GCODE has invalid headers when output to file

[jeromechrist]

Description

GCODE has invalid headers when output to file while the executable standard output is correct

Steps to Reproduce

CuraEngine.exe slice -v -j "C:\Program Files\Ultimaker Cura 3.0\resources\definitions\ultimaker3.def.json" -l "C:\Users\jerome.christ\Desktop\cura\screw.stl" -o "C:\Users\jerome.christ\Desktop\cura\output.gcode"

This will produce a GCODE with correct instructions except for the headers, from the console :

But the written file has incorrect headers, when send to the UM3 it is deemed as invalid :

Reproduces how often:
Always

Versions

CuraEngine.exe v.3.0.3 used in command line
OS : Windows 10
CURA_ENGINE_SEARCH_PATH = "C:\Program Files\Ultimaker Cura 3.0\resources\definitions;C:\Program Files\Ultimaker Cura 3.0\resources\extruders"

[Ghostkeeper]

This also reproduces for me.

It seems like the problem here is that when slicing via command line, gcodeExport's output stream is std::cout or the target file, and then it has to put the header in front before any of the g-code has been output, so before any g-code is known and before the bounding box has been set. When slicing via an Arcus socket, the output is commandSocket's gcode_output_stream which can be finalized later.