Implement &pin const self and &pin mut self sugars

Author: frank-king

src/items.rs

@@ -2395,6 +2395,33 @@ fn rewrite_explicit_self(
                 )?),
             }
         }
+        ast::SelfKind::Pinned(lt, m) => {
+            let mut_str = m.ptr_str();
+            match lt {
+                Some(ref l) => {
+                    let lifetime_str = l.rewrite_result(
+                        context,
+                        Shape::legacy(context.config.max_width(), Indent::empty()),
+                    )?;
+                    Ok(combine_strs_with_missing_comments(
+                        context,
+                        param_attrs,
+                        &format!("&{lifetime_str} pin {mut_str} self"),
+                        span,
+                        shape,
+                        !has_multiple_attr_lines,
+                    )?)
+                }
+                None => Ok(combine_strs_with_missing_comments(
+                    context,
+                    param_attrs,
+                    &format!("&pin {mut_str} self"),
+                    span,
+                    shape,
+                    !has_multiple_attr_lines,
+                )?),
+            }
+        }
         ast::SelfKind::Explicit(ref ty, mutability) => {
             let type_str = ty.rewrite_result(
                 context,

tests/source/pin_sugar.rs

@@ -8,3 +8,13 @@ fn g<'a>(x: &  'a pin const  i32) {}
 fn h<'a>(x: &  'a pin  
 mut i32) {}
 fn i(x: &pin      mut  i32) {}
+
+struct Foo;
+
+impl Foo {
+    fn f(&pin   const self) {}
+    fn g<'a>(&   'a pin const    self) {}
+    fn h<'a>(&    'a pin
+mut self) {}
+    fn i(&pin      mut   self) {}
+}

tests/target/pin_sugar.rs

@@ -7,3 +7,12 @@ 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) {}
+
+struct Foo;
+
+impl Foo {
+    fn f(&pin const self) {}
+    fn g<'a>(&'a pin const self) {}
+    fn h<'a>(&'a pin mut self) {}
+    fn i(&pin mut self) {}
+}