Fix a few unnecessary header inclusions to avoid inclusion loops.

src/collectgroup.c

@@ -31,6 +31,7 @@
 /* Local headers. */
 #include "engine.h"
 #include "error.h"
+#include "star_formation_logger.h"
 
 #ifdef WITH_MPI
 

src/engine.c

@@ -51,6 +51,7 @@
 /* Local headers. */
 #include "active.h"
 #include "atomic.h"
+#include "black_holes.h"
 #include "cell.h"
 #include "chemistry.h"
 #include "clocks.h"
@@ -83,7 +84,6 @@
 #include "sort_part.h"
 #include "star_formation.h"
 #include "star_formation_logger.h"
-#include "star_formation_logger_struct.h"
 #include "stars_io.h"
 #include "statistics.h"
 #include "timers.h"

src/engine.h

@@ -34,13 +34,9 @@
 
 /* Includes. */
 #include "barrier.h"
-#include "black_holes_properties.h"
-#include "chemistry_struct.h"
 #include "clocks.h"
 #include "collectgroup.h"
-#include "cooling_struct.h"
 #include "dump.h"
-#include "gravity_properties.h"
 #include "mesh_gravity.h"
 #include "parser.h"
 #include "partition.h"
@@ -48,11 +44,12 @@
 #include "runner.h"
 #include "scheduler.h"
 #include "space.h"
-#include "star_formation_logger.h"
 #include "task.h"
 #include "units.h"
 #include "velociraptor_interface.h"
 
+struct black_holes_properties;
+
 /**
  * @brief The different policies the #engine can follow.
  */

src/engine_collect_end_of_step.c

@@ -27,6 +27,7 @@
 
 /* Local headers. */
 #include "active.h"
+#include "star_formation_logger.h"
 #include "timeline.h"
 
 /**

src/runner_doiact_hydro.c

@@ -25,6 +25,7 @@
 /* Local headers. */
 #include "active.h"
 #include "cell.h"
+#include "chemistry.h"
 #include "engine.h"
 #include "pressure_floor_iact.h"
 #include "runner.h"

src/space.h

@@ -30,7 +30,6 @@
 #include <stddef.h>
 
 /* Includes. */
-#include "gravity_properties.h"
 #include "hydro_space.h"
 #include "lock.h"
 #include "parser.h"
@@ -40,6 +39,7 @@
 /* Avoid cyclic inclusions */
 struct cell;
 struct cosmology;
+struct gravity_props;
 
 /* Some constants. */
 #define space_cellallocchunk 1000