fixup! rewrite #[pin_data] using syn

Author: BennoLossin

internal/src/pin_data.rs

@@ -258,50 +258,47 @@ fn generate_projections(
     let projection = format_ident!("{ident}Projection");
     let this = format_ident!("this");
 
-    let (fields_decl, fields_proj) = fields
-        .iter()
-        .map(
-            |f @ Field {
-                 vis,
-                 ident,
-                 ty,
-                 attrs,
-                 ..
-             }| {
-                let mut attrs = attrs.clone();
-                attrs.retain(|a| !a.path().is_ident("pin"));
-                let mut no_doc_attrs = attrs.clone();
-                no_doc_attrs.retain(|a| !a.path().is_ident("doc"));
-                let ident = ident
-                    .as_ref()
-                    .expect("only structs with named fields are supported");
-                if is_field_structurally_pinned(f) {
-                    (
-                        quote!(
-                            #(#attrs)*
-                            #vis #ident: ::core::pin::Pin<&'__pin mut #ty>,
-                        ),
-                        quote!(
-                            #(#no_doc_attrs)*
-                            // SAFETY: this field is structurally pinned.
-                            #ident: unsafe { ::core::pin::Pin::new_unchecked(&mut #this.#ident) },
-                        ),
-                    )
-                } else {
-                    (
-                        quote!(
-                            #(#attrs)*
-                            #vis #ident: &'__pin mut #ty,
-                        ),
-                        quote!(
-                            #(#no_doc_attrs)*
-                            #ident: &mut #this.#ident,
-                        ),
-                    )
-                }
-            },
-        )
-        .collect::<(Vec<_>, Vec<_>)>();
+    let (fields_decl, fields_proj) = collect_tuple(fields.iter().map(
+        |f @ Field {
+             vis,
+             ident,
+             ty,
+             attrs,
+             ..
+         }| {
+            let mut attrs = attrs.clone();
+            attrs.retain(|a| !a.path().is_ident("pin"));
+            let mut no_doc_attrs = attrs.clone();
+            no_doc_attrs.retain(|a| !a.path().is_ident("doc"));
+            let ident = ident
+                .as_ref()
+                .expect("only structs with named fields are supported");
+            if is_field_structurally_pinned(f) {
+                (
+                    quote!(
+                        #(#attrs)*
+                        #vis #ident: ::core::pin::Pin<&'__pin mut #ty>,
+                    ),
+                    quote!(
+                        #(#no_doc_attrs)*
+                        // SAFETY: this field is structurally pinned.
+                        #ident: unsafe { ::core::pin::Pin::new_unchecked(&mut #this.#ident) },
+                    ),
+                )
+            } else {
+                (
+                    quote!(
+                        #(#attrs)*
+                        #vis #ident: &'__pin mut #ty,
+                    ),
+                    quote!(
+                        #(#no_doc_attrs)*
+                        #ident: &mut #this.#ident,
+                    ),
+                )
+            }
+        },
+    ));
     let structurally_pinned_fields_docs = fields
         .iter()
         .filter(|f| is_field_structurally_pinned(f))
@@ -523,3 +520,14 @@ impl VisitMut for SelfReplacer {
         // Do not descend into items, since items reset/change what `Self` refers to.
     }
 }
+
+// replace with `.collect()` once MSRV is above 1.79
+fn collect_tuple<A, B>(iter: impl Iterator<Item = (A, B)>) -> (Vec<A>, Vec<B>) {
+    let mut res_a = vec![];
+    let mut res_b = vec![];
+    for (a, b) in iter {
+        res_a.push(a);
+        res_b.push(b);
+    }
+    (res_a, res_b)
+}