Auto merge of #1071 - pepyakin:emit-hex-bitfield-masks, r=fitzgen

Emit hex bitfield masks

r? @fitzgen

Author: bors-servo

src/codegen/helpers.rs

@@ -143,6 +143,13 @@ pub mod ast_ty {
         tokens
     }
 
+    /// Returns hex representation of the given value.
+    pub fn hex_expr(val: u64) -> quote::Tokens {
+        let mut tokens = quote! {};
+        tokens.append(format!("{:#x}", val));
+        tokens
+    }
+
     pub fn byte_array_expr(bytes: &[u8]) -> quote::Tokens {
         let mut bytes: Vec<_> = bytes.iter().cloned().collect();
         bytes.push(0);

src/codegen/mod.rs

@@ -1121,7 +1121,7 @@ impl Bitfield {
         let bitfield_int_ty = helpers::blob(bitfield_ty_layout);
 
         let offset = self.offset_into_unit();
-        let mask = self.mask();
+        let mask = helpers::ast_ty::hex_expr(self.mask());
 
         // Don't use variables or blocks because const functions do not allow
         // them.
@@ -1304,7 +1304,7 @@ impl<'a> FieldCodegen<'a> for Bitfield {
             bitfield_ty.to_rust_ty_or_opaque(ctx, bitfield_ty_item);
 
         let offset = self.offset_into_unit();
-        let mask = self.mask();
+        let mask = helpers::ast_ty::hex_expr(self.mask());
 
         methods.extend(Some(quote! {
             #[inline]