3D Alpha Wrapping segfault with gcc 15.1 and inline activated

[ptitjano]

Issue Details

When using 3D Alpha Wrapping on the bunny dataset with GCC 15.1, a segmentation fault occurs as soon as an optimization level is activated. Disabling inline fixes the issue. This problem does not occur with GCC 14.

Source Code

#include <CGAL/Exact_predicates_inexact_constructions_kernel.h>
#include <CGAL/Surface_mesh.h>

#include <CGAL/alpha_wrap_3.h>
#include <CGAL/IO/read_points.h>
#include <CGAL/Real_timer.h>

#include <iostream>
#include <string>

using InexactKernel   = CGAL::Exact_predicates_inexact_constructions_kernel;
using Inexact_Point_3 = InexactKernel::Point_3;
using Mesh            = CGAL::Surface_mesh<Inexact_Point_3>;


int main(int argc, char** argv)
{
  // read the input
  std::list<Inexact_Point_3> points;

  //read input
  std::ifstream inputStream("bunny_1000");
  int nrPoints;
  inputStream >> nrPoints;
  std::cout << "Reading " << nrPoints << " points " << std::endl;
  Inexact_Point_3 point;
  for( ; nrPoints>0 ; nrPoints--)
  {
    inputStream >> point;
    points.push_back(point);
  }

  std::cout << points.size() << " points" << std::endl;

  // Compute the alpha and offset values
  const double relativeAlpha = 20.;

  CGAL::Bbox_3 bbox = CGAL::bbox_3(std::cbegin(points), std::cend(points));
  const double diag_length = std::sqrt(CGAL::square(bbox.xmax() - bbox.xmin()) +
                                       CGAL::square(bbox.ymax() - bbox.ymin()) +
                                       CGAL::square(bbox.zmax() - bbox.zmin()));
  const double alpha = diag_length / relativeAlpha;
  std::cout << "diag length = " << diag_length << "\n";
  std::cout << "relative alpha = " << relativeAlpha << "\n";
  std::cout << "absolute alpha = " << alpha << "\n";

  // Construct the wrapMesh
  CGAL::Real_timer timer;
  timer.start();

  Mesh wrapMesh;
  CGAL::alpha_wrap_3(points, alpha, wrapMesh);

  timer.stop();
  std::cout << "Result: " << num_vertices(wrapMesh) << " vertices, " << num_faces(wrapMesh) << " faces" << std::endl;
  std::cout << "Took " << timer.time() << " s." << std::endl;

  // Save the result
  const std::string output_name = "output_bunny.off";
  std::cout << "Writing to " << output_name << std::endl;
  CGAL::IO::write_polygon_mesh(output_name, wrapMesh, CGAL::parameters::stream_precision(17));

  return EXIT_SUCCESS;
}

with inline

g++ -Wall -O1 main_cgal.cpp -lgmp -lgmpxx -lmpfr -o main_cga

Reading 1000 points 
1000 points
diag length = 0.248131
relative alpha = 20
absolute alpha = 0.0124066
terminate called after throwing an instance of 'CGAL::Assertion_exception'
  what():  CGAL ERROR: assertion violation!
Expr: n == N[3]
File: /usr/include/CGAL/Triangulation_ds_cell_base_3.h
Line: 122
Aborted (core dumped)

without inline

g++ -Wall -O1 -fno-inline main_cgal.cpp -lgmp -lgmpxx -lmpfr -o main_cgal

Reading 1000 points 
1000 points
diag length = 0.248131
relative alpha = 20
absolute alpha = 0.0124066
Result: 1193 vertices, 2386 faces
Took 0.788322 s.
Writing to output_bunny.off

Environment

• Operating system (Windows/Mac/Linux, 32/64 bits): can reproduce on windows with mingw and fedora 42
• Compiler: gcc 15.1
• Release or debug mode: Release
• Specific flags used (if any): 01/02/03
• CGAL version: 6.0.1
• Boost version: 1.83
• Other libraries versions if used (Eigen, TBB, etc.): N/A

[sloriot]

I think we already fixed the issue in master. Could you give it a try?

[sloriot]

More precisely here: #8820

[ptitjano]

Thanks for the quick answer. This is indeed fixed on master.