Generate Compilation Database (compile_command.json) Using Qmake (not GUI)

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Generate Compilation Database (compile_command.json) using qmake (not GUI)

Discussion Category: Qmake, Compilation Database

When working on a Qt project, generating a compilation database (compile_command.json) can be a crucial step in debugging and testing. However, when using the command-line interface of qmake (not the GUI), it can be challenging to generate this database. In this article, we will explore how to generate a compilation database using qmake without relying on the GUI.

A compilation database is a JSON file that contains information about the compilation commands used to build a project. This database can be used by tools like clang-tidy and clang-check to provide more accurate and detailed feedback on the code. The compilation database is typically generated by the build system, but in the case of qmake, we need to use a workaround to achieve this.

To generate a compilation database using qmake, we can use the following steps:

Step 1: Create a qmake project

First, we need to create a qmake project. This can be done by creating a new directory for our project and adding a qmake project file (e.g., project.pro) to it. The project file should contain the necessary information about the project, such as the source files, include paths, and libraries.

Step 2: Configure qmake to generate compilation database

Next, we need to configure qmake to generate the compilation database. We can do this by adding the following line to the project.pro file:

QMAKE_COMPILE_COMMANDS = compile_command.json

This will tell qmake to generate a compilation database file named compile_command.json.

Step 3: Run qmake to generate compilation database

Once we have configured qmake to generate the compilation database, we can run qmake to generate the database. We can do this by running the following command:

qmake -r

The -r option tells qmake to regenerate the project files and generate the compilation database.

Step 4: Verify the compilation database

After running qmake, we can verify that the compilation database has been generated by checking the compile_command.json file. This file should contain the necessary information about the compilation commands used to build the project.

Let's consider an example use case where we have a Qt project that uses the qmake build system. We want to generate a compilation database to use with clang-tidy and clang-check. We can follow the steps outlined above to generate the compilation database.

Here is an example project.pro file:

QT += core gui

SOURCES = main.cpp
HEADERS = main.h
FORMS = main.ui


QMAKE_COMPILE_COMMANDS = compile_command.json

We can then run qmake to generate the compilation database:

qmake -r

After running qmake, we can verify that the compilation database has been generated by checking the compile_command.json file.

In this article, we have explored how to generate a compilation database using qmake without relying on the GUI. We have outlined the necessary steps to configure qmake to generate the compilation database and provided an example use case to illustrate the process. By following these steps, developers can generate a compilation database for their Qt projects and use it with tools like clang-tidy and clang-check.

For more information on generating compilation databases using qmake, you can refer to the following resources:

  • Q: How do I configure qmake to generate a compilation database? A: You can configure qmake to generate a compilation database by adding the QMAKE_COMPILE_COMMANDS variable to your project.pro file.
  • Q: How do I run qmake to generate the compilation database? A: You can run qmake to generate the compilation database by running the qmake -r command.
  • Q: How do I verify that the compilation database has been generated? A: You can verify that the compilation database has been generated by checking the compile_command.json file.
    Q&A: Generating Compilation Database using qmake (not GUI)

In our previous article, we explored how to generate a compilation database using qmake without relying on the GUI. In this article, we will answer some frequently asked questions about generating compilation databases using qmake.

A compilation database is a JSON file that contains information about the compilation commands used to build a project. This database can be used by tools like clang-tidy and clang-check to provide more accurate and detailed feedback on the code.

You need a compilation database to use tools like clang-tidy and clang-check to analyze and improve your code. These tools rely on the compilation database to provide accurate and detailed feedback on the code.

You can configure qmake to generate a compilation database by adding the QMAKE_COMPILE_COMMANDS variable to your project.pro file. For example:

QMAKE_COMPILE_COMMANDS = compile_command.json

This will tell qmake to generate a compilation database file named compile_command.json.

You can run qmake to generate the compilation database by running the qmake -r command. This will regenerate the project files and generate the compilation database.

You can verify that the compilation database has been generated by checking the compile_command.json file. This file should contain the necessary information about the compilation commands used to build the project.

Yes, you can use a different name for the compilation database file by modifying the QMAKE_COMPILE_COMMANDS variable. For example:

QMAKE_COMPILE_COMMANDS = my_compile_commands.json

This will generate a compilation database file named my_compile_commands.json.

Yes, you can generate a compilation database for a specific target by using the QMAKE_TARGET variable. For example:

QMAKE_TARGET = my_target
QMAKE_COMPILE_COMMANDS = compile_command.json

This will generate a compilation database file named compile_command.json for the my_target target.

Yes, you can use a different compiler to generate the compilation database by modifying the QMAKE_CXX variable. For example:

QMAKE_CXX = clang++
QMAKE_COMPILE_COMMANDS = compile_command.json

This will generate a compilation database file named compile_command.json using the clang++ compiler.

Yes, you can generate a compilation database for a Qt project that uses a different build system by using the QMAKE_GENERATE_COMPILATION_DATABASE variable. For example:

QMAKE_GENERATE_COMPILATION_DATABASE = 1
QMAKE_COMPILE_COMMANDS = compile_command.json

This will generate a compilation database file named compile_command.json for the project.

In this article, we have answered some frequently asked questions about generating compilation databases using qmake. We hope this article has provided you with the information you need to generate a compilation database for your Qt project.

For more information on generating compilation databases using qmake, you can refer to the following resources:

  • Q: How do I configure qmake to generate a compilation database? A: You can configure qmake to generate a compilation database by adding the QMAKE_COMPILE_COMMANDS variable to your project.pro file.
  • Q: How do I run qmake to generate the compilation database? A: You can run qmake to generate the compilation database by running the qmake -r command.
  • Q: How do I verify that the compilation database has been generated? A: You can verify that the compilation database has been generated by checking the compile_command.json file.