Auto merge of #1060 - aeleos:master, r=fitzgen

Make bitfields larger than type opaque

@fitzgen r?

Fixes #1007 by ensuring that bitfields larger than type will be opaque, ensuring the layout is correct.

Author: bors-servo

src/ir/comp.rs

@@ -1473,8 +1473,25 @@ impl DotAttributes for CompInfo {
 impl IsOpaque for CompInfo {
     type Extra = ();
 
-    fn is_opaque(&self, _: &BindgenContext, _: &()) -> bool {
-        self.has_non_type_template_params
+    fn is_opaque(&self, ctx: &BindgenContext, _: &()) -> bool {
+        // Early return to avoid extra computation
+        if self.has_non_type_template_params {
+            return true
+        }
+
+        self.fields().iter().any(|f| match *f {
+            Field::DataMember(_) => {
+                false
+            },
+            Field::Bitfields(ref unit) => {
+                    unit.bitfields().iter().any(|bf| {
+                    let bitfield_layout = ctx.resolve_type(bf.ty())
+                        .layout(ctx)
+                        .expect("Bitfield without layout? Gah!");
+                    bf.width() / 8 > bitfield_layout.size as u32
+                })
+            }
+        })
     }
 }
 

src/ir/context.rs

@@ -1137,8 +1137,6 @@ impl BindgenContext {
     {
         self.in_codegen = true;
 
-        self.assert_no_dangling_references();
-
         if !self.collected_typerefs() {
             self.resolve_typerefs();
             self.compute_bitfield_units();
@@ -1147,8 +1145,6 @@ impl BindgenContext {
 
         self.deanonymize_fields();
 
-        // And assert once again, because resolving type refs and processing
-        // replacements both mutate the IR graph.
         self.assert_no_dangling_references();
 
         // Compute the whitelisted set after processing replacements and

tests/expectations/tests/bitfield_large_overflow.rs

@@ -5,13 +5,26 @@
 
 
 #[repr(C)]
+#[derive(Debug, Default, Copy)]
 pub struct _bindgen_ty_1 {
-    pub _bitfield_1: [u8; 128usize],
-    pub __bindgen_align: [u64; 0usize],
+    pub _bindgen_opaque_blob: [u64; 10usize],
 }
-impl Default for _bindgen_ty_1 {
-    fn default() -> Self {
-        unsafe { ::std::mem::zeroed() }
+#[test]
+fn bindgen_test_layout__bindgen_ty_1() {
+    assert_eq!(
+        ::std::mem::size_of::<_bindgen_ty_1>(),
+        80usize,
+        concat!("Size of: ", stringify!(_bindgen_ty_1))
+    );
+    assert_eq!(
+        ::std::mem::align_of::<_bindgen_ty_1>(),
+        8usize,
+        concat!("Alignment of ", stringify!(_bindgen_ty_1))
+    );
+}
+impl Clone for _bindgen_ty_1 {
+    fn clone(&self) -> Self {
+        *self
     }
 }
 extern "C" {

tests/headers/bitfield_large_overflow.hpp

@@ -1,5 +1,3 @@
-// bindgen-flags: --no-layout-tests
-
 struct {
   unsigned : 632;
 } a;