//! Intermediate representation for C/C++ functions and methods.
use super::comp::MethodKind;
use super::context::{BindgenContext, TypeId};
use super::dot::DotAttributes;
use super::item::Item;
use super::traversal::{EdgeKind, Trace, Tracer};
use super::ty::TypeKind;
use crate::callbacks::{ItemInfo, ItemKind};
use crate::clang::{self, ABIKind, Attribute};
use crate::parse::{ClangSubItemParser, ParseError, ParseResult};
use clang_sys::{self, CXCallingConv};
use quote::TokenStreamExt;
use std::io;
use std::str::FromStr;
const RUST_DERIVE_FUNPTR_LIMIT: usize = 12;
/// What kind of a function are we looking at?
#[derive(Debug, Copy, Clone, PartialEq, Eq)]
pub(crate) enum FunctionKind {
/// A plain, free function.
Function,
/// A method of some kind.
Method(MethodKind),
}
impl FunctionKind {
/// Given a clang cursor, return the kind of function it represents, or
/// `None` otherwise.
pub(crate) fn from_cursor(cursor: &clang::Cursor) -> Option<FunctionKind> {
// FIXME(emilio): Deduplicate logic with `ir::comp`.
Some(match cursor.kind() {
clang_sys::CXCursor_FunctionDecl => FunctionKind::Function,
clang_sys::CXCursor_Constructor => {
FunctionKind::Method(MethodKind::Constructor)
}
clang_sys::CXCursor_Destructor => {
FunctionKind::Method(if cursor.method_is_virtual() {
MethodKind::VirtualDestructor {
pure_virtual: cursor.method_is_pure_virtual(),
}
} else {
MethodKind::Destructor
})
}
clang_sys::CXCursor_CXXMethod => {
if cursor.method_is_virtual() {
FunctionKind::Method(MethodKind::Virtual {
pure_virtual: cursor.method_is_pure_virtual(),
})
} else if cursor.method_is_static() {
FunctionKind::Method(MethodKind::Static)
} else {
FunctionKind::Method(MethodKind::Normal)
}
}
_ => return None,
})
}
}
/// The style of linkage
#[derive(Debug, Clone, Copy)]
pub(crate) enum Linkage {
/// Externally visible and can be linked against
External,
/// Not exposed externally. 'static inline' functions will have this kind of linkage
Internal,
}
/// A function declaration, with a signature, arguments, and argument names.
///
/// The argument names vector must be the same length as the ones in the
/// signature.
#[derive(Debug)]
pub(crate) struct Function {
/// The name of this function.
name: String,
/// The mangled name, that is, the symbol.
mangled_name: Option<String>,
/// The link name. If specified, overwrite mangled_name.
link_name: Option<String>,
/// The ID pointing to the current function signature.
signature: TypeId,
/// The kind of function this is.
kind: FunctionKind,
/// The linkage of the function.
linkage: Linkage,
}
impl Function {
/// Construct a new function.
pub(crate) fn new(
name: String,
mangled_name: Option<String>,
link_name: Option<String>,
signature: TypeId,
kind: FunctionKind,
linkage: Linkage,
) -> Self {
Function {
name,
mangled_name,
link_name,
signature,
kind,
linkage,
}
}
/// Get this function's name.
pub(crate) fn name(&self) -> &str {
&self.name
}
/// Get this function's name.
pub(crate) fn mangled_name(&self) -> Option<&str> {
self.mangled_name.as_deref()
}
/// Get this function's link name.
pub fn link_name(&self) -> Option<&str> {
self.link_name.as_deref()
}
/// Get this function's signature type.
pub(crate) fn signature(&self) -> TypeId {
self.signature
}
/// Get this function's kind.
pub(crate) fn kind(&self) -> FunctionKind {
self.kind
}
/// Get this function's linkage.
pub(crate) fn linkage(&self) -> Linkage {
self.linkage
}
}
impl DotAttributes for Function {
fn dot_attributes<W>(
&self,
_ctx: &BindgenContext,
out: &mut W,
) -> io::Result<()>
where
W: io::Write,
{
if let Some(ref mangled) = self.mangled_name {
let mangled: String =
mangled.chars().flat_map(|c| c.escape_default()).collect();
writeln!(
out,
"<tr><td>mangled name</td><td>{}</td></tr>",
mangled
)?;
}
Ok(())
}
}
/// A valid rust ABI.
#[derive(Debug, Copy, Clone, Hash, Eq, PartialEq)]
pub enum Abi {
/// The default C ABI.
C,
/// The "stdcall" ABI.
Stdcall,
/// The "efiapi" ABI.
EfiApi,
/// The "fastcall" ABI.
Fastcall,
/// The "thiscall" ABI.
ThisCall,
/// The "vectorcall" ABI.
Vectorcall,
/// The "aapcs" ABI.
Aapcs,
/// The "win64" ABI.
Win64,
/// The "C-unwind" ABI.
CUnwind,
/// The "system" ABI.
System,
}
impl FromStr for Abi {
type Err = String;
fn from_str(s: &str) -> Result<Self, Self::Err> {
match s {
"C" => Ok(Self::C),
"stdcall" => Ok(Self::Stdcall),
"efiapi" => Ok(Self::EfiApi),
"fastcall" => Ok(Self::Fastcall),
"thiscall" => Ok(Self::ThisCall),
"vectorcall" => Ok(Self::Vectorcall),
"aapcs" => Ok(Self::Aapcs),
"win64" => Ok(Self::Win64),
"C-unwind" => Ok(Self::CUnwind),
"system" => Ok(Self::System),
_ => Err(format!("Invalid or unknown ABI {:?}", s)),
}
}
}
impl std::fmt::Display for Abi {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
let s = match *self {
Self::C => "C",
Self::Stdcall => "stdcall",
Self::EfiApi => "efiapi",
Self::Fastcall => "fastcall",
Self::ThisCall => "thiscall",
Self::Vectorcall => "vectorcall",
Self::Aapcs => "aapcs",
Self::Win64 => "win64",
Self::CUnwind => "C-unwind",
Abi::System => "system",
};
s.fmt(f)
}
}
impl quote::ToTokens for Abi {
fn to_tokens(&self, tokens: &mut proc_macro2::TokenStream) {
let abi = self.to_string();
tokens.append_all(quote! { #abi });
}
}
/// An ABI extracted from a clang cursor.
#[derive(Debug, Copy, Clone)]
pub(crate) enum ClangAbi {
/// An ABI known by Rust.
Known(Abi),
/// An unknown or invalid ABI.
Unknown(CXCallingConv),
}
impl ClangAbi {
/// Returns whether this Abi is known or not.
fn is_unknown(&self) -> bool {
matches!(*self, ClangAbi::Unknown(..))
}
}
impl quote::ToTokens for ClangAbi {
fn to_tokens(&self, tokens: &mut proc_macro2::TokenStream) {
match *self {
Self::Known(abi) => abi.to_tokens(tokens),
Self::Unknown(cc) => panic!(
"Cannot turn unknown calling convention to tokens: {:?}",
cc
),
}
}
}
/// A function signature.
#[derive(Debug)]
pub(crate) struct FunctionSig {
/// The name of this function signature.
name: String,
/// The return type of the function.
return_type: TypeId,
/// The type of the arguments, optionally with the name of the argument when
/// declared.
argument_types: Vec<(Option<String>, TypeId)>,
/// Whether this function is variadic.
is_variadic: bool,
is_divergent: bool,
/// Whether this function's return value must be used.
must_use: bool,
/// The ABI of this function.
abi: ClangAbi,
}
fn get_abi(cc: CXCallingConv) -> ClangAbi {
use clang_sys::*;
match cc {
CXCallingConv_Default => ClangAbi::Known(Abi::C),
CXCallingConv_C => ClangAbi::Known(Abi::C),
CXCallingConv_X86StdCall => ClangAbi::Known(Abi::Stdcall),
CXCallingConv_X86FastCall => ClangAbi::Known(Abi::Fastcall),
CXCallingConv_X86ThisCall => ClangAbi::Known(Abi::ThisCall),
CXCallingConv_X86VectorCall => ClangAbi::Known(Abi::Vectorcall),
CXCallingConv_AAPCS => ClangAbi::Known(Abi::Aapcs),
CXCallingConv_X86_64Win64 => ClangAbi::Known(Abi::Win64),
CXCallingConv_AArch64VectorCall => ClangAbi::Known(Abi::Vectorcall),
other => ClangAbi::Unknown(other),
}
}
/// Get the mangled name for the cursor's referent.
pub(crate) fn cursor_mangling(
ctx: &BindgenContext,
cursor: &clang::Cursor,
) -> Option<String> {
if !ctx.options().enable_mangling {
return None;
}
// We early return here because libclang may crash in some case
// if we pass in a variable inside a partial specialized template.
// See rust-lang/rust-bindgen#67, and rust-lang/rust-bindgen#462.
if cursor.is_in_non_fully_specialized_template() {
return None;
}
let is_itanium_abi = ctx.abi_kind() == ABIKind::GenericItanium;
let is_destructor = cursor.kind() == clang_sys::CXCursor_Destructor;
if let Ok(mut manglings) = cursor.cxx_manglings() {
while let Some(m) = manglings.pop() {
// Only generate the destructor group 1, see below.
if is_itanium_abi && is_destructor && !m.ends_with("D1Ev") {
continue;
}
return Some(m);
}
}
let mut mangling = cursor.mangling();
if mangling.is_empty() {
return None;
}
if is_itanium_abi && is_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
// memory, which definitely isn't what we want.
//
// Explicitly force the destructor group 1 symbol.
//
// See
http://refspecs.linuxbase.org/cxxabi-1.83.html#mangling-special
// for the reference, and
http://stackoverflow.com/a/6614369/1091587 for
// a more friendly explanation.
//
// We don't need to do this for constructors since clang seems to always
// have returned the C1 constructor.
//
// FIXME(emilio): Can a legit symbol in other ABIs end with this string?
// I don't think so, but if it can this would become a linker error
// anyway, not an invalid free at runtime.
//
// TODO(emilio, #611): Use cpp_demangle if this becomes nastier with
// time.
if mangling.ends_with("D0Ev") {
let new_len = mangling.len() - 4;
mangling.truncate(new_len);
mangling.push_str("D1Ev");
}
}
Some(mangling)
}
fn args_from_ty_and_cursor(
ty: &clang::Type,
cursor: &clang::Cursor,
ctx: &mut BindgenContext,
) -> Vec<(Option<String>, TypeId)> {
let cursor_args = cursor.args().unwrap_or_default().into_iter();
let type_args = ty.args().unwrap_or_default().into_iter();
// Argument types can be found in either the cursor or the type, but argument names may only be
// found on the cursor. We often have access to both a type and a cursor for each argument, but
// in some cases we may only have one.
//
// Prefer using the type as the source of truth for the argument's type, but fall back to
// inspecting the cursor (this happens for Objective C interfaces).
//
// Prefer using the cursor for the argument's type, but fall back to using the parent's cursor
// (this happens for function pointer return types).
cursor_args
.map(Some)
.chain(std::iter::repeat(None))
.zip(type_args.map(Some).chain(std::iter::repeat(None)))
.take_while(|(cur, ty)| cur.is_some() || ty.is_some())
.map(|(arg_cur, arg_ty)| {
let name = arg_cur.map(|a| a.spelling()).and_then(|name| {
if name.is_empty() {
None
} else {
Some(name)
}
});
let cursor = arg_cur.unwrap_or(*cursor);
let ty = arg_ty.unwrap_or_else(|| cursor.cur_type());
(name, Item::from_ty_or_ref(ty, cursor, None, ctx))
})
.collect()
}
impl FunctionSig {
/// Get the function name.
pub(crate) fn name(&self) -> &str {
&self.name
}
/// Construct a new function signature from the given Clang type.
pub(crate) fn from_ty(
ty: &clang::Type,
cursor: &clang::Cursor,
ctx: &mut BindgenContext,
) -> Result<Self, ParseError> {
use clang_sys::*;
debug!("FunctionSig::from_ty {:?} {:?}", ty, cursor);
// Skip function templates
let kind = cursor.kind();
if kind == CXCursor_FunctionTemplate {
return Err(ParseError::Continue);
}
let spelling = cursor.spelling();
// Don't parse operatorxx functions in C++
let is_operator = |spelling: &str| {
spelling.starts_with("operator") &&
!clang::is_valid_identifier(spelling)
};
if is_operator(&spelling) {
return Err(ParseError::Continue);
}
// Constructors of non-type template parameter classes for some reason
// include the template parameter in their name. Just skip them, since
// we don't handle well non-type template parameters anyway.
if (kind == CXCursor_Constructor || kind == CXCursor_Destructor) &&
spelling.contains('<')
{
return Err(ParseError::Continue);
}
let cursor = if cursor.is_valid() {
*cursor
} else {
ty.declaration()
};
let mut args = match kind {
CXCursor_FunctionDecl |
CXCursor_Constructor |
CXCursor_CXXMethod |
CXCursor_ObjCInstanceMethodDecl |
CXCursor_ObjCClassMethodDecl => {
args_from_ty_and_cursor(ty, &cursor, ctx)
}
_ => {
// For non-CXCursor_FunctionDecl, visiting the cursor's children
// is the only reliable way to get parameter names.
let mut args = vec![];
cursor.visit(|c| {
if c.kind() == CXCursor_ParmDecl {
let ty =
Item::from_ty_or_ref(c.cur_type(), c, None, ctx);
let name = c.spelling();
let name =
if name.is_empty() { None } else { Some(name) };
args.push((name, ty));
}
CXChildVisit_Continue
});
if args.is_empty() {
// FIXME(emilio): Sometimes libclang doesn't expose the
// right AST for functions tagged as stdcall and such...
//
//
https://bugs.llvm.org/show_bug.cgi?id=45919
args_from_ty_and_cursor(ty, &cursor, ctx)
} else {
args
}
}
};
let (must_use, mut is_divergent) =
if ctx.options().enable_function_attribute_detection {
let [must_use, no_return, no_return_cpp] = cursor.has_attrs(&[
Attribute::MUST_USE,
Attribute::NO_RETURN,
Attribute::NO_RETURN_CPP,
]);
(must_use, no_return || no_return_cpp)
} else {
Default::default()
};
// Check if the type contains __attribute__((noreturn)) outside of parentheses. This is
// somewhat fragile, but it seems to be the only way to get at this information as of
// libclang 9.
let ty_spelling = ty.spelling();
let has_attribute_noreturn = ty_spelling
.match_indices("__attribute__((noreturn))")
.any(|(i, _)| {
let depth = ty_spelling[..i]
.bytes()
.filter_map(|ch| match ch {
b'(' => Some(1),
b')' => Some(-1),
_ => None,
})
.sum::<isize>();
depth == 0
});
is_divergent = is_divergent || has_attribute_noreturn;
let is_method = kind == CXCursor_CXXMethod;
let is_constructor = kind == CXCursor_Constructor;
let is_destructor = kind == CXCursor_Destructor;
if (is_constructor || is_destructor || is_method) &&
cursor.lexical_parent() != cursor.semantic_parent()
{
// Only parse constructors once.
return Err(ParseError::Continue);
}
if is_method || is_constructor || is_destructor {
let is_const = is_method && cursor.method_is_const();
let is_virtual = is_method && cursor.method_is_virtual();
let is_static = is_method && cursor.method_is_static();
if !is_static && !is_virtual {
let parent = cursor.semantic_parent();
let class = Item::parse(parent, None, ctx)
.expect("Expected to parse the class");
// The `class` most likely is not finished parsing yet, so use
// the unchecked variant.
let class = class.as_type_id_unchecked();
let class = if is_const {
let const_class_id = ctx.next_item_id();
ctx.build_const_wrapper(
const_class_id,
class,
None,
&parent.cur_type(),
)
} else {
class
};
let ptr =
Item::builtin_type(TypeKind::Pointer(class), false, ctx);
args.insert(0, (Some("this".into()), ptr));
} else if is_virtual {
let void = Item::builtin_type(TypeKind::Void, false, ctx);
let ptr =
Item::builtin_type(TypeKind::Pointer(void), false, ctx);
args.insert(0, (Some("this".into()), ptr));
}
}
let ty_ret_type = if kind == CXCursor_ObjCInstanceMethodDecl ||
kind == CXCursor_ObjCClassMethodDecl
{
ty.ret_type()
.or_else(|| cursor.ret_type())
.ok_or(ParseError::Continue)?
} else {
ty.ret_type().ok_or(ParseError::Continue)?
};
let ret = if is_constructor && ctx.is_target_wasm32() {
// Constructors in Clang wasm32 target return a pointer to the object
// being constructed.
let void = Item::builtin_type(TypeKind::Void, false, ctx);
Item::builtin_type(TypeKind::Pointer(void), false, ctx)
} else {
Item::from_ty_or_ref(ty_ret_type, cursor, None, ctx)
};
// Clang plays with us at "find the calling convention", see #549 and
// co. This seems to be a better fix than that commit.
let mut call_conv = ty.call_conv();
if let Some(ty) = cursor.cur_type().canonical_type().pointee_type() {
let cursor_call_conv = ty.call_conv();
if cursor_call_conv != CXCallingConv_Invalid {
call_conv = cursor_call_conv;
}
}
let abi = get_abi(call_conv);
if abi.is_unknown() {
warn!("Unknown calling convention: {:?}", call_conv);
}
Ok(Self {
name: spelling,
return_type: ret,
argument_types: args,
is_variadic: ty.is_variadic(),
is_divergent,
must_use,
abi,
})
}
/// Get this function signature's return type.
pub(crate) fn return_type(&self) -> TypeId {
self.return_type
}
/// Get this function signature's argument (name, type) pairs.
pub(crate) fn argument_types(&self) -> &[(Option<String>, TypeId)] {
&self.argument_types
}
/// Get this function signature's ABI.
pub(crate) fn abi(
&self,
ctx: &BindgenContext,
name: Option<&str>,
) -> crate::codegen::error::Result<ClangAbi> {
// FIXME (pvdrz): Try to do this check lazily instead. Maybe store the ABI inside `ctx`
// instead?.
let abi = if let Some(name) = name {
if let Some((abi, _)) = ctx
.options()
.abi_overrides
.iter()
.find(|(_, regex_set)| regex_set.matches(name))
{
ClangAbi::Known(*abi)
} else {
self.abi
}
} else if let Some((abi, _)) = ctx
.options()
.abi_overrides
.iter()
.find(|(_, regex_set)| regex_set.matches(&self.name))
{
ClangAbi::Known(*abi)
} else {
self.abi
};
match abi {
ClangAbi::Known(Abi::ThisCall)
if !ctx.options().rust_features().thiscall_abi =>
{
Err(crate::codegen::error::Error::UnsupportedAbi("thiscall"))
}
ClangAbi::Known(Abi::Vectorcall)
if !ctx.options().rust_features().vectorcall_abi =>
{
Err(crate::codegen::error::Error::UnsupportedAbi("vectorcall"))
}
ClangAbi::Known(Abi::CUnwind)
if !ctx.options().rust_features().c_unwind_abi =>
{
Err(crate::codegen::error::Error::UnsupportedAbi("C-unwind"))
}
ClangAbi::Known(Abi::EfiApi)
if !ctx.options().rust_features().abi_efiapi =>
{
Err(crate::codegen::error::Error::UnsupportedAbi("efiapi"))
}
ClangAbi::Known(Abi::Win64) if self.is_variadic() => {
Err(crate::codegen::error::Error::UnsupportedAbi("Win64"))
}
abi => Ok(abi),
}
}
/// Is this function signature variadic?
pub(crate) fn is_variadic(&self) -> bool {
// Clang reports some functions as variadic when they *might* be
// variadic. We do the argument check because rust doesn't codegen well
// variadic functions without an initial argument.
self.is_variadic && !self.argument_types.is_empty()
}
/// Must this function's return value be used?
pub(crate) fn must_use(&self) -> bool {
self.must_use
}
/// Are function pointers with this signature able to derive Rust traits?
/// Rust only supports deriving traits for function pointers with a limited
/// number of parameters and a couple ABIs.
///
/// For more details, see:
///
/// * <
https://github.com/rust-lang/rust-bindgen/issues/547>,
/// * <
https://github.com/rust-lang/rust/issues/38848>,
/// * and <
https://github.com/rust-lang/rust/issues/40158>
pub(crate) fn function_pointers_can_derive(&self) -> bool {
if self.argument_types.len() > RUST_DERIVE_FUNPTR_LIMIT {
return false;
}
matches!(self.abi, ClangAbi::Known(Abi::C) | ClangAbi::Unknown(..))
}
/// Whether this function has attributes marking it as divergent.
pub(crate) fn is_divergent(&self) -> bool {
self.is_divergent
}
}
impl ClangSubItemParser for Function {
fn parse(
cursor: clang::Cursor,
context: &mut BindgenContext,
) -> Result<ParseResult<Self>, ParseError> {
use clang_sys::*;
let kind = match FunctionKind::from_cursor(&cursor) {
None => return Err(ParseError::Continue),
Some(k) => k,
};
debug!("Function::parse({:?}, {:?})", cursor, cursor.cur_type());
let visibility = cursor.visibility();
if visibility != CXVisibility_Default {
return Err(ParseError::Continue);
}
if cursor.access_specifier() == CX_CXXPrivate {
return Err(ParseError::Continue);
}
let linkage = cursor.linkage();
let linkage = match linkage {
CXLinkage_External | CXLinkage_UniqueExternal => Linkage::External,
CXLinkage_Internal => Linkage::Internal,
_ => return Err(ParseError::Continue),
};
if cursor.is_inlined_function() ||
cursor
.definition()
.map_or(false, |x| x.is_inlined_function())
{
if !context.options().generate_inline_functions &&
!context.options().wrap_static_fns
{
return Err(ParseError::Continue);
}
if cursor.is_deleted_function() {
return Err(ParseError::Continue);
}
// We cannot handle `inline` functions that are not `static`.
if context.options().wrap_static_fns &&
cursor.is_inlined_function() &&
matches!(linkage, Linkage::External)
{
return Err(ParseError::Continue);
}
}
// Grab the signature using Item::from_ty.
let sig = Item::from_ty(&cursor.cur_type(), cursor, None, context)?;
let mut name = cursor.spelling();
assert!(!name.is_empty(), "Empty function name?");
if cursor.kind() == CXCursor_Destructor {
// Remove the leading `~`. The alternative to this is special-casing
// code-generation for destructor functions, which seems less than
// ideal.
if name.starts_with('~') {
name.remove(0);
}
// Add a suffix to avoid colliding with constructors. This would be
// technically fine (since we handle duplicated functions/methods),
// but seems easy enough to handle it here.
name.push_str("_destructor");
}
if let Some(nm) = context.options().last_callback(|callbacks| {
callbacks.generated_name_override(ItemInfo {
name: name.as_str(),
kind: ItemKind::Function,
})
}) {
name = nm;
}
assert!(!name.is_empty(), "Empty function name.");
let mangled_name = cursor_mangling(context, &cursor);
let link_name = context.options().last_callback(|callbacks| {
callbacks.generated_link_name_override(ItemInfo {
name: name.as_str(),
kind: ItemKind::Function,
})
});
let function = Self::new(
name.clone(),
mangled_name,
link_name,
sig,
kind,
linkage,
);
Ok(ParseResult::New(function, Some(cursor)))
}
}
impl Trace for FunctionSig {
type Extra = ();
fn trace<T>(&self, _: &BindgenContext, tracer: &mut T, _: &())
where
T: Tracer,
{
tracer.visit_kind(self.return_type().into(), EdgeKind::FunctionReturn);
for &(_, ty) in self.argument_types() {
tracer.visit_kind(ty.into(), EdgeKind::FunctionParameter);
}
}
}
