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Deal with additional wrapping of async closure body in clippy
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compiler-errors committed Jan 16, 2024
1 parent 0d19fb3 commit 65e5dcb
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Showing 3 changed files with 82 additions and 42 deletions.
98 changes: 60 additions & 38 deletions src/tools/clippy/clippy_lints/src/async_yields_async.rs
Original file line number Diff line number Diff line change
Expand Up @@ -45,50 +45,72 @@ declare_lint_pass!(AsyncYieldsAsync => [ASYNC_YIELDS_ASYNC]);

impl<'tcx> LateLintPass<'tcx> for AsyncYieldsAsync {
fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) {
// For functions, with explicitly defined types, don't warn.
// XXXkhuey maybe we should?
if let ExprKind::Closure(Closure {
kind:
ClosureKind::Coroutine(CoroutineKind::Desugared(
CoroutineDesugaring::Async,
CoroutineSource::Block | CoroutineSource::Closure,
)),
let ExprKind::Closure(Closure {
kind: ClosureKind::Coroutine(CoroutineKind::Desugared(CoroutineDesugaring::Async, kind)),
body: body_id,
..
}) = expr.kind
{
if let Some(future_trait_def_id) = cx.tcx.lang_items().future_trait() {
let typeck_results = cx.tcx.typeck_body(*body_id);
let body = cx.tcx.hir().body(*body_id);
let expr_ty = typeck_results.expr_ty(body.value);
else {
return;
};

if implements_trait(cx, expr_ty, future_trait_def_id, &[]) {
let return_expr_span = match &body.value.kind {
// XXXkhuey there has to be a better way.
ExprKind::Block(block, _) => block.expr.map(|e| e.span),
ExprKind::Path(QPath::Resolved(_, path)) => Some(path.span),
_ => None,
};
if let Some(return_expr_span) = return_expr_span {
span_lint_hir_and_then(
cx,
ASYNC_YIELDS_ASYNC,
body.value.hir_id,
let body_expr = match kind {
CoroutineSource::Fn => {
// For functions, with explicitly defined types, don't warn.
// XXXkhuey maybe we should?
return;
},
CoroutineSource::Block => cx.tcx.hir().body(*body_id).value,
CoroutineSource::Closure => {
// Like `async fn`, async closures are wrapped in an additional block
// to move all of the closure's arguments into the future.

let async_closure_body = cx.tcx.hir().body(*body_id).value;
let ExprKind::Block(block, _) = async_closure_body.kind else {
return;
};
let Some(block_expr) = block.expr else {
return;
};
let ExprKind::DropTemps(body_expr) = block_expr.kind else {
return;
};
body_expr
},
};

let Some(future_trait_def_id) = cx.tcx.lang_items().future_trait() else {
return;
};

let typeck_results = cx.tcx.typeck_body(*body_id);
let expr_ty = typeck_results.expr_ty(body_expr);

if implements_trait(cx, expr_ty, future_trait_def_id, &[]) {
let return_expr_span = match &body_expr.kind {
// XXXkhuey there has to be a better way.
ExprKind::Block(block, _) => block.expr.map(|e| e.span),
ExprKind::Path(QPath::Resolved(_, path)) => Some(path.span),
_ => None,
};
if let Some(return_expr_span) = return_expr_span {
span_lint_hir_and_then(
cx,
ASYNC_YIELDS_ASYNC,
body_expr.hir_id,
return_expr_span,
"an async construct yields a type which is itself awaitable",
|db| {
db.span_label(body_expr.span, "outer async construct");
db.span_label(return_expr_span, "awaitable value not awaited");
db.span_suggestion(
return_expr_span,
"an async construct yields a type which is itself awaitable",
|db| {
db.span_label(body.value.span, "outer async construct");
db.span_label(return_expr_span, "awaitable value not awaited");
db.span_suggestion(
return_expr_span,
"consider awaiting this value",
format!("{}.await", snippet(cx, return_expr_span, "..")),
Applicability::MaybeIncorrect,
);
},
"consider awaiting this value",
format!("{}.await", snippet(cx, return_expr_span, "..")),
Applicability::MaybeIncorrect,
);
}
}
},
);
}
}
}
Expand Down
20 changes: 17 additions & 3 deletions src/tools/clippy/clippy_lints/src/redundant_closure_call.rs
Original file line number Diff line number Diff line change
Expand Up @@ -5,7 +5,9 @@ use clippy_utils::sugg::Sugg;
use rustc_errors::Applicability;
use rustc_hir as hir;
use rustc_hir::intravisit::{Visitor as HirVisitor, Visitor};
use rustc_hir::{intravisit as hir_visit, ClosureKind, CoroutineDesugaring, CoroutineKind, CoroutineSource, Node};
use rustc_hir::{
intravisit as hir_visit, ClosureKind, CoroutineDesugaring, CoroutineKind, CoroutineSource, ExprKind, Node,
};
use rustc_lint::{LateContext, LateLintPass};
use rustc_middle::hir::nested_filter;
use rustc_middle::lint::in_external_macro;
Expand Down Expand Up @@ -166,10 +168,22 @@ impl<'tcx> LateLintPass<'tcx> for RedundantClosureCall {
if coroutine_kind.is_async()
&& let hir::ExprKind::Closure(closure) = body.kind
{
let async_closure_body = cx.tcx.hir().body(closure.body);
// Like `async fn`, async closures are wrapped in an additional block
// to move all of the closure's arguments into the future.

let async_closure_body = cx.tcx.hir().body(closure.body).value;
let ExprKind::Block(block, _) = async_closure_body.kind else {
return;
};
let Some(block_expr) = block.expr else {
return;
};
let ExprKind::DropTemps(body_expr) = block_expr.kind else {
return;
};

// `async x` is a syntax error, so it becomes `async { x }`
if !matches!(async_closure_body.value.kind, hir::ExprKind::Block(_, _)) {
if !matches!(body_expr.kind, hir::ExprKind::Block(_, _)) {
hint = hint.blockify();
}

Expand Down
6 changes: 5 additions & 1 deletion src/tools/clippy/tests/ui/author/blocks.stdout
Original file line number Diff line number Diff line change
Expand Up @@ -48,7 +48,11 @@ if let ExprKind::Closure { capture_clause: CaptureBy::Value { .. }, fn_decl: fn_
&& expr2 = &cx.tcx.hir().body(body_id1).value
&& let ExprKind::Block(block, None) = expr2.kind
&& block.stmts.is_empty()
&& block.expr.is_none()
&& let Some(trailing_expr) = block.expr
&& let ExprKind::DropTemps(expr3) = trailing_expr.kind
&& let ExprKind::Block(block1, None) = expr3.kind
&& block1.stmts.is_empty()
&& block1.expr.is_none()
{
// report your lint here
}

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