use crate::syntax::atom::Atom::{self, *};
use crate::syntax::report::Errors;
use crate::syntax::visit::{self, Visit};
use crate::syntax::{
error, ident, trivial, Api, Array, Enum, ExternFn, ExternType, Impl, Lang, Lifetimes,
NamedType, Ptr, Receiver, Ref, Signature, SliceRef, Struct, Trait, Ty1, Type, TypeAlias, Types,
};
use proc_macro2::{Delimiter, Group, Ident, TokenStream};
use quote::{quote, ToTokens};
use std::fmt::Display;
use syn::{GenericParam, Generics, Lifetime};
pub(crate) struct Check<'a> {
apis: &'a [Api],
types: &'a Types<'a>,
errors: &'a mut Errors,
generator: Generator,
}
pub(crate) enum Generator {
// cxx-build crate, cxxbridge cli, cxx-gen.
#[allow(dead_code)]
Build,
// cxxbridge-macro. This is relevant in that the macro output is going to
// get fed straight to rustc, so for errors that rustc already contains
// logic to catch (probably with a better diagnostic than what the proc
// macro API is able to produce), we avoid duplicating them in our own
// diagnostics.
#[allow(dead_code)]
Macro,
}
pub(crate) fn typecheck(cx: &mut Errors, apis: &[Api], types: &Types, generator: Generator) {
do_typecheck(&mut Check {
apis,
types,
errors: cx,
generator,
});
}
fn do_typecheck(cx: &mut Check) {
ident::check_all(cx, cx.apis);
for ty in cx.types {
match ty {
Type::Ident(ident) => check_type_ident(cx, ident),
Type::RustBox(ptr) => check_type_box(cx, ptr),
Type::RustVec(ty) => check_type_rust_vec(cx, ty),
Type::UniquePtr(ptr) => check_type_unique_ptr(cx, ptr),
Type::SharedPtr(ptr) => check_type_shared_ptr(cx, ptr),
Type::WeakPtr(ptr) => check_type_weak_ptr(cx, ptr),
Type::CxxVector(ptr) => check_type_cxx_vector(cx, ptr),
Type::Ref(ty) => check_type_ref(cx, ty),
Type::Ptr(ty) => check_type_ptr(cx, ty),
Type::Array(array) => check_type_array(cx, array),
Type::Fn(ty) => check_type_fn(cx, ty),
Type::SliceRef(ty) => check_type_slice_ref(cx, ty),
Type::Str(_) | Type::Void(_) => {}
}
}
for api in cx.apis {
match api {
Api::Include(_) => {}
Api::Struct(strct) => check_api_struct(cx, strct),
Api::Enum(enm) => check_api_enum(cx, enm),
Api::CxxType(ety) | Api::RustType(ety) => check_api_type(cx, ety),
Api::CxxFunction(efn) | Api::RustFunction(efn) => check_api_fn(cx, efn),
Api::TypeAlias(alias) => check_api_type_alias(cx, alias),
Api::Impl(imp) => check_api_impl(cx, imp),
}
}
}
impl Check<'_> {
pub(crate) fn error(&mut self, sp: impl ToTokens, msg: impl Display) {
self.errors.error(sp, msg);
}
}
fn check_type_ident(cx: &mut Check, name: &NamedType) {
let ident = &name.rust;
if Atom::from(ident).is_none()
&& !cx.types.structs.contains_key(ident)
&& !cx.types.enums.contains_key(ident)
&& !cx.types.cxx.contains(ident)
&& !cx.types.rust.contains(ident)
{
let msg = format!("unsupported type: {}", ident);
cx.error(ident, msg);
}
}
fn check_type_box(cx: &mut Check, ptr: &Ty1) {
if let Type::Ident(ident) = &ptr.inner {
if cx.types.cxx.contains(&ident.rust)
&& !cx.types.aliases.contains_key(&ident.rust)
&& !cx.types.structs.contains_key(&ident.rust)
&& !cx.types.enums.contains_key(&ident.rust)
{
cx.error(ptr, error::BOX_CXX_TYPE.msg);
}
if Atom::from(&ident.rust).is_none() {
return;
}
}
cx.error(ptr, "unsupported target type of Box");
}
fn check_type_rust_vec(cx: &mut Check, ty: &Ty1) {
match &ty.inner {
Type::Ident(ident) => {
if cx.types.cxx.contains(&ident.rust)
&& !cx.types.aliases.contains_key(&ident.rust)
&& !cx.types.structs.contains_key(&ident.rust)
&& !cx.types.enums.contains_key(&ident.rust)
{
cx.error(ty, "Rust Vec containing C++ type is not supported yet");
return;
}
match Atom::from(&ident.rust) {
None
| Some(
Bool | Char | U8 | U16 | U32 | U64 | Usize | I8 | I16 | I32 | I64 | Isize | F32
| F64 | RustString,
) => return,
Some(CxxString) => {}
}
}
Type::Str(_) => return,
_ => {}
}
cx.error(ty, "unsupported element type of Vec");
}
fn check_type_unique_ptr(cx: &mut Check, ptr: &Ty1) {
if let Type::Ident(ident) = &ptr.inner {
if cx.types.rust.contains(&ident.rust) {
cx.error(ptr, "unique_ptr of a Rust type is not supported yet");
return;
}
match Atom::from(&ident.rust) {
None | Some(CxxString) => return,
_ => {}
}
} else if let Type::CxxVector(_) = &ptr.inner {
return;
}
cx.error(ptr, "unsupported unique_ptr target type");
}
fn check_type_shared_ptr(cx: &mut Check, ptr: &Ty1) {
if let Type::Ident(ident) = &ptr.inner {
if cx.types.rust.contains(&ident.rust) {
cx.error(ptr, "shared_ptr of a Rust type is not supported yet");
return;
}
match Atom::from(&ident.rust) {
None
| Some(
Bool | U8 | U16 | U32 | U64 | Usize | I8 | I16 | I32 | I64 | Isize | F32 | F64
| CxxString,
) => return,
Some(Char | RustString) => {}
}
} else if let Type::CxxVector(_) = &ptr.inner {
cx.error(ptr, "std::shared_ptr<std::vector> is not supported yet");
return;
}
cx.error(ptr, "unsupported shared_ptr target type");
}
fn check_type_weak_ptr(cx: &mut Check, ptr: &Ty1) {
if let Type::Ident(ident) = &ptr.inner {
if cx.types.rust.contains(&ident.rust) {
cx.error(ptr, "weak_ptr of a Rust type is not supported yet");
return;
}
match Atom::from(&ident.rust) {
None
| Some(
Bool | U8 | U16 | U32 | U64 | Usize | I8 | I16 | I32 | I64 | Isize | F32 | F64
| CxxString,
) => return,
Some(Char | RustString) => {}
}
} else if let Type::CxxVector(_) = &ptr.inner {
cx.error(ptr, "std::weak_ptr<std::vector> is not supported yet");
return;
}
cx.error(ptr, "unsupported weak_ptr target type");
}
fn check_type_cxx_vector(cx: &mut Check, ptr: &Ty1) {
if let Type::Ident(ident) = &ptr.inner {
if cx.types.rust.contains(&ident.rust) {
cx.error(
ptr,
"C++ vector containing a Rust type is not supported yet",
);
return;
}
match Atom::from(&ident.rust) {
None
| Some(
U8 | U16 | U32 | U64 | Usize | I8 | I16 | I32 | I64 | Isize | F32 | F64 | CxxString,
) => return,
Some(Char) => { /* todo */ }
Some(Bool | RustString) => {}
}
}
cx.error(ptr, "unsupported vector element type");
}
fn check_type_ref(cx: &mut Check, ty: &Ref) {
if ty.mutable && !ty.pinned {
if let Some(requires_pin) = match &ty.inner {
Type::Ident(ident) if ident.rust == CxxString || is_opaque_cxx(cx, &ident.rust) => {
Some(ident.rust.to_string())
}
Type::CxxVector(_) => Some("CxxVector<...>".to_owned()),
_ => None,
} {
cx.error(
ty,
format!(
"mutable reference to C++ type requires a pin -- use Pin<&mut {}>",
requires_pin,
),
);
}
}
match ty.inner {
Type::Fn(_) | Type::Void(_) => {}
Type::Ref(_) => {
cx.error(ty, "C++ does not allow references to references");
return;
}
_ => return,
}
cx.error(ty, "unsupported reference type");
}
fn check_type_ptr(cx: &mut Check, ty: &Ptr) {
match ty.inner {
Type::Fn(_) | Type::Void(_) => {}
Type::Ref(_) => {
cx.error(ty, "C++ does not allow pointer to reference as a type");
return;
}
_ => return,
}
cx.error(ty, "unsupported pointer type");
}
fn check_type_slice_ref(cx: &mut Check, ty: &SliceRef) {
let supported = !is_unsized(cx, &ty.inner)
|| match &ty.inner {
Type::Ident(ident) => {
cx.types.rust.contains(&ident.rust) || cx.types.aliases.contains_key(&ident.rust)
}
_ => false,
};
if !supported {
let mutable = if ty.mutable { "mut " } else { "" };
let mut msg = format!("unsupported &{}[T] element type", mutable);
if let Type::Ident(ident) = &ty.inner {
if is_opaque_cxx(cx, &ident.rust) {
msg += ": opaque C++ type is not supported yet";
}
}
cx.error(ty, msg);
}
}
fn check_type_array(cx: &mut Check, ty: &Array) {
let supported = !is_unsized(cx, &ty.inner);
if !supported {
cx.error(ty, "unsupported array element type");
}
}
fn check_type_fn(cx: &mut Check, ty: &Signature) {
if ty.throws {
cx.error(ty, "function pointer returning Result is not supported yet");
}
for arg in &ty.args {
if let Type::Ptr(_) = arg.ty {
if ty.unsafety.is_none() {
cx.error(
arg,
"pointer argument requires that the function pointer be marked unsafe",
);
}
}
}
}
fn check_api_struct(cx: &mut Check, strct: &Struct) {
let name = &strct.name;
check_reserved_name(cx, &name.rust);
check_lifetimes(cx, &strct.generics);
if strct.fields.is_empty() {
let span = span_for_struct_error(strct);
cx.error(span, "structs without any fields are not supported");
}
if cx.types.cxx.contains(&name.rust) {
if let Some(ety) = cx.types.untrusted.get(&name.rust) {
let msg = "extern shared struct must be declared in an `unsafe extern` block";
cx.error(ety, msg);
}
}
for derive in &strct.derives {
if derive.what == Trait::ExternType {
let msg = format!("derive({}) on shared struct is not supported", derive);
cx.error(derive, msg);
}
}
for field in &strct.fields {
if let Type::Fn(_) = field.ty {
cx.error(
field,
"function pointers in a struct field are not implemented yet",
);
} else if is_unsized(cx, &field.ty) {
let desc = describe(cx, &field.ty);
let msg = format!("using {} by value is not supported", desc);
cx.error(field, msg);
}
}
}
fn check_api_enum(cx: &mut Check, enm: &Enum) {
check_reserved_name(cx, &enm.name.rust);
check_lifetimes(cx, &enm.generics);
if enm.variants.is_empty() && !enm.explicit_repr && !enm.variants_from_header {
let span = span_for_enum_error(enm);
cx.error(
span,
"explicit #[repr(...)] is required for enum without any variants",
);
}
for derive in &enm.derives {
if derive.what == Trait::Default || derive.what == Trait::ExternType {
let msg = format!("derive({}) on shared enum is not supported", derive);
cx.error(derive, msg);
}
}
}
fn check_api_type(cx: &mut Check, ety: &ExternType) {
check_reserved_name(cx, &ety.name.rust);
check_lifetimes(cx, &ety.generics);
for derive in &ety.derives {
if derive.what == Trait::ExternType && ety.lang == Lang::Rust {
continue;
}
let lang = match ety.lang {
Lang::Rust => "Rust",
Lang::Cxx => "C++",
};
let msg = format!(
"derive({}) on opaque {} type is not supported yet",
derive, lang,
);
cx.error(derive, msg);
}
if !ety.bounds.is_empty() {
let bounds = &ety.bounds;
let span = quote!(#(#bounds)*);
cx.error(span, "extern type bounds are not implemented yet");
}
if let Some(reasons) = cx.types.required_trivial.get(&ety.name.rust) {
let msg = format!(
"needs a cxx::ExternType impl in order to be used as {}",
trivial::as_what(&ety.name, reasons),
);
cx.error(ety, msg);
}
}
fn check_api_fn(cx: &mut Check, efn: &ExternFn) {
match efn.lang {
Lang::Cxx => {
if !efn.generics.params.is_empty() && !efn.trusted {
let ref span = span_for_generics_error(efn);
cx.error(span, "extern C++ function with lifetimes must be declared in `unsafe extern \"C++\"` block");
}
}
Lang::Rust => {
if !efn.generics.params.is_empty() && efn.unsafety.is_none() {
let ref span = span_for_generics_error(efn);
let message = format!(
"must be `unsafe fn {}` in order to expose explicit lifetimes to C++",
efn.name.rust,
);
cx.error(span, message);
}
}
}
check_generics(cx, &efn.sig.generics);
if let Some(receiver) = &efn.receiver {
let ref span = span_for_receiver_error(receiver);
if receiver.ty.rust == "Self" {
let mutability = match receiver.mutable {
true => "mut ",
false => "",
};
let msg = format!(
"unnamed receiver type is only allowed if the surrounding extern block contains exactly one extern type; use `self: &{mutability}TheType`",
mutability = mutability,
);
cx.error(span, msg);
} else if cx.types.enums.contains_key(&receiver.ty.rust) {
cx.error(
span,
"unsupported receiver type; C++ does not allow member functions on enums",
);
} else if !cx.types.structs.contains_key(&receiver.ty.rust)
&& !cx.types.cxx.contains(&receiver.ty.rust)
&& !cx.types.rust.contains(&receiver.ty.rust)
{
cx.error(span, "unrecognized receiver type");
} else if receiver.mutable && !receiver.pinned && is_opaque_cxx(cx, &receiver.ty.rust) {
cx.error(
span,
format!(
"mutable reference to opaque C++ type requires a pin -- use `self: Pin<&mut {}>`",
receiver.ty.rust,
),
);
}
}
for arg in &efn.args {
if let Type::Fn(_) = arg.ty {
if efn.lang == Lang::Rust {
cx.error(
arg,
"passing a function pointer from C++ to Rust is not implemented yet",
);
}
} else if let Type::Ptr(_) = arg.ty {
if efn.sig.unsafety.is_none() {
cx.error(
arg,
"pointer argument requires that the function be marked unsafe",
);
}
} else if is_unsized(cx, &arg.ty) {
let desc = describe(cx, &arg.ty);
let msg = format!("passing {} by value is not supported", desc);
cx.error(arg, msg);
}
}
if let Some(ty) = &efn.ret {
if let Type::Fn(_) = ty {
cx.error(ty, "returning a function pointer is not implemented yet");
} else if is_unsized(cx, ty) {
let desc = describe(cx, ty);
let msg = format!("returning {} by value is not supported", desc);
cx.error(ty, msg);
}
}
if efn.lang == Lang::Cxx {
check_mut_return_restriction(cx, efn);
}
}
fn check_api_type_alias(cx: &mut Check, alias: &TypeAlias) {
check_lifetimes(cx, &alias.generics);
for derive in &alias.derives {
let msg = format!("derive({}) on extern type alias is not supported", derive);
cx.error(derive, msg);
}
}
fn check_api_impl(cx: &mut Check, imp: &Impl) {
let ty = &imp.ty;
check_lifetimes(cx, &imp.impl_generics);
if let Some(negative) = imp.negative_token {
let span = quote!(#negative #ty);
cx.error(span, "negative impl is not supported yet");
return;
}
match ty {
Type::RustBox(ty)
| Type::RustVec(ty)
| Type::UniquePtr(ty)
| Type::SharedPtr(ty)
| Type::WeakPtr(ty)
| Type::CxxVector(ty) => {
if let Type::Ident(inner) = &ty.inner {
if Atom::from(&inner.rust).is_none() {
return;
}
}
}
_ => {}
}
cx.error(imp, "unsupported Self type of explicit impl");
}
fn check_mut_return_restriction(cx: &mut Check, efn: &ExternFn) {
if efn.sig.unsafety.is_some() {
// Unrestricted as long as the function is made unsafe-to-call.
return;
}
match &efn.ret {
Some(Type::Ref(ty)) if ty.mutable => {}
Some(Type::SliceRef(slice)) if slice.mutable => {}
_ => return,
}
if let Some(receiver) = &efn.receiver {
if receiver.mutable {
return;
}
let Some(resolve) = cx.types.try_resolve(&receiver.ty) else {
return;
};
if !resolve.generics.lifetimes.is_empty() {
return;
}
}
struct FindLifetimeMut<'a> {
cx: &'a Check<'a>,
found: bool,
}
impl<'t, 'a> Visit<'t> for FindLifetimeMut<'a> {
fn visit_type(&mut self, ty: &'t Type) {
self.found |= match ty {
Type::Ref(ty) => ty.mutable,
Type::SliceRef(slice) => slice.mutable,
Type::Ident(ident) if Atom::from(&ident.rust).is_none() => {
match self.cx.types.try_resolve(ident) {
Some(resolve) => !resolve.generics.lifetimes.is_empty(),
None => true,
}
}
_ => false,
};
visit::visit_type(self, ty);
}
}
let mut visitor = FindLifetimeMut { cx, found: false };
for arg in &efn.args {
visitor.visit_type(&arg.ty);
}
if visitor.found {
return;
}
cx.error(
efn,
"&mut return type is not allowed unless there is a &mut argument",
);
}
fn check_reserved_name(cx: &mut Check, ident: &Ident) {
if ident == "Box"
|| ident == "UniquePtr"
|| ident == "SharedPtr"
|| ident == "WeakPtr"
|| ident == "Vec"
|| ident == "CxxVector"
|| ident == "str"
|| Atom::from(ident).is_some()
{
cx.error(ident, "reserved name");
}
}
fn check_reserved_lifetime(cx: &mut Check, lifetime: &Lifetime) {
if lifetime.ident == "static" {
match cx.generator {
Generator::Macro => { /* rustc already reports this */ }
Generator::Build => {
cx.error(lifetime, error::RESERVED_LIFETIME);
}
}
}
}
fn check_lifetimes(cx: &mut Check, generics: &Lifetimes) {
for lifetime in &generics.lifetimes {
check_reserved_lifetime(cx, lifetime);
}
}
fn check_generics(cx: &mut Check, generics: &Generics) {
for generic_param in &generics.params {
if let GenericParam::Lifetime(def) = generic_param {
check_reserved_lifetime(cx, &def.lifetime);
}
}
}
fn is_unsized(cx: &mut Check, ty: &Type) -> bool {
match ty {
Type::Ident(ident) => {
let ident = &ident.rust;
ident == CxxString || is_opaque_cxx(cx, ident) || cx.types.rust.contains(ident)
}
Type::Array(array) => is_unsized(cx, &array.inner),
Type::CxxVector(_) | Type::Fn(_) | Type::Void(_) => true,
Type::RustBox(_)
| Type::RustVec(_)
| Type::UniquePtr(_)
| Type::SharedPtr(_)
| Type::WeakPtr(_)
| Type::Ref(_)
| Type::Ptr(_)
| Type::Str(_)
| Type::SliceRef(_) => false,
}
}
fn is_opaque_cxx(cx: &mut Check, ty: &Ident) -> bool {
cx.types.cxx.contains(ty)
&& !cx.types.structs.contains_key(ty)
&& !cx.types.enums.contains_key(ty)
&& !(cx.types.aliases.contains_key(ty) && cx.types.required_trivial.contains_key(ty))
}
fn span_for_struct_error(strct: &Struct) -> TokenStream {
let struct_token = strct.struct_token;
let mut brace_token = Group::new(Delimiter::Brace, TokenStream::new());
brace_token.set_span(strct.brace_token.span.join());
quote!(#struct_token #brace_token)
}
fn span_for_enum_error(enm: &Enum) -> TokenStream {
let enum_token = enm.enum_token;
let mut brace_token = Group::new(Delimiter::Brace, TokenStream::new());
brace_token.set_span(enm.brace_token.span.join());
quote!(#enum_token #brace_token)
}
fn span_for_receiver_error(receiver: &Receiver) -> TokenStream {
let ampersand = receiver.ampersand;
let lifetime = &receiver.lifetime;
let mutability = receiver.mutability;
if receiver.shorthand {
let var = receiver.var;
quote!(#ampersand #lifetime #mutability #var)
} else {
let ty = &receiver.ty;
quote!(#ampersand #lifetime #mutability #ty)
}
}
fn span_for_generics_error(efn: &ExternFn) -> TokenStream {
let unsafety = efn.unsafety;
let fn_token = efn.fn_token;
let generics = &efn.generics;
quote!(#unsafety #fn_token #generics)
}
fn describe(cx: &mut Check, ty: &Type) -> String {
match ty {
Type::Ident(ident) => {
if cx.types.structs.contains_key(&ident.rust) {
"struct".to_owned()
} else if cx.types.enums.contains_key(&ident.rust) {
"enum".to_owned()
} else if cx.types.aliases.contains_key(&ident.rust) {
"C++ type".to_owned()
} else if cx.types.cxx.contains(&ident.rust) {
"opaque C++ type".to_owned()
} else if cx.types.rust.contains(&ident.rust) {
"opaque Rust type".to_owned()
} else if Atom::from(&ident.rust) == Some(CxxString) {
"C++ string".to_owned()
} else if Atom::from(&ident.rust) == Some(Char) {
"C char".to_owned()
} else {
ident.rust.to_string()
}
}
Type::RustBox(_) => "Box".to_owned(),
Type::RustVec(_) => "Vec".to_owned(),
Type::UniquePtr(_) => "unique_ptr".to_owned(),
Type::SharedPtr(_) => "shared_ptr".to_owned(),
Type::WeakPtr(_) => "weak_ptr".to_owned(),
Type::Ref(_) => "reference".to_owned(),
Type::Ptr(_) => "raw pointer".to_owned(),
Type::Str(_) => "&str".to_owned(),
Type::CxxVector(_) => "C++ vector".to_owned(),
Type::SliceRef(_) => "slice".to_owned(),
Type::Fn(_) => "function pointer".to_owned(),
Type::Void(_) => "()".to_owned(),
Type::Array(_) => "array".to_owned(),
}
}
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