Temporarily write the time-bins to the snapshots to make sure we only write real particles.

src/gravity/Default/gravity_io.h

@@ -92,6 +92,15 @@ INLINE static void darkmatter_read_particles(struct gpart* gparts,
                                 UNIT_CONV_NO_UNITS, gparts, id_or_neg_offset);
 }
 
+INLINE static void test_time_bin_gpart(const struct engine* e,
+                                       const struct gpart* gp, float* ret) {
+
+  if (gp->time_bin >= time_bin_inhibited)
+    error("Writing inhibited or extra particle time_bin=%d", gp->time_bin);
+
+  *ret = gp->time_bin;
+}
+
 /**
  * @brief Specifies which g-particle fields to write to a dataset
  *
@@ -104,7 +113,7 @@ INLINE static void darkmatter_write_particles(const struct gpart* gparts,
                                               int* num_fields) {
 
   /* Say how much we want to write */
-  *num_fields = 4;
+  *num_fields = 5;
 
   /* List what we want to write */
   list[0] = io_make_output_field_convert_gpart(
@@ -115,6 +124,8 @@ INLINE static void darkmatter_write_particles(const struct gpart* gparts,
       io_make_output_field("Masses", FLOAT, 1, UNIT_CONV_MASS, gparts, mass);
   list[3] = io_make_output_field("ParticleIDs", ULONGLONG, 1,
                                  UNIT_CONV_NO_UNITS, gparts, id_or_neg_offset);
+  list[4] = io_make_output_field_convert_gpart(
+      "TimeBin", FLOAT, 1, UNIT_CONV_NO_UNITS, gparts, test_time_bin_gpart);
 }
 
 #endif /* SWIFT_DEFAULT_GRAVITY_IO_H */

src/hydro/Gadget2/hydro_io.h

@@ -128,6 +128,16 @@ INLINE static void convert_part_potential(const struct engine* e,
     ret[0] = 0.f;
 }
 
+INLINE static void test_time_bin_part(const struct engine* e,
+                                      const struct part* p,
+                                      const struct xpart* xp, float* ret) {
+
+  if (p->time_bin >= time_bin_inhibited)
+    error("Writing inhibited or extra particle time_bin=%d", p->time_bin);
+
+  *ret = p->time_bin;
+}
+
 /**
  * @brief Specifies which particle fields to write to a dataset
  *
@@ -141,7 +151,7 @@ INLINE static void hydro_write_particles(const struct part* parts,
                                          struct io_props* list,
                                          int* num_fields) {
 
-  *num_fields = 10;
+  *num_fields = 11;
 
   /* List what we want to write */
   list[0] = io_make_output_field_convert_part("Coordinates", DOUBLE, 3,
@@ -168,6 +178,9 @@ INLINE static void hydro_write_particles(const struct part* parts,
   list[9] = io_make_output_field_convert_part("Potential", FLOAT, 1,
                                               UNIT_CONV_POTENTIAL, parts,
                                               xparts, convert_part_potential);
+  list[10] =
+      io_make_output_field_convert_part("TimeBin", FLOAT, 1, UNIT_CONV_NO_UNITS,
+                                        parts, xparts, test_time_bin_part);
 
 #ifdef DEBUG_INTERACTIONS_SPH
 

src/stars/Default/stars_io.h

@@ -22,6 +22,15 @@
 #include "io_properties.h"
 #include "stars_part.h"
 
+INLINE static void test_time_bin_spart(const struct engine *e,
+                                       const struct spart *sp, float *ret) {
+
+  if (sp->time_bin >= time_bin_inhibited)
+    error("Writing inhibited or extra particle time_bin=%d", sp->time_bin);
+
+  *ret = sp->time_bin;
+}
+
 /**
  * @brief Specifies which s-particle fields to read from a dataset
  *
@@ -60,8 +69,8 @@ INLINE static void stars_write_particles(const struct spart *sparts,
                                          struct io_props *list,
                                          int *num_fields) {
 
-  /* Say how much we want to read */
-  *num_fields = 5;
+  /* Say how much we want to write */
+  *num_fields = 6;
 
   /* List what we want to read */
   list[0] = io_make_output_field("Coordinates", DOUBLE, 3, UNIT_CONV_LENGTH,
@@ -74,6 +83,9 @@ INLINE static void stars_write_particles(const struct spart *sparts,
                                  sparts, id);
   list[4] = io_make_output_field("SmoothingLength", FLOAT, 1, UNIT_CONV_LENGTH,
                                  sparts, h);
+
+  list[5] = io_make_output_field_convert_spart(
+      "TimeBin", FLOAT, 1, UNIT_CONV_NO_UNITS, sparts, test_time_bin_spart);
 }
 
 /**