Rollup merge of #98879 - compiler-errors:async-closure-wrap-parens, r=oli-obk

Fix "wrap closure in parenthesis" suggestion for `async` closure

Fixes #98023

Author: matthiaskrgr

compiler/rustc_typeck/src/check/callee.rs

@@ -280,15 +280,36 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         callee_node: &hir::ExprKind<'_>,
         callee_span: Span,
     ) {
-        let hir_id = self.tcx.hir().get_parent_node(hir_id);
-        let parent_node = self.tcx.hir().get(hir_id);
+        let hir = self.tcx.hir();
+        let parent_hir_id = hir.get_parent_node(hir_id);
+        let parent_node = hir.get(parent_hir_id);
         if let (
             hir::Node::Expr(hir::Expr {
-                kind: hir::ExprKind::Closure { fn_decl_span, .. }, ..
+                kind: hir::ExprKind::Closure { fn_decl_span, body, .. },
+                ..
             }),
             hir::ExprKind::Block(..),
         ) = (parent_node, callee_node)
         {
+            let fn_decl_span = if hir.body(*body).generator_kind
+                == Some(hir::GeneratorKind::Async(hir::AsyncGeneratorKind::Closure))
+            {
+                // Actually need to unwrap a few more layers of HIR to get to
+                // the _real_ closure...
+                let async_closure = hir.get_parent_node(hir.get_parent_node(parent_hir_id));
+                if let hir::Node::Expr(hir::Expr {
+                    kind: hir::ExprKind::Closure { fn_decl_span, .. },
+                    ..
+                }) = hir.get(async_closure)
+                {
+                    *fn_decl_span
+                } else {
+                    return;
+                }
+            } else {
+                *fn_decl_span
+            };
+
             let start = fn_decl_span.shrink_to_lo();
             let end = callee_span.shrink_to_hi();
             err.multipart_suggestion(

src/test/ui/suggestions/suggest-on-bare-closure-call.rs

@@ -1,4 +1,11 @@
+// edition:2021
+
+#![feature(async_closure)]
+
 fn main() {
     let _ = ||{}();
     //~^ ERROR expected function, found `()`
+
+    let _ = async ||{}();
+    //~^ ERROR expected function, found `()`
 }

src/test/ui/suggestions/suggest-on-bare-closure-call.stderr

@@ -1,5 +1,5 @@
 error[E0618]: expected function, found `()`
-  --> $DIR/suggest-on-bare-closure-call.rs:2:15
+  --> $DIR/suggest-on-bare-closure-call.rs:6:15
    |
 LL |     let _ = ||{}();
    |               ^^--
@@ -11,6 +11,19 @@ help: if you meant to create this closure and immediately call it, surround the
 LL |     let _ = (||{})();
    |             +    +
 
-error: aborting due to previous error
+error[E0618]: expected function, found `()`
+  --> $DIR/suggest-on-bare-closure-call.rs:9:21
+   |
+LL |     let _ = async ||{}();
+   |                     ^^--
+   |                     |
+   |                     call expression requires function
+   |
+help: if you meant to create this closure and immediately call it, surround the closure with parentheses
+   |
+LL |     let _ = (async ||{})();
+   |             +          +
+
+error: aborting due to 2 previous errors
 
 For more information about this error, try `rustc --explain E0618`.