Adapting a Windows .bat script with @call vcvars64.bat

[nigels-com]

I'm interested in using just as an alternative to a Windows .bat script.
The first step of the script is to call a vendor-provided script that sets various environment variables:

setlocal
@call  "C:\Program Files (x86)\Microsoft Visual Studio\2019\Professional\VC\Auxiliary\Build\vcvars64.bat"

My understanding is that this step is necessary for the subsequent cmake invocations to detect and use the appropriate C/C++ toolchain. The rest converts to a cross-platform set of just recipes:

# cmake configuration step
cmake:
	cmake -S . -B {{BUILD}} \
		{{ if os_family() == 'windows' { '-A x64'} else { '' } }} \
		-DCMAKE_INSTALL_PREFIX={{CMAKE_INSTALL_PREFIX}} \
		-DCMAKE_BUILD_TYPE={{CMAKE_BUILD_TYPE}} \
		{{CMAKE_FLAGS}}

# cmake build step
build:
	cmake --build {{BUILD}} -j

# installation step
install:
	cmake --build {{BUILD}} -j --target {{INSTALL}}

# packaging step
package:
	cmake --build {{BUILD}} -j --target dist

But it's not at all clear how I can use the environment variables via vcvars64.bat using just.

Edit: I'm expecting to use cmd.exe for windows-shell, but would be happy to have a powershell solution.

Thanks in advance for any suggestions.

[casey]

This has come up a few times before, in different contexts, and I've never been able to figure out how to support this pattern well. Just runs every line of every recipe in a fresh shell, so environment variables aren't persisted across invocations.

[nigels-com]

I think in our specific setup we could possibly move this "up" to the Jenkinsfile pipeline with some awkward cmd.exe invocation of just.
My team may well push back on that idea, but may well accept it as a good price to pay for cross-platform build script, and no more batch or GNU make wrangling.

[nigels-com]

It does make me think of cmd.exe /k or bash --rcfile as something that just could possibly support doing, but alas I'm not sure I have the opportunity to learn enough rust to take a stab at that.

[casey]

Thinking about it now, is there any way that you can write the env variables that the bat file creates to a .env file? If so, just supports loading .env files and exporting variables to recipes.

[nigels-com]

Yes, I did look into that to discover the true horror of various batch files that MS Visual Studio is using to populate those environment variables. It would work here and now to bake them into an .env, but does seem fragile in terms of adding a newer toolchain, or whatnot. MS do specifically advise against that specifically. Some have gone to the trouble to unpack them, but I think that would be maintenance burden in our case.
https://renenyffenegger.ch/notes/Windows/development/Visual-Studio/environment-variables/index

I would say that despite this particular issue, I'm quite pleased with the way just slots into this particular niche - doing things in the make sort of way without the historical baggage, and happily without the necessity of tabs! We definitely don't want to run cmake directly, and this codifies various things very nicely.

[nigels-com]

If I never need to write or debug another batch file, you've made me very happy indeed.

[nigels-com]

The workaround I've proposed to our team is to move the vcvars64.bat up the stack into the Jenkinsfile CI script.
This means that Windows devs need to source that into their environment, rather than have it handled by the batch file as it previously was.
But I think this is workable for us.

    stages {
        stage('Build') {
            steps {
                bat '@call "C:\\Program Files (x86)\\Microsoft Visual Studio\\2019\\Professional\\VC\\Auxiliary\\Build\\vcvars64.bat" && just all'
            }
        }

[runeimp]

Couldn't you shebang the invocation? Just does some shebang magic on Windows for PowerShell shebang scripting. Is that also true for CMD @casey?

[nigels-com]

Our intention is to use Just as a simplified cross-platform make alternative. But since just isn't cmd.exe I've mostly come around to solving this "upstream" of Just.