From 635eae2d4fc724cb53a3a45975bc18779a3293b1 Mon Sep 17 00:00:00 2001
From: Eric Holk <ericholk@microsoft.com>
Date: Thu, 13 Mar 2025 14:36:02 -0700
Subject: [PATCH] Teach rustfmt to handle postfix yield

---
 .../clippy/clippy_utils/src/ast_utils/mod.rs      |  5 +++--
 src/tools/rustfmt/src/expr.rs                     |  5 +++--
 src/tools/rustfmt/tests/source/postfix-yield.rs   | 15 +++++++++++++++
 src/tools/rustfmt/tests/target/postfix-yield.rs   | 12 ++++++++++++
 4 files changed, 33 insertions(+), 4 deletions(-)
 create mode 100644 src/tools/rustfmt/tests/source/postfix-yield.rs
 create mode 100644 src/tools/rustfmt/tests/target/postfix-yield.rs

diff --git a/src/tools/clippy/clippy_utils/src/ast_utils/mod.rs b/src/tools/clippy/clippy_utils/src/ast_utils/mod.rs
index 707312a97f3b..deda6030831e 100644
--- a/src/tools/clippy/clippy_utils/src/ast_utils/mod.rs
+++ b/src/tools/clippy/clippy_utils/src/ast_utils/mod.rs
@@ -201,7 +201,8 @@ pub fn eq_expr(l: &Expr, r: &Expr) -> bool {
         (Loop(lt, ll, _), Loop(rt, rl, _)) => eq_label(ll.as_ref(), rl.as_ref()) && eq_block(lt, rt),
         (Block(lb, ll), Block(rb, rl)) => eq_label(ll.as_ref(), rl.as_ref()) && eq_block(lb, rb),
         (TryBlock(l), TryBlock(r)) => eq_block(l, r),
-        (Yield(l), Yield(r)) | (Ret(l), Ret(r)) => eq_expr_opt(l.as_ref(), r.as_ref()),
+        (Yield(l, lk), Yield(r, rk)) => eq_expr_opt(l.as_ref(), r.as_ref()) && lk == rk,
+        (Ret(l), Ret(r)) => eq_expr_opt(l.as_ref(), r.as_ref()),
         (Break(ll, le), Break(rl, re)) => eq_label(ll.as_ref(), rl.as_ref()) && eq_expr_opt(le.as_ref(), re.as_ref()),
         (Continue(ll), Continue(rl)) => eq_label(ll.as_ref(), rl.as_ref()),
         (Assign(l1, l2, _), Assign(r1, r2, _)) | (Index(l1, l2, _), Index(r1, r2, _)) => {
@@ -688,7 +689,7 @@ pub fn eq_generics(l: &Generics, r: &Generics) -> bool {
 
 pub fn eq_where_predicate(l: &WherePredicate, r: &WherePredicate) -> bool {
     use WherePredicateKind::*;
-    over(&l.attrs, &r.attrs, eq_attr) 
+    over(&l.attrs, &r.attrs, eq_attr)
         && match (&l.kind, &r.kind) {
             (BoundPredicate(l), BoundPredicate(r)) => {
                 over(&l.bound_generic_params, &r.bound_generic_params, |l, r| {
diff --git a/src/tools/rustfmt/src/expr.rs b/src/tools/rustfmt/src/expr.rs
index eff2d2e3ff4a..92c1ffa6076d 100644
--- a/src/tools/rustfmt/src/expr.rs
+++ b/src/tools/rustfmt/src/expr.rs
@@ -221,7 +221,7 @@ pub(crate) fn format_expr(
                 Ok(format!("break{id_str}"))
             }
         }
-        ast::ExprKind::Yield(ref opt_expr) => {
+        ast::ExprKind::Yield(ref opt_expr, ast::YieldKind::Prefix) => {
             if let Some(ref expr) = *opt_expr {
                 rewrite_unary_prefix(context, "yield ", &**expr, shape)
             } else {
@@ -243,7 +243,8 @@ pub(crate) fn format_expr(
         ast::ExprKind::Try(..)
         | ast::ExprKind::Field(..)
         | ast::ExprKind::MethodCall(..)
-        | ast::ExprKind::Await(_, _) => rewrite_chain(expr, context, shape),
+        | ast::ExprKind::Await(_, _)
+        | ast::ExprKind::Yield(_, ast::YieldKind::Postfix) => rewrite_chain(expr, context, shape),
         ast::ExprKind::MacCall(ref mac) => {
             rewrite_macro(mac, None, context, shape, MacroPosition::Expression).or_else(|_| {
                 wrap_str(
diff --git a/src/tools/rustfmt/tests/source/postfix-yield.rs b/src/tools/rustfmt/tests/source/postfix-yield.rs
new file mode 100644
index 000000000000..8a8958f3ad4e
--- /dev/null
+++ b/src/tools/rustfmt/tests/source/postfix-yield.rs
@@ -0,0 +1,15 @@
+// This demonstrates a proposed alternate or additional option of having yield in postfix position.
+//@ edition: 2024
+
+#![feature(gen_blocks, coroutines, coroutine_trait, yield_expr)]
+
+use std::ops::{Coroutine, CoroutineState};
+use std::pin::pin;
+
+fn main() {
+    let mut coro =
+        pin!(#[coroutine] |_: i32| { let x = 1.yield;
+            
+            
+             (x + 2).yield; });
+}
diff --git a/src/tools/rustfmt/tests/target/postfix-yield.rs b/src/tools/rustfmt/tests/target/postfix-yield.rs
new file mode 100644
index 000000000000..7e94e1e095ad
--- /dev/null
+++ b/src/tools/rustfmt/tests/target/postfix-yield.rs
@@ -0,0 +1,12 @@
+// This demonstrates a proposed alternate or additional option of having yield in postfix position.
+//@ edition: 2024
+
+#![feature(gen_blocks, coroutines, coroutine_trait, yield_expr)]
+
+use std::ops::{Coroutine, CoroutineState};
+use std::pin::pin;
+
+fn main() {
+    let mut coro =
+        pin!(#[coroutine] |_: i32| { let x = 1.yield; (x + 2).yield; });
+}