Rollup merge of #150358 - fee1-dead-contrib:push-utvysrrzsvvm, r=oli-obk

fix rustfmt on `const impl Ty {}`

r? `@oli-obk` on rust-lang/rust#148434, cc `@ytmimi` for https://github.com/rust-lang/rust/pull/148434/changes#r2637972310

format_constness_right outputs `" const"` whereas format_constness outputs `"const "`

Not making this change to rust-lang/rustfmt since I'm not sure if that repo has these changes yet.

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 {

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 {}

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 {}