How to pass find_program()s into custom_target()s?

[nils-werner]

I am writing a few shellscripts for custom_target()s, which will then call buildtools that I want to be able to parameterize in --cross-files. To that end I have a cross.ini which lets me customize the binary

[binaries]
xsct = 'sdk/xsct'

a meson.build that finds the binary,

sh_script = files('build/build.sh')
bash = find_program('bash')
xsct = find_program('xsct')

custom_target(
    'target',
    # ...
    command : [
        bash,
        sh_script,
        xsct,
        '@INPUT@',
        '@OUTDIR@'
    ],
    console : true,
)

and a build.sh that get's passed the binary, to later call it

#!/usr/bin/env bash

xsct=$1

# ...

"$xsct" 

exit 0

However it turns out that on Linux find_program('xsct') returns sdk/xsct, and on Windows ['bash', 'sdk/xsct'], which breaks the parameters to the shellscript.

Am I doing all of this wrong? How should I be doing this?