Preserve self as segment of path

CHANGELOG.md

@@ -10,6 +10,8 @@ Note: In this file, do not use the hard wrap in the middle of a sentence for com
 
 ## [Unreleased]
 
+- Fix compile error when using `self::` as prefix of path inside `#[pinned_drop]` impl.
+
 ## [1.0.6] - 2021-03-25
 
 - [Suppress `clippy::semicolon_if_nothing_returned` lint in generated code.](https://github.com/taiki-e/pin-project/pull/318)

pin-project-internal/src/utils.rs

@@ -176,7 +176,9 @@ impl<'a> ParseBufferExt<'a> for ParseBuffer<'a> {
 // visitors
 
 // Replace `self`/`Self` with `__self`/`self_ty`.
-// Based on https://github.com/dtolnay/async-trait/blob/0.1.35/src/receiver.rs
+// Based on:
+// - https://github.com/dtolnay/async-trait/blob/0.1.35/src/receiver.rs
+// - https://github.com/dtolnay/async-trait/commit/6029cbf375c562ca98fa5748e9d950a8ff93b0e7
 
 pub(crate) struct ReplaceReceiver<'a>(pub(crate) &'a TypePath);
 
@@ -313,7 +315,6 @@ impl VisitMut for ReplaceReceiver<'_> {
     // `Self::method` -> `<Receiver>::method`
     fn visit_expr_path_mut(&mut self, expr: &mut ExprPath) {
         if expr.qself.is_none() {
-            prepend_underscore_to_self(&mut expr.path.segments[0].ident);
             self.self_to_qself(&mut expr.qself, &mut expr.path);
         }
         visit_mut::visit_expr_path_mut(self, expr);
@@ -341,6 +342,16 @@ impl VisitMut for ReplaceReceiver<'_> {
         visit_mut::visit_pat_tuple_struct_mut(self, pat);
     }
 
+    fn visit_path_mut(&mut self, path: &mut Path) {
+        if path.segments.len() == 1 {
+            // Replace `self`, but not `self::function`.
+            prepend_underscore_to_self(&mut path.segments[0].ident);
+        }
+        for segment in &mut path.segments {
+            self.visit_path_arguments_mut(&mut segment.arguments);
+        }
+    }
+
     fn visit_item_mut(&mut self, item: &mut Item) {
         match item {
             // Visit `macro_rules!` because locally defined macros can refer to `self`.

tests/pinned_drop.rs

@@ -262,3 +262,23 @@ fn inside_macro() {
 
     mac!(1);
 }
+
+pub mod self_path {
+    use super::*;
+
+    #[pin_project(PinnedDrop)]
+    pub struct S<T: Unpin>(T);
+
+    fn f() {}
+
+    #[pinned_drop]
+    impl<T: Unpin> PinnedDrop for self::S<T> {
+        fn drop(mut self: Pin<&mut Self>) {
+            self::f();
+            let _: self::S<()> = self::S(());
+            let _: self::S<Pin<&mut Self>> = self::S(self.as_mut());
+            let self::S(()) = self::S(());
+            let self::S(&mut Self(_)) = self::S(&mut *self);
+        }
+    }
+}