL | let _ = opt.map_or(None, |x| Some(x + 1));
= note: `-D clippy::option-map-or-none` implied by `-D warnings`
error: called `map_or(None, f)` on an Option value. This can be done more directly by calling `and_then(f)` instead
--> $DIR/methods.rs:203:13
--> $DIR/methods.rs:210:13
|
LL | let _ = opt.map_or(None, |x| {
| _____________^
@ -146,7 +154,7 @@ LL | });
|
error: called `filter(p).next()` on an `Iterator`. This is more succinctly expressed by calling `.find(p)` instead.
--> $DIR/methods.rs:229:13
--> $DIR/methods.rs:236:13
|
LL | let _ = v.iter().filter(|&x| *x < 0).next();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@ -155,7 +163,7 @@ LL | let _ = v.iter().filter(|&x| *x < 0).next();
= 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:232:13
--> $DIR/methods.rs:239:13
|
LL | let _ = v.iter().filter(|&x| {
| _____________^
@ -165,7 +173,7 @@ LL | | ).next();
| |___________________________^
error: called `is_some()` after searching an `Iterator` with find. This is more succinctly expressed by calling `any()`.
--> $DIR/methods.rs:248:13
--> $DIR/methods.rs:255:13
|
LL | let _ = v.iter().find(|&x| *x < 0).is_some();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@ -174,7 +182,7 @@ LL | let _ = v.iter().find(|&x| *x < 0).is_some();
= 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:251:13
--> $DIR/methods.rs:258:13
|
LL | let _ = v.iter().find(|&x| {
| _____________^
@ -184,7 +192,7 @@ LL | | ).is_some();
| |______________________________^
error: called `is_some()` after searching an `Iterator` with position. This is more succinctly expressed by calling `any()`.
--> $DIR/methods.rs:257:13
--> $DIR/methods.rs:264:13
|
LL | let _ = v.iter().position(|&x| x < 0).is_some();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@ -192,7 +200,7 @@ LL | 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:260:13
--> $DIR/methods.rs:267:13
|
LL | let _ = v.iter().position(|&x| {
| _____________^
@ -202,7 +210,7 @@ LL | | ).is_some();
| |______________________________^
error: called `is_some()` after searching an `Iterator` with rposition. This is more succinctly expressed by calling `any()`.
--> $DIR/methods.rs:266:13
--> $DIR/methods.rs:273:13
|
LL | let _ = v.iter().rposition(|&x| x < 0).is_some();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@ -210,7 +218,7 @@ LL | 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:269:13
--> $DIR/methods.rs:276:13
|
LL | let _ = v.iter().rposition(|&x| {
| _____________^
@ -220,7 +228,7 @@ LL | | ).is_some();
| |______________________________^
error: use of `unwrap_or` followed by a function call
--> $DIR/methods.rs:306:22
--> $DIR/methods.rs:313:22
|
LL | with_constructor.unwrap_or(make());
| ^^^^^^^^^^^^^^^^^ help: try this: `unwrap_or_else(make)`
@ -228,73 +236,73 @@ LL | with_constructor.unwrap_or(make());
= note: `-D clippy::or-fun-call` implied by `-D warnings`
error: use of `unwrap_or` followed by a call to `new`
--> $DIR/methods.rs:309:5
--> $DIR/methods.rs:316:5
|
LL | 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:312:21
--> $DIR/methods.rs:319:21
|
LL | with_const_args.unwrap_or(Vec::with_capacity(12));
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `unwrap_or_else(|| Vec::with_capacity(12))`
error: use of `unwrap_or` followed by a function call
--> $DIR/methods.rs:315:14
--> $DIR/methods.rs:322:14
|
LL | with_err.unwrap_or(make());
| ^^^^^^^^^^^^^^^^^ help: try this: `unwrap_or_else(|_| make())`
error: use of `unwrap_or` followed by a function call
--> $DIR/methods.rs:318:19
--> $DIR/methods.rs:325:19
|
LL | with_err_args.unwrap_or(Vec::with_capacity(12));
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `unwrap_or_else(|_| Vec::with_capacity(12))`
error: use of `unwrap_or` followed by a call to `default`
--> $DIR/methods.rs:321:5
--> $DIR/methods.rs:328:5
|
LL | 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:324:5
--> $DIR/methods.rs:331:5
|
LL | 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:327:14
--> $DIR/methods.rs:334:14
|
LL | with_vec.unwrap_or(vec![]);
| ^^^^^^^^^^^^^^^^^ help: try this: `unwrap_or_else(|| vec![])`
error: use of `unwrap_or` followed by a function call
--> $DIR/methods.rs:332:21
--> $DIR/methods.rs:339:21
|
LL | without_default.unwrap_or(Foo::new());
| ^^^^^^^^^^^^^^^^^^^^^ help: try this: `unwrap_or_else(Foo::new)`
error: use of `or_insert` followed by a function call
--> $DIR/methods.rs:335:19
--> $DIR/methods.rs:342:19
|
LL | map.entry(42).or_insert(String::new());
| ^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `or_insert_with(String::new)`
error: use of `or_insert` followed by a function call
--> $DIR/methods.rs:338:21
--> $DIR/methods.rs:345:21
|
LL | btree.entry(42).or_insert(String::new());
| ^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `or_insert_with(String::new)`
error: use of `unwrap_or` followed by a function call
--> $DIR/methods.rs:341:21
--> $DIR/methods.rs:348:21
|
LL | let _ = stringy.unwrap_or("".to_owned());
| ^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `unwrap_or_else(|| "".to_owned())`
error: called `.iter().nth()` on a Vec. Calling `.get()` is both faster and more readable
--> $DIR/methods.rs:352:23
--> $DIR/methods.rs:359:23
|
LL | let bad_vec = some_vec.iter().nth(3);
| ^^^^^^^^^^^^^^^^^^^^^^
@ -302,48 +310,48 @@ LL | let bad_vec = some_vec.iter().nth(3);
= note: `-D clippy::iter-nth` implied by `-D warnings`
error: called `.iter().nth()` on a slice. Calling `.get()` is both faster and more readable
--> $DIR/methods.rs:353:26
--> $DIR/methods.rs:360:26
|
LL | 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:354:31
--> $DIR/methods.rs:361:31
|
LL | 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:355:29
--> $DIR/methods.rs:362:29
|
LL | 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:360:23
--> $DIR/methods.rs:367:23
|
LL | 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:363:26
--> $DIR/methods.rs:370:26
|
LL | 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:366:29
--> $DIR/methods.rs:373:29
|
LL | let bad_vec_deque = some_vec_deque.iter_mut().nth(3);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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:378:13
--> $DIR/methods.rs:385:13
|
LL | let _ = opt.unwrap();
| ^^^^^^^^^^^^
|
= note: `-D clippy::option-unwrap-used` implied by `-D warnings`
error: aborting due to 43 previous errors
error: aborting due to 44 previous errors