#[swift_bridge::bridge] macro forces module to be private

[gabbifish]

I defined a transparent type in one ffi submodule:

// error.rs
#[swift_bridge::bridge]
pub mod ffi {
    #[swift_bridge(swift_repr="struct")]
    pub struct RuntimeError {
        pub error: String
    }
}

and tried to import it in another module:

// lib.rs
mod error

use error:ffi:RuntimeError;

but saw the following error for this line: use error:ffi:RuntimeError:

module `ffi` is private

It seems the #[swift_bridge::bridge] macro forces its module to be private--is this intentional, or can its private/public status be passed through?

[chinedufn]

Not intentional, we've just been adding things as we need them and you're the first to make note of this.

One workaround is to use pub use self::ffi::Foo from outside of mod foo to expose Foo to other module.

---

Supporting this should be easy though if you're interested. Roughly two lines of implementation code + a couple of tests.

Here's how one might add support for preserving the module's visibility, in case you or any future person wants to tackle this:

Potential Solution

Add a parsing test where we verify that we can store the module's visibility

swift-bridge/crates/swift-bridge-ir/src/parse.rs

Lines 164 to 210 in 72e1759

	#[cfg(test)]
	mod tests {
	use super::*;
	use crate::test_utils::{parse_errors, parse_ok};
	/// Verify that we can parse a cfg feature from a module.
	#[test]
	fn parse_module_cfg_feature() {
	let tokens = quote! {
	#[swift_bridge::bridge]
	#[cfg(feature = "some-feature")]
	mod foo {}
	};
	let module = parse_ok(tokens);
	assert_eq!(module.cfg_attrs.len(), 1);
	match &module.cfg_attrs[0] {
	CfgAttr::Feature(feature) => {
	assert_eq!(feature.value(), "some-feature")
	}
	};
	}
	/// Verify that we get an error when parsing an unsupported module item, such as a
	/// `use` statement.
	#[test]
	fn invalid_module_item() {
	let tokens = quote! {
	#[swift_bridge::bridge]
	mod foo {
	use std;
	}
	};
	let errors = parse_errors(tokens);
	assert_eq!(errors.len(), 1);
	match &errors[0] {
	ParseError::InvalidModuleItem { item } => {
	assert!(matches!(item, Item::Use(_)))
	}
	_ => panic!(),
	}
	}
	}

---

Add a codegen test where we confirm that the module's visibility is preserved in the generated Rust tokens:

Perhaps in a mod module_visibility_tests in here

swift-bridge/crates/swift-bridge-ir/src/codegen/codegen_tests.rs

Lines 30 to 54 in 4fbd30f

	mod already_declared_attribute_codegen_tests;
	mod argument_label_codegen_tests;
	mod async_function_codegen_tests;
	mod boxed_fnonce_codegen_tests;
	mod built_in_tuple_codegen_tests;
	mod c_header_declaration_order_codegen_tests;
	mod conditional_compilation_codegen_tests;
	mod derive_attribute_codegen_tests;
	mod derive_struct_attribute_codegen_tests;
	mod extern_rust_function_opaque_rust_type_argument_codegen_tests;
	mod extern_rust_function_opaque_rust_type_return_codegen_tests;
	mod extern_rust_method_swift_class_placement_codegen_tests;
	mod extern_swift_function_opaque_swift_type_return_codegen_tests;
	mod function_attribute_codegen_tests;
	mod generic_opaque_rust_type_codegen_tests;
	mod opaque_rust_type_codegen_tests;
	mod opaque_swift_type_codegen_tests;
	mod option_codegen_tests;
	mod result_codegen_tests;
	mod return_into_attribute_codegen_tests;
	mod single_representation_type_elision_codegen_tests;
	mod string_codegen_tests;
	mod transparent_enum_codegen_tests;
	mod transparent_struct_codegen_tests;
	mod vec_codegen_tests;

---

Add a field SwiftBridgeModule.visibility: syn::Visibility

swift-bridge/crates/swift-bridge-ir/src/lib.rs

Lines 59 to 60 in b077451

	pub struct SwiftBridgeModule {
	name: Ident,

---

Then set the field during parsing visibility: item_mod.visibility

swift-bridge/crates/swift-bridge-ir/src/parse.rs

Lines 126 to 127 in 72e1759

	let module = SwiftBridgeModule {
	name: module_name,

---

Interpolate the visibility here #visibility #mod_name

swift-bridge/crates/swift-bridge-ir/src/codegen/generate_rust_tokens.rs

Line 305 in d03f772

mod #mod_name {

---

Verify that tests pass using cargo test -p swift-bridge-ir

[gabbifish]

Awesome! I'll try and get a PR open for this soon :)