Auto merge of #226 - emilio:bitfields, r=fitzgen

Generate and add options for bitfield-like enums.

r? @fitzgen or @Manishearth

cc @bholley @upsuper @heycam

Followups:

 * Reduce duplication a bit in that code (probably E-easy)
 * Generate an impl of `BitOr` for bitfield-like enums (E-easy/E-less-easy).

Author: bors-servo

src/bin/bindgen.rs

@@ -28,6 +28,7 @@ Usage:
         [--whitelist-type=<type>...] \
         [--whitelist-function=<name>...] \
         [--whitelist-var=<name>...] \
+        [--bitfield-enum=<name>...] \
         <input-header> \
         [-- <clang-args>...]
 
@@ -91,6 +92,10 @@ Options:
                                   matching <regex>.  Same behavior on emptyness
                                   than the type whitelisting.
 
+    --bitfield-enum=<regex>       Mark any enum whose name matches <regex> as a
+                                  set of bitfield flags instead of an
+                                  enumeration.
+
     --dummy-uses=<path>           For testing purposes, generate a C/C++ file
                                   containing dummy uses of all types defined in
                                   the input header.
@@ -163,6 +168,11 @@ fn parse_args_or_exit(args: Vec<String>) -> (BindgenOptions, Box<io::Write>) {
                     .expect("--whitelist-var expects a pattern");
                 options.whitelisted_vars.insert(&var_pat);
             }
+            "--bitfield-enum" => {
+                let enum_pat = iter.next()
+                    .expect("--bitfield-enum expects a pattern");
+                options.bitfield_enums.insert(&enum_pat);
+            }
             "--" => {
                 while let Some(clang_arg) = iter.next() {
                     options.clang_args.push(clang_arg);

src/clang.rs

@@ -102,7 +102,9 @@ impl Cursor {
     /// lexical parents.
     pub fn fallible_semantic_parent(&self) -> Option<Cursor> {
         let sp = unsafe {
-            Cursor { x: clang_getCursorSemanticParent(self.x) }
+            Cursor {
+                x: clang_getCursorSemanticParent(self.x),
+            }
         };
         if sp == *self || !sp.is_valid() {
             return None;
@@ -161,7 +163,8 @@ impl Cursor {
               (semantic_parent.unwrap().kind() == CXCursor_Namespace ||
                semantic_parent.unwrap().kind() == CXCursor_NamespaceAlias ||
                semantic_parent.unwrap().kind() == CXCursor_NamespaceRef) {
-            semantic_parent = semantic_parent.unwrap().fallible_semantic_parent();
+            semantic_parent = semantic_parent.unwrap()
+                .fallible_semantic_parent();
         }
 
         let tu = self.translation_unit();
@@ -363,9 +366,9 @@ impl Cursor {
     ///
     /// Returns None if the cursor's referent is not an enum variant.
     pub fn enum_val_unsigned(&self) -> Option<u64> {
-        unsafe { 
+        unsafe {
             if self.kind() == CXCursor_EnumConstantDecl {
-                Some(clang_getEnumConstantDeclUnsignedValue(self.x) as u64)   
+                Some(clang_getEnumConstantDeclUnsignedValue(self.x) as u64)
             } else {
                 None
             }
@@ -691,11 +694,7 @@ impl Type {
         let rt = Type {
             x: unsafe { clang_getResultType(self.x) },
         };
-        if rt.is_valid() {
-            Some(rt)
-        } else {
-            None
-        }
+        if rt.is_valid() { Some(rt) } else { None }
     }
 
     /// Given that this type is a function type, get its calling convention. If

src/codegen/mod.rs

@@ -6,7 +6,7 @@ use aster;
 use ir::annotations::FieldAccessorKind;
 use ir::comp::{CompInfo, CompKind, Field, Method};
 use ir::context::BindgenContext;
-use ir::enum_ty::Enum;
+use ir::enum_ty::{Enum, EnumVariant, EnumVariantValue};
 use ir::function::{Function, FunctionSig};
 use ir::int::IntKind;
 use ir::item::{Item, ItemCanonicalName, ItemCanonicalPath, ItemId};
@@ -1224,17 +1224,127 @@ impl MethodCodegen for Method {
     }
 }
 
+/// A helper type to construct enums, either bitfield ones or rust-style ones.
+enum EnumBuilder<'a> {
+    Rust(aster::item::ItemEnumBuilder<aster::invoke::Identity>),
+    Bitfield {
+        canonical_name: &'a str,
+        aster: P<ast::Item>,
+    },
+}
+
+impl<'a> EnumBuilder<'a> {
+    /// Create a new enum given an item builder, a canonical name, a name for
+    /// the representation, and whether it should be represented as a rust enum.
+    fn new(aster: aster::item::ItemBuilder<aster::invoke::Identity>,
+           name: &'a str,
+           repr_name: &str,
+           is_rust: bool)
+           -> Self {
+        if is_rust {
+            EnumBuilder::Rust(aster.enum_(name))
+        } else {
+            EnumBuilder::Bitfield {
+                canonical_name: name,
+                aster: aster.tuple_struct(name)
+                    .field()
+                    .pub_()
+                    .ty()
+                    .id(repr_name)
+                    .build(),
+            }
+        }
+    }
+
+    /// Add a variant to this enum.
+    fn with_variant(self,
+                    ctx: &BindgenContext,
+                    variant: &EnumVariant,
+                    mangling_prefix: Option<&String>,
+                    rust_ty: P<ast::Ty>,
+                    result: &mut CodegenResult)
+                    -> Self {
+        let variant_name = ctx.rust_mangle(variant.name());
+        let expr = aster::AstBuilder::new().expr();
+        let expr = match variant.val() {
+            EnumVariantValue::Signed(v) => expr.int(v),
+            EnumVariantValue::Unsigned(v) => expr.uint(v),
+        };
+
+        match self {
+            EnumBuilder::Rust(b) => {
+                EnumBuilder::Rust(b.with_variant_(ast::Variant_ {
+                    name: ctx.rust_ident(&*variant_name),
+                    attrs: vec![],
+                    data: ast::VariantData::Unit(ast::DUMMY_NODE_ID),
+                    disr_expr: Some(expr),
+                }))
+            }
+            EnumBuilder::Bitfield { canonical_name, .. } => {
+                let constant_name = match mangling_prefix {
+                    Some(prefix) => {
+                        Cow::Owned(format!("{}_{}", prefix, variant_name))
+                    }
+                    None => variant_name,
+                };
+
+                let constant = aster::AstBuilder::new()
+                    .item()
+                    .pub_()
+                    .const_(&*constant_name)
+                    .expr()
+                    .call()
+                    .id(canonical_name)
+                    .arg()
+                    .build(expr)
+                    .build()
+                    .build(rust_ty);
+                result.push(constant);
+                self
+            }
+        }
+    }
+
+    fn build(self,
+             ctx: &BindgenContext,
+             rust_ty: P<ast::Ty>,
+             result: &mut CodegenResult)
+             -> P<ast::Item> {
+        match self {
+            EnumBuilder::Rust(b) => b.build(),
+            EnumBuilder::Bitfield { canonical_name, aster } => {
+                let rust_ty_name = ctx.rust_ident_raw(canonical_name);
+                let prefix = ctx.trait_prefix();
+
+                let impl_ = quote_item!(ctx.ext_cx(),
+                    impl ::$prefix::ops::BitOr<$rust_ty> for $rust_ty {
+                        type Output = Self;
+
+                        #[inline]
+                        fn bitor(self, other: Self) -> Self {
+                            $rust_ty_name(self.0 | other.0)
+                        }
+                    }
+                )
+                    .unwrap();
+
+                result.push(impl_);
+                aster
+            }
+        }
+    }
+}
+
 impl CodeGenerator for Enum {
     type Extra = Item;
 
     fn codegen(&self,
                ctx: &BindgenContext,
                result: &mut CodegenResult,
                item: &Item) {
-        use ir::enum_ty::EnumVariantValue;
-
         let name = item.canonical_name(ctx);
-        let layout = item.expect_type().layout(ctx);
+        let enum_ty = item.expect_type();
+        let layout = enum_ty.layout(ctx);
 
         let repr = self.repr().map(|repr| ctx.resolve_type(repr));
         let repr = match repr {
@@ -1270,10 +1380,24 @@ impl CodeGenerator for Enum {
 
         let mut builder = aster::AstBuilder::new().item().pub_();
 
+        let is_bitfield = {
+            ctx.options().bitfield_enums.matches(&name) ||
+            (enum_ty.name().is_none() &&
+             self.variants()
+                .iter()
+                .any(|v| ctx.options().bitfield_enums.matches(&v.name())))
+        };
+
+        let is_rust_enum = !is_bitfield;
+
         // FIXME: Rust forbids repr with empty enums. Remove this condition when
         // this is allowed.
-        if !self.variants().is_empty() {
-            builder = builder.with_attr(attributes::repr(repr_name));
+        if is_rust_enum {
+            if !self.variants().is_empty() {
+                builder = builder.with_attr(attributes::repr(repr_name));
+            }
+        } else {
+            builder = builder.with_attr(attributes::repr("C"));
         }
 
         if let Some(comment) = item.comment() {
@@ -1289,8 +1413,6 @@ impl CodeGenerator for Enum {
 
         builder = builder.with_attr(derives);
 
-        let mut builder = builder.enum_(&name);
-
         fn add_constant(enum_: &Type,
                         // Only to avoid recomputing every time.
                         enum_canonical_name: &str,
@@ -1318,52 +1440,64 @@ impl CodeGenerator for Enum {
             result.push(constant);
         }
 
-        // Used to mangle the constants we generate in the unnamed-enum case.
-        let mut parent_canonical_name = None;
+        let mut builder =
+            EnumBuilder::new(builder, &name, repr_name, is_rust_enum);
 
         // A map where we keep a value -> variant relation.
         let mut seen_values = HashMap::<_, String>::new();
-        let enum_ty = item.expect_type();
         let enum_rust_ty = item.to_rust_ty(ctx);
+        let is_toplevel = item.is_toplevel(ctx);
+
+        // Used to mangle the constants we generate in the unnamed-enum case.
+        let parent_canonical_name = if is_toplevel {
+            None
+        } else {
+            Some(item.parent_id().canonical_name(ctx))
+        };
+
+        let constant_mangling_prefix = if enum_ty.name().is_none() {
+            parent_canonical_name.as_ref().map(|n| &*n)
+        } else {
+            Some(&name)
+        };
+
         for variant in self.variants().iter() {
             match seen_values.entry(variant.val()) {
                 Entry::Occupied(ref entry) => {
-                    let existing_variant_name = entry.get();
-                    let variant_name = ctx.rust_mangle(variant.name());
-                    add_constant(enum_ty,
-                                 &name,
-                                 &*variant_name,
-                                 existing_variant_name,
-                                 enum_rust_ty.clone(),
-                                 result);
+                    if is_rust_enum {
+                        let existing_variant_name = entry.get();
+                        let variant_name = ctx.rust_mangle(variant.name());
+                        add_constant(enum_ty,
+                                     &name,
+                                     &*variant_name,
+                                     existing_variant_name,
+                                     enum_rust_ty.clone(),
+                                     result);
+                    } else {
+                        builder = builder.with_variant(ctx,
+                                          variant,
+                                          constant_mangling_prefix,
+                                          enum_rust_ty.clone(),
+                                          result);
+                    }
                 }
                 Entry::Vacant(entry) => {
-                    let expr = aster::AstBuilder::new().expr();
-                    let expr = match variant.val() {
-                        EnumVariantValue::Signed(val) => expr.int(val),
-                        EnumVariantValue::Unsigned(val) => expr.uint(val),
-                    };
+                    builder = builder.with_variant(ctx,
+                                                   variant,
+                                                   constant_mangling_prefix,
+                                                   enum_rust_ty.clone(),
+                                                   result);
+
                     let variant_name = ctx.rust_mangle(variant.name());
-                    builder = builder.with_variant_(ast::Variant_ {
-                        name: ctx.rust_ident(&*variant_name),
-                        attrs: vec![],
-                        data: ast::VariantData::Unit(ast::DUMMY_NODE_ID),
-                        disr_expr: Some(expr),
-                    });
 
                     // If it's an unnamed enum, we also generate a constant so
                     // it can be properly accessed.
-                    if enum_ty.name().is_none() {
+                    if is_rust_enum && enum_ty.name().is_none() {
                         // NB: if we want to do this for other kind of nested
                         // enums we can probably mangle the name.
-                        let mangled_name = if item.is_toplevel(ctx) {
+                        let mangled_name = if is_toplevel {
                             variant_name.clone()
                         } else {
-                            if parent_canonical_name.is_none() {
-                                parent_canonical_name = Some(item.parent_id()
-                                    .canonical_name(ctx));
-                            }
-
                             let parent_name = parent_canonical_name.as_ref()
                                 .unwrap();
 
@@ -1384,8 +1518,8 @@ impl CodeGenerator for Enum {
             }
         }
 
-
-        result.push(builder.build());
+        let enum_ = builder.build(ctx, enum_rust_ty, result);
+        result.push(enum_);
     }
 }
 

src/lib.rs

@@ -166,6 +166,15 @@ impl Builder {
         self
     }
 
+    /// Mark the given enum (or set of enums, if using a pattern) as being
+    /// bitfield-like.
+    ///
+    /// This makes bindgen generate a type that isn't a rust `enum`.
+    pub fn bitfield_enum<T: Borrow<str>>(mut self, arg: T) -> Builder {
+        self.options.bitfield_enums.insert(&arg);
+        self
+    }
+
     /// Add a string to prepend to the generated bindings. The string is passed
     /// through without any modification.
     pub fn raw_line<T: Into<String>>(mut self, arg: T) -> Builder {
@@ -262,6 +271,9 @@ pub struct BindgenOptions {
     /// Whitelisted variables. See docs for `whitelisted_types` for more.
     pub whitelisted_vars: RegexSet,
 
+    /// The enum patterns to mark an enum as bitfield.
+    pub bitfield_enums: RegexSet,
+
     /// Whether we should generate builtins or not.
     pub builtins: bool,
 
@@ -329,6 +341,7 @@ impl Default for BindgenOptions {
             whitelisted_types: Default::default(),
             whitelisted_functions: Default::default(),
             whitelisted_vars: Default::default(),
+            bitfield_enums: Default::default(),
             builtins: false,
             links: vec![],
             emit_ast: false,