The function computing the gas temperature should not modify the xpart.

src/cooling/EAGLE/cooling.c

@@ -653,7 +653,7 @@ float cooling_get_temperature(
     const struct unit_system *restrict us,
     const struct cosmology *restrict cosmo,
     const struct cooling_function_data *restrict cooling,
-    const struct part *restrict p, struct xpart *restrict xp) {
+    const struct part *restrict p, const struct xpart *restrict xp) {
 
   /* Get physical internal energy */
   const float u = hydro_get_physical_internal_energy(p, xp, cosmo);

src/cooling/EAGLE/cooling.h

@@ -64,7 +64,7 @@ float cooling_get_temperature(
     const struct unit_system *restrict us,
     const struct cosmology *restrict cosmo,
     const struct cooling_function_data *restrict cooling,
-    const struct part *restrict p, struct xpart *restrict xp);
+    const struct part *restrict p, const struct xpart *restrict xp);
 
 float cooling_get_radiated_energy(const struct xpart *restrict xp);