Added debugging checks to the pair and self tasks to make sure cells have been...

Added debugging checks to the pair and self tasks to make sure cells have been drifted to this point before they get updated.

src/active.h

@@ -28,6 +28,34 @@
 #include "engine.h"
 #include "part.h"
 
+/**
+ * @brief Check that a cell been drifted to the current time.
+ *
+ * Only used for debugging. Calls error() if the cell has not
+ * been drifted. Does nothing if SWIFT_DEBUG_CHECKS is not defined.
+ *
+ * @param c The #cell.
+ * @param e The #engine containing information about the current time.
+ */
+__attribute__((always_inline)) INLINE static void cell_is_drifted(
+    const struct cell *c, const struct engine *e) {
+
+#ifdef SWIFT_DEBUG_CHECKS
+  if (c->ti_old > e->ti_current)
+    error(
+        "Cell has been drifted too far forward in time! c->ti_old=%d "
+        "e->ti_current=%d",
+        c->ti_old, e->ti_current);
+
+  if (c->ti_old != e->ti_current) {
+    error(
+        "Cell has not been drifted to the current time c->ti_old=%d, "
+        "e->ti_current=%d",
+        c->ti_old, e->ti_current);
+  }
+#endif
+}
+
 /**
  * @brief Does a cell contain any active particle ?
  *

src/runner_doiact.h

@@ -721,6 +721,11 @@ void DOPAIR1(struct runner *r, struct cell *ci, struct cell *cj) {
   /* Anything to do here? */
   if (!cell_is_active(ci, e) && !cell_is_active(cj, e)) return;
 
+#ifdef SWIFT_DEBUG_CHECKS
+  cell_is_drifted(ci, e);
+  cell_is_drifted(cj, e);
+#endif
+
   /* Get the sort ID. */
   double shift[3] = {0.0, 0.0, 0.0};
   const int sid = space_getsid(e->s, &ci, &cj, shift);
@@ -913,6 +918,11 @@ void DOPAIR2(struct runner *r, struct cell *ci, struct cell *cj) {
   /* Anything to do here? */
   if (!cell_is_active(ci, e) && !cell_is_active(cj, e)) return;
 
+#ifdef SWIFT_DEBUG_CHECKS
+  cell_is_drifted(ci, e);
+  cell_is_drifted(cj, e);
+#endif
+
   /* Get the shift ID. */
   double shift[3] = {0.0, 0.0, 0.0};
   const int sid = space_getsid(e->s, &ci, &cj, shift);
@@ -1303,6 +1313,10 @@ void DOSELF1(struct runner *r, struct cell *restrict c) {
 
   if (!cell_is_active(c, e)) return;
 
+#ifdef SWIFT_DEBUG_CHECKS
+  cell_is_drifted(ci, e);
+#endif
+
   struct part *restrict parts = c->parts;
   const int count = c->count;
 
@@ -1534,6 +1548,10 @@ void DOSELF2(struct runner *r, struct cell *restrict c) {
 
   if (!cell_is_active(c, e)) return;
 
+#ifdef SWIFT_DEBUG_CHECKS
+  cell_is_drifted(ci, e);
+#endif
+
   struct part *restrict parts = c->parts;
   const int count = c->count;