user0/rust
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

unnecessary_{find,filter}_map: make diagnostic spans more precise (#15929)

Browse source 
changelog: [`unnecessary_find_map`]: make diagnostic spans more precise
changelog: [`unnecessary_filter_map`]: make diagnostic spans more
precise
This commit is contained in:
dswij 2025-10-27 15:32:05 +00:00 • committed by GitHub
commit ca168c07a6
No known key found for this signature in database
GPG key ID: B5690EEEBB952194
5 changed files with 83 additions and 63 deletions
Download patch file Download diff file Expand all files Collapse all files

4
clippy_lints/src/methods/mod.rs
View file

@ -5217,7 +5217,7 @@ impl Methods {
},
(sym::filter_map, [arg]) => {
unused_enumerate_index::check(cx, expr, recv, arg);
unnecessary_filter_map::check(cx, expr, arg, name);
unnecessary_filter_map::check(cx, expr, arg, call_span, unnecessary_filter_map::Kind::FilterMap);
filter_map_bool_then::check(cx, expr, arg, call_span);
filter_map_identity::check(cx, expr, arg, span);
lines_filter_map_ok::check_filter_or_flat_map(
@ -5232,7 +5232,7 @@ impl Methods {
},
(sym::find_map, [arg]) => {
unused_enumerate_index::check(cx, expr, recv, arg);
unnecessary_filter_map::check(cx, expr, arg, name);
unnecessary_filter_map::check(cx, expr, arg, call_span, unnecessary_filter_map::Kind::FindMap);
},
(sym::flat_map, [arg]) => {
unused_enumerate_index::check(cx, expr, recv, arg);

96
clippy_lints/src/methods/unnecessary_filter_map.rs
View file

@ -2,15 +2,15 @@ use super::utils::clone_or_copy_needed;
use clippy_utils::diagnostics::span_lint;
use clippy_utils::res::{MaybeDef, MaybeQPath, MaybeResPath, MaybeTypeckRes};
use clippy_utils::sym;
use clippy_utils::ty::is_copy;
use clippy_utils::ty::{is_copy, option_arg_ty};
use clippy_utils::usage::mutated_variables;
use clippy_utils::visitors::{Descend, for_each_expr_without_closures};
use core::ops::ControlFlow;
use rustc_hir as hir;
use rustc_hir::LangItem::{OptionNone, OptionSome};
use rustc_lint::LateContext;
use rustc_middle::ty;
use rustc_span::Symbol;
use rustc_span::Span;
use std::fmt::Display;
use super::{UNNECESSARY_FILTER_MAP, UNNECESSARY_FIND_MAP};
@ -18,7 +18,8 @@ pub(super) fn check<'tcx>(
cx: &LateContext<'tcx>,
expr: &'tcx hir::Expr<'tcx>,
arg: &'tcx hir::Expr<'tcx>,
name: Symbol,
call_span: Span,
kind: Kind,
) {
if !cx.ty_based_def(expr).opt_parent(cx).is_diag_item(cx, sym::Iterator) {
return;
@ -45,61 +46,88 @@ pub(super) fn check<'tcx>(
let in_ty = cx.typeck_results().node_type(body.params[0].hir_id);
let sugg = if !found_filtering {
// Check if the closure is .filter_map(|x| Some(x))
if name == sym::filter_map
&& let hir::ExprKind::Call(expr, args) = body.value.kind
if kind.is_filter_map()
&& let hir::ExprKind::Call(expr, [arg]) = body.value.kind
&& expr.res(cx).ctor_parent(cx).is_lang_item(cx, OptionSome)
&& let hir::ExprKind::Path(_) = args[0].kind
&& let hir::ExprKind::Path(_) = arg.kind
{
span_lint(
cx,
UNNECESSARY_FILTER_MAP,
expr.span,
call_span,
String::from("this call to `.filter_map(..)` is unnecessary"),
);
return;
}
if name == sym::filter_map {
"map(..)"
} else {
"map(..).next()"
match kind {
Kind::FilterMap => "map(..)",
Kind::FindMap => "map(..).next()",
}
} else if !found_mapping && !mutates_arg && (!clone_or_copy_needed || is_copy(cx, in_ty)) {
match cx.typeck_results().expr_ty(body.value).kind() {
ty::Adt(adt, subst)
if cx.tcx.is_diagnostic_item(sym::Option, adt.did()) && in_ty == subst.type_at(0) =>
{
if name == sym::filter_map {
"filter(..)"
} else {
"find(..)"
}
},
_ => return,
let ty = cx.typeck_results().expr_ty(body.value);
if option_arg_ty(cx, ty).is_some_and(|t| t == in_ty) {
match kind {
Kind::FilterMap => "filter(..)",
Kind::FindMap => "find(..)",
}
} else {
return;
}
} else {
return;
};
span_lint(
cx,
if name == sym::filter_map {
UNNECESSARY_FILTER_MAP
} else {
UNNECESSARY_FIND_MAP
match kind {
Kind::FilterMap => UNNECESSARY_FILTER_MAP,
Kind::FindMap => UNNECESSARY_FIND_MAP,
},
expr.span,
format!("this `.{name}(..)` can be written more simply using `.{sugg}`"),
call_span,
format!("this `.{kind}(..)` can be written more simply using `.{sugg}`"),
);
}
}
#[derive(Clone, Copy)]
pub(super) enum Kind {
FilterMap,
FindMap,
}
impl Kind {
fn is_filter_map(self) -> bool {
matches!(self, Self::FilterMap)
}
}
impl Display for Kind {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
match self {
Self::FilterMap => f.write_str("filter_map"),
Self::FindMap => f.write_str("find_map"),
}
}
}
// returns (found_mapping, found_filtering)
fn check_expression<'tcx>(cx: &LateContext<'tcx>, arg_id: hir::HirId, expr: &'tcx hir::Expr<'_>) -> (bool, bool) {
match expr.kind {
hir::ExprKind::Path(ref path)
if cx
.qpath_res(path, expr.hir_id)
.ctor_parent(cx)
.is_lang_item(cx, OptionNone) =>
{
// None
(false, true)
},
hir::ExprKind::Call(func, args) => {
if func.res(cx).ctor_parent(cx).is_lang_item(cx, OptionSome) {
if args[0].res_local_id() == Some(arg_id) {
// Some(arg_id)
return (false, false);
}
// Some(not arg_id)
return (true, false);
}
(true, true)
@ -109,8 +137,10 @@ fn check_expression<'tcx>(cx: &LateContext<'tcx>, arg_id: hir::HirId, expr: &'tc
&& cx.typeck_results().expr_ty(recv).is_bool()
&& arg.res_local_id() == Some(arg_id)
{
// bool.then_some(arg_id)
(false, true)
} else {
// bool.then_some(not arg_id)
(true, true)
}
},
@ -134,14 +164,6 @@ fn check_expression<'tcx>(cx: &LateContext<'tcx>, arg_id: hir::HirId, expr: &'tc
let else_check = check_expression(cx, arg_id, else_arm);
(if_check.0 | else_check.0, if_check.1 | else_check.1)
},
hir::ExprKind::Path(ref path)
if cx
.qpath_res(path, expr.hir_id)
.ctor_parent(cx)
.is_lang_item(cx, OptionNone) =>
{
(false, true)
},
_ => (true, true),
}
}

24
tests/ui/unnecessary_filter_map.stderr
View file

@ -1,17 +1,17 @@
error: this `.filter_map(..)` can be written more simply using `.filter(..)`
--> tests/ui/unnecessary_filter_map.rs:4:13
--> tests/ui/unnecessary_filter_map.rs:4:20
|
LL | let _ = (0..4).filter_map(|x| if x > 1 { Some(x) } else { None });
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: `-D clippy::unnecessary-filter-map` implied by `-D warnings`
= help: to override `-D warnings` add `#[allow(clippy::unnecessary_filter_map)]`
error: this `.filter_map(..)` can be written more simply using `.filter(..)`
--> tests/ui/unnecessary_filter_map.rs:7:13
--> tests/ui/unnecessary_filter_map.rs:7:20
|
LL | let _ = (0..4).filter_map(|x| {
| _____________^
| ____________________^
LL | |
LL | |
LL | | if x > 1 {
@ -21,10 +21,10 @@ LL | | });
| |______^
error: this `.filter_map(..)` can be written more simply using `.filter(..)`
--> tests/ui/unnecessary_filter_map.rs:15:13
--> tests/ui/unnecessary_filter_map.rs:15:20
|
LL | let _ = (0..4).filter_map(|x| match x {
| _____________^
| ____________________^
LL | |
LL | | 0 | 1 => None,
LL | | _ => Some(x),
@ -32,22 +32,22 @@ LL | | });
| |______^
error: this `.filter_map(..)` can be written more simply using `.map(..)`
--> tests/ui/unnecessary_filter_map.rs:21:13
--> tests/ui/unnecessary_filter_map.rs:21:20
|
LL | let _ = (0..4).filter_map(|x| Some(x + 1));
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: this call to `.filter_map(..)` is unnecessary
--> tests/ui/unnecessary_filter_map.rs:28:61
--> tests/ui/unnecessary_filter_map.rs:28:46
|
LL | let _ = vec![Some(10), None].into_iter().filter_map(|x| Some(x));
| ^^^^
| ^^^^^^^^^^^^^^^^^^^^^^^
error: this `.filter_map(..)` can be written more simply using `.filter(..)`
--> tests/ui/unnecessary_filter_map.rs:166:14
--> tests/ui/unnecessary_filter_map.rs:166:33
|
LL | let _x = std::iter::once(1).filter_map(|n| (n > 1).then_some(n));
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: aborting due to 6 previous errors

2
tests/ui/unnecessary_find_map.rs
View file

@ -1,5 +1,3 @@
#![allow(dead_code)]
fn main() {
let _ = (0..4).find_map(|x| if x > 1 { Some(x) } else { None });
//~^ unnecessary_find_map

20
tests/ui/unnecessary_find_map.stderr
View file

@ -1,17 +1,17 @@
error: this `.find_map(..)` can be written more simply using `.find(..)`
--> tests/ui/unnecessary_find_map.rs:4:13
--> tests/ui/unnecessary_find_map.rs:2:20
|
LL | let _ = (0..4).find_map(|x| if x > 1 { Some(x) } else { None });
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: `-D clippy::unnecessary-find-map` implied by `-D warnings`
= help: to override `-D warnings` add `#[allow(clippy::unnecessary_find_map)]`
error: this `.find_map(..)` can be written more simply using `.find(..)`
--> tests/ui/unnecessary_find_map.rs:7:13
--> tests/ui/unnecessary_find_map.rs:5:20
|
LL | let _ = (0..4).find_map(|x| {
| _____________^
| ____________________^
LL | |
LL | |
LL | | if x > 1 {
@ -21,10 +21,10 @@ LL | | });
| |______^
error: this `.find_map(..)` can be written more simply using `.find(..)`
--> tests/ui/unnecessary_find_map.rs:15:13
--> tests/ui/unnecessary_find_map.rs:13:20
|
LL | let _ = (0..4).find_map(|x| match x {
| _____________^
| ____________________^
LL | |
LL | | 0 | 1 => None,
LL | | _ => Some(x),
@ -32,16 +32,16 @@ LL | | });
| |______^
error: this `.find_map(..)` can be written more simply using `.map(..).next()`
--> tests/ui/unnecessary_find_map.rs:21:13
--> tests/ui/unnecessary_find_map.rs:19:20
|
LL | let _ = (0..4).find_map(|x| Some(x + 1));
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
| ^^^^^^^^^^^^^^^^^^^^^^^^^
error: this `.find_map(..)` can be written more simply using `.find(..)`
--> tests/ui/unnecessary_find_map.rs:33:14
--> tests/ui/unnecessary_find_map.rs:31:33
|
LL | let _x = std::iter::once(1).find_map(|n| (n > 1).then_some(n));
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: aborting due to 5 previous errors