From 1793ee06589193a33f7f3d6670928dcb5a0f4742 Mon Sep 17 00:00:00 2001
From: Nika Layzell <nika@thelayzells.com>
Date: Thu, 1 Jul 2021 12:56:07 -0400
Subject: [PATCH] proc_macro: support encoding/decoding Vec<T>

---
 library/proc_macro/src/bridge/mod.rs | 15 +++++++++++++++
 library/proc_macro/src/bridge/rpc.rs | 20 ++++++++++++++++++++
 2 files changed, 35 insertions(+)

diff --git a/library/proc_macro/src/bridge/mod.rs b/library/proc_macro/src/bridge/mod.rs
index 4d3e89ba093..aca43945491 100644
--- a/library/proc_macro/src/bridge/mod.rs
+++ b/library/proc_macro/src/bridge/mod.rs
@@ -337,6 +337,21 @@ impl<T: Unmark, E: Unmark> Unmark for Result<T, E> {
     }
 }
 
+impl<T: Mark> Mark for Vec<T> {
+    type Unmarked = Vec<T::Unmarked>;
+    fn mark(unmarked: Self::Unmarked) -> Self {
+        // Should be a no-op due to std's in-place collect optimizations.
+        unmarked.into_iter().map(T::mark).collect()
+    }
+}
+impl<T: Unmark> Unmark for Vec<T> {
+    type Unmarked = Vec<T::Unmarked>;
+    fn unmark(self) -> Self::Unmarked {
+        // Should be a no-op due to std's in-place collect optimizations.
+        self.into_iter().map(T::unmark).collect()
+    }
+}
+
 macro_rules! mark_noop {
     ($($ty:ty),* $(,)?) => {
         $(
diff --git a/library/proc_macro/src/bridge/rpc.rs b/library/proc_macro/src/bridge/rpc.rs
index e19fcf68c5c..a94334e0736 100644
--- a/library/proc_macro/src/bridge/rpc.rs
+++ b/library/proc_macro/src/bridge/rpc.rs
@@ -248,6 +248,26 @@ impl<S> DecodeMut<'_, '_, S> for String {
     }
 }
 
+impl<S, T: Encode<S>> Encode<S> for Vec<T> {
+    fn encode(self, w: &mut Writer, s: &mut S) {
+        self.len().encode(w, s);
+        for x in self {
+            x.encode(w, s);
+        }
+    }
+}
+
+impl<'a, S, T: for<'s> DecodeMut<'a, 's, S>> DecodeMut<'a, '_, S> for Vec<T> {
+    fn decode(r: &mut Reader<'a>, s: &mut S) -> Self {
+        let len = usize::decode(r, s);
+        let mut vec = Vec::with_capacity(len);
+        for _ in 0..len {
+            vec.push(T::decode(r, s));
+        }
+        vec
+    }
+}
+
 /// Simplified version of panic payloads, ignoring
 /// types other than `&'static str` and `String`.
 pub enum PanicMessage {