Skip to content

needless_return: Support #[expect] on the return statement #13027

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 1 commit into from
Jul 3, 2024
Merged

needless_return: Support #[expect] on the return statement #13027

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
47 changes: 38 additions & 9 deletions clippy_lints/src/returns.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -7,20 +7,21 @@ use clippy_utils::{
path_to_local_id, span_contains_cfg, span_find_starting_semi,
};
use core::ops::ControlFlow;
use rustc_ast::NestedMetaItem;
use rustc_errors::Applicability;
use rustc_hir::intravisit::FnKind;
use rustc_hir::LangItem::ResultErr;
use rustc_hir::{
Block, Body, Expr, ExprKind, FnDecl, HirId, ItemKind, LangItem, MatchSource, Node, OwnerNode, PatKind, QPath, Stmt,
StmtKind,
};
use rustc_lint::{LateContext, LateLintPass, LintContext};
use rustc_lint::{LateContext, LateLintPass, Level, LintContext};
use rustc_middle::lint::in_external_macro;
use rustc_middle::ty::adjustment::Adjust;
use rustc_middle::ty::{self, GenericArgKind, Ty};
use rustc_session::declare_lint_pass;
use rustc_span::def_id::LocalDefId;
use rustc_span::{BytePos, Pos, Span};
use rustc_span::{sym, BytePos, Pos, Span};
use std::borrow::Cow;
use std::fmt::Display;

Expand Down Expand Up @@ -80,6 +81,9 @@ declare_clippy_lint! {
/// ```
#[clippy::version = "pre 1.29.0"]
pub NEEDLESS_RETURN,
// This lint requires some special handling in `check_final_expr` for `#[expect]`.
// This handling needs to be updated if the group gets changed. This should also
// be caught by tests.
style,
"using a return statement like `return expr;` where an expression would suffice"
}
Expand All @@ -91,6 +95,9 @@ declare_clippy_lint! {
/// ### Why is this bad?
/// The `return` is unnecessary.
///
/// Returns may be used to add attributes to the return expression. Return
/// statements with attributes are therefore be accepted by this lint.
///
/// ### Example
/// ```rust,ignore
/// fn foo(x: usize) -> Result<(), Box<dyn Error>> {
Expand Down Expand Up @@ -377,13 +384,39 @@ fn check_final_expr<'tcx>(
}
};

if !cx.tcx.hir().attrs(expr.hir_id).is_empty() {
return;
}
let borrows = inner.map_or(false, |inner| last_statement_borrows(cx, inner));
if borrows {
return;
}
if ret_span.from_expansion() {
return;
}

// Returns may be used to turn an expression into a statement in rustc's AST.
// This allows the addition of attributes, like `#[allow]` (See: clippy#9361)
// `#[expect(clippy::needless_return)]` needs to be handled separatly to
// actually fullfil the expectation (clippy::#12998)
match cx.tcx.hir().attrs(expr.hir_id) {
[] => {},
[attr] => {
if matches!(Level::from_attr(attr), Some(Level::Expect(_)))
&& let metas = attr.meta_item_list()
&& let Some(lst) = metas
&& let [NestedMetaItem::MetaItem(meta_item)] = lst.as_slice()
&& let [tool, lint_name] = meta_item.path.segments.as_slice()
&& tool.ident.name == sym::clippy
&& matches!(
lint_name.ident.name.as_str(),
"needless_return" | "style" | "all" | "warnings"
)
{
// This is an expectation of the `needless_return` lint
} else {
return;
}
},
_ => return,
}

emit_return_lint(cx, ret_span, semi_spans, &replacement, expr.hir_id);
},
Expand Down Expand Up @@ -415,10 +448,6 @@ fn emit_return_lint(
replacement: &RetReplacement<'_>,
at: HirId,
) {
if ret_span.from_expansion() {
return;
}

span_lint_hir_and_then(
cx,
NEEDLESS_RETURN,
Expand Down
35 changes: 32 additions & 3 deletions tests/ui/needless_return.fixed
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -228,12 +228,41 @@ fn needless_return_macro() -> String {
format!("Hello {}", "world!")
}

fn issue_9361() -> i32 {
let n = 1;
#[allow(clippy::arithmetic_side_effects)]
fn issue_9361(n: i32) -> i32 {
#[expect(clippy::arithmetic_side_effects)]
return n + n;
}

mod issue_12998 {
fn expect_lint() -> i32 {
let x = 1;

#[expect(clippy::needless_return)]
return x;
}

fn expect_group() -> i32 {
let x = 1;

#[expect(clippy::style)]
return x;
}

fn expect_all() -> i32 {
let x = 1;

#[expect(clippy::all)]
return x;
}

fn expect_warnings() -> i32 {
let x = 1;

#[expect(warnings)]
return x;
}
}

fn issue8336(x: i32) -> bool {
if x > 0 {
println!("something");
Expand Down
35 changes: 32 additions & 3 deletions tests/ui/needless_return.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -236,12 +236,41 @@ fn needless_return_macro() -> String {
return format!("Hello {}", "world!");
}

fn issue_9361() -> i32 {
let n = 1;
#[allow(clippy::arithmetic_side_effects)]
fn issue_9361(n: i32) -> i32 {
#[expect(clippy::arithmetic_side_effects)]
return n + n;
}

mod issue_12998 {
fn expect_lint() -> i32 {
let x = 1;

#[expect(clippy::needless_return)]
return x;
}

fn expect_group() -> i32 {
let x = 1;

#[expect(clippy::style)]
return x;
}

fn expect_all() -> i32 {
let x = 1;

#[expect(clippy::all)]
return x;
}

fn expect_warnings() -> i32 {
let x = 1;

#[expect(warnings)]
return x;
}
}

fn issue8336(x: i32) -> bool {
if x > 0 {
println!("something");
Expand Down
28 changes: 14 additions & 14 deletions tests/ui/needless_return.stderr
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -483,7 +483,7 @@ LL + format!("Hello {}", "world!")
|

error: unneeded `return` statement
--> tests/ui/needless_return.rs:248:9
--> tests/ui/needless_return.rs:277:9
|
LL | return true;
| ^^^^^^^^^^^
Expand All @@ -497,7 +497,7 @@ LL ~ }
|

error: unneeded `return` statement
--> tests/ui/needless_return.rs:250:9
--> tests/ui/needless_return.rs:279:9
|
LL | return false;
| ^^^^^^^^^^^^
Expand All @@ -509,7 +509,7 @@ LL ~ }
|

error: unneeded `return` statement
--> tests/ui/needless_return.rs:257:13
--> tests/ui/needless_return.rs:286:13
|
LL | return 10;
| ^^^^^^^^^
Expand All @@ -524,7 +524,7 @@ LL ~ }
|

error: unneeded `return` statement
--> tests/ui/needless_return.rs:260:13
--> tests/ui/needless_return.rs:289:13
|
LL | return 100;
| ^^^^^^^^^^
Expand All @@ -537,7 +537,7 @@ LL ~ }
|

error: unneeded `return` statement
--> tests/ui/needless_return.rs:268:9
--> tests/ui/needless_return.rs:297:9
|
LL | return 0;
| ^^^^^^^^
Expand All @@ -549,7 +549,7 @@ LL ~ }
|

error: unneeded `return` statement
--> tests/ui/needless_return.rs:275:13
--> tests/ui/needless_return.rs:304:13
|
LL | return *(x as *const isize);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^
Expand All @@ -564,7 +564,7 @@ LL ~ }
|

error: unneeded `return` statement
--> tests/ui/needless_return.rs:277:13
--> tests/ui/needless_return.rs:306:13
|
LL | return !*(x as *const isize);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Expand All @@ -577,7 +577,7 @@ LL ~ }
|

error: unneeded `return` statement
--> tests/ui/needless_return.rs:284:20
--> tests/ui/needless_return.rs:313:20
|
LL | let _ = 42;
| ____________________^
Expand All @@ -594,7 +594,7 @@ LL + let _ = 42;
|

error: unneeded `return` statement
--> tests/ui/needless_return.rs:291:20
--> tests/ui/needless_return.rs:320:20
|
LL | let _ = 42; return;
| ^^^^^^^
Expand All @@ -606,7 +606,7 @@ LL + let _ = 42;
|

error: unneeded `return` statement
--> tests/ui/needless_return.rs:303:9
--> tests/ui/needless_return.rs:332:9
|
LL | return Ok(format!("ok!"));
| ^^^^^^^^^^^^^^^^^^^^^^^^^
Expand All @@ -618,7 +618,7 @@ LL + Ok(format!("ok!"))
|

error: unneeded `return` statement
--> tests/ui/needless_return.rs:305:9
--> tests/ui/needless_return.rs:334:9
|
LL | return Err(format!("err!"));
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^
Expand All @@ -630,7 +630,7 @@ LL + Err(format!("err!"))
|

error: unneeded `return` statement
--> tests/ui/needless_return.rs:311:9
--> tests/ui/needless_return.rs:340:9
|
LL | return if true { 1 } else { 2 };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Expand All @@ -642,7 +642,7 @@ LL + if true { 1 } else { 2 }
|

error: unneeded `return` statement
--> tests/ui/needless_return.rs:315:9
--> tests/ui/needless_return.rs:344:9
|
LL | return if b1 { 0 } else { 1 } | if b2 { 2 } else { 3 } | if b3 { 4 } else { 5 };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Expand All @@ -654,7 +654,7 @@ LL + (if b1 { 0 } else { 1 } | if b2 { 2 } else { 3 } | if b3 { 4 } else
|

error: unneeded `return` statement
--> tests/ui/needless_return.rs:336:5
--> tests/ui/needless_return.rs:365:5
|
LL | return { "a".to_string() } + "b" + { "c" };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Expand Down