Resolving "No CMAKE_C_COMPILER" Error in CMake for Visual Studio and GCC

Introduction

When working with CMake to configure build environments, especially when integrating it with IDEs like Visual Studio or compilers such as GCC, you may encounter the error:

No CMAKE_C_COMPILER could be found.
No CMAKE_CXX_COMPILER could be found.

This tutorial provides a comprehensive guide on how to resolve these errors by configuring your development environment correctly. We will cover both Windows (Visual Studio) and Linux (GCC) environments.

Understanding the Error

The error messages indicate that CMake is unable to find the necessary compiler tools to proceed with configuration. This could be due to several reasons, such as missing installations, incorrect paths, or misconfigured environments.

Common Causes

1. Missing Compiler Installation: The required compiler (C/C++) might not be installed.
2. Path Issues: CMake cannot locate the compiler binaries because they are not in the system PATH.
3. Environment Misconfiguration: Environment variables necessary for the compilers are not set correctly.

Resolving the Error on Windows with Visual Studio

Pre-requisites

• Ensure that you have a version of Visual Studio installed, such as Visual Studio 2015 or later.
• Verify that the C++ components are installed if they were not included by default.

Steps to Resolve

1. Install C++ Components: If using Visual Studio 2015, ensure that the "Desktop development with C++" workload is installed. This can be done via the Visual Studio Installer.

2. Set Up Environment Variables:

   • Open a Command Prompt and execute the vcvarsall.bat script to set up the necessary environment variables.

     "C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\vcvarsall.bat"
     

   • Alternatively, use the "Developer Command Prompt for VS2015" from the Start Menu.

3. Specify Generator:

   • Run CMake with a specific generator to match your Visual Studio version.

     cmake -G "Visual Studio 14 2015" ..
     

4. Windows SDK: If issues persist, ensure that the Windows 10 SDK is installed and configured in Visual Studio.

Resolving the Error on Linux with GCC

Pre-requisites

• Ensure GCC (or MinGW for cross-compilation) is installed.
• Use a package manager like apt to install necessary build tools.

Steps to Resolve

1. Install Build Essentials:

   • On Ubuntu, use the following command to install essential build tools including GCC.

     sudo apt-get update && sudo apt-get install build-essential
     

2. Set Compiler Path:

   • If CMake still cannot find GCC, explicitly set the compiler path using environment variables.

     export CC=/usr/bin/gcc
     export CXX=/usr/bin/g++
     cmake ..
     

3. Use MSYS Shell for MinGW:

   • If working with MinGW on Windows via MSys shell, ensure you start with msys.bat and verify GCC availability.

     $ gcc --version
     

   • Use the appropriate generator for Makefiles if using MinGW.

     cmake -G "MSYS Makefiles" ..
     

Best Practices

• Clean Build Directory: Before running CMake, ensure your build directory is clean to prevent caching issues.
• Latest CMake Version: Always use the latest version of CMake for improved compatibility and features.
• Check Logs: Review CMakeError.log and CMakeOutput.log for detailed error messages.

Conclusion

By following these steps, you should be able to resolve "No CMAKE_C_COMPILER" errors in both Windows and Linux environments. Ensuring that your compilers are correctly installed and configured is key to a smooth build configuration process with CMake.