From cf8d0c82dc2e3de67d29a09389dbf035c5723c57 Mon Sep 17 00:00:00 2001
From: Deadbeef <ent3rm4n@gmail.com>
Date: Wed, 24 Dec 2025 14:42:14 -0500
Subject: [PATCH] fix rustfmt on `const impl Ty {}`

---
 src/tools/rustfmt/src/items.rs                |  2 +-
 src/tools/rustfmt/tests/source/const_trait.rs | 14 ++++++++++++++
 src/tools/rustfmt/tests/target/const_trait.rs |  9 +++++++++
 3 files changed, 24 insertions(+), 1 deletion(-)
 create mode 100644 src/tools/rustfmt/tests/source/const_trait.rs

diff --git a/src/tools/rustfmt/src/items.rs b/src/tools/rustfmt/src/items.rs
index d1778f324c6aa..c9e32492c50b0 100644
--- a/src/tools/rustfmt/src/items.rs
+++ b/src/tools/rustfmt/src/items.rs
@@ -971,7 +971,7 @@ fn format_impl_ref_and_type(
         result.push_str(format_defaultness(of_trait.defaultness));
         result.push_str(format_safety(of_trait.safety));
     } else {
-        result.push_str(format_constness_right(*constness));
+        result.push_str(format_constness(*constness));
     }
 
     let shape = if context.config.style_edition() >= StyleEdition::Edition2024 {
diff --git a/src/tools/rustfmt/tests/source/const_trait.rs b/src/tools/rustfmt/tests/source/const_trait.rs
new file mode 100644
index 0000000000000..99414a74f250c
--- /dev/null
+++ b/src/tools/rustfmt/tests/source/const_trait.rs
@@ -0,0 +1,14 @@
+#![feature(trait_alias, const_trait_impl)]
+
+const trait Bar {}
+
+const trait Foo = Bar;
+
+impl const Bar for () {}
+
+// const impl gets reformatted to impl const.. for now
+const impl Bar for u8 {}
+
+struct X;
+
+const impl X {}
diff --git a/src/tools/rustfmt/tests/target/const_trait.rs b/src/tools/rustfmt/tests/target/const_trait.rs
index c4c88b17fc500..337a4cf4140e8 100644
--- a/src/tools/rustfmt/tests/target/const_trait.rs
+++ b/src/tools/rustfmt/tests/target/const_trait.rs
@@ -3,3 +3,12 @@
 const trait Bar {}
 
 const trait Foo = Bar;
+
+impl const Bar for () {}
+
+// const impl gets reformatted to impl const.. for now
+impl const Bar for u8 {}
+
+struct X;
+
+const impl X {}