gcc/gcc/testsuite/gfortran.dg/external_initializer.f90

! { dg-do compile }
! PR20849 - An external symbol may not have a initializer.
! Contributed by Joost VandeVondele <jv244@cam.ac.uk>
REAL, EXTERNAL :: X=0 ! { dg-error "may not have an initializer" }
END