Merge pull request #83604 from charles-dyfis-net/curaengine-fix-openmp-compat

curaLulzbot: Fix build breakage around OpenMP compatibility

pkgs/applications/misc/cura/lulzbot/curaengine-openmp-compat.patch

@@ -0,0 +1,47 @@
+# Notes by Charles Duffy <charles@dyfis.net> --
+#
+# - The new version of OpenMP does not allow outside variables to be referenced
+#   *at all* without an explicit declaration of how they're supposed to be
+#   handled. Thus, this was an outright build failure beforehand. The new
+#   pragmas copy the initial value from the outer scope into each parallel
+#   thread. Since these variables are all constant within the loops, this is
+#   clearly correct. (Not sure it's *optimal*, but quite sure it isn't
+#   *wrong*).
+# - Upstream has been contacted -- I'm a Lulzbot customer with an active
+#   support contract and sent them the patch. That said, they're in the middle
+#   of some major corporate churn (sold themselves out of near-bankruptcy to an
+#   out-of-state business entity formed as a holding company; moved to that
+#   state; have been slowly restaffing after), so a response may take a while.
+# - The patch is purely my own work.
+
+--- curaengine/src/support.cpp.orig	2020-03-28 10:38:01.953912363 -0500
++++ curaengine/src/support.cpp	2020-03-28 10:45:28.999791908 -0500
+@@ -854,7 +854,7 @@
+     const double tan_angle = tan(angle) - 0.01;  // the XY-component of the supportAngle
+     xy_disallowed_per_layer[0] = storage.getLayerOutlines(0, false).offset(xy_distance);
+     // for all other layers (of non support meshes) compute the overhang area and possibly use that when calculating the support disallowed area
+-    #pragma omp parallel for default(none) shared(xy_disallowed_per_layer, storage, mesh) schedule(dynamic)
++    #pragma omp parallel for default(none) firstprivate(layer_count, is_support_mesh_place_holder, use_xy_distance_overhang, z_distance_top, tan_angle, xy_distance, xy_distance_overhang) shared(xy_disallowed_per_layer, storage, mesh) schedule(dynamic)
+     for (unsigned int layer_idx = 1; layer_idx < layer_count; layer_idx++)
+     {
+         Polygons outlines = storage.getLayerOutlines(layer_idx, false);
+@@ -1054,7 +1054,7 @@
+         const int max_checking_layer_idx = std::min(static_cast<int>(storage.support.supportLayers.size())
+                                                   , static_cast<int>(layer_count - (layer_z_distance_top - 1)));
+         const size_t max_checking_idx_size_t = std::max(0, max_checking_layer_idx);
+-#pragma omp parallel for default(none) shared(support_areas, storage) schedule(dynamic)
++#pragma omp parallel for default(none) firstprivate(max_checking_idx_size_t, layer_z_distance_top) shared(support_areas, storage) schedule(dynamic)
+         for (size_t layer_idx = 0; layer_idx < max_checking_idx_size_t; layer_idx++)
+         {
+             support_areas[layer_idx] = support_areas[layer_idx].difference(storage.getLayerOutlines(layer_idx + layer_z_distance_top - 1, false));
+--- curaengine/src/layerPart.cpp.orig	2020-03-28 10:36:40.381023651 -0500
++++ curaengine/src/layerPart.cpp	2020-03-28 10:39:54.584140465 -0500
+@@ -49,7 +49,7 @@
+ {
+     const auto total_layers = slicer->layers.size();
+     assert(mesh.layers.size() == total_layers);
+-#pragma omp parallel for default(none) shared(mesh, slicer) schedule(dynamic)
++#pragma omp parallel for default(none) firstprivate(total_layers) shared(mesh, slicer) schedule(dynamic)
+     for (unsigned int layer_nr = 0; layer_nr < total_layers; layer_nr++)
+     {
+         SliceLayer& layer_storage = mesh.layers[layer_nr];

pkgs/applications/misc/cura/lulzbot/curaengine.nix

@@ -10,6 +10,8 @@ gcc8Stdenv.mkDerivation rec {
     sha256 = "0wdkvg1hmqp1gaym804lw09x4ngf5ffasd861jhflpy7djbmkfn8";
   };
 
+  patches = [ ./curaengine-openmp-compat.patch ];
+
   nativeBuildInputs = [ cmake ];
   buildInputs = [ libarcusLulzbot stb protobuf ];