Support `private` modules

[jmackie]

A module marked as private can only be imported by other modules in the same package.

private module Implementation.Details exports (..);

The implementation should be fairly straightforward - we just need to check during build planning whether a module imported from a different package is private: true (and raise an error if it is):

Relevant bit of the build planning logic is here:

ditto/crates/ditto-make/src/build_ninja.rs

Lines 305 to 337 in 8c3b1c9

	// Add the edges
	for (node_index, node) in build_graph_nodes.iter() {
	for import_line in node.imports.iter() {
	let import_package_name = import_line
	.package
	.as_ref()
	.map(|parens| parens.value.0.value.as_str());
	let import_module_name = ast::ModuleName::from(import_line.module_name.clone());
	for (
	idx,
	BuildGraphNode {
	package_name,
	module_name,
	..
	},
	) in build_graph_nodes.iter()
	{
	let same_package_name = match (package_name, import_package_name) {
	(None, None) => true,
	(Some(a), Some(b)) => a.as_str() == b,
	_ => false,
	};
	let same_module_name = *module_name == import_module_name;
	if same_package_name && same_module_name {
	build_graph.add_edge(*node_index, *idx, "");
	break;
	}
	}
	// If we can't find the import then we just ignore it,
	// let the checker throw an error.
	}
	}

The ditto_ast::Module type will also need a private: bool field adding:

ditto/crates/ditto-ast/src/module.rs

Line 9 in 8c3b1c9

pub struct Module {

[ritikBhandari]

Hi,
Can I take up this issue if possible?

[jmackie]

Hi, Can I take up this issue if possible?

Sure thing 🙏