Support #[repr(packed(N))] on Rust 1.33+

Fixes https://github.com/rust-lang/rust-bindgen/issues/537.

2 files changed, 6 insertions, 2 deletions

diff --git a/src/codegen/helpers.rs b/src/codegen/helpers.rs
index d6377194..457979b6 100644
--- a/src/codegen/helpers.rs
+++ b/src/codegen/helpers.rs
@@ -7,6 +7,7 @@ use quote::TokenStreamExt;
 
 pub mod attributes {
     use proc_macro2::{Ident, Span, TokenStream};
+    use std::str::FromStr;
 
     pub fn repr(which: &str) -> TokenStream {
         let which = Ident::new(which, Span::call_site());
@@ -16,7 +17,7 @@ pub mod attributes {
     }
 
     pub fn repr_list(which_ones: &[&str]) -> TokenStream {
-        let which_ones = which_ones.iter().cloned().map(|one| Ident::new(one, Span::call_site()));
+        let which_ones = which_ones.iter().cloned().map(|one| TokenStream::from_str(one).expect("repr to be valid"));
         quote! {
             #[repr( #( #which_ones ),* )]
         }
diff --git a/src/codegen/mod.rs b/src/codegen/mod.rs
index 6fd7e7d3..d3395edf 100644
--- a/src/codegen/mod.rs
+++ b/src/codegen/mod.rs
@@ -1673,7 +1673,10 @@ impl CodeGenerator for CompInfo {
             attributes.push(attributes::doc(comment));
         }
         if packed && !is_opaque {
-            attributes.push(attributes::repr_list(&["C", "packed"]));
+            let n = layout.map_or(1, |l| l.align);
+            assert!(ctx.options().rust_features().repr_packed_n || n == 1);
+            let packed_repr = if n == 1 { "packed".to_string() } else { format!("packed({})", n) };
+            attributes.push(attributes::repr_list(&["C", &packed_repr]));
         } else {
             attributes.push(attributes::repr("C"));
         }