Add attribute for C++ special members.

See google/autocxx#456 for details.

If I was submitting this upstream, I would have put the information
about special members directly in the MethodKind enum, but that would
have been a pretty invasive change that could cause merge conflicts when
merging from upstream. I've therefore decided to put add a separate enum
that is used in as few places as possible.

src/clang.rs

@@ -683,6 +683,21 @@ impl Cursor {
         unsafe { clang_isVirtualBase(self.x) != 0 }
     }
 
+    // Is this cursor's referent a default constructor?
+    pub fn is_default_constructor(&self) -> bool {
+        unsafe { clang_CXXConstructor_isDefaultConstructor(self.x) != 0 }
+    }
+
+    // Is this cursor's referent a copy constructor?
+    pub fn is_copy_constructor(&self) -> bool {
+        unsafe { clang_CXXConstructor_isCopyConstructor(self.x) != 0 }
+    }
+
+    // Is this cursor's referent a move constructor?
+    pub fn is_move_constructor(&self) -> bool {
+        unsafe { clang_CXXConstructor_isMoveConstructor(self.x) != 0 }
+    }
+
     /// Try to evaluate this cursor.
     pub fn evaluate(&self) -> Option<EvalResult> {
         EvalResult::new(*self)

src/codegen/helpers.rs

@@ -6,6 +6,7 @@ use proc_macro2::{Ident, Span, TokenStream};
 use quote::TokenStreamExt;
 
 pub mod attributes {
+    use crate::ir::comp::SpecialMemberKind;
     use proc_macro2::{Ident, Span, TokenStream};
     use std::str::FromStr;
 
@@ -104,6 +105,18 @@ pub mod attributes {
             #[bindgen_unused_template_param]
         }
     }
+
+    pub fn special_member(kind: SpecialMemberKind) -> TokenStream {
+        let kind_str = match kind {
+            SpecialMemberKind::DefaultConstructor => "default_ctor",
+            SpecialMemberKind::CopyConstructor => "copy_ctor",
+            SpecialMemberKind::MoveConstructor => "move_ctor",
+            SpecialMemberKind::Destructor => "dtor",
+        };
+        quote! {
+            #[bindgen_special_member(#kind_str)]
+        }
+    }
 }
 
 /// Generates a proper type for a field or type with a given `Layout`, that is,

src/codegen/mod.rs

@@ -3977,6 +3977,10 @@ impl CodeGenerator for Function {
             attributes.push(attributes::original_name(self.name()));
         }
 
+        if let Some(special_member_kind) = self.special_member() {
+            attributes.push(attributes::special_member(special_member_kind));
+        }
+
         let link_name = mangled_name.unwrap_or(name);
         if !utils::names_will_be_identical_after_mangling(
             &canonical_name,

src/ir/comp.rs

@@ -73,6 +73,17 @@ impl MethodKind {
     }
 }
 
+// The kind of C++ special member.
+// TODO: We don't currently cover copy assignment or move assignment operator
+// because libclang doesn't provide a way to query for them.
+#[derive(Debug, Copy, Clone, PartialEq)]
+pub enum SpecialMemberKind {
+    DefaultConstructor,
+    CopyConstructor,
+    MoveConstructor,
+    Destructor,
+}
+
 /// A struct representing a C++ method, either static, normal, or virtual.
 #[derive(Debug)]
 pub struct Method {

src/ir/function.rs

@@ -1,6 +1,6 @@
 //! Intermediate representation for C/C++ functions and methods.
 
-use super::comp::MethodKind;
+use super::comp::{MethodKind, SpecialMemberKind};
 use super::context::{BindgenContext, TypeId};
 use super::dot::DotAttributes;
 use super::item::Item;
@@ -92,6 +92,9 @@ pub struct Function {
 
     /// The linkage of the function.
     linkage: Linkage,
+
+    /// C++ special member kind, if any.
+    special_member: Option<SpecialMemberKind>,
 }
 
 impl Function {
@@ -103,6 +106,7 @@ impl Function {
         comment: Option<String>,
         kind: FunctionKind,
         linkage: Linkage,
+        special_member: Option<SpecialMemberKind>,
     ) -> Self {
         Function {
             name,
@@ -111,6 +115,7 @@ impl Function {
             comment,
             kind,
             linkage,
+            special_member,
         }
     }
 
@@ -138,6 +143,11 @@ impl Function {
     pub fn linkage(&self) -> Linkage {
         self.linkage
     }
+
+    /// Get this function's C++ special member kind.
+    pub fn special_member(&self) -> Option<SpecialMemberKind> {
+        self.special_member
+    }
 }
 
 impl DotAttributes for Function {
@@ -631,8 +641,27 @@ impl ClangSubItemParser for Function {
         let mangled_name = cursor_mangling(context, &cursor);
         let comment = cursor.raw_comment();
 
-        let function =
-            Self::new(name, mangled_name, sig, comment, kind, linkage);
+        let special_member = if cursor.is_default_constructor() {
+            Some(SpecialMemberKind::DefaultConstructor)
+        } else if cursor.is_copy_constructor() {
+            Some(SpecialMemberKind::CopyConstructor)
+        } else if cursor.is_move_constructor() {
+            Some(SpecialMemberKind::MoveConstructor)
+        } else if cursor.kind() == clang_sys::CXCursor_Destructor {
+            Some(SpecialMemberKind::Destructor)
+        } else {
+            None
+        };
+
+        let function = Self::new(
+            name,
+            mangled_name,
+            sig,
+            comment,
+            kind,
+            linkage,
+            special_member,
+        );
         Ok(ParseResult::New(function, Some(cursor)))
     }
 }

tests/expectations/tests/constructor-tp.rs

@@ -30,6 +30,7 @@ fn bindgen_test_layout_Bar() {
 }
 extern "C" {
     #[bindgen_original_name("Bar")]
+    #[bindgen_special_member("default_ctor")]
     #[link_name = "\u{1}_ZN3BarC1Ev"]
     pub fn Bar_Bar(this: *mut Bar);
 }

tests/expectations/tests/constructors.rs

@@ -70,6 +70,7 @@ fn bindgen_test_layout_TestPublicNoArgs() {
 }
 extern "C" {
     #[bindgen_original_name("TestPublicNoArgs")]
+    #[bindgen_special_member("default_ctor")]
     #[link_name = "\u{1}_ZN16TestPublicNoArgsC1Ev"]
     pub fn TestPublicNoArgs_TestPublicNoArgs(this: *mut TestPublicNoArgs);
 }

tests/expectations/tests/constructors_1_33.rs

@@ -72,6 +72,7 @@ fn bindgen_test_layout_TestPublicNoArgs() {
 }
 extern "C" {
     #[bindgen_original_name("TestPublicNoArgs")]
+    #[bindgen_special_member("default_ctor")]
     #[link_name = "\u{1}_ZN16TestPublicNoArgsC1Ev"]
     pub fn TestPublicNoArgs_TestPublicNoArgs(this: *mut TestPublicNoArgs);
 }

tests/expectations/tests/gen-destructors.rs

@@ -30,6 +30,7 @@ fn bindgen_test_layout_Foo() {
 }
 extern "C" {
     #[bindgen_original_name("Foo_destructor")]
+    #[bindgen_special_member("dtor")]
     #[link_name = "\u{1}_ZN3FooD1Ev"]
     pub fn Foo_Foo_destructor(this: *mut Foo);
 }

tests/expectations/tests/issue-1197-pure-virtual-stuff.rs

@@ -39,6 +39,7 @@ extern "C" {
 extern "C" {
     #[bindgen_pure_virtual]
     #[bindgen_original_name("Foo_destructor")]
+    #[bindgen_special_member("dtor")]
     #[link_name = "\u{1}_ZN3FooD1Ev"]
     pub fn Foo_Foo_destructor(this: *mut Foo);
 }

tests/expectations/tests/packed-vtable.rs

@@ -33,6 +33,7 @@ impl Default for PackedVtable {
 }
 extern "C" {
     #[bindgen_original_name("PackedVtable_destructor")]
+    #[bindgen_special_member("dtor")]
     #[link_name = "\u{1}_ZN12PackedVtableD1Ev"]
     pub fn PackedVtable_PackedVtable_destructor(this: *mut PackedVtable);
 }

tests/expectations/tests/public-dtor.rs

@@ -25,6 +25,7 @@ fn bindgen_test_layout_cv_String() {
 }
 extern "C" {
     #[bindgen_original_name("String_destructor")]
+    #[bindgen_special_member("dtor")]
     #[link_name = "\u{1}_ZN2cv6StringD1Ev"]
     pub fn cv_String_String_destructor(this: *mut cv_String);
 }

tests/expectations/tests/special-members.rs

@@ -0,0 +1,77 @@
+#![allow(
+    dead_code,
+    non_snake_case,
+    non_camel_case_types,
+    non_upper_case_globals
+)]
+
+#[repr(C)]
+#[derive(Debug, Default)]
+pub struct A {
+    pub _address: u8,
+}
+#[test]
+fn bindgen_test_layout_A() {
+    assert_eq!(
+        ::std::mem::size_of::<A>(),
+        1usize,
+        concat!("Size of: ", stringify!(A))
+    );
+    assert_eq!(
+        ::std::mem::align_of::<A>(),
+        1usize,
+        concat!("Alignment of ", stringify!(A))
+    );
+}
+extern "C" {
+    #[bindgen_original_name("A")]
+    #[bindgen_special_member("default_ctor")]
+    #[link_name = "\u{1}_ZN1AC1Ev"]
+    pub fn A_A(this: *mut A);
+}
+extern "C" {
+    #[bindgen_arg_type_reference(arg1)]
+    #[bindgen_original_name("A")]
+    #[bindgen_special_member("copy_ctor")]
+    #[link_name = "\u{1}_ZN1AC1ERS_"]
+    pub fn A_A1(this: *mut A, arg1: *mut A);
+}
+extern "C" {
+    #[bindgen_arg_type_reference(arg1)]
+    #[bindgen_original_name("A")]
+    #[bindgen_special_member("move_ctor")]
+    #[link_name = "\u{1}_ZN1AC1EOS_"]
+    pub fn A_A2(this: *mut A, arg1: *mut A);
+}
+extern "C" {
+    #[bindgen_original_name("A_destructor")]
+    #[bindgen_special_member("dtor")]
+    #[link_name = "\u{1}_ZN1AD1Ev"]
+    pub fn A_A_destructor(this: *mut A);
+}
+impl A {
+    #[inline]
+    pub unsafe fn new() -> Self {
+        let mut __bindgen_tmp = ::std::mem::MaybeUninit::uninit();
+        A_A(__bindgen_tmp.as_mut_ptr());
+        __bindgen_tmp.assume_init()
+    }
+    #[bindgen_arg_type_reference(arg1)]
+    #[inline]
+    pub unsafe fn new1(arg1: *mut A) -> Self {
+        let mut __bindgen_tmp = ::std::mem::MaybeUninit::uninit();
+        A_A1(__bindgen_tmp.as_mut_ptr(), arg1);
+        __bindgen_tmp.assume_init()
+    }
+    #[bindgen_arg_type_reference(arg1)]
+    #[inline]
+    pub unsafe fn new2(arg1: *mut A) -> Self {
+        let mut __bindgen_tmp = ::std::mem::MaybeUninit::uninit();
+        A_A2(__bindgen_tmp.as_mut_ptr(), arg1);
+        __bindgen_tmp.assume_init()
+    }
+    #[inline]
+    pub unsafe fn destruct(&mut self) {
+        A_A_destructor(self)
+    }
+}

tests/expectations/tests/union_dtor.rs

@@ -49,6 +49,7 @@ fn bindgen_test_layout_UnionWithDtor() {
 }
 extern "C" {
     #[bindgen_original_name("UnionWithDtor_destructor")]
+    #[bindgen_special_member("dtor")]
     #[link_name = "\u{1}_ZN13UnionWithDtorD1Ev"]
     pub fn UnionWithDtor_UnionWithDtor_destructor(this: *mut UnionWithDtor);
 }

tests/expectations/tests/union_dtor_1_0.rs

@@ -94,6 +94,7 @@ fn bindgen_test_layout_UnionWithDtor() {
 }
 extern "C" {
     #[bindgen_original_name("UnionWithDtor_destructor")]
+    #[bindgen_special_member("dtor")]
     #[link_name = "\u{1}_ZN13UnionWithDtorD1Ev"]
     pub fn UnionWithDtor_UnionWithDtor_destructor(this: *mut UnionWithDtor);
 }

tests/expectations/tests/virtual_dtor.rs

@@ -32,6 +32,7 @@ impl Default for nsSlots {
 }
 extern "C" {
     #[bindgen_original_name("nsSlots_destructor")]
+    #[bindgen_special_member("dtor")]
     #[link_name = "\u{1}_ZN7nsSlotsD1Ev"]
     pub fn nsSlots_nsSlots_destructor(this: *mut nsSlots);
 }

tests/headers/special-members.hpp

@@ -0,0 +1,7 @@
+class A {
+public:
+    A();
+    A(A&);
+    A(A&&);
+    ~A();
+};