[PATCH 11/11] rust: pin-init: internal: remove `collect_tuple` polyfill after MSRV bump

[Gary Guo]

Tuples implement `FromIterator` since Rust 1.79. Remove the `collect_tuple`
polyfill now the MSRV is above 1.79.

To avoid over-identing the closure, I move the `Field` destructure from the
closure parameter to a let binding. This keeps the diff small.

Signed-off-by: Gary Guo <gary@xxxxxxxxxxx>
---
I've missed out one remaining case where we kept a workaround for old MSRV.
Send as a follow up to the series as this'll be in the same upstream PR as patch 9 in this series.
---
 rust/pin-init/internal/src/pin_data.rs | 27 ++++++++------------------
 1 file changed, 8 insertions(+), 19 deletions(-)

diff --git a/rust/pin-init/internal/src/pin_data.rs b/rust/pin-init/internal/src/pin_data.rs
index 163a31ed1556..be3d97a38225 100644
--- a/rust/pin-init/internal/src/pin_data.rs
+++ b/rust/pin-init/internal/src/pin_data.rs
@@ -247,17 +247,17 @@ fn generate_projections(
     let projection = format_ident!("{ident}Projection");
     let this = format_ident!("this");
 
-    let (fields_decl, fields_proj) = collect_tuple(fields.iter().map(
-        |(
-            pinned,
-            Field {
+    let (fields_decl, fields_proj): (Vec<_>, Vec<_>) = fields
+        .iter()
+        .map(|(pinned, field)| {
+            let Field {
                 vis,
                 ident,
                 ty,
                 attrs,
                 ..
-            },
-        )| {
+            } = field;
+
             let mut no_doc_attrs = attrs.clone();
             no_doc_attrs.retain(|a| !a.path().is_ident("doc"));
             let ident = ident
@@ -287,8 +287,8 @@ fn generate_projections(
                     ),
                 )
             }
-        },
-    ));
+        })
+        .collect();
     let structurally_pinned_fields_docs = fields
         .iter()
         .filter_map(|(pinned, field)| pinned.then_some(field))
@@ -498,14 +498,3 @@ fn visit_item_mut(&mut self, _: &mut Item) {
         // 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)
-}

base-commit: 320c27bef338777831ec8615a8ec7e08812d0374
-- 
2.51.2