Debugging OpenFOAM® with Visual Studio Code

Motivation

I remember when I started learning OpenFOAM a few years back (in 2017), I wondered how OpenFOAM works and usually new enthusiast wonders too. Over these years while learning OpenFOAM, I came across HowTo Debugging OpenFOAM which helped me to get more insights of OpenFOAM and its Architecture. However it is very difficult to debug a application on command line (terminal in Ubuntu) which limits the study. Also, a few tools viz., eclipse, Data Display Debugger (ddd) can be used to debug OpenFOAM application interactively. In addition to these tool there is one more code editor i.e. Visual Studio Code (VSCode) which let you to debug OpenFOAM application interactively. So, in this tutorial i will be sharing my experiences and explaining how to setup VSCode environment for OpenFOAM development i.e. debug an application which will help you to create enhanced application(s).

Requirements

• VSCode - with c/c++ Microsoft extension installed.
• OpenFOAM - compiled in DEBUG mode - V1912.
• Third Party - Default with OpenFOAM version.
• OS - Ubuntu - V1804.
• Basic VSCode terminology like build task, launch task, debug etc and how to debug simple c++ code.
• Basic/Advance C++ topics such as pointers,references, classes, inheritance, polymorphism, templates, STL - Only for deep dive into source code.

Steps for setting up the requirements.

1. Installing VSCode and extensions

• Download latest VSCode from this link.
• Install C/C++ extension for intellisense from here.

2. Compiling OpenFOAM in debug mode.

• Download OpenFOAM v1912 and Third Party from here.
• Extract packages into $HOME/OpenFOAM
• Edit ~/OpenFOAM/OpenFOAM-v1912/etc/bashrc and change WM_COMPILE_OPTION=Debug (mind spaces before and after '=' ).
• Append ~/.bashrc with source ~/OpenFOAM/OpenFOAM-v1912/etc/bashrc then cd into ~/OpenFOAM/OpenFOAM-v1912/ and compile with ./Allwmake.
• Note:
  • Make appropriate changes for new OF version or read the documentation.

Setting up VSCode environment for OpenFOAM Debugging

• Create and cd into user directory.

  mkdir -p $FOAM_RUN 
  cd $FOAM_RUN

• Make local copy of OpenFOAM tests and cd into vector test case.

  cp -r $WM_PROJECT_DIR/applications/test $FOAM_RUN
  cd test/vector

• Understand the following process once and then can be eliminated just by copy and pasting the vscode folder contents.

• Open VSCode in present directory.

  code .

  • Go to Terminal tab in VSCode, select configure build task and choose g++ build active file ; Edit task.json as follows and remove args options.

    "label": "wmake-build",
    "command": "wmake"

  • Go to Debug symbol in VSCode and create launch.json for g++ build and debug active file. Edit following fields

    "name": "OF-Debug",
    "program": "${env:FOAM_USER_APPBIN}/${fileBasenameNoExtension}",
    "preLaunchTask": "wmake-build",

  • For OF standard applications such as interFoam, interFoam etc, change program field to "${env:FOAM_APPBIN}/${fileBasenameNoExtension}".
  • Now it is time to lunch debugger. So, put breakpoint at line no 123 in Test-vector.C and hit F5.
  • Perform step in, step out, continue as per study.

• Owing to large source code and high use of c++ templates it is quite difficult for any IDE to provide code completion and intellisense but to some extent it is available in VSCode.

  • Open command pallet ctrl+shift+p and select c/c++ : Edit Configuration UI which creates c_cpp_properties.json file.
  • Edit includePath

    "includePath": [
        "${workspaceFolder}/**",
        "${FOAM_SRC}"
    ],
    "intelliSenseMode": "gcc-x64"

  • Then go to File > Preferences > Settings and change C_Cpp: IntelliSense Engine to Tag Parser.

• Now to develope OpenFOAM application like icoFoam, repeat same procedure.

• To avoid all setting up manually, copy above vscode folder and replace or paste in your working directory then launch vscode as code . in terminal.

References:

• VSCode
• OpenFOAM
• Probabilistic Money
• OpenFOAM wiki
• YouTube Tutorials