commit 503d01902a6cd9b0f2dfd81f2b39c361144c06da
author David Tolnay <dtolnay@gmail.com> Fri Apr 24 22:18:56 2020 -0700
committer David Tolnay <dtolnay@gmail.com> Sat Apr 25 18:02:15 2020 -0700
tree 2a758ffb28d0fff0028e83c358286115264fe697
parent 219c0790d4e157ca358d5a7baa08972ab6fcd4af

Add stride accessor for Vec

Will be required for implementing an iterator.

gen/write.rs

diff --git a/gen/write.rs b/gen/write.rs
index 9192a7e..d963bb9 100644
--- a/gen/write.rs
+++ b/gen/write.rs
@@ -1026,6 +1026,11 @@
         "const {} *cxxbridge02$rust_vec${}$data(const ::rust::Vec<{0}> *ptr) noexcept;",
         inner, instance,
     );
+    writeln!(
+        out,
+        "size_t cxxbridge02$rust_vec${}$stride() noexcept;",
+        instance,
+    );
     writeln!(out, "#endif // CXXBRIDGE02_RUST_VEC_{}", instance);
 }
 
@@ -1075,6 +1080,11 @@
         instance,
     );
     writeln!(out, "}}");
+
+    writeln!(out, "template <>");
+    writeln!(out, "size_t Vec<{}>::stride() noexcept {{", inner);
+    writeln!(out, "  return cxxbridge02$rust_vec${}$stride();", instance);
+    writeln!(out, "}}");
 }
 
 fn write_unique_ptr(out: &mut OutFile, ty: &Type, types: &Types) {

include/cxx.h

diff --git a/include/cxx.h b/include/cxx.h
index c3037bd..f40614b 100644
--- a/include/cxx.h
+++ b/include/cxx.h
@@ -212,6 +212,7 @@
   const T *data() const noexcept;
 
 private:
+  static size_t stride() noexcept;
   void drop() noexcept;
 
   // Size and alignment statically verified by rust_vec.rs.

macro/src/expand.rs

diff --git a/macro/src/expand.rs b/macro/src/expand.rs
index 15351f0..7503f3a 100644
--- a/macro/src/expand.rs
+++ b/macro/src/expand.rs
@@ -541,11 +541,13 @@
     let link_drop = format!("{}drop", link_prefix);
     let link_len = format!("{}len", link_prefix);
     let link_data = format!("{}data", link_prefix);
+    let link_stride = format!("{}stride", link_prefix);
 
     let local_prefix = format_ident!("{}__vec_", ident);
     let local_drop = format_ident!("{}drop", local_prefix);
     let local_len = format_ident!("{}len", local_prefix);
     let local_data = format_ident!("{}data", local_prefix);
+    let local_stride = format_ident!("{}stride", local_prefix);
 
     let span = ty.span();
     quote_spanned! {span=>
@@ -564,6 +566,11 @@
         unsafe extern "C" fn #local_data(this: *const ::cxx::private::RustVec<#inner>) -> *const #inner {
             (*this).as_ptr()
         }
+        #[doc(hidden)]
+        #[export_name = #link_stride]
+        unsafe extern "C" fn #local_stride() -> usize {
+            ::std::mem::size_of::<#inner>()
+        }
     }
 }