cxx_build/syntax/
check.rs

1use crate::syntax::atom::Atom::{self, *};
2use crate::syntax::report::Errors;
3use crate::syntax::visit::{self, Visit};
4use crate::syntax::{
5    error, ident, trivial, Api, Array, Enum, ExternFn, ExternType, FnKind, Impl, Lang, Lifetimes,
6    NamedType, Ptr, Receiver, Ref, Signature, SliceRef, Struct, Trait, Ty1, Type, TypeAlias, Types,
7};
8use proc_macro2::{Delimiter, Group, Ident, TokenStream};
9use quote::{quote, ToTokens};
10use std::fmt::Display;
11use syn::{GenericParam, Generics, Lifetime};
12
13pub(crate) struct Check<'a> {
14    apis: &'a [Api],
15    types: &'a Types<'a>,
16    errors: &'a mut Errors,
17    generator: Generator,
18}
19
20pub(crate) enum Generator {
21    // cxx-build crate, cxxbridge cli, cxx-gen.
22    #[allow(dead_code)]
23    Build,
24    // cxxbridge-macro. This is relevant in that the macro output is going to
25    // get fed straight to rustc, so for errors that rustc already contains
26    // logic to catch (probably with a better diagnostic than what the proc
27    // macro API is able to produce), we avoid duplicating them in our own
28    // diagnostics.
29    #[allow(dead_code)]
30    Macro,
31}
32
33pub(crate) fn typecheck(cx: &mut Errors, apis: &[Api], types: &Types, generator: Generator) {
34    do_typecheck(&mut Check {
35        apis,
36        types,
37        errors: cx,
38        generator,
39    });
40}
41
42fn do_typecheck(cx: &mut Check) {
43    ident::check_all(cx, cx.apis);
44
45    for ty in cx.types {
46        match ty {
47            Type::Ident(ident) => check_type_ident(cx, ident),
48            Type::RustBox(ptr) => check_type_box(cx, ptr),
49            Type::RustVec(ty) => check_type_rust_vec(cx, ty),
50            Type::UniquePtr(ptr) => check_type_unique_ptr(cx, ptr),
51            Type::SharedPtr(ptr) => check_type_shared_ptr(cx, ptr),
52            Type::WeakPtr(ptr) => check_type_weak_ptr(cx, ptr),
53            Type::CxxVector(ptr) => check_type_cxx_vector(cx, ptr),
54            Type::Ref(ty) => check_type_ref(cx, ty),
55            Type::Ptr(ty) => check_type_ptr(cx, ty),
56            Type::Array(array) => check_type_array(cx, array),
57            Type::Fn(ty) => check_type_fn(cx, ty),
58            Type::SliceRef(ty) => check_type_slice_ref(cx, ty),
59            Type::Str(_) | Type::Void(_) => {}
60        }
61    }
62
63    for api in cx.apis {
64        match api {
65            Api::Include(_) => {}
66            Api::Struct(strct) => check_api_struct(cx, strct),
67            Api::Enum(enm) => check_api_enum(cx, enm),
68            Api::CxxType(ety) | Api::RustType(ety) => check_api_type(cx, ety),
69            Api::CxxFunction(efn) | Api::RustFunction(efn) => check_api_fn(cx, efn),
70            Api::TypeAlias(alias) => check_api_type_alias(cx, alias),
71            Api::Impl(imp) => check_api_impl(cx, imp),
72        }
73    }
74}
75
76impl Check<'_> {
77    pub(crate) fn error(&mut self, sp: impl ToTokens, msg: impl Display) {
78        self.errors.error(sp, msg);
79    }
80}
81
82fn check_type_ident(cx: &mut Check, name: &NamedType) {
83    let ident = &name.rust;
84    if Atom::from(ident).is_none()
85        && !cx.types.structs.contains_key(ident)
86        && !cx.types.enums.contains_key(ident)
87        && !cx.types.cxx.contains(ident)
88        && !cx.types.rust.contains(ident)
89    {
90        let msg = format!("unsupported type: {}", ident);
91        cx.error(ident, msg);
92    }
93}
94
95fn check_type_box(cx: &mut Check, ptr: &Ty1) {
96    if let Type::Ident(ident) = &ptr.inner {
97        if cx.types.cxx.contains(&ident.rust)
98            && !cx.types.aliases.contains_key(&ident.rust)
99            && !cx.types.structs.contains_key(&ident.rust)
100            && !cx.types.enums.contains_key(&ident.rust)
101        {
102            cx.error(ptr, error::BOX_CXX_TYPE.msg);
103        }
104
105        if Atom::from(&ident.rust).is_none() {
106            return;
107        }
108    }
109
110    cx.error(ptr, "unsupported target type of Box");
111}
112
113fn check_type_rust_vec(cx: &mut Check, ty: &Ty1) {
114    match &ty.inner {
115        Type::Ident(ident) => {
116            if cx.types.cxx.contains(&ident.rust)
117                && !cx.types.aliases.contains_key(&ident.rust)
118                && !cx.types.structs.contains_key(&ident.rust)
119                && !cx.types.enums.contains_key(&ident.rust)
120            {
121                cx.error(ty, "Rust Vec containing C++ type is not supported yet");
122                return;
123            }
124
125            match Atom::from(&ident.rust) {
126                None
127                | Some(
128                    Bool | Char | U8 | U16 | U32 | U64 | Usize | I8 | I16 | I32 | I64 | Isize | F32
129                    | F64 | RustString,
130                ) => return,
131                Some(CxxString) => {}
132            }
133        }
134        Type::Str(_) => return,
135        _ => {}
136    }
137
138    cx.error(ty, "unsupported element type of Vec");
139}
140
141fn check_type_unique_ptr(cx: &mut Check, ptr: &Ty1) {
142    if let Type::Ident(ident) = &ptr.inner {
143        if cx.types.rust.contains(&ident.rust) {
144            cx.error(ptr, "unique_ptr of a Rust type is not supported yet");
145            return;
146        }
147
148        match Atom::from(&ident.rust) {
149            None | Some(CxxString) => return,
150            _ => {}
151        }
152    } else if let Type::CxxVector(_) = &ptr.inner {
153        return;
154    }
155
156    cx.error(ptr, "unsupported unique_ptr target type");
157}
158
159fn check_type_shared_ptr(cx: &mut Check, ptr: &Ty1) {
160    if let Type::Ident(ident) = &ptr.inner {
161        if cx.types.rust.contains(&ident.rust) {
162            cx.error(ptr, "shared_ptr of a Rust type is not supported yet");
163            return;
164        }
165
166        match Atom::from(&ident.rust) {
167            None
168            | Some(
169                Bool | U8 | U16 | U32 | U64 | Usize | I8 | I16 | I32 | I64 | Isize | F32 | F64
170                | CxxString,
171            ) => return,
172            Some(Char | RustString) => {}
173        }
174    } else if let Type::CxxVector(_) = &ptr.inner {
175        cx.error(ptr, "std::shared_ptr<std::vector> is not supported yet");
176        return;
177    }
178
179    cx.error(ptr, "unsupported shared_ptr target type");
180}
181
182fn check_type_weak_ptr(cx: &mut Check, ptr: &Ty1) {
183    if let Type::Ident(ident) = &ptr.inner {
184        if cx.types.rust.contains(&ident.rust) {
185            cx.error(ptr, "weak_ptr of a Rust type is not supported yet");
186            return;
187        }
188
189        match Atom::from(&ident.rust) {
190            None
191            | Some(
192                Bool | U8 | U16 | U32 | U64 | Usize | I8 | I16 | I32 | I64 | Isize | F32 | F64
193                | CxxString,
194            ) => return,
195            Some(Char | RustString) => {}
196        }
197    } else if let Type::CxxVector(_) = &ptr.inner {
198        cx.error(ptr, "std::weak_ptr<std::vector> is not supported yet");
199        return;
200    }
201
202    cx.error(ptr, "unsupported weak_ptr target type");
203}
204
205fn check_type_cxx_vector(cx: &mut Check, ptr: &Ty1) {
206    if let Type::Ident(ident) = &ptr.inner {
207        if cx.types.rust.contains(&ident.rust) {
208            cx.error(
209                ptr,
210                "C++ vector containing a Rust type is not supported yet",
211            );
212            return;
213        }
214
215        match Atom::from(&ident.rust) {
216            None
217            | Some(
218                U8 | U16 | U32 | U64 | Usize | I8 | I16 | I32 | I64 | Isize | F32 | F64 | CxxString,
219            ) => return,
220            Some(Char) => { /* todo */ }
221            Some(Bool | RustString) => {}
222        }
223    }
224
225    cx.error(ptr, "unsupported vector element type");
226}
227
228fn check_type_ref(cx: &mut Check, ty: &Ref) {
229    if ty.mutable && !ty.pinned {
230        if let Some(requires_pin) = match &ty.inner {
231            Type::Ident(ident) if ident.rust == CxxString || is_opaque_cxx(cx, &ident.rust) => {
232                Some(ident.rust.to_string())
233            }
234            Type::CxxVector(_) => Some("CxxVector<...>".to_owned()),
235            _ => None,
236        } {
237            cx.error(
238                ty,
239                format!(
240                    "mutable reference to C++ type requires a pin -- use Pin<&mut {}>",
241                    requires_pin,
242                ),
243            );
244        }
245    }
246
247    match ty.inner {
248        Type::Fn(_) | Type::Void(_) => {}
249        Type::Ref(_) => {
250            cx.error(ty, "C++ does not allow references to references");
251            return;
252        }
253        _ => return,
254    }
255
256    cx.error(ty, "unsupported reference type");
257}
258
259fn check_type_ptr(cx: &mut Check, ty: &Ptr) {
260    match ty.inner {
261        Type::Fn(_) | Type::Void(_) => {}
262        Type::Ref(_) => {
263            cx.error(ty, "C++ does not allow pointer to reference as a type");
264            return;
265        }
266        _ => return,
267    }
268
269    cx.error(ty, "unsupported pointer type");
270}
271
272fn check_type_slice_ref(cx: &mut Check, ty: &SliceRef) {
273    let supported = !is_unsized(cx, &ty.inner)
274        || match &ty.inner {
275            Type::Ident(ident) => {
276                cx.types.rust.contains(&ident.rust) || cx.types.aliases.contains_key(&ident.rust)
277            }
278            _ => false,
279        };
280
281    if !supported {
282        let mutable = if ty.mutable { "mut " } else { "" };
283        let mut msg = format!("unsupported &{}[T] element type", mutable);
284        if let Type::Ident(ident) = &ty.inner {
285            if is_opaque_cxx(cx, &ident.rust) {
286                msg += ": opaque C++ type is not supported yet";
287            }
288        }
289        cx.error(ty, msg);
290    }
291}
292
293fn check_type_array(cx: &mut Check, ty: &Array) {
294    let supported = !is_unsized(cx, &ty.inner);
295
296    if !supported {
297        cx.error(ty, "unsupported array element type");
298    }
299}
300
301fn check_type_fn(cx: &mut Check, ty: &Signature) {
302    if ty.throws {
303        cx.error(ty, "function pointer returning Result is not supported yet");
304    }
305
306    for arg in &ty.args {
307        if let Type::Ptr(_) = arg.ty {
308            if ty.unsafety.is_none() {
309                cx.error(
310                    arg,
311                    "pointer argument requires that the function pointer be marked unsafe",
312                );
313            }
314        }
315    }
316}
317
318fn check_api_struct(cx: &mut Check, strct: &Struct) {
319    let name = &strct.name;
320    check_reserved_name(cx, &name.rust);
321    check_lifetimes(cx, &strct.generics);
322
323    if strct.fields.is_empty() {
324        let span = span_for_struct_error(strct);
325        cx.error(span, "structs without any fields are not supported");
326    }
327
328    if cx.types.cxx.contains(&name.rust) {
329        if let Some(ety) = cx.types.untrusted.get(&name.rust) {
330            let msg = "extern shared struct must be declared in an `unsafe extern` block";
331            cx.error(ety, msg);
332        }
333    }
334
335    for derive in &strct.derives {
336        if derive.what == Trait::ExternType {
337            let msg = format!("derive({}) on shared struct is not supported", derive);
338            cx.error(derive, msg);
339        }
340    }
341
342    for field in &strct.fields {
343        if let Type::Fn(_) = field.ty {
344            cx.error(
345                field,
346                "function pointers in a struct field are not implemented yet",
347            );
348        } else if is_unsized(cx, &field.ty) {
349            let desc = describe(cx, &field.ty);
350            let msg = format!("using {} by value is not supported", desc);
351            cx.error(field, msg);
352        }
353    }
354}
355
356fn check_api_enum(cx: &mut Check, enm: &Enum) {
357    check_reserved_name(cx, &enm.name.rust);
358    check_lifetimes(cx, &enm.generics);
359
360    if enm.variants.is_empty() && !enm.explicit_repr {
361        let span = span_for_enum_error(enm);
362        cx.error(
363            span,
364            "explicit #[repr(...)] is required for enum without any variants",
365        );
366    }
367
368    for derive in &enm.derives {
369        if derive.what == Trait::Default || derive.what == Trait::ExternType {
370            let msg = format!("derive({}) on shared enum is not supported", derive);
371            cx.error(derive, msg);
372        }
373    }
374}
375
376fn check_api_type(cx: &mut Check, ety: &ExternType) {
377    check_reserved_name(cx, &ety.name.rust);
378    check_lifetimes(cx, &ety.generics);
379
380    for derive in &ety.derives {
381        if derive.what == Trait::ExternType && ety.lang == Lang::Rust {
382            continue;
383        }
384        let lang = match ety.lang {
385            Lang::Rust => "Rust",
386            Lang::Cxx | Lang::CxxUnwind => "C++",
387        };
388        let msg = format!(
389            "derive({}) on opaque {} type is not supported yet",
390            derive, lang,
391        );
392        cx.error(derive, msg);
393    }
394
395    if !ety.bounds.is_empty() {
396        let bounds = &ety.bounds;
397        let span = quote!(#(#bounds)*);
398        cx.error(span, "extern type bounds are not implemented yet");
399    }
400
401    if let Some(reasons) = cx.types.required_trivial.get(&ety.name.rust) {
402        let msg = format!(
403            "needs a cxx::ExternType impl in order to be used as {}",
404            trivial::as_what(&ety.name, reasons),
405        );
406        cx.error(ety, msg);
407    }
408}
409
410fn check_api_fn(cx: &mut Check, efn: &ExternFn) {
411    match efn.lang {
412        Lang::Cxx | Lang::CxxUnwind => {
413            if !efn.generics.params.is_empty() && !efn.trusted {
414                let ref span = span_for_generics_error(efn);
415                cx.error(span, "extern C++ function with lifetimes must be declared in `unsafe extern \"C++\"` block");
416            }
417        }
418        Lang::Rust => {
419            if !efn.generics.params.is_empty() && efn.unsafety.is_none() {
420                let ref span = span_for_generics_error(efn);
421                let message = format!(
422                    "must be `unsafe fn {}` in order to expose explicit lifetimes to C++",
423                    efn.name.rust,
424                );
425                cx.error(span, message);
426            }
427        }
428    }
429
430    check_generics(cx, &efn.generics);
431
432    match &efn.kind {
433        FnKind::Method(receiver) => {
434            let ref span = span_for_receiver_error(receiver);
435
436            if receiver.ty.rust == "Self" {
437                let mutability = match receiver.mutable {
438                    true => "mut ",
439                    false => "",
440                };
441                let msg = format!(
442                    "unnamed receiver type is only allowed if the surrounding extern block contains exactly one extern type; use `self: &{mutability}TheType`",
443                    mutability = mutability,
444                );
445                cx.error(span, msg);
446            } else if cx.types.enums.contains_key(&receiver.ty.rust) {
447                cx.error(
448                    span,
449                    "unsupported receiver type; C++ does not allow member functions on enums",
450                );
451            } else if !cx.types.structs.contains_key(&receiver.ty.rust)
452                && !cx.types.cxx.contains(&receiver.ty.rust)
453                && !cx.types.rust.contains(&receiver.ty.rust)
454            {
455                cx.error(span, "unrecognized receiver type");
456            } else if receiver.mutable && !receiver.pinned && is_opaque_cxx(cx, &receiver.ty.rust) {
457                cx.error(
458                    span,
459                    format!(
460                        "mutable reference to opaque C++ type requires a pin -- use `self: Pin<&mut {}>`",
461                        receiver.ty.rust,
462                    ),
463                );
464            }
465        }
466        FnKind::Assoc(self_type) => {
467            if cx.types.enums.contains_key(self_type) {
468                cx.error(
469                    self_type,
470                    "unsupported self type; C++ does not allow member functions on enums",
471                );
472            } else if !cx.types.structs.contains_key(self_type)
473                && !cx.types.cxx.contains(self_type)
474                && !cx.types.rust.contains(self_type)
475            {
476                cx.error(self_type, "unrecognized self type");
477            }
478        }
479        FnKind::Free => {}
480    }
481
482    for arg in &efn.args {
483        if let Type::Fn(_) = arg.ty {
484            if efn.lang == Lang::Rust {
485                cx.error(
486                    arg,
487                    "passing a function pointer from C++ to Rust is not implemented yet",
488                );
489            }
490        } else if let Type::Ptr(_) = arg.ty {
491            if efn.unsafety.is_none() {
492                cx.error(
493                    arg,
494                    "pointer argument requires that the function be marked unsafe",
495                );
496            }
497        } else if is_unsized(cx, &arg.ty) {
498            let desc = describe(cx, &arg.ty);
499            let msg = format!("passing {} by value is not supported", desc);
500            cx.error(arg, msg);
501        }
502    }
503
504    if let Some(ty) = &efn.ret {
505        if let Type::Fn(_) = ty {
506            cx.error(ty, "returning a function pointer is not implemented yet");
507        } else if is_unsized(cx, ty) {
508            let desc = describe(cx, ty);
509            let msg = format!("returning {} by value is not supported", desc);
510            cx.error(ty, msg);
511        }
512    }
513
514    if efn.lang == Lang::Cxx {
515        check_mut_return_restriction(cx, efn);
516    }
517}
518
519fn check_api_type_alias(cx: &mut Check, alias: &TypeAlias) {
520    check_lifetimes(cx, &alias.generics);
521
522    for derive in &alias.derives {
523        let msg = format!("derive({}) on extern type alias is not supported", derive);
524        cx.error(derive, msg);
525    }
526}
527
528fn check_api_impl(cx: &mut Check, imp: &Impl) {
529    let ty = &imp.ty;
530
531    check_lifetimes(cx, &imp.impl_generics);
532
533    if let Some(negative) = imp.negative_token {
534        let span = quote!(#negative #ty);
535        cx.error(span, "negative impl is not supported yet");
536        return;
537    }
538
539    match ty {
540        Type::RustBox(ty)
541        | Type::RustVec(ty)
542        | Type::UniquePtr(ty)
543        | Type::SharedPtr(ty)
544        | Type::WeakPtr(ty)
545        | Type::CxxVector(ty) => {
546            if let Type::Ident(inner) = &ty.inner {
547                if Atom::from(&inner.rust).is_none() {
548                    return;
549                }
550            }
551        }
552        _ => {}
553    }
554
555    cx.error(imp, "unsupported Self type of explicit impl");
556}
557
558fn check_mut_return_restriction(cx: &mut Check, efn: &ExternFn) {
559    if efn.unsafety.is_some() {
560        // Unrestricted as long as the function is made unsafe-to-call.
561        return;
562    }
563
564    match &efn.ret {
565        Some(Type::Ref(ty)) if ty.mutable => {}
566        Some(Type::SliceRef(slice)) if slice.mutable => {}
567        _ => return,
568    }
569
570    if let Some(receiver) = efn.receiver() {
571        if receiver.mutable {
572            return;
573        }
574        let Some(resolve) = cx.types.try_resolve(&receiver.ty) else {
575            return;
576        };
577        if !resolve.generics.lifetimes.is_empty() {
578            return;
579        }
580    }
581
582    struct FindLifetimeMut<'a> {
583        cx: &'a Check<'a>,
584        found: bool,
585    }
586
587    impl<'t, 'a> Visit<'t> for FindLifetimeMut<'a> {
588        fn visit_type(&mut self, ty: &'t Type) {
589            self.found |= match ty {
590                Type::Ref(ty) => ty.mutable,
591                Type::SliceRef(slice) => slice.mutable,
592                Type::Ident(ident) if Atom::from(&ident.rust).is_none() => {
593                    match self.cx.types.try_resolve(ident) {
594                        Some(resolve) => !resolve.generics.lifetimes.is_empty(),
595                        None => true,
596                    }
597                }
598                _ => false,
599            };
600            visit::visit_type(self, ty);
601        }
602    }
603
604    let mut visitor = FindLifetimeMut { cx, found: false };
605
606    for arg in &efn.args {
607        visitor.visit_type(&arg.ty);
608    }
609
610    if visitor.found {
611        return;
612    }
613
614    cx.error(
615        efn,
616        "&mut return type is not allowed unless there is a &mut argument",
617    );
618}
619
620fn check_reserved_name(cx: &mut Check, ident: &Ident) {
621    if ident == "Box"
622        || ident == "UniquePtr"
623        || ident == "SharedPtr"
624        || ident == "WeakPtr"
625        || ident == "Vec"
626        || ident == "CxxVector"
627        || ident == "str"
628        || Atom::from(ident).is_some()
629    {
630        cx.error(ident, "reserved name");
631    }
632}
633
634fn check_reserved_lifetime(cx: &mut Check, lifetime: &Lifetime) {
635    if lifetime.ident == "static" {
636        match cx.generator {
637            Generator::Macro => { /* rustc already reports this */ }
638            Generator::Build => {
639                cx.error(lifetime, error::RESERVED_LIFETIME);
640            }
641        }
642    }
643}
644
645fn check_lifetimes(cx: &mut Check, generics: &Lifetimes) {
646    for lifetime in &generics.lifetimes {
647        check_reserved_lifetime(cx, lifetime);
648    }
649}
650
651fn check_generics(cx: &mut Check, generics: &Generics) {
652    for generic_param in &generics.params {
653        if let GenericParam::Lifetime(def) = generic_param {
654            check_reserved_lifetime(cx, &def.lifetime);
655        }
656    }
657}
658
659fn is_unsized(cx: &mut Check, ty: &Type) -> bool {
660    match ty {
661        Type::Ident(ident) => {
662            let ident = &ident.rust;
663            ident == CxxString || is_opaque_cxx(cx, ident) || cx.types.rust.contains(ident)
664        }
665        Type::Array(array) => is_unsized(cx, &array.inner),
666        Type::CxxVector(_) | Type::Fn(_) | Type::Void(_) => true,
667        Type::RustBox(_)
668        | Type::RustVec(_)
669        | Type::UniquePtr(_)
670        | Type::SharedPtr(_)
671        | Type::WeakPtr(_)
672        | Type::Ref(_)
673        | Type::Ptr(_)
674        | Type::Str(_)
675        | Type::SliceRef(_) => false,
676    }
677}
678
679fn is_opaque_cxx(cx: &mut Check, ty: &Ident) -> bool {
680    cx.types.cxx.contains(ty)
681        && !cx.types.structs.contains_key(ty)
682        && !cx.types.enums.contains_key(ty)
683        && !(cx.types.aliases.contains_key(ty) && cx.types.required_trivial.contains_key(ty))
684}
685
686fn span_for_struct_error(strct: &Struct) -> TokenStream {
687    let struct_token = strct.struct_token;
688    let mut brace_token = Group::new(Delimiter::Brace, TokenStream::new());
689    brace_token.set_span(strct.brace_token.span.join());
690    quote!(#struct_token #brace_token)
691}
692
693fn span_for_enum_error(enm: &Enum) -> TokenStream {
694    let enum_token = enm.enum_token;
695    let mut brace_token = Group::new(Delimiter::Brace, TokenStream::new());
696    brace_token.set_span(enm.brace_token.span.join());
697    quote!(#enum_token #brace_token)
698}
699
700fn span_for_receiver_error(receiver: &Receiver) -> TokenStream {
701    let ampersand = receiver.ampersand;
702    let lifetime = &receiver.lifetime;
703    let mutability = receiver.mutability;
704    if receiver.shorthand {
705        let var = receiver.var;
706        quote!(#ampersand #lifetime #mutability #var)
707    } else {
708        let ty = &receiver.ty;
709        quote!(#ampersand #lifetime #mutability #ty)
710    }
711}
712
713fn span_for_generics_error(efn: &ExternFn) -> TokenStream {
714    let unsafety = efn.unsafety;
715    let fn_token = efn.fn_token;
716    let generics = &efn.generics;
717    quote!(#unsafety #fn_token #generics)
718}
719
720fn describe(cx: &mut Check, ty: &Type) -> String {
721    match ty {
722        Type::Ident(ident) => {
723            if cx.types.structs.contains_key(&ident.rust) {
724                "struct".to_owned()
725            } else if cx.types.enums.contains_key(&ident.rust) {
726                "enum".to_owned()
727            } else if cx.types.aliases.contains_key(&ident.rust) {
728                "C++ type".to_owned()
729            } else if cx.types.cxx.contains(&ident.rust) {
730                "opaque C++ type".to_owned()
731            } else if cx.types.rust.contains(&ident.rust) {
732                "opaque Rust type".to_owned()
733            } else if Atom::from(&ident.rust) == Some(CxxString) {
734                "C++ string".to_owned()
735            } else if Atom::from(&ident.rust) == Some(Char) {
736                "C char".to_owned()
737            } else {
738                ident.rust.to_string()
739            }
740        }
741        Type::RustBox(_) => "Box".to_owned(),
742        Type::RustVec(_) => "Vec".to_owned(),
743        Type::UniquePtr(_) => "unique_ptr".to_owned(),
744        Type::SharedPtr(_) => "shared_ptr".to_owned(),
745        Type::WeakPtr(_) => "weak_ptr".to_owned(),
746        Type::Ref(_) => "reference".to_owned(),
747        Type::Ptr(_) => "raw pointer".to_owned(),
748        Type::Str(_) => "&str".to_owned(),
749        Type::CxxVector(_) => "C++ vector".to_owned(),
750        Type::SliceRef(_) => "slice".to_owned(),
751        Type::Fn(_) => "function pointer".to_owned(),
752        Type::Void(_) => "()".to_owned(),
753        Type::Array(_) => "array".to_owned(),
754    }
755}
cxx_build/syntax/check.rs

cxx_build/syntax/
check.rs
