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[infinite_loops]: fix incorrect suggestions on async functions/closures #13608

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merged 1 commit into from
Nov 1, 2024
Merged

[infinite_loops]: fix incorrect suggestions on async functions/closures #13608

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62 changes: 54 additions & 8 deletions clippy_lints/src/loops/infinite_loop.rs
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Original file line number Diff line number Diff line change
@@ -1,12 +1,13 @@
use clippy_utils::diagnostics::span_lint_and_then;
use clippy_utils::{fn_def_id, is_from_proc_macro, is_lint_allowed};
use hir::intravisit::{Visitor, walk_expr};
use hir::{Expr, ExprKind, FnRetTy, FnSig, Node};
use hir::{Expr, ExprKind, FnRetTy, FnSig, Node, TyKind};
use rustc_ast::Label;
use rustc_errors::Applicability;
use rustc_hir as hir;
use rustc_lint::{LateContext, LintContext};
use rustc_middle::lint::in_external_macro;
use rustc_span::sym;

use super::INFINITE_LOOP;

Expand All @@ -25,13 +26,7 @@ pub(super) fn check<'tcx>(
return;
};
// Or, its parent function is already returning `Never`
if matches!(
parent_fn_ret,
FnRetTy::Return(hir::Ty {
kind: hir::TyKind::Never,
..
})
) {
if is_never_return(parent_fn_ret) {
return;
}

Expand Down Expand Up @@ -69,6 +64,16 @@ pub(super) fn check<'tcx>(
fn get_parent_fn_ret_ty<'tcx>(cx: &LateContext<'tcx>, expr: &Expr<'_>) -> Option<FnRetTy<'tcx>> {
for (_, parent_node) in cx.tcx.hir().parent_iter(expr.hir_id) {
match parent_node {
// Skip `Coroutine` closures, these are the body of `async fn`, not async closures.
// This is because we still need to backtrack one parent node to get the `OpaqueDef` ty.
Node::Expr(Expr {
kind:
ExprKind::Closure(hir::Closure {
kind: hir::ClosureKind::Coroutine(_),
..
}),
..
}) => (),
Node::Item(hir::Item {
kind: hir::ItemKind::Fn(FnSig { decl, .. }, _, _),
..
Expand Down Expand Up @@ -143,3 +148,44 @@ impl<'hir> Visitor<'hir> for LoopVisitor<'hir, '_> {
}
}
}

/// Return `true` if the given [`FnRetTy`] is never (!).
///
/// Note: This function also take care of return type of async fn,
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Suggested change
/// Note: This function also take care of return type of async fn,
/// Note: This function also takes care of the return type of async fn,

/// as the actual type is behind an [`OpaqueDef`](TyKind::OpaqueDef).
fn is_never_return(ret_ty: FnRetTy<'_>) -> bool {
let FnRetTy::Return(hir_ty) = ret_ty else { return false };

match hir_ty.kind {
TyKind::Never => true,
TyKind::OpaqueDef(
hir::OpaqueTy {
origin: hir::OpaqueTyOrigin::AsyncFn { .. },
bounds,
..
},
_,
) => {
if let Some(trait_ref) = bounds.iter().find_map(|b| b.trait_ref())
&& let Some(segment) = trait_ref
.path
.segments
.iter()
.find(|seg| seg.ident.name == sym::future_trait)
&& let Some(args) = segment.args
&& let Some(cst_kind) = args
.constraints
.iter()
.find_map(|cst| (cst.ident.name == sym::Output).then_some(cst.kind))
&& let hir::AssocItemConstraintKind::Equality {
term: hir::Term::Ty(ty),
} = cst_kind
{
matches!(ty.kind, TyKind::Never)
} else {
false
}
},
_ => false,
}
}
20 changes: 20 additions & 0 deletions tests/ui/infinite_loops.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,7 @@

#![allow(clippy::never_loop)]
#![warn(clippy::infinite_loop)]
#![feature(async_closure)]

extern crate proc_macros;
use proc_macros::{external, with_span};
Expand Down Expand Up @@ -428,4 +429,23 @@ fn continue_outer() {
}
}

// don't suggest adding `-> !` to async fn/closure that already returning `-> !`
mod issue_12338 {
use super::do_something;

async fn foo() -> ! {
loop {
do_something();
}
}

fn bar() {
let _ = async || -> ! {
loop {
do_something();
}
};
}
}

fn main() {}
42 changes: 21 additions & 21 deletions tests/ui/infinite_loops.stderr
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Open in desktop
Original file line number Diff line number Diff line change
@@ -1,5 +1,5 @@
error: infinite loop detected
--> tests/ui/infinite_loops.rs:13:5
--> tests/ui/infinite_loops.rs:14:5
|
LL | / loop {
LL | |
Expand All @@ -15,7 +15,7 @@ LL | fn no_break() -> ! {
| ++++

error: infinite loop detected
--> tests/ui/infinite_loops.rs:20:5
--> tests/ui/infinite_loops.rs:21:5
|
LL | / loop {
LL | |
Expand All @@ -32,7 +32,7 @@ LL | fn all_inf() -> ! {
| ++++

error: infinite loop detected
--> tests/ui/infinite_loops.rs:22:9
--> tests/ui/infinite_loops.rs:23:9
|
LL | / loop {
LL | |
Expand All @@ -49,7 +49,7 @@ LL | fn all_inf() -> ! {
| ++++

error: infinite loop detected
--> tests/ui/infinite_loops.rs:24:13
--> tests/ui/infinite_loops.rs:25:13
|
LL | / loop {
LL | |
Expand All @@ -63,7 +63,7 @@ LL | fn all_inf() -> ! {
| ++++

error: infinite loop detected
--> tests/ui/infinite_loops.rs:38:5
--> tests/ui/infinite_loops.rs:39:5
|
LL | / loop {
LL | |
Expand All @@ -74,7 +74,7 @@ LL | | }
= help: if this is not intended, try adding a `break` or `return` condition in the loop

error: infinite loop detected
--> tests/ui/infinite_loops.rs:51:5
--> tests/ui/infinite_loops.rs:52:5
|
LL | / loop {
LL | | fn inner_fn() -> ! {
Expand All @@ -90,7 +90,7 @@ LL | fn no_break_never_ret_noise() -> ! {
| ++++

error: infinite loop detected
--> tests/ui/infinite_loops.rs:94:5
--> tests/ui/infinite_loops.rs:95:5
|
LL | / loop {
LL | |
Expand All @@ -107,7 +107,7 @@ LL | fn break_inner_but_not_outer_1(cond: bool) -> ! {
| ++++

error: infinite loop detected
--> tests/ui/infinite_loops.rs:105:5
--> tests/ui/infinite_loops.rs:106:5
|
LL | / loop {
LL | |
Expand All @@ -124,7 +124,7 @@ LL | fn break_inner_but_not_outer_2(cond: bool) -> ! {
| ++++

error: infinite loop detected
--> tests/ui/infinite_loops.rs:119:9
--> tests/ui/infinite_loops.rs:120:9
|
LL | / loop {
LL | |
Expand All @@ -138,7 +138,7 @@ LL | fn break_outer_but_not_inner() -> ! {
| ++++

error: infinite loop detected
--> tests/ui/infinite_loops.rs:142:9
--> tests/ui/infinite_loops.rs:143:9
|
LL | / loop {
LL | |
Expand All @@ -155,7 +155,7 @@ LL | fn break_wrong_loop(cond: bool) -> ! {
| ++++

error: infinite loop detected
--> tests/ui/infinite_loops.rs:182:5
--> tests/ui/infinite_loops.rs:183:5
|
LL | / loop {
LL | |
Expand All @@ -172,7 +172,7 @@ LL | fn match_like() -> ! {
| ++++

error: infinite loop detected
--> tests/ui/infinite_loops.rs:223:5
--> tests/ui/infinite_loops.rs:224:5
|
LL | / loop {
LL | |
Expand All @@ -186,7 +186,7 @@ LL | fn match_like() -> ! {
| ++++

error: infinite loop detected
--> tests/ui/infinite_loops.rs:228:5
--> tests/ui/infinite_loops.rs:229:5
|
LL | / loop {
LL | |
Expand All @@ -203,7 +203,7 @@ LL | fn match_like() -> ! {
| ++++

error: infinite loop detected
--> tests/ui/infinite_loops.rs:333:9
--> tests/ui/infinite_loops.rs:334:9
|
LL | / loop {
LL | |
Expand All @@ -217,7 +217,7 @@ LL | fn problematic_trait_method() -> ! {
| ++++

error: infinite loop detected
--> tests/ui/infinite_loops.rs:343:9
--> tests/ui/infinite_loops.rs:344:9
|
LL | / loop {
LL | |
Expand All @@ -231,7 +231,7 @@ LL | fn could_be_problematic() -> ! {
| ++++

error: infinite loop detected
--> tests/ui/infinite_loops.rs:352:9
--> tests/ui/infinite_loops.rs:353:9
|
LL | / loop {
LL | |
Expand All @@ -245,7 +245,7 @@ LL | let _loop_forever = || -> ! {
| ++++

error: infinite loop detected
--> tests/ui/infinite_loops.rs:366:8
--> tests/ui/infinite_loops.rs:367:8
|
LL | Ok(loop {
| ________^
Expand All @@ -256,7 +256,7 @@ LL | | })
= help: if this is not intended, try adding a `break` or `return` condition in the loop

error: infinite loop detected
--> tests/ui/infinite_loops.rs:408:5
--> tests/ui/infinite_loops.rs:409:5
|
LL | / 'infinite: loop {
LL | |
Expand All @@ -272,7 +272,7 @@ LL | fn continue_outer() -> ! {
| ++++

error: infinite loop detected
--> tests/ui/infinite_loops.rs:415:5
--> tests/ui/infinite_loops.rs:416:5
|
LL | / loop {
LL | |
Expand All @@ -289,7 +289,7 @@ LL | fn continue_outer() -> ! {
| ++++

error: infinite loop detected
--> tests/ui/infinite_loops.rs:417:9
--> tests/ui/infinite_loops.rs:418:9
|
LL | / 'inner: loop {
LL | | loop {
Expand All @@ -304,7 +304,7 @@ LL | fn continue_outer() -> ! {
| ++++

error: infinite loop detected
--> tests/ui/infinite_loops.rs:425:5
--> tests/ui/infinite_loops.rs:426:5
|
LL | / loop {
LL | |
Expand Down