From 3aabe1e4a3518f943a20b692a0db90189fc5898c Mon Sep 17 00:00:00 2001
From: Eric Holk <ericholk@microsoft.com>
Date: Mon, 23 Sep 2024 16:07:31 -0700
Subject: [PATCH] Add basic pin sugar support to rustfmt

---
 src/tools/rustfmt/src/types.rs              |  8 +++++++-
 src/tools/rustfmt/tests/source/pin_sugar.rs | 10 ++++++++++
 src/tools/rustfmt/tests/target/pin_sugar.rs |  9 +++++++++
 3 files changed, 26 insertions(+), 1 deletion(-)
 create mode 100644 src/tools/rustfmt/tests/source/pin_sugar.rs
 create mode 100644 src/tools/rustfmt/tests/target/pin_sugar.rs

diff --git a/src/tools/rustfmt/src/types.rs b/src/tools/rustfmt/src/types.rs
index 999deb5dd4aa7..f7177c7f85464 100644
--- a/src/tools/rustfmt/src/types.rs
+++ b/src/tools/rustfmt/src/types.rs
@@ -829,7 +829,6 @@ impl Rewrite for ast::Ty {
             }
             ast::TyKind::Ref(ref lifetime, ref mt)
             | ast::TyKind::PinnedRef(ref lifetime, ref mt) => {
-                // FIXME(pin_ergonomics): correctly format pinned reference syntax
                 let mut_str = format_mutability(mt.mutbl);
                 let mut_len = mut_str.len();
                 let mut result = String::with_capacity(128);
@@ -863,6 +862,13 @@ impl Rewrite for ast::Ty {
                     cmnt_lo = lifetime.ident.span.hi();
                 }
 
+                if let ast::TyKind::PinnedRef(..) = self.kind {
+                    result.push_str("pin ");
+                    if ast::Mutability::Not == mt.mutbl {
+                        result.push_str("const ");
+                    }
+                }
+
                 if ast::Mutability::Mut == mt.mutbl {
                     let mut_hi = context.snippet_provider.span_after(self.span(), "mut");
                     let before_mut_span = mk_sp(cmnt_lo, mut_hi - BytePos::from_usize(3));
diff --git a/src/tools/rustfmt/tests/source/pin_sugar.rs b/src/tools/rustfmt/tests/source/pin_sugar.rs
new file mode 100644
index 0000000000000..0eb3c0770c482
--- /dev/null
+++ b/src/tools/rustfmt/tests/source/pin_sugar.rs
@@ -0,0 +1,10 @@
+// See #130494
+
+#![feature(pin_ergonomics)]
+#![allow(incomplete_features)]
+
+fn f(x: &pin  const i32) {}
+fn g<'a>(x: &  'a pin const  i32) {}
+fn h<'a>(x: &  'a pin  
+mut i32) {}
+fn i(x: &pin      mut  i32) {}
diff --git a/src/tools/rustfmt/tests/target/pin_sugar.rs b/src/tools/rustfmt/tests/target/pin_sugar.rs
new file mode 100644
index 0000000000000..c9fa883e238fd
--- /dev/null
+++ b/src/tools/rustfmt/tests/target/pin_sugar.rs
@@ -0,0 +1,9 @@
+// See #130494
+
+#![feature(pin_ergonomics)]
+#![allow(incomplete_features)]
+
+fn f(x: &pin const i32) {}
+fn g<'a>(x: &'a pin const i32) {}
+fn h<'a>(x: &'a pin mut i32) {}
+fn i(x: &pin mut i32) {}