segfault during preprocessing (swapping)

[MariusCausemann]

Hi, first of all, thanks for this great meshing tool! In most cases, fTetWild works very well for me, but recently, I encountered a segfault in the preprocessing stage. It is quite a complex mesh (consisting of ~200 separate surfaces) and unfortunately, I can reproduce using a simpler example. If necessary, I can provide the input files.

Here is fTetWild output:

6 10 12 2 9 5 16 13 0 14 4 1 19 8 18 11 3 17 15 7 
TBB threads 7
[2024-08-14 10:07:12.503] [geogram] [info] Loading file results/cortical_mm3/surfaces/size+20000/dx+20_ncells+200/roi.ply...
[2024-08-14 10:07:12.504] [geogram] [info] (FP64) nb_v:8 nb_e:0 nb_f:6 nb_b:0 tri:0 dim:3
[2024-08-14 10:07:12.504] [geogram] [info] Attributes on vertices: point[3]
[2024-08-14 10:07:12.505] [geogram] [info] Loading file results/cortical_mm3/surfaces/size+20000/dx+20_ncells+200/2.ply...
[2024-08-14 10:07:12.521] [geogram] [info] (FP64) nb_v:20838 nb_e:0 nb_f:41650 nb_b:19 tri:1 dim:3
[2024-08-14 10:07:12.521] [geogram] [info] Attributes on vertices: point[3]
[2024-08-14 10:07:12.522] [geogram] [info] Loading file results/cortical_mm3/surfaces/size+20000/dx+20_ncells+200/3.ply...
[2024-08-14 10:07:12.533] [geogram] [info] (FP64) nb_v:16564 nb_e:0 nb_f:33120 nb_b:4 tri:1 dim:3
[2024-08-14 10:07:12.533] [geogram] [info] Attributes on vertices: point[3]
[2024-08-14 10:07:12.533] [geogram] [info] Loading file results/cortical_mm3/surfaces/size+20000/dx+20_ncells+200/4.ply...
[2024-08-14 10:07:12.547] [geogram] [info] (FP64) nb_v:24800 nb_e:0 nb_f:49587 nb_b:228 tri:1 dim:3
[2024-08-14 10:07:12.547] [geogram] [info] Attributes on vertices: point[3]
[2024-08-14 10:07:12.548] [geogram] [info] Loading file results/cortical_mm3/surfaces/size+20000/dx+20_ncells+200/5.ply...
[2024-08-14 10:07:12.558] [geogram] [info] (FP64) nb_v:19343 nb_e:0 nb_f:38678 nb_b:13 tri:1 dim:3
[2024-08-14 10:07:12.559] [geogram] [info] Attributes on vertices: point[3]
[2024-08-14 10:07:12.559] [geogram] [info] Loading file results/cortical_mm3/surfaces/size+20000/dx+20_ncells+200/6.ply...
[2024-08-14 10:07:12.586] [geogram] [info] (FP64) nb_v:13240 nb_e:0 nb_f:26475 nb_b:2 tri:1 dim:3
[2024-08-14 10:07:12.586] [geogram] [info] Attributes on vertices: point[3]
...

bbox_diag_length = 34575
ideal_edge_length = 1728.75
stage = 2
eps_input = 18.2627
eps = 10.1101
eps_simplification = 8.08806
eps_coplanar = 0.034575
dd = 12.1752
dd_simplification = 9.74013
[2024-08-14 10:07:59.389] [float-tetwild] [info] remove duplicates: 
[2024-08-14 10:07:59.389] [float-tetwild] [info] #v: 10072385 -> 10072385
[2024-08-14 10:07:59.389] [float-tetwild] [info] #f: 20149242 -> 20149242
[2024-08-14 10:07:59.801] [float-tetwild] [info] remove degenerate triangles and duplicated opposite-oriented triangles:
[2024-08-14 10:07:59.801] [float-tetwild] [info] (removing degenerate triangles might leave lone vertices that will be removed later)
[2024-08-14 10:07:59.801] [float-tetwild] [info] #v: 10072385 -> 10072385
[2024-08-14 10:07:59.801] [float-tetwild] [info] #f: 20149242 -> 20149242
collapsing 1410.3s
segfault

Any idea what the problem could be? @nmnoble, I also tried your fTetWild branch, leading to the same issue. Any ideas?