Do not derive Copy for blacklisted types

Presumably they are blacklisted because we can't understand them properly, so be
pessimistic about what we can derive for it.

Fixes #944.

Author: fitzgen

src/ir/analysis/derive_copy.rs

@@ -88,6 +88,13 @@ impl<'ctx, 'gen> CannotDeriveCopy<'ctx, 'gen> {
 
         ConstrainResult::Changed
     }
+
+    /// A type is not `Copy` if we've determined it is not copy, or if it is
+    /// blacklisted.
+    fn is_not_copy(&self, id: ItemId) -> bool {
+        self.cannot_derive_copy.contains(&id) ||
+            !self.ctx.whitelisted_items().contains(&id)
+    }
 }
 
 impl<'ctx, 'gen> MonotoneFramework for CannotDeriveCopy<'ctx, 'gen> {
@@ -118,6 +125,15 @@ impl<'ctx, 'gen> MonotoneFramework for CannotDeriveCopy<'ctx, 'gen> {
             return ConstrainResult::Same;
         }
 
+        // If an item is reachable from the whitelisted items set, but isn't
+        // itself whitelisted, then it must be blacklisted. We assume that
+        // blacklisted items are not `Copy`, since they are presumably
+        // blacklisted because they are too complicated for us to understand.
+        if !self.ctx.whitelisted_items().contains(&id) {
+            trace!("    blacklisted items are assumed not to be Copy");
+            return ConstrainResult::Same;
+        }
+
         let item = self.ctx.resolve_item(id);
         let ty = match item.as_type() {
             Some(ty) => ty,
@@ -163,7 +179,7 @@ impl<'ctx, 'gen> MonotoneFramework for CannotDeriveCopy<'ctx, 'gen> {
             }
 
             TypeKind::Array(t, len) => {
-                let cant_derive_copy = self.cannot_derive_copy.contains(&t);
+                let cant_derive_copy = self.is_not_copy(t);
                 if cant_derive_copy {
                     trace!(
                         "    arrays of T for which we cannot derive Copy \
@@ -184,7 +200,7 @@ impl<'ctx, 'gen> MonotoneFramework for CannotDeriveCopy<'ctx, 'gen> {
             TypeKind::ResolvedTypeRef(t) |
             TypeKind::TemplateAlias(t, _) |
             TypeKind::Alias(t) => {
-                let cant_derive_copy = self.cannot_derive_copy.contains(&t);
+                let cant_derive_copy = self.is_not_copy(t);
                 if cant_derive_copy {
                     trace!(
                         "    arrays of T for which we cannot derive Copy \
@@ -237,7 +253,7 @@ impl<'ctx, 'gen> MonotoneFramework for CannotDeriveCopy<'ctx, 'gen> {
 
                 let bases_cannot_derive =
                     info.base_members().iter().any(|base| {
-                        self.cannot_derive_copy.contains(&base.ty)
+                        self.is_not_copy(base.ty)
                     });
                 if bases_cannot_derive {
                     trace!(
@@ -250,11 +266,11 @@ impl<'ctx, 'gen> MonotoneFramework for CannotDeriveCopy<'ctx, 'gen> {
                 let fields_cannot_derive =
                     info.fields().iter().any(|f| match *f {
                         Field::DataMember(ref data) => {
-                            self.cannot_derive_copy.contains(&data.ty())
+                            self.is_not_copy(data.ty())
                         }
                         Field::Bitfields(ref bfu) => {
                             bfu.bitfields().iter().any(|b| {
-                                self.cannot_derive_copy.contains(&b.ty())
+                                self.is_not_copy(b.ty())
                             })
                         }
                     });
@@ -270,7 +286,7 @@ impl<'ctx, 'gen> MonotoneFramework for CannotDeriveCopy<'ctx, 'gen> {
             TypeKind::TemplateInstantiation(ref template) => {
                 let args_cannot_derive =
                     template.template_arguments().iter().any(|arg| {
-                        self.cannot_derive_copy.contains(&arg)
+                        self.is_not_copy(*arg)
                     });
                 if args_cannot_derive {
                     trace!(
@@ -284,8 +300,8 @@ impl<'ctx, 'gen> MonotoneFramework for CannotDeriveCopy<'ctx, 'gen> {
                     !template.template_definition().is_opaque(self.ctx, &()),
                     "The early ty.is_opaque check should have handled this case"
                 );
-                let def_cannot_derive = self.cannot_derive_copy.contains(
-                    &template.template_definition(),
+                let def_cannot_derive = self.is_not_copy(
+                    template.template_definition(),
                 );
                 if def_cannot_derive {
                     trace!(

tests/expectations/tests/issue-944-derive-copy-and-blacklisting.rs

@@ -0,0 +1,28 @@
+/* automatically generated by rust-bindgen */
+
+
+#![allow(dead_code, non_snake_case, non_camel_case_types, non_upper_case_globals)]
+
+#[derive(Debug)] pub struct BlacklistMe(u8);
+
+/// Because this type contains a blacklisted type, it should not derive Copy.
+#[repr(C)]
+#[derive(Debug)]
+pub struct ShouldNotBeCopy {
+    pub a: BlacklistMe,
+}
+#[test]
+fn bindgen_test_layout_ShouldNotBeCopy() {
+    assert_eq!(::std::mem::size_of::<ShouldNotBeCopy>() , 1usize , concat ! (
+               "Size of: " , stringify ! ( ShouldNotBeCopy ) ));
+    assert_eq! (::std::mem::align_of::<ShouldNotBeCopy>() , 1usize , concat !
+                ( "Alignment of " , stringify ! ( ShouldNotBeCopy ) ));
+    assert_eq! (unsafe {
+                & ( * ( 0 as * const ShouldNotBeCopy ) ) . a as * const _ as
+                usize } , 0usize , concat ! (
+                "Alignment of field: " , stringify ! ( ShouldNotBeCopy ) ,
+                "::" , stringify ! ( a ) ));
+}
+impl Default for ShouldNotBeCopy {
+    fn default() -> Self { unsafe { ::std::mem::zeroed() } }
+}

tests/headers/issue-944-derive-copy-and-blacklisting.hpp

@@ -0,0 +1,10 @@
+// bindgen-flags: --blacklist-type BlacklistMe --raw-line '#[derive(Debug)] pub struct BlacklistMe(u8);'
+
+struct BlacklistMe {};
+
+/**
+ * Because this type contains a blacklisted type, it should not derive Copy.
+ */
+struct ShouldNotBeCopy {
+    BlacklistMe a;
+};