project('extra args', 'swift') trace_fname = 'trace.json' lib = static_library('lib', 'lib.swift', swift_args: [ '-emit-loaded-module-trace', '-emit-loaded-module-trace-path', '../' + trace_fname ], ) custom_target('trace_check', output: trace_fname, command: ['cat', '@OUTPUT@'], depends: lib, build_always: true, )