Merge pull request #541 from dtolnay/vec-extern

Fix Vec containing shared type from other module

Author: dtolnay

syntax/check.rs

@@ -93,6 +93,7 @@ fn check_type_box(cx: &mut Check, ptr: &Ty1) {
 fn check_type_rust_vec(cx: &mut Check, ty: &Ty1) {
     if let Type::Ident(ident) = &ty.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)
         {
@@ -328,6 +329,7 @@ fn check_api_type(cx: &mut Check, ety: &ExternType) {
             TrivialReason::StructField(strct) => format!("a field of `{}`", strct.name.rust),
             TrivialReason::FunctionArgument(efn) => format!("an argument of `{}`", efn.name.rust),
             TrivialReason::FunctionReturn(efn) => format!("a return value of `{}`", efn.name.rust),
+            TrivialReason::VecElement => format!("a vector element in Vec<{}>", ety.name.rust),
         };
         let msg = format!(
             "needs a cxx::ExternType impl in order to be used as {}",

syntax/types.rs

@@ -201,6 +201,12 @@ impl<'a> Types<'a> {
                 _ => {}
             }
         }
+        for ty in &all {
+            if let Type::RustVec(ty) = ty {
+                let reason = TrivialReason::VecElement;
+                insist_alias_types_are_trivial(&ty.inner, reason);
+            }
+        }
 
         let mut types = Types {
             all,
@@ -297,6 +303,7 @@ pub enum TrivialReason<'a> {
     StructField(&'a Struct),
     FunctionArgument(&'a ExternFn),
     FunctionReturn(&'a ExternFn),
+    VecElement,
 }
 
 fn duplicate_name(cx: &mut Errors, sp: impl ToTokens, ident: &Ident) {

tests/BUCK

@@ -32,6 +32,7 @@ cxx_library(
     ],
     headers = {
         "ffi/lib.rs.h": ":bridge/header",
+        "ffi/module.rs.h": ":module/header",
         "ffi/tests.h": "ffi/tests.h",
     },
     deps = ["//:core"],

tests/BUILD

@@ -35,6 +35,7 @@ cc_library(
     hdrs = ["ffi/tests.h"],
     deps = [
         ":bridge/include",
+        ":module/include",
         "//:core",
     ],
 )

tests/ffi/lib.rs

@@ -184,7 +184,10 @@ pub mod ffi {
     }
 
     extern "C++" {
+        include!("tests/ffi/module.rs.h");
+
         type COwnedEnum;
+        type Job = crate::module::ffi::Job;
     }
 
     #[repr(u32)]
@@ -211,6 +214,7 @@ pub mod ffi {
         fn r_return_unique_ptr_string() -> UniquePtr<CxxString>;
         fn r_return_rust_vec() -> Vec<u8>;
         fn r_return_rust_vec_string() -> Vec<String>;
+        fn r_return_rust_vec_extern_struct() -> Vec<Job>;
         fn r_return_ref_rust_vec(shared: &Shared) -> &Vec<u8>;
         fn r_return_mut_rust_vec(shared: &mut Shared) -> &mut Vec<u8>;
         fn r_return_identity(_: usize) -> usize;
@@ -435,6 +439,10 @@ fn r_return_rust_vec_string() -> Vec<String> {
     Vec::new()
 }
 
+fn r_return_rust_vec_extern_struct() -> Vec<ffi::Job> {
+    Vec::new()
+}
+
 fn r_return_ref_rust_vec(shared: &ffi::Shared) -> &Vec<u8> {
     let _ = shared;
     unimplemented!()

tests/ffi/module.rs

@@ -1,5 +1,9 @@
 #[cxx::bridge(namespace = "tests")]
 pub mod ffi {
+    struct Job {
+        raw: u32,
+    }
+
     unsafe extern "C++" {
         include!("tests/ffi/tests.h");
 

tests/ui/vec_opaque.rs

@@ -0,0 +1,34 @@
+#[cxx::bridge]
+mod handle {
+    extern "C++" {
+        type Job;
+    }
+}
+
+#[cxx::bridge]
+mod ffi1 {
+    extern "C++" {
+        type Job;
+    }
+
+    extern "Rust" {
+        fn f() -> Vec<Job>;
+    }
+}
+
+#[cxx::bridge]
+mod ffi2 {
+    extern "C++" {
+        type Job = crate::handle::Job;
+    }
+
+    extern "Rust" {
+        fn f() -> Vec<Job>;
+    }
+}
+
+fn f() -> Vec<handle::Job> {
+    unimplemented!()
+}
+
+fn main() {}

tests/ui/vec_opaque.stderr

@@ -0,0 +1,22 @@
+error: Rust Vec containing C++ type is not supported yet
+  --> $DIR/vec_opaque.rs:15:19
+   |
+15 |         fn f() -> Vec<Job>;
+   |                   ^^^^^^^^
+
+error: needs a cxx::ExternType impl in order to be used as a vector element in Vec<Job>
+  --> $DIR/vec_opaque.rs:11:9
+   |
+11 |         type Job;
+   |         ^^^^^^^^
+
+error[E0271]: type mismatch resolving `<handle::Job as ExternType>::Kind == Trivial`
+   --> $DIR/vec_opaque.rs:22:9
+    |
+22  |         type Job = crate::handle::Job;
+    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected enum `Trivial`, found enum `cxx::kind::Opaque`
+    |
+   ::: $WORKSPACE/src/extern_type.rs
+    |
+    | pub fn verify_extern_kind<T: ExternType<Kind = Kind>, Kind: self::Kind>() {}
+    |                                         ----------- required by this bound in `verify_extern_kind`