_ prefixed top-level symbols now file-local

compiler_tests.odin

@@ -6645,6 +6645,49 @@ imports_are_file_local :: proc(t: ^testing.T) {
 	testing.expect(t, !state.success)
 }
 
+@(test)
+leading_underscore_declarations_are_file_hidden :: proc(t: ^testing.T) {
+	output := "/tmp/brolang-test-hidden-declarations"
+	defer _ = os.remove(output)
+	status := compiler_core.compile_package("examples/packages/hidden_valid/app", output)
+	testing.expect_value(t, status, 0)
+	state := run_executable(output)
+	testing.expect_value(t, state.exit_code, 7)
+}
+
+@(test)
+file_hidden_declarations_are_not_package_members :: proc(t: ^testing.T) {
+	sources := source.init_store()
+	defer source.destroy_store(&sources)
+	diagnostics := source.init_store_diagnostics(&sources)
+	defer source.destroy_diagnostics(&diagnostics)
+	symbols := symbol.init_table()
+	defer symbol.destroy_table(&symbols)
+	module, loaded := loader.load("examples/packages/hidden_invalid/app", &sources, &diagnostics, &symbols)
+	defer ast.destroy_module(&module)
+	hir_module := checker.check(&module, &diagnostics, &symbols)
+	defer hir.destroy_module(&hir_module)
+
+	testing.expect(t, loaded)
+	found_sibling := false
+	found_sibling_value := false
+	found_sibling_type := false
+	found_import := false
+	found_collision := false
+	for diagnostic in diagnostics.items {
+		found_sibling = found_sibling || strings.contains(diagnostic.message, "unresolved function '_sibling'")
+		found_sibling_value = found_sibling_value || strings.contains(diagnostic.message, "unresolved global '_sibling_value'")
+		found_sibling_type = found_sibling_type || strings.contains(diagnostic.message, "unknown or opaque record type '_Sibling'")
+		found_import = found_import || strings.contains(diagnostic.message, "package 'dep' has no member '_secret'")
+		found_collision = found_collision || strings.contains(diagnostic.message, "duplicate function '_collision'")
+	}
+	testing.expect(t, found_sibling)
+	testing.expect(t, found_sibling_value)
+	testing.expect(t, found_sibling_type)
+	testing.expect(t, found_import)
+	testing.expect(t, found_collision)
+}
+
 @(test)
 package_import_cycles_are_valid :: proc(t: ^testing.T) {
 	output := "/tmp/brolang-test-package-cycle"