https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64921
--- Comment #2 from H.J. Lu <hjl.tools at gmail dot com> --- I got Program received signal SIGSEGV: Segmentation fault - invalid memory reference. Backtrace for this error: #0 0xF763FACE #1 0xF763EBDE #2 0xF773CBBF #3 0x8048BA5 in __final_main_T2.3337 at class_allocate_18.f90:? #4 0x8048D68 in __final_main_T3.3328 at class_allocate_18.f90:? #5 0x8048A59 in MAIN__ at class_allocate_18.f90:? FAIL: gfortran.dg/class_allocate_18.f90 -O1 execution test But I couldn't reproduce it on another machine. I will keep an eye on it.