Auto merge of #1063 - liranringel:disable-mangling-if-link-name-is-specified, r=emilio

Tell LLVM to not mangle names if they're already mangled

LLVM mangles the name by default but functions are already mangled because the `link_name` attribute's value is mangled.
Prefixing the name with `\u{1}` should tell LLVM to not mangle it.

I originally thought it's a bug in rustc, but it was clarified here: rust-lang/rust#45073

Author: bors-servo

src/codegen/helpers.rs

@@ -45,6 +45,9 @@ pub mod attributes {
     }
 
     pub fn link_name(name: &str) -> quote::Tokens {
+        // LLVM mangles the name by default but it's already mangled.
+        // Prefixing the name with \u{1} should tell LLVM to not mangle it.
+        let name = format!("\u{1}{}", name);
         quote! {
             #[link_name = #name]
         }

src/ir/context.rs

@@ -391,9 +391,6 @@ pub struct BindgenContext {
     /// bitfield allocation units computed. Drained in `compute_bitfield_units`.
     need_bitfield_allocation: Vec<ItemId>,
 
-    /// Whether we need the mangling hack which removes the prefixing underscore.
-    needs_mangling_hack: bool,
-
     /// The set of (`ItemId`s of) types that can't derive debug.
     ///
     /// This is populated when we enter codegen by `compute_cannot_derive_debug`
@@ -558,15 +555,6 @@ impl BindgenContext {
             ).expect("TranslationUnit::parse failed")
         };
 
-        // Mac os, iOS and Win32 need __ for mangled symbols but rust will
-        // automatically prepend the extra _.
-        //
-        // We need to make sure that we don't include __ because rust will turn
-        // into ___.
-        let needs_mangling_hack = effective_target.contains("darwin") ||
-            effective_target.contains("ios") ||
-            effective_target == "i686-pc-win32";
-
         let root_module = Self::build_root_module(ItemId(0));
         let root_module_id = root_module.id().as_module_id_unchecked();
 
@@ -592,7 +580,6 @@ impl BindgenContext {
             codegen_items: None,
             used_template_parameters: None,
             need_bitfield_allocation: Default::default(),
-            needs_mangling_hack: needs_mangling_hack,
             cannot_derive_debug: None,
             cannot_derive_default: None,
             cannot_derive_copy: None,
@@ -1415,11 +1402,6 @@ impl BindgenContext {
         Item::new(id, None, None, id, ItemKind::Module(module))
     }
 
-    /// Returns the target triple bindgen is running over.
-    pub fn needs_mangling_hack(&self) -> bool {
-        self.needs_mangling_hack
-    }
-
     /// Get the root module.
     pub fn root_module(&self) -> ModuleId {
         self.root_module

src/ir/function.rs

@@ -206,23 +206,6 @@ fn get_abi(cc: CXCallingConv) -> Abi {
     }
 }
 
-fn mangling_hack_if_needed(ctx: &BindgenContext, symbol: &mut String) {
-    if ctx.needs_mangling_hack() {
-        match symbol.chars().next().unwrap() {
-            // Stripping leading underscore for all names on Darwin and
-            // C linkage functions on Win32.
-            '_' => {
-                symbol.remove(0);
-            }
-            // Stop Rust from prepending underscore for variables on Win32.
-            '?' => {
-                symbol.insert(0, '\x01');
-            }
-            _ => {}
-        }
-    }
-}
-
 /// Get the mangled name for the cursor's referent.
 pub fn cursor_mangling(
     ctx: &BindgenContext,
@@ -241,8 +224,7 @@ pub fn cursor_mangling(
     }
 
     if let Ok(mut manglings) = cursor.cxx_manglings() {
-        if let Some(mut m) = manglings.pop() {
-            mangling_hack_if_needed(ctx, &mut m);
+        if let Some(m) = manglings.pop() {
             return Some(m);
         }
     }
@@ -252,8 +234,6 @@ pub fn cursor_mangling(
         return None;
     }
 
-    mangling_hack_if_needed(ctx, &mut mangling);
-
     if cursor.kind() == clang_sys::CXCursor_Destructor {
         // With old (3.8-) libclang versions, and the Itanium ABI, clang returns
         // the "destructor group 0" symbol, which means that it'll try to free

tests/expectations/tests/arg_keyword.rs

@@ -5,6 +5,6 @@
 
 
 extern "C" {
-    #[link_name = "_Z3fooPKc"]
+    #[link_name = "\u{1}_Z3fooPKc"]
     pub fn foo(type_: *const ::std::os::raw::c_char);
 }

tests/expectations/tests/bitfield-method-same-name.rs

@@ -24,15 +24,15 @@ fn bindgen_test_layout_Foo() {
     );
 }
 extern "C" {
-    #[link_name = "_ZN3Foo4typeEv"]
+    #[link_name = "\u{1}_ZN3Foo4typeEv"]
     pub fn Foo_type(this: *mut Foo) -> ::std::os::raw::c_char;
 }
 extern "C" {
-    #[link_name = "_ZN3Foo9set_type_Ec"]
+    #[link_name = "\u{1}_ZN3Foo9set_type_Ec"]
     pub fn Foo_set_type_(this: *mut Foo, c: ::std::os::raw::c_char);
 }
 extern "C" {
-    #[link_name = "_ZN3Foo8set_typeEc"]
+    #[link_name = "\u{1}_ZN3Foo8set_typeEc"]
     pub fn Foo_set_type(this: *mut Foo, c: ::std::os::raw::c_char);
 }
 impl Clone for Foo {

tests/expectations/tests/bitfield_large_overflow.rs

@@ -28,6 +28,6 @@ impl Clone for _bindgen_ty_1 {
     }
 }
 extern "C" {
-    #[link_name = "a"]
+    #[link_name = "\u{1}a"]
     pub static mut a: _bindgen_ty_1;
 }

tests/expectations/tests/canonical_path_without_namespacing.rs

@@ -20,6 +20,6 @@ impl Clone for Bar {
     fn clone(&self) -> Self { *self }
 }
 extern "C" {
-    #[link_name = "_Z3bazPN3foo3BarE"]
+    #[link_name = "\u{1}_Z3bazPN3foo3BarE"]
     pub fn baz(arg1: *mut Bar);
 }

tests/expectations/tests/class.rs

@@ -245,23 +245,23 @@ fn bindgen_test_layout_RealAbstractionWithTonsOfMethods() {
                 RealAbstractionWithTonsOfMethods ) ));
 }
 extern "C" {
-    #[link_name = "_ZNK32RealAbstractionWithTonsOfMethods3barEv"]
+    #[link_name = "\u{1}_ZNK32RealAbstractionWithTonsOfMethods3barEv"]
     pub fn RealAbstractionWithTonsOfMethods_bar(this:
                                                     *const RealAbstractionWithTonsOfMethods);
 }
 extern "C" {
-    #[link_name = "_ZN32RealAbstractionWithTonsOfMethods3barEv"]
+    #[link_name = "\u{1}_ZN32RealAbstractionWithTonsOfMethods3barEv"]
     pub fn RealAbstractionWithTonsOfMethods_bar1(this:
                                                      *mut RealAbstractionWithTonsOfMethods);
 }
 extern "C" {
-    #[link_name = "_ZN32RealAbstractionWithTonsOfMethods3barEi"]
+    #[link_name = "\u{1}_ZN32RealAbstractionWithTonsOfMethods3barEi"]
     pub fn RealAbstractionWithTonsOfMethods_bar2(this:
                                                      *mut RealAbstractionWithTonsOfMethods,
                                                  foo: ::std::os::raw::c_int);
 }
 extern "C" {
-    #[link_name = "_ZN32RealAbstractionWithTonsOfMethods3staEv"]
+    #[link_name = "\u{1}_ZN32RealAbstractionWithTonsOfMethods3staEv"]
     pub fn RealAbstractionWithTonsOfMethods_sta();
 }
 impl Clone for RealAbstractionWithTonsOfMethods {

tests/expectations/tests/class_1_0.rs

@@ -395,22 +395,22 @@ fn bindgen_test_layout_RealAbstractionWithTonsOfMethods() {
     );
 }
 extern "C" {
-    #[link_name = "_ZNK32RealAbstractionWithTonsOfMethods3barEv"]
+    #[link_name = "\u{1}_ZNK32RealAbstractionWithTonsOfMethods3barEv"]
     pub fn RealAbstractionWithTonsOfMethods_bar(this: *const RealAbstractionWithTonsOfMethods);
 }
 extern "C" {
-    #[link_name = "_ZN32RealAbstractionWithTonsOfMethods3barEv"]
+    #[link_name = "\u{1}_ZN32RealAbstractionWithTonsOfMethods3barEv"]
     pub fn RealAbstractionWithTonsOfMethods_bar1(this: *mut RealAbstractionWithTonsOfMethods);
 }
 extern "C" {
-    #[link_name = "_ZN32RealAbstractionWithTonsOfMethods3barEi"]
+    #[link_name = "\u{1}_ZN32RealAbstractionWithTonsOfMethods3barEi"]
     pub fn RealAbstractionWithTonsOfMethods_bar2(
         this: *mut RealAbstractionWithTonsOfMethods,
         foo: ::std::os::raw::c_int,
     );
 }
 extern "C" {
-    #[link_name = "_ZN32RealAbstractionWithTonsOfMethods3staEv"]
+    #[link_name = "\u{1}_ZN32RealAbstractionWithTonsOfMethods3staEv"]
     pub fn RealAbstractionWithTonsOfMethods_sta();
 }
 impl Clone for RealAbstractionWithTonsOfMethods {

tests/expectations/tests/class_nested.rs

@@ -115,7 +115,7 @@ impl Clone for A_C {
     }
 }
 extern "C" {
-    #[link_name = "var"]
+    #[link_name = "\u{1}var"]
     pub static mut var: A_B;
 }
 #[test]
@@ -131,7 +131,7 @@ fn __bindgen_test_layout_A_D_open0_int_close0_instantiation() {
     assert_eq ! ( :: std :: mem :: align_of :: < A_D < :: std :: os :: raw :: c_int > > ( ) , 4usize , concat ! ( "Alignment of template specialization: " , stringify ! ( A_D < :: std :: os :: raw :: c_int > ) ) );
 }
 extern "C" {
-    #[link_name = "baz"]
+    #[link_name = "\u{1}baz"]
     pub static mut baz: A_D<::std::os::raw::c_int>;
 }
 #[repr(C)]

tests/expectations/tests/class_static.rs

@@ -10,11 +10,11 @@ pub struct MyClass {
     pub _address: u8,
 }
 extern "C" {
-    #[link_name = "_ZN7MyClass7exampleE"]
+    #[link_name = "\u{1}_ZN7MyClass7exampleE"]
     pub static mut MyClass_example: *const ::std::os::raw::c_int;
 }
 extern "C" {
-    #[link_name = "_ZN7MyClass26example_check_no_collisionE"]
+    #[link_name = "\u{1}_ZN7MyClass26example_check_no_collisionE"]
     pub static mut MyClass_example_check_no_collision:
                *const ::std::os::raw::c_int;
 }
@@ -29,6 +29,6 @@ impl Clone for MyClass {
     fn clone(&self) -> Self { *self }
 }
 extern "C" {
-    #[link_name = "_ZL26example_check_no_collision"]
+    #[link_name = "\u{1}_ZL26example_check_no_collision"]
     pub static mut example_check_no_collision: *const ::std::os::raw::c_int;
 }

tests/expectations/tests/class_with_typedef.rs

@@ -47,19 +47,19 @@ fn bindgen_test_layout_C() {
                 ! ( other_ptr ) ));
 }
 extern "C" {
-    #[link_name = "_ZN1C6methodEi"]
+    #[link_name = "\u{1}_ZN1C6methodEi"]
     pub fn C_method(this: *mut C, c: C_MyInt);
 }
 extern "C" {
-    #[link_name = "_ZN1C9methodRefERi"]
+    #[link_name = "\u{1}_ZN1C9methodRefERi"]
     pub fn C_methodRef(this: *mut C, c: *mut C_MyInt);
 }
 extern "C" {
-    #[link_name = "_ZN1C16complexMethodRefERPKc"]
+    #[link_name = "\u{1}_ZN1C16complexMethodRefERPKc"]
     pub fn C_complexMethodRef(this: *mut C, c: *mut C_Lookup);
 }
 extern "C" {
-    #[link_name = "_ZN1C13anotherMethodEi"]
+    #[link_name = "\u{1}_ZN1C13anotherMethodEi"]
     pub fn C_anotherMethod(this: *mut C, c: AnotherInt);
 }
 impl Clone for C {

tests/expectations/tests/complex_global.rs

@@ -11,14 +11,14 @@ pub struct __BindgenComplex<T> {
     pub im: T,
 }
 extern "C" {
-    #[link_name = "globalValueFloat"]
+    #[link_name = "\u{1}globalValueFloat"]
     pub static mut globalValueFloat: __BindgenComplex<f32>;
 }
 extern "C" {
-    #[link_name = "globalValueDouble"]
+    #[link_name = "\u{1}globalValueDouble"]
     pub static mut globalValueDouble: __BindgenComplex<f64>;
 }
 extern "C" {
-    #[link_name = "globalValueLongDouble"]
+    #[link_name = "\u{1}globalValueLongDouble"]
     pub static mut globalValueLongDouble: __BindgenComplex<f64>;
 }

tests/expectations/tests/constify-module-enums-types.rs

@@ -165,12 +165,12 @@ impl Default for Bar {
     fn default() -> Self { unsafe { ::std::mem::zeroed() } }
 }
 extern "C" {
-    #[link_name = "_Z5func13fooPS_PS0_"]
+    #[link_name = "\u{1}_Z5func13fooPS_PS0_"]
     pub fn func1(arg1: foo::Type, arg2: *mut foo::Type,
                  arg3: *mut *mut foo::Type) -> *mut foo::Type;
 }
 extern "C" {
-    #[link_name = "_Z5func23fooPS_PS0_"]
+    #[link_name = "\u{1}_Z5func23fooPS_PS0_"]
     pub fn func2(arg1: foo_alias1, arg2: *mut foo_alias1,
                  arg3: *mut *mut foo_alias1) -> *mut foo_alias1;
 }
@@ -184,10 +184,10 @@ impl <T> Default for Thing<T> {
     fn default() -> Self { unsafe { ::std::mem::zeroed() } }
 }
 extern "C" {
-    #[link_name = "_Z5func35ThingI3fooE"]
+    #[link_name = "\u{1}_Z5func35ThingI3fooE"]
     pub fn func3(arg1: Thing<foo::Type>) -> foo::Type;
 }
 extern "C" {
-    #[link_name = "_Z5func45ThingIS_I3fooEE"]
+    #[link_name = "\u{1}_Z5func45ThingIS_I3fooEE"]
     pub fn func4(arg1: Thing<Thing<foo::Type>>) -> foo::Type;
 }

tests/expectations/tests/constructor-tp.rs

@@ -22,7 +22,7 @@ fn bindgen_test_layout_Bar() {
                 "Alignment of " , stringify ! ( Bar ) ));
 }
 extern "C" {
-    #[link_name = "_ZN3BarC1Ev"]
+    #[link_name = "\u{1}_ZN3BarC1Ev"]
     pub fn Bar_Bar(this: *mut Bar);
 }
 impl Clone for Bar {

tests/expectations/tests/constructors.rs

@@ -17,12 +17,12 @@ fn bindgen_test_layout_TestOverload() {
                 "Alignment of " , stringify ! ( TestOverload ) ));
 }
 extern "C" {
-    #[link_name = "_ZN12TestOverloadC1Ei"]
+    #[link_name = "\u{1}_ZN12TestOverloadC1Ei"]
     pub fn TestOverload_TestOverload(this: *mut TestOverload,
                                      arg1: ::std::os::raw::c_int);
 }
 extern "C" {
-    #[link_name = "_ZN12TestOverloadC1Ed"]
+    #[link_name = "\u{1}_ZN12TestOverloadC1Ed"]
     pub fn TestOverload_TestOverload1(this: *mut TestOverload, arg1: f64);
 }
 impl Clone for TestOverload {
@@ -55,7 +55,7 @@ fn bindgen_test_layout_TestPublicNoArgs() {
                 ( "Alignment of " , stringify ! ( TestPublicNoArgs ) ));
 }
 extern "C" {
-    #[link_name = "_ZN16TestPublicNoArgsC1Ev"]
+    #[link_name = "\u{1}_ZN16TestPublicNoArgsC1Ev"]
     pub fn TestPublicNoArgs_TestPublicNoArgs(this: *mut TestPublicNoArgs);
 }
 impl Clone for TestPublicNoArgs {

tests/expectations/tests/decl_extern_int_twice.rs

@@ -5,6 +5,6 @@
 
 
 extern "C" {
-    #[link_name = "foo"]
+    #[link_name = "\u{1}foo"]
     pub static mut foo: ::std::os::raw::c_int;
 }

tests/expectations/tests/decl_ptr_to_array.rs

@@ -5,6 +5,6 @@
 
 
 extern "C" {
-    #[link_name = "foo"]
+    #[link_name = "\u{1}foo"]
     pub static mut foo: *mut [::std::os::raw::c_int; 1usize];
 }

tests/expectations/tests/default-template-parameter.rs

@@ -37,6 +37,6 @@ fn __bindgen_test_layout_Foo_open0_bool__int_close0_instantiation() {
     );
 }
 extern "C" {
-    #[link_name = "_ZL3bar"]
+    #[link_name = "\u{1}_ZL3bar"]
     pub static mut bar: Foo<bool, ::std::os::raw::c_int>;
 }

tests/expectations/tests/derive-bitfield-method-same-name.rs

@@ -39,15 +39,15 @@ fn bindgen_test_layout_Foo() {
     );
 }
 extern "C" {
-    #[link_name = "_ZN3Foo4typeEv"]
+    #[link_name = "\u{1}_ZN3Foo4typeEv"]
     pub fn Foo_type(this: *mut Foo) -> ::std::os::raw::c_char;
 }
 extern "C" {
-    #[link_name = "_ZN3Foo9set_type_Ec"]
+    #[link_name = "\u{1}_ZN3Foo9set_type_Ec"]
     pub fn Foo_set_type_(this: *mut Foo, c: ::std::os::raw::c_char);
 }
 extern "C" {
-    #[link_name = "_ZN3Foo8set_typeEc"]
+    #[link_name = "\u{1}_ZN3Foo8set_typeEc"]
     pub fn Foo_set_type(this: *mut Foo, c: ::std::os::raw::c_char);
 }
 impl Clone for Foo {

tests/expectations/tests/elaborated.rs

@@ -6,6 +6,6 @@
 
 pub type whatever_whatever_t = ::std::os::raw::c_int;
 extern "C" {
-    #[link_name = "_Z9somethingPKi"]
+    #[link_name = "\u{1}_Z9somethingPKi"]
     pub fn something(wat: *const whatever_whatever_t);
 }

tests/expectations/tests/enum_and_vtable_mangling.rs

@@ -35,6 +35,6 @@ impl Default for C {
     fn default() -> Self { unsafe { ::std::mem::zeroed() } }
 }
 extern "C" {
-    #[link_name = "_ZN1C5matchEv"]
+    #[link_name = "\u{1}_ZN1C5matchEv"]
     pub fn C_match(this: *mut ::std::os::raw::c_void);
 }