Fix `async_yields_async` wrongly unmangled macros (#15553)

Closes rust-lang/rust-clippy#15552

changelog: [`async_yields_async`] fix wrong unmangle of macros

5 files changed, 176 insertions, 29 deletions

diff --git a/clippy_lints/src/async_yields_async.rs b/clippy_lints/src/async_yields_async.rs
index 013819b0da8..1a10db291cd 100644
--- a/clippy_lints/src/async_yields_async.rs
+++ b/clippy_lints/src/async_yields_async.rs
@@ -1,8 +1,12 @@
 use clippy_utils::diagnostics::span_lint_hir_and_then;
-use clippy_utils::source::snippet;
+use clippy_utils::is_expr_async_block;
+use clippy_utils::source::walk_span_to_context;
+use clippy_utils::sugg::Sugg;
 use clippy_utils::ty::implements_trait;
 use rustc_errors::Applicability;
-use rustc_hir::{Closure, ClosureKind, CoroutineDesugaring, CoroutineKind, CoroutineSource, Expr, ExprKind, QPath};
+use rustc_hir::{
+    Block, Closure, ClosureKind, CoroutineDesugaring, CoroutineKind, CoroutineSource, Expr, ExprKind, QPath,
+};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_session::declare_lint_pass;
 
@@ -87,31 +91,37 @@ impl<'tcx> LateLintPass<'tcx> for AsyncYieldsAsync {
         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,
+            let (return_expr, return_expr_span) = match &body_expr.kind {
+                ExprKind::Block(Block { expr: Some(e), .. }, _) => (*e, e.span),
+                ExprKind::Path(QPath::Resolved(_, path)) => (body_expr, path.span),
+                _ => return,
             };
-            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,
-                            "consider awaiting this value",
-                            format!("{}.await", snippet(cx, return_expr_span, "..")),
-                            Applicability::MaybeIncorrect,
-                        );
-                    },
-                );
+
+            let return_expr_span = walk_span_to_context(return_expr_span, expr.span.ctxt()).unwrap_or(return_expr_span);
+            let mut applicability = Applicability::MaybeIncorrect;
+            let mut return_expr_snip =
+                Sugg::hir_with_context(cx, return_expr, expr.span.ctxt(), "..", &mut applicability);
+            if !is_expr_async_block(return_expr) {
+                return_expr_snip = return_expr_snip.maybe_paren();
             }
+
+            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,
+                        "consider awaiting this value",
+                        format!("{return_expr_snip}.await"),
+                        applicability,
+                    );
+                },
+            );
         }
     }
 }
diff --git a/clippy_utils/src/lib.rs b/clippy_utils/src/lib.rs
index 71254f30af7..e038a33dca3 100644
--- a/clippy_utils/src/lib.rs
+++ b/clippy_utils/src/lib.rs
@@ -102,9 +102,9 @@ use rustc_hir::hir_id::{HirIdMap, HirIdSet};
 use rustc_hir::intravisit::{FnKind, Visitor, walk_expr};
 use rustc_hir::{
     self as hir, Arm, BindingMode, Block, BlockCheckMode, Body, ByRef, Closure, ConstArgKind, CoroutineDesugaring,
-    CoroutineKind, Destination, Expr, ExprField, ExprKind, FnDecl, FnRetTy, GenericArg, GenericArgs, HirId, Impl,
-    ImplItem, ImplItemKind, Item, ItemKind, LangItem, LetStmt, MatchSource, Mutability, Node, OwnerId, OwnerNode,
-    Param, Pat, PatExpr, PatExprKind, PatKind, Path, PathSegment, QPath, Stmt, StmtKind, TraitFn, TraitItem,
+    CoroutineKind, CoroutineSource, Destination, Expr, ExprField, ExprKind, FnDecl, FnRetTy, GenericArg, GenericArgs,
+    HirId, Impl, ImplItem, ImplItemKind, Item, ItemKind, LangItem, LetStmt, MatchSource, Mutability, Node, OwnerId,
+    OwnerNode, Param, Pat, PatExpr, PatExprKind, PatKind, Path, PathSegment, QPath, Stmt, StmtKind, TraitFn, TraitItem,
     TraitItemKind, TraitRef, TyKind, UnOp, def, find_attr,
 };
 use rustc_lexer::{FrontmatterAllowed, TokenKind, tokenize};
@@ -3631,3 +3631,17 @@ pub fn expr_adjustment_requires_coercion(cx: &LateContext<'_>, expr: &Expr<'_>)
         )
     })
 }
+
+/// Checks if the expression is an async block (i.e., `async { ... }`).
+pub fn is_expr_async_block(expr: &Expr<'_>) -> bool {
+    matches!(
+        expr.kind,
+        ExprKind::Closure(Closure {
+            kind: hir::ClosureKind::Coroutine(CoroutineKind::Desugared(
+                CoroutineDesugaring::Async,
+                CoroutineSource::Block
+            )),
+            ..
+        })
+    )
+}
diff --git a/tests/ui/async_yields_async.fixed b/tests/ui/async_yields_async.fixed
index 93c573d3086..bd1b31f74ee 100644
--- a/tests/ui/async_yields_async.fixed
+++ b/tests/ui/async_yields_async.fixed
@@ -80,3 +80,42 @@ fn check_expect_suppression() {
         }
     };
 }
+
+#[allow(clippy::let_underscore_future)]
+fn issue15552() {
+    async fn bar(i: i32) {}
+
+    macro_rules! call_bar {
+        () => {
+            async { bar(5).await }
+        };
+        ($e:expr) => {
+            bar($e)
+        };
+    }
+    let x = async { call_bar!(5).await };
+    //~^ async_yields_async
+    let y = async { call_bar!().await };
+    //~^ async_yields_async
+    //~| async_yields_async
+
+    use std::future::{Future, Ready};
+    use std::ops::Add;
+    use std::pin::Pin;
+    use std::task::{Context, Poll};
+    struct CustomFutureType;
+    impl Add for CustomFutureType {
+        type Output = Self;
+        fn add(self, other: Self) -> Self {
+            self
+        }
+    }
+    impl Future for CustomFutureType {
+        type Output = ();
+        fn poll(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<Self::Output> {
+            Poll::Ready(())
+        }
+    }
+    let _ = async { (CustomFutureType + CustomFutureType).await };
+    //~^ async_yields_async
+}
diff --git a/tests/ui/async_yields_async.rs b/tests/ui/async_yields_async.rs
index 166d522e1c0..605d2734157 100644
--- a/tests/ui/async_yields_async.rs
+++ b/tests/ui/async_yields_async.rs
@@ -80,3 +80,42 @@ fn check_expect_suppression() {
         }
     };
 }
+
+#[allow(clippy::let_underscore_future)]
+fn issue15552() {
+    async fn bar(i: i32) {}
+
+    macro_rules! call_bar {
+        () => {
+            async { bar(5) }
+        };
+        ($e:expr) => {
+            bar($e)
+        };
+    }
+    let x = async { call_bar!(5) };
+    //~^ async_yields_async
+    let y = async { call_bar!() };
+    //~^ async_yields_async
+    //~| async_yields_async
+
+    use std::future::{Future, Ready};
+    use std::ops::Add;
+    use std::pin::Pin;
+    use std::task::{Context, Poll};
+    struct CustomFutureType;
+    impl Add for CustomFutureType {
+        type Output = Self;
+        fn add(self, other: Self) -> Self {
+            self
+        }
+    }
+    impl Future for CustomFutureType {
+        type Output = ();
+        fn poll(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<Self::Output> {
+            Poll::Ready(())
+        }
+    }
+    let _ = async { CustomFutureType + CustomFutureType };
+    //~^ async_yields_async
+}
diff --git a/tests/ui/async_yields_async.stderr b/tests/ui/async_yields_async.stderr
index 17a35076fa3..3041cf65789 100644
--- a/tests/ui/async_yields_async.stderr
+++ b/tests/ui/async_yields_async.stderr
@@ -89,5 +89,50 @@ LL | |         CustomFutureType
 LL | |     };
    | |_____- outer async construct
 
-error: aborting due to 6 previous errors
+error: an async construct yields a type which is itself awaitable
+  --> tests/ui/async_yields_async.rs:96:21
+   |
+LL |     let x = async { call_bar!(5) };
+   |                   --^^^^^^^^^^^^--
+   |                   | |
+   |                   | awaitable value not awaited
+   |                   | help: consider awaiting this value: `call_bar!(5).await`
+   |                   outer async construct
+
+error: an async construct yields a type which is itself awaitable
+  --> tests/ui/async_yields_async.rs:98:21
+   |
+LL |     let y = async { call_bar!() };
+   |                   --^^^^^^^^^^^--
+   |                   | |
+   |                   | awaitable value not awaited
+   |                   | help: consider awaiting this value: `call_bar!().await`
+   |                   outer async construct
+
+error: an async construct yields a type which is itself awaitable
+  --> tests/ui/async_yields_async.rs:90:21
+   |
+LL |             async { bar(5) }
+   |                   --^^^^^^--
+   |                   | |
+   |                   | awaitable value not awaited
+   |                   | help: consider awaiting this value: `bar(5).await`
+   |                   outer async construct
+...
+LL |     let y = async { call_bar!() };
+   |                     ----------- in this macro invocation
+   |
+   = note: this error originates in the macro `call_bar` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: an async construct yields a type which is itself awaitable
+  --> tests/ui/async_yields_async.rs:119:21
+   |
+LL |     let _ = async { CustomFutureType + CustomFutureType };
+   |                   --^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^--
+   |                   | |
+   |                   | awaitable value not awaited
+   |                   | help: consider awaiting this value: `(CustomFutureType + CustomFutureType).await`
+   |                   outer async construct
+
+error: aborting due to 10 previous errors