From 4dfe84c4d1feae8c48fa57ca5b89798b62d8d7ab Mon Sep 17 00:00:00 2001
From: Amanieu d'Antras <amanieu@gmail.com>
Date: Mon, 13 Dec 2021 00:33:07 +0000
Subject: [PATCH 1/2] Fix wasm_importtype_new's Rust signature to not assume
 boxed vectors

Fixes #2718
---
 lib/c-api/src/wasm_c_api/types/import.rs | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/lib/c-api/src/wasm_c_api/types/import.rs b/lib/c-api/src/wasm_c_api/types/import.rs
index 5e075ece7a9..dc2e891d77e 100644
--- a/lib/c-api/src/wasm_c_api/types/import.rs
+++ b/lib/c-api/src/wasm_c_api/types/import.rs
@@ -14,13 +14,13 @@ wasm_declare_boxed_vec!(importtype);
 
 #[no_mangle]
 pub extern "C" fn wasm_importtype_new(
-    module: Option<Box<wasm_name_t>>,
-    name: Option<Box<wasm_name_t>>,
+    module: Option<&mut wasm_name_t>,
+    name: Option<&mut wasm_name_t>,
     extern_type: Option<Box<wasm_externtype_t>>,
 ) -> Option<Box<wasm_importtype_t>> {
     Some(Box::new(wasm_importtype_t {
-        name: *name?,
-        module: *module?,
+        name: name?.take().into(),
+        module: module?.take().into(),
         extern_type: *extern_type?,
     }))
 }

From 0f963929664c7edc1e1c65748f49af365c085458 Mon Sep 17 00:00:00 2001
From: Amanieu d'Antras <amanieu@gmail.com>
Date: Mon, 13 Dec 2021 10:59:34 +0000
Subject: [PATCH 2/2] Update C API development docs

---
 lib/c-api/src/wasm_c_api/DEVELOPMENT.md | 17 +++++++++++------
 1 file changed, 11 insertions(+), 6 deletions(-)

diff --git a/lib/c-api/src/wasm_c_api/DEVELOPMENT.md b/lib/c-api/src/wasm_c_api/DEVELOPMENT.md
index 76a56234a32..048a82cacb3 100644
--- a/lib/c-api/src/wasm_c_api/DEVELOPMENT.md
+++ b/lib/c-api/src/wasm_c_api/DEVELOPMENT.md
@@ -21,14 +21,19 @@ This ownership property translates well in Rust. We have decided to
 use the `Box<T>` type to represent an owned pointer. `Box<T>` drops
 its content when it's dropped.
 
+However, vectors (such as `wasm_name_t`) are a special case: for those, `own`
+means that the ownership of contents of the vector are transfered, not the
+allocation of the vector type itself. Hence these are represented using
+`&mut T` instead.
+
 Consequently, apart from other patterns, the code above can be written
 as follows in Rust:
 
 ```rust
 #[no_mangle]
 pub extern "C" fn wasm_importtype_new(
-    module: Box<wasm_name_t>,
-    name: Box<wasm_name_t>,
+    module: &mut wasm_name_t,
+    name: &mut wasm_name_t,
     extern_type: Box<wasm_externtype_t>,
 ) -> Box<wasm_importtype_t> {
     …
@@ -81,13 +86,13 @@ translates into Rust as:
 ```rust
 #[no_mangle]
 pub extern "C" fn wasm_importtype_new(
-    module: Option<Box<wasm_name_t>>,
-    name: Option<Box<wasm_name_t>>,
+    module: Option<&mut wasm_name_t>,
+    name: Option<&mut wasm_name_t>,
     extern_type: Option<Box<wasm_externtype_t>>,
 ) -> Option<Box<wasm_importtype_t>> {
     Some(Box::new(wasm_importtype_t {
-        name: name?,
-        module: module?,
+        name: name?.take().into(),
+        module: module?.take().into(),
         extern_type: extern_type?,
     }))
 }