G71 introduces a circle when using the D parameter (remaining distance to stock)

[sundtek]

In Lathe mode G71 introduces a half circle when using the D parameter, it disappears when not using the D parameter.
I'm using the latest linuxcnc git version (15. March 2024)

G17 G54 G40 G80 G90
G21
G54
G97
G61
g18 g64 g8
G1 F140
S700
M3
G4 P1
G0 Z14.4
#<_startX>=14.3
#<_startZ>=12.5
o100 sub
G1 X#<_startX> Z#<_startZ>
G1 X0.01
G1 Z0 X14.325
G1 X15
o100 endsub
G71 Q100 X#<_startX> Z#<_startZ> D0.25 I0.2 R1
M2

that half circle is not correct.

[andypugh]

Is D meant to be a "stock to leave" number? The docs for G71 are terrible, which annoys me as I wrote much better ones for a different implementation of the cycles.

Does it always fail? Or is is sometimes usable?

[sundtek]

I only tested it once and put the result here for the record until someone (or I) have more time to fix it.
D should be stock to leave yes.
Once the stock to leave is removed it's okay - the entire circle should not be there when stock to leave is used.