Misplaced if-statement leading to 0-sized time-step for gparts with counterparts

src/runner.c

@@ -929,75 +929,78 @@ void runner_dokick(struct runner *r, struct cell *c, int timer) {
       struct gpart *const gp = &gparts[k];
 
       /* If the g-particle has no counterpart and needs to be kicked */
-      if (gp->id < 0 && (is_fixdt || gp->ti_end <= ti_current)) {
-
-        /* First, finish the force calculation */
-        gravity_end_force(gp);
-
-        /* Now we are ready to compute the next time-step size */
-        int new_dti;
-
-        if (is_fixdt) {
-
-          /* Now we have a time step, proceed with the kick */
-          new_dti = global_dt_max * timeBase_inv;
-
-        } else {
-
-          /* Compute the next timestep (gravity condition) */
-          const float new_dt_external =
+      if (gp->id < 0) {
+
+	if (is_fixdt || gp->ti_end <= ti_current) {
+	  
+	  /* First, finish the force calculation */
+	  gravity_end_force(gp);
+	  
+	  /* Now we are ready to compute the next time-step size */
+	  int new_dti;
+	  
+	  if (is_fixdt) {
+	    
+	    /* Now we have a time step, proceed with the kick */
+	    new_dti = global_dt_max * timeBase_inv;
+	    
+	  } else {
+	    
+	    /* Compute the next timestep (gravity condition) */
+	    const float new_dt_external =
               gravity_compute_timestep_external(potential, constants, gp);
-          const float new_dt_self =
+	    const float new_dt_self =
               gravity_compute_timestep_self(constants, gp);
-
-          float new_dt = fminf(new_dt_external, new_dt_self);
-
-          /* Limit timestep within the allowed range */
-          new_dt = fminf(new_dt, global_dt_max);
-          new_dt = fmaxf(new_dt, global_dt_min);
-
-          /* Convert to integer time */
-          new_dti = new_dt * timeBase_inv;
-
-          /* Recover the current timestep */
-          const int current_dti = gp->ti_end - gp->ti_begin;
-
-          /* Limit timestep increase */
-          if (current_dti > 0) new_dti = min(new_dti, 2 * current_dti);
-
-          /* Put this timestep on the time line */
-          int dti_timeline = max_nr_timesteps;
-          while (new_dti < dti_timeline) dti_timeline /= 2;
-
-          /* Now we have a time step, proceed with the kick */
-          new_dti = dti_timeline;
-        }
-
-        /* Compute the time step for this kick */
-        const int ti_start = (gp->ti_begin + gp->ti_end) / 2;
-        const int ti_end = gp->ti_end + new_dti / 2;
-        const double dt = (ti_end - ti_start) * timeBase;
-        const double half_dt = (ti_end - gp->ti_end) * timeBase;
-
-        /* Move particle forward in time */
-        gp->ti_begin = gp->ti_end;
-        gp->ti_end = gp->ti_begin + new_dti;
-
-        /* Kick particles in momentum space */
-        gp->v_full[0] += gp->a_grav[0] * dt;
-        gp->v_full[1] += gp->a_grav[1] * dt;
-        gp->v_full[2] += gp->a_grav[2] * dt;
-
-        /* Extra kick work */
-        gravity_kick_extra(gp, dt, half_dt);
-
-        /* Number of updated g-particles */
-        g_updated++;
+	    
+	    float new_dt = fminf(new_dt_external, new_dt_self);
+	    
+	    /* Limit timestep within the allowed range */
+	    new_dt = fminf(new_dt, global_dt_max);
+	    new_dt = fmaxf(new_dt, global_dt_min);
+	    
+	    /* Convert to integer time */
+	    new_dti = new_dt * timeBase_inv;
+	    
+	    /* Recover the current timestep */
+	    const int current_dti = gp->ti_end - gp->ti_begin;
+	    
+	    /* Limit timestep increase */
+	    if (current_dti > 0) new_dti = min(new_dti, 2 * current_dti);
+	    
+	    /* Put this timestep on the time line */
+	    int dti_timeline = max_nr_timesteps;
+	    while (new_dti < dti_timeline) dti_timeline /= 2;
+	    
+	    /* Now we have a time step, proceed with the kick */
+	    new_dti = dti_timeline;
+	  }
+	  
+	  /* Compute the time step for this kick */
+	  const int ti_start = (gp->ti_begin + gp->ti_end) / 2;
+	  const int ti_end = gp->ti_end + new_dti / 2;
+	  const double dt = (ti_end - ti_start) * timeBase;
+	  const double half_dt = (ti_end - gp->ti_end) * timeBase;
+	  
+	  /* Move particle forward in time */
+	  gp->ti_begin = gp->ti_end;
+	  gp->ti_end = gp->ti_begin + new_dti;
+	  
+	  /* Kick particles in momentum space */
+	  gp->v_full[0] += gp->a_grav[0] * dt;
+	  gp->v_full[1] += gp->a_grav[1] * dt;
+	  gp->v_full[2] += gp->a_grav[2] * dt;
+	  
+	  /* Extra kick work */
+	  gravity_kick_extra(gp, dt, half_dt);
+	  
+	  /* Number of updated g-particles */
+	  g_updated++;
+	}
+	
+	/* Minimal time for next end of time-step */
+	ti_end_min = min(gp->ti_end, ti_end_min);
+	ti_end_max = max(gp->ti_end, ti_end_max);
       }
-
-      /* Minimal time for next end of time-step */
-      ti_end_min = min(gp->ti_end, ti_end_min);
-      ti_end_max = max(gp->ti_end, ti_end_max);
     }
 
     /* Now do the hydro ones... */