https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68225
--- Comment #1 from Gerhard Steinmetz <gerhard.steinmetz.fort...@t-online.de> --- Adding one type extension : $ cat z0.f90 program p type t integer, allocatable :: a end type type, extends(t) :: t2 integer, allocatable :: b end type type(t2) :: x x = t2() print *, allocated(x%a), x%a print *, allocated(x%b), x%b end $ gfortran -g -O0 -Wall -Wrealloc-lhs-all z0.f90 z0.f90:9:0: x = t2() 1 in gfc_format_decoder, at fortran/error.c:1124 --- $ gfortran -g -O0 -Wall -fcheck=all z0.f90 $ a.out F 0 T 0 Note that allocation status is different.