bindgen: Change how opaque comp types are managed

So it's not awfully broken.

Author: emilio

src/gen.rs

@@ -376,7 +376,14 @@ fn gen_mod(mut ctx: &mut GenCtx,
     }
 }
 
+// XXX: Replace the name-based lookup, or do it at parse-time,
+// to keep all the mess in the same place.
 fn type_opaque(ctx: &GenCtx, ty: &Type) -> bool {
+    match *ty {
+        TComp(ref ci) if ci.borrow().opaque => return true,
+        _ => {}
+    }
+
     let ty_name = ty.name();
 
     match ty_name {
@@ -389,6 +396,12 @@ fn type_opaque(ctx: &GenCtx, ty: &Type) -> bool {
 fn global_opaque(ctx: &GenCtx, global: &Global) -> bool {
     let global_name = global.name();
 
+    match *global {
+        GCompDecl(ref ci) |
+        GComp(ref ci) if ci.borrow().opaque => return true,
+        _ => {}
+    }
+
     // Can't make an opaque type without layout
     global.layout().is_some() &&
     ctx.options.opaque_types.iter().any(|name| *name == global_name)

src/parser.rs

@@ -902,7 +902,7 @@ fn visit_top(cursor: &Cursor,
                     visit_composite(c, p, ctx_, &mut ci_)
                 });
                 if anno.opaque {
-                    ci.borrow_mut().members = vec!();
+                    ci.borrow_mut().opaque = true;
                 }
                 if anno.hide {
                     ci.borrow_mut().hide = true;

src/types.rs

@@ -308,6 +308,11 @@ pub struct CompInfo {
     pub has_destructor: bool,
     pub has_nonempty_base: bool,
     pub hide: bool,
+    /// If this struct should be replaced by an opaque blob.
+    ///
+    /// This is useful if for some reason we can't generate
+    /// the correct layout.
+    pub opaque: bool,
     pub base_members: usize,
     pub layout: Layout,
     /// Typedef'd types names, that we'll resolve early to avoid name conflicts
@@ -347,6 +352,7 @@ impl CompInfo {
             has_destructor: false,
             has_nonempty_base: false,
             hide: false,
+            opaque: false,
             base_members: 0,
             layout: layout,
             typedefs: vec!(),

tests/headers/annotation_hide.hpp

@@ -3,3 +3,10 @@
  * <div rustbindgen="true" hide="true"></div>
  */
 struct C;
+
+/**
+ * <div rustbindgen opaque></div>
+ */
+struct D {
+    int a;
+};