Fix for matplotlib#3789, segfault in _tri

Author: ianthomas23

lib/matplotlib/tri/_tri.cpp

@@ -530,7 +530,8 @@ int Triangulation::get_triangle_point(const TriEdge& tri_edge) const
 bool Triangulation::is_masked(int tri) const
 {
     assert(tri >= 0 && tri < get_ntri() && "Triangle index out of bounds.");
-    return !_mask.empty() && _mask(tri);
+    const npy_bool* mask_ptr = reinterpret_cast<const npy_bool*>(_mask.data());
+    return !_mask.empty() && mask_ptr[tri];
 }
 
 void Triangulation::set_mask(const MaskArray& mask)

src/numpy_cpp.h

@@ -479,6 +479,12 @@ class array_view : public detail::array_view_accessors<array_view, T, ND>
         return size() == 0;
     }
 
+    // Do not use this for array_view<bool, ND>.  See comment near top of file.
+    const T *data() const
+    {
+        return (const T *)m_data;
+    }
+
     // Do not use this for array_view<bool, ND>.  See comment near top of file.
     T *data()
     {