launch.json parameters do not fully support cmake settings

[matthewdhunt]

Brief Issue Summary

Although you can refer to various CMake (vector-of-bool plugin) settings in launch.json, they cannot contain any variables. For example, in a launch.json, it is valid to write:

 {
    "name": "MFDApp Launch",
    "type": "cppvsdbg",
    "request": "launch",
    "program": "${config:cmake.buildDirectory}/MFDApp/MFDApp.exe",
    <etc...>
},

However, if the cmake.buildDirectory contains any variables itself, this will not work. For example:

 "cmake.buildDirectory": "../SomeDir/${buildKit}/${buildType}"

If this is done, when you attempt to launch the program, it will look for folders literally named ${buildKit}/${buildType} without substitution, which will of course fail. This means you can't use any relative paths in the cmake variables if they appear in the launch.json.

Expected:

When launching an application, VSCode would properly substitude paths for variables such as ${buildKit} or ${buildType}

Apparent Behavior:

When launching an application, VSCode treats cmake variables as string literals.

Platform and Versions

• Operating System: Windows 10 or Ubuntu 18.04
• CMake Version: 3.12 or 3.14
• VSCode Version: 1.44.0
• CMake Tools Extension Version: 1.3.1

[bobbrow]

Does it work if you use:

"cmake.buildDirectory": "../SomeDir/${command:cmake.buildKit}/${command:cmake.buildType}"

[bobbrow]

Though looking past the specific details of the question, you may also be interested to know that you can update your launch.json to use:

  "program": "${command:cmake.launchTargetPath}"

which will point to the target selected through the status bar UI or the "Set Debug Target" command.

[matthewdhunt]

No, I'm not sure exactly what it does if you use ${command:cmake.buildKit}/${command:cmake.buildType}. It seems to replace the entire contents of what is in " " with an absolute path of just "build" or something like that. It definitely doesn't just substitute the variables. I'll see if I can figure out what it's doing in a test project without messing with the build folder of the main project.

But, the tip of command:cmake.launchTargetPath is very helpful! That might resolve my use case although not really this bug.