---
title: Debugging Module Maps
framework: Swift Package Manager
role: article
role_heading: Article
path: swift-package-manager/documentation/packagemanagerdocs/debuggingmodulemaps
---

# Debugging Module Maps

Diagnose and resolve issues when Swift can’t import your C or C++ libraries.

## Overview

Overview When you create module maps for C libraries, compilation errors or import failures indicate problems with your configuration. This article shows you how to test module maps and fix common issues. Use these techniques when: Swift can’t find your module Headers fail to import C++ code produces compilation errors You need to verify Swift Package Manager configures your module correctly Test your module map Verify that Swift can import your module before distributing it. Create a simple import test Create a test Swift file that imports your module: // test.swift import MyLibrary

print("Module imported successfully") Build the test file: swiftc -I path/to/module/directory test.swift If the module map has errors, the compiler produces diagnostic messages that indicates what’s wrong. Verify build configuration Use verbose output to verify Swift Package Manager configures your module correctly: swift build --verbose Look for these compiler flags in the output: -I flags pointing to your header directories -fmodule-map-file= flags pointing to your module map Link flags for binary libraries Resolve common issues When Swift can’t find your module or headers, check these common causes. Fix module name mismatches Verify the module name in the module map matches the artifact or target name. If Swift can’t find your module, verify: The module name in the module map matches the artifact or target name exactly. The module map file is named module.modulemap. The moduleMapPath in info.json points to the correct file. For system libraries, the target directory contains the module map. Locate missing headers Verify header paths and file locations when the compiler reports missing headers. If the compiler reports a missing header: Check that the header path in the module map is relative to the module map file. Verify the header file exists at the specified location. Ensure the headerPaths array in info.json includes the directory. Fix C++ compilation errors Add C++ language support directives to resolve C++ syntax errors. If you get errors about C++ syntax: Add requires cplusplus to your module map. For C++11 or later features, use requires cplusplus11. Verify your headers use appropriate #ifdef __cplusplus guards for mixed C/C++ code.

## See Also

- [Module Map Syntax Reference](swift-package-manager/documentation/packagemanagerdocs/modulemapreference.md)