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Auto merge of #9750 - kraktus:lazy_eval, r=xFrednet

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Fix [`unnecessary_lazy_eval`] when type has significant drop

fix for https://github.com/rust-lang/rust-clippy/issues/9427#issuecomment-1295742590

However current implementation gives too many false positive, rending the lint almost useless.

I don't know what's the best way to check if a type has a "significant" drop (in the common meaning, not the internal rustc one, for example Option<(u8, u8)> should not be considered significant)

changelog: Fix [`unnecessary_lazy_eval`] when type has significant drop
This commit is contained in:
bors 2022-11-22 17:21:23 +00:00
commit 5595d7f5d5
4 changed files with 92 additions and 64 deletions
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26
clippy_utils/src/eager_or_lazy.rs
View File

@ -91,6 +91,16 @@ fn fn_eagerness(cx: &LateContext<'_>, fn_id: DefId, name: Symbol, have_one_arg:
}
}
fn res_has_significant_drop(res: Res, cx: &LateContext<'_>, e: &Expr<'_>) -> bool {
if let Res::Def(DefKind::Ctor(..) | DefKind::Variant, _) | Res::SelfCtor(_) = res {
cx.typeck_results()
.expr_ty(e)
.has_significant_drop(cx.tcx, cx.param_env)
} else {
false
}
}
#[expect(clippy::too_many_lines)]
fn expr_eagerness<'tcx>(cx: &LateContext<'tcx>, e: &'tcx Expr<'_>) -> EagernessSuggestion {
struct V<'cx, 'tcx> {
@ -113,13 +123,8 @@ fn visit_expr(&mut self, e: &'tcx Expr<'_>) {
},
args,
) => match self.cx.qpath_res(path, hir_id) {
Res::Def(DefKind::Ctor(..) | DefKind::Variant, _) | Res::SelfCtor(_) => {
if self
.cx
.typeck_results()
.expr_ty(e)
.has_significant_drop(self.cx.tcx, self.cx.param_env)
{
res @ (Res::Def(DefKind::Ctor(..) | DefKind::Variant, _) | Res::SelfCtor(_)) => {
if res_has_significant_drop(res, self.cx, e) {
self.eagerness = ForceNoChange;
return;
}
@ -147,6 +152,12 @@ fn visit_expr(&mut self, e: &'tcx Expr<'_>) {
self.eagerness |= NoChange;
return;
},
ExprKind::Path(ref path) => {
if res_has_significant_drop(self.cx.qpath_res(path, e.hir_id), self.cx, e) {
self.eagerness = ForceNoChange;
return;
}
},
ExprKind::MethodCall(name, ..) => {
self.eagerness |= self
.cx
@ -206,7 +217,6 @@ fn visit_expr(&mut self, e: &'tcx Expr<'_>) {
| ExprKind::Match(..)
| ExprKind::Closure { .. }
| ExprKind::Field(..)
| ExprKind::Path(_)
| ExprKind::AddrOf(..)
| ExprKind::Struct(..)
| ExprKind::Repeat(..)

23
tests/ui/unnecessary_lazy_eval.fixed
View File

@ -33,6 +33,14 @@ impl Drop for Issue9427 {
}
}
struct Issue9427FollowUp;
impl Drop for Issue9427FollowUp {
fn drop(&mut self) {
panic!("side effect drop");
}
}
fn main() {
let astronomers_pi = 10;
let ext_arr: [usize; 1] = [2];
@ -87,6 +95,7 @@ fn main() {
// Should not lint - bool
let _ = (0 == 1).then(|| Issue9427(0)); // Issue9427 has a significant drop
let _ = false.then(|| Issue9427FollowUp); // Issue9427FollowUp has a significant drop
// should not lint, bind_instead_of_map takes priority
let _ = Some(10).and_then(|idx| Some(ext_arr[idx]));
@ -133,13 +142,13 @@ fn main() {
let _: Result<usize, usize> = res.or(Ok(astronomers_pi));
let _: Result<usize, usize> = res.or(Ok(ext_str.some_field));
let _: Result<usize, usize> = res.
// some lines
// some lines
// some lines
// some lines
// some lines
// some lines
or(Ok(ext_str.some_field));
// some lines
// some lines
// some lines
// some lines
// some lines
// some lines
or(Ok(ext_str.some_field));
// neither bind_instead_of_map nor unnecessary_lazy_eval applies here
let _: Result<usize, usize> = res.and_then(|x| Err(x));

23
tests/ui/unnecessary_lazy_eval.rs
View File

@ -33,6 +33,14 @@ fn drop(&mut self) {
}
}
struct Issue9427FollowUp;
impl Drop for Issue9427FollowUp {
fn drop(&mut self) {
panic!("side effect drop");
}
}
fn main() {
let astronomers_pi = 10;
let ext_arr: [usize; 1] = [2];
@ -87,6 +95,7 @@ fn main() {
// Should not lint - bool
let _ = (0 == 1).then(|| Issue9427(0)); // Issue9427 has a significant drop
let _ = false.then(|| Issue9427FollowUp); // Issue9427FollowUp has a significant drop
// should not lint, bind_instead_of_map takes priority
let _ = Some(10).and_then(|idx| Some(ext_arr[idx]));
@ -133,13 +142,13 @@ fn main() {
let _: Result<usize, usize> = res.or_else(|_| Ok(astronomers_pi));
let _: Result<usize, usize> = res.or_else(|_| Ok(ext_str.some_field));
let _: Result<usize, usize> = res.
// some lines
// some lines
// some lines
// some lines
// some lines
// some lines
or_else(|_| Ok(ext_str.some_field));
// some lines
// some lines
// some lines
// some lines
// some lines
// some lines
or_else(|_| Ok(ext_str.some_field));
// neither bind_instead_of_map nor unnecessary_lazy_eval applies here
let _: Result<usize, usize> = res.and_then(|x| Err(x));

84
tests/ui/unnecessary_lazy_eval.stderr
View File

@ -1,5 +1,5 @@
error: unnecessary closure used to substitute value for `Option::None`
--> $DIR/unnecessary_lazy_eval.rs:48:13
--> $DIR/unnecessary_lazy_eval.rs:56:13
|
LL | let _ = opt.unwrap_or_else(|| 2);
| ^^^^--------------------
@ -9,7 +9,7 @@ LL | let _ = opt.unwrap_or_else(|| 2);
= note: `-D clippy::unnecessary-lazy-evaluations` implied by `-D warnings`
error: unnecessary closure used to substitute value for `Option::None`
--> $DIR/unnecessary_lazy_eval.rs:49:13
--> $DIR/unnecessary_lazy_eval.rs:57:13
|
LL | let _ = opt.unwrap_or_else(|| astronomers_pi);
| ^^^^---------------------------------
@ -17,7 +17,7 @@ LL | let _ = opt.unwrap_or_else(|| astronomers_pi);
| help: use `unwrap_or(..)` instead: `unwrap_or(astronomers_pi)`
error: unnecessary closure used to substitute value for `Option::None`
--> $DIR/unnecessary_lazy_eval.rs:50:13
--> $DIR/unnecessary_lazy_eval.rs:58:13
|
LL | let _ = opt.unwrap_or_else(|| ext_str.some_field);
| ^^^^-------------------------------------
@ -25,7 +25,7 @@ LL | let _ = opt.unwrap_or_else(|| ext_str.some_field);
| help: use `unwrap_or(..)` instead: `unwrap_or(ext_str.some_field)`
error: unnecessary closure used to substitute value for `Option::None`
--> $DIR/unnecessary_lazy_eval.rs:52:13
--> $DIR/unnecessary_lazy_eval.rs:60:13
|
LL | let _ = opt.and_then(|_| ext_opt);
| ^^^^---------------------
@ -33,7 +33,7 @@ LL | let _ = opt.and_then(|_| ext_opt);
| help: use `and(..)` instead: `and(ext_opt)`
error: unnecessary closure used to substitute value for `Option::None`
--> $DIR/unnecessary_lazy_eval.rs:53:13
--> $DIR/unnecessary_lazy_eval.rs:61:13
|
LL | let _ = opt.or_else(|| ext_opt);
| ^^^^-------------------
@ -41,7 +41,7 @@ LL | let _ = opt.or_else(|| ext_opt);
| help: use `or(..)` instead: `or(ext_opt)`
error: unnecessary closure used to substitute value for `Option::None`
--> $DIR/unnecessary_lazy_eval.rs:54:13
--> $DIR/unnecessary_lazy_eval.rs:62:13
|
LL | let _ = opt.or_else(|| None);
| ^^^^----------------
@ -49,7 +49,7 @@ LL | let _ = opt.or_else(|| None);
| help: use `or(..)` instead: `or(None)`
error: unnecessary closure used to substitute value for `Option::None`
--> $DIR/unnecessary_lazy_eval.rs:55:13
--> $DIR/unnecessary_lazy_eval.rs:63:13
|
LL | let _ = opt.get_or_insert_with(|| 2);
| ^^^^------------------------
@ -57,7 +57,7 @@ LL | let _ = opt.get_or_insert_with(|| 2);
| help: use `get_or_insert(..)` instead: `get_or_insert(2)`
error: unnecessary closure used to substitute value for `Option::None`
--> $DIR/unnecessary_lazy_eval.rs:56:13
--> $DIR/unnecessary_lazy_eval.rs:64:13
|
LL | let _ = opt.ok_or_else(|| 2);
| ^^^^----------------
@ -65,7 +65,7 @@ LL | let _ = opt.ok_or_else(|| 2);
| help: use `ok_or(..)` instead: `ok_or(2)`
error: unnecessary closure used to substitute value for `Option::None`
--> $DIR/unnecessary_lazy_eval.rs:57:13
--> $DIR/unnecessary_lazy_eval.rs:65:13
|
LL | let _ = nested_tuple_opt.unwrap_or_else(|| Some((1, 2)));
| ^^^^^^^^^^^^^^^^^-------------------------------
@ -73,7 +73,7 @@ LL | let _ = nested_tuple_opt.unwrap_or_else(|| Some((1, 2)));
| help: use `unwrap_or(..)` instead: `unwrap_or(Some((1, 2)))`
error: unnecessary closure used with `bool::then`
--> $DIR/unnecessary_lazy_eval.rs:58:13
--> $DIR/unnecessary_lazy_eval.rs:66:13
|
LL | let _ = cond.then(|| astronomers_pi);
| ^^^^^-----------------------
@ -81,7 +81,7 @@ LL | let _ = cond.then(|| astronomers_pi);
| help: use `then_some(..)` instead: `then_some(astronomers_pi)`
error: unnecessary closure used to substitute value for `Option::None`
--> $DIR/unnecessary_lazy_eval.rs:61:13
--> $DIR/unnecessary_lazy_eval.rs:69:13
|
LL | let _ = Some(10).unwrap_or_else(|| 2);
| ^^^^^^^^^--------------------
@ -89,7 +89,7 @@ LL | let _ = Some(10).unwrap_or_else(|| 2);
| help: use `unwrap_or(..)` instead: `unwrap_or(2)`
error: unnecessary closure used to substitute value for `Option::None`
--> $DIR/unnecessary_lazy_eval.rs:62:13
--> $DIR/unnecessary_lazy_eval.rs:70:13
|
LL | let _ = Some(10).and_then(|_| ext_opt);
| ^^^^^^^^^---------------------
@ -97,7 +97,7 @@ LL | let _ = Some(10).and_then(|_| ext_opt);
| help: use `and(..)` instead: `and(ext_opt)`
error: unnecessary closure used to substitute value for `Option::None`
--> $DIR/unnecessary_lazy_eval.rs:63:28
--> $DIR/unnecessary_lazy_eval.rs:71:28
|
LL | let _: Option<usize> = None.or_else(|| ext_opt);
| ^^^^^-------------------
@ -105,7 +105,7 @@ LL | let _: Option<usize> = None.or_else(|| ext_opt);
| help: use `or(..)` instead: `or(ext_opt)`
error: unnecessary closure used to substitute value for `Option::None`
--> $DIR/unnecessary_lazy_eval.rs:64:13
--> $DIR/unnecessary_lazy_eval.rs:72:13
|
LL | let _ = None.get_or_insert_with(|| 2);
| ^^^^^------------------------
@ -113,7 +113,7 @@ LL | let _ = None.get_or_insert_with(|| 2);
| help: use `get_or_insert(..)` instead: `get_or_insert(2)`
error: unnecessary closure used to substitute value for `Option::None`
--> $DIR/unnecessary_lazy_eval.rs:65:35
--> $DIR/unnecessary_lazy_eval.rs:73:35
|
LL | let _: Result<usize, usize> = None.ok_or_else(|| 2);
| ^^^^^----------------
@ -121,7 +121,7 @@ LL | let _: Result<usize, usize> = None.ok_or_else(|| 2);
| help: use `ok_or(..)` instead: `ok_or(2)`
error: unnecessary closure used to substitute value for `Option::None`
--> $DIR/unnecessary_lazy_eval.rs:66:28
--> $DIR/unnecessary_lazy_eval.rs:74:28
|
LL | let _: Option<usize> = None.or_else(|| None);
| ^^^^^----------------
@ -129,7 +129,7 @@ LL | let _: Option<usize> = None.or_else(|| None);
| help: use `or(..)` instead: `or(None)`
error: unnecessary closure used to substitute value for `Option::None`
--> $DIR/unnecessary_lazy_eval.rs:69:13
--> $DIR/unnecessary_lazy_eval.rs:77:13
|
LL | let _ = deep.0.unwrap_or_else(|| 2);
| ^^^^^^^--------------------
@ -137,7 +137,7 @@ LL | let _ = deep.0.unwrap_or_else(|| 2);
| help: use `unwrap_or(..)` instead: `unwrap_or(2)`
error: unnecessary closure used to substitute value for `Option::None`
--> $DIR/unnecessary_lazy_eval.rs:70:13
--> $DIR/unnecessary_lazy_eval.rs:78:13
|
LL | let _ = deep.0.and_then(|_| ext_opt);
| ^^^^^^^---------------------
@ -145,7 +145,7 @@ LL | let _ = deep.0.and_then(|_| ext_opt);
| help: use `and(..)` instead: `and(ext_opt)`
error: unnecessary closure used to substitute value for `Option::None`
--> $DIR/unnecessary_lazy_eval.rs:71:13
--> $DIR/unnecessary_lazy_eval.rs:79:13
|
LL | let _ = deep.0.or_else(|| None);
| ^^^^^^^----------------
@ -153,7 +153,7 @@ LL | let _ = deep.0.or_else(|| None);
| help: use `or(..)` instead: `or(None)`
error: unnecessary closure used to substitute value for `Option::None`
--> $DIR/unnecessary_lazy_eval.rs:72:13
--> $DIR/unnecessary_lazy_eval.rs:80:13
|
LL | let _ = deep.0.get_or_insert_with(|| 2);
| ^^^^^^^------------------------
@ -161,7 +161,7 @@ LL | let _ = deep.0.get_or_insert_with(|| 2);
| help: use `get_or_insert(..)` instead: `get_or_insert(2)`
error: unnecessary closure used to substitute value for `Option::None`
--> $DIR/unnecessary_lazy_eval.rs:73:13
--> $DIR/unnecessary_lazy_eval.rs:81:13
|
LL | let _ = deep.0.ok_or_else(|| 2);
| ^^^^^^^----------------
@ -169,7 +169,7 @@ LL | let _ = deep.0.ok_or_else(|| 2);
| help: use `ok_or(..)` instead: `ok_or(2)`
error: unnecessary closure used to substitute value for `Option::None`
--> $DIR/unnecessary_lazy_eval.rs:96:28
--> $DIR/unnecessary_lazy_eval.rs:105:28
|
LL | let _: Option<usize> = None.or_else(|| Some(3));
| ^^^^^-------------------
@ -177,7 +177,7 @@ LL | let _: Option<usize> = None.or_else(|| Some(3));
| help: use `or(..)` instead: `or(Some(3))`
error: unnecessary closure used to substitute value for `Option::None`
--> $DIR/unnecessary_lazy_eval.rs:97:13
--> $DIR/unnecessary_lazy_eval.rs:106:13
|
LL | let _ = deep.0.or_else(|| Some(3));
| ^^^^^^^-------------------
@ -185,7 +185,7 @@ LL | let _ = deep.0.or_else(|| Some(3));
| help: use `or(..)` instead: `or(Some(3))`
error: unnecessary closure used to substitute value for `Option::None`
--> $DIR/unnecessary_lazy_eval.rs:98:13
--> $DIR/unnecessary_lazy_eval.rs:107:13
|
LL | let _ = opt.or_else(|| Some(3));
| ^^^^-------------------
@ -193,7 +193,7 @@ LL | let _ = opt.or_else(|| Some(3));
| help: use `or(..)` instead: `or(Some(3))`
error: unnecessary closure used to substitute value for `Result::Err`
--> $DIR/unnecessary_lazy_eval.rs:104:13
--> $DIR/unnecessary_lazy_eval.rs:113:13
|
LL | let _ = res2.unwrap_or_else(|_| 2);
| ^^^^^---------------------
@ -201,7 +201,7 @@ LL | let _ = res2.unwrap_or_else(|_| 2);
| help: use `unwrap_or(..)` instead: `unwrap_or(2)`
error: unnecessary closure used to substitute value for `Result::Err`
--> $DIR/unnecessary_lazy_eval.rs:105:13
--> $DIR/unnecessary_lazy_eval.rs:114:13
|
LL | let _ = res2.unwrap_or_else(|_| astronomers_pi);
| ^^^^^----------------------------------
@ -209,7 +209,7 @@ LL | let _ = res2.unwrap_or_else(|_| astronomers_pi);
| help: use `unwrap_or(..)` instead: `unwrap_or(astronomers_pi)`
error: unnecessary closure used to substitute value for `Result::Err`
--> $DIR/unnecessary_lazy_eval.rs:106:13
--> $DIR/unnecessary_lazy_eval.rs:115:13
|
LL | let _ = res2.unwrap_or_else(|_| ext_str.some_field);
| ^^^^^--------------------------------------
@ -217,7 +217,7 @@ LL | let _ = res2.unwrap_or_else(|_| ext_str.some_field);
| help: use `unwrap_or(..)` instead: `unwrap_or(ext_str.some_field)`
error: unnecessary closure used to substitute value for `Result::Err`
--> $DIR/unnecessary_lazy_eval.rs:128:35
--> $DIR/unnecessary_lazy_eval.rs:137:35
|
LL | let _: Result<usize, usize> = res.and_then(|_| Err(2));
| ^^^^--------------------
@ -225,7 +225,7 @@ LL | let _: Result<usize, usize> = res.and_then(|_| Err(2));
| help: use `and(..)` instead: `and(Err(2))`
error: unnecessary closure used to substitute value for `Result::Err`
--> $DIR/unnecessary_lazy_eval.rs:129:35
--> $DIR/unnecessary_lazy_eval.rs:138:35
|
LL | let _: Result<usize, usize> = res.and_then(|_| Err(astronomers_pi));
| ^^^^---------------------------------
@ -233,7 +233,7 @@ LL | let _: Result<usize, usize> = res.and_then(|_| Err(astronomers_pi));
| help: use `and(..)` instead: `and(Err(astronomers_pi))`
error: unnecessary closure used to substitute value for `Result::Err`
--> $DIR/unnecessary_lazy_eval.rs:130:35
--> $DIR/unnecessary_lazy_eval.rs:139:35
|
LL | let _: Result<usize, usize> = res.and_then(|_| Err(ext_str.some_field));
| ^^^^-------------------------------------
@ -241,7 +241,7 @@ LL | let _: Result<usize, usize> = res.and_then(|_| Err(ext_str.some_field))
| help: use `and(..)` instead: `and(Err(ext_str.some_field))`
error: unnecessary closure used to substitute value for `Result::Err`
--> $DIR/unnecessary_lazy_eval.rs:132:35
--> $DIR/unnecessary_lazy_eval.rs:141:35
|
LL | let _: Result<usize, usize> = res.or_else(|_| Ok(2));
| ^^^^------------------
@ -249,7 +249,7 @@ LL | let _: Result<usize, usize> = res.or_else(|_| Ok(2));
| help: use `or(..)` instead: `or(Ok(2))`
error: unnecessary closure used to substitute value for `Result::Err`
--> $DIR/unnecessary_lazy_eval.rs:133:35
--> $DIR/unnecessary_lazy_eval.rs:142:35
|
LL | let _: Result<usize, usize> = res.or_else(|_| Ok(astronomers_pi));
| ^^^^-------------------------------
@ -257,7 +257,7 @@ LL | let _: Result<usize, usize> = res.or_else(|_| Ok(astronomers_pi));
| help: use `or(..)` instead: `or(Ok(astronomers_pi))`
error: unnecessary closure used to substitute value for `Result::Err`
--> $DIR/unnecessary_lazy_eval.rs:134:35
--> $DIR/unnecessary_lazy_eval.rs:143:35
|
LL | let _: Result<usize, usize> = res.or_else(|_| Ok(ext_str.some_field));
| ^^^^-----------------------------------
@ -265,19 +265,19 @@ LL | let _: Result<usize, usize> = res.or_else(|_| Ok(ext_str.some_field));
| help: use `or(..)` instead: `or(Ok(ext_str.some_field))`
error: unnecessary closure used to substitute value for `Result::Err`
--> $DIR/unnecessary_lazy_eval.rs:135:35
--> $DIR/unnecessary_lazy_eval.rs:144:35
|
LL | let _: Result<usize, usize> = res.
| ___________________________________^
LL | | // some lines
LL | | // some lines
LL | | // some lines
LL | | // some lines
LL | | // some lines
LL | | // some lines
... |
LL | | // some lines
LL | | or_else(|_| Ok(ext_str.some_field));
| |_________----------------------------------^
| |
| help: use `or(..)` instead: `or(Ok(ext_str.some_field))`
LL | | // some lines
LL | | or_else(|_| Ok(ext_str.some_field));
| |_____----------------------------------^
| |
| help: use `or(..)` instead: `or(Ok(ext_str.some_field))`
error: aborting due to 34 previous errors