Wiping and Firmware Retraction may result in too much retraction

[NameOfTheDragon]

Before opening a bug report for this, I thought some discussion might be useful in case there's something I'm missing.

I have noticed that it is possible to enable both

• Use Firmware Retraction
• Wipe while retracting

Two lots of retraction are then written to the gcode, but only one de-retraction. This means that there may be a net excess retraction.

For example, consider the following gcode generated with the above settings...

G10 ; retract
;WIPE_START
G1 F14400
G1 X16.964 Y16.963 E-0.03273
G1 X16.429 Y17.615 E-0.16692
G1 X16.056 Y18.312 E-0.1566
;WIPE_END
G1 Z0.8 F18000
; printing object Corner Hidey House id:0 copy 0
G1 X20.982 Y20.994
G1 Z0.4
G11 ; unretract
;TYPE:Internal perimeter
G1 F2100.4507
G1 X27.584 Y21.075 E0.6469

You can see the initial G10 firmware retraction - this will retract by whatever the firmware setting is.
Then in the wipe movement, the extruder position is further retracted in 3 steps by almost 0.4 mm
Finally there is a travel move with Z-hop, and then the G11 unretract command is sent, which will unretract by the firmware setting.
The print then continues with extrusion moves.

In my estimation, this results in too much retraction.

In this situation, shouldn't the wipe move be done without any further retraction?

I suppose, arguably, it shouldn't be possible to set this combination of settings, but it is. And in fact, I like that, because otherwise to use firmware retraction, one has to give up the benefits of wiping.