[Bug fortran/51310] New: -finit-bla doesn't initialize *all* items of type bla to the requested constant.

[toon at moene dot org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51310

             Bug #: 51310
           Summary: -finit-bla doesn't initialize *all* items of type bla
                    to the requested constant.
    Classification: Unclassified
           Product: gcc
           Version: 4.6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: toon@moene.org


The following source:

program nan
implicit none
real(8) :: joo(3)
joo(2) = 0
print *,joo
call sub(3)
end program nan
subroutine sub(n)
implicit none
integer, intent(in) :: n
real(8) :: a(n), var, b(3)
real(8), allocatable :: c(:)
!a(1) = 1
print *,'n=',n
print *,'a=',a
print *,'var=',var
print *,'b=',b
allocate(c(size(b)))
print *,'c=',c
a(1) = a(1) + 1
end subroutine sub

when compiled with gfortran -g -finit-real=snan outputs:

                       NaN   0.0000000000000000                            NaN
 n=           3
 a=   0.0000000000000000        0.0000000000000000        0.0000000000000000    
 var=                       NaN
 b=                       NaN                       NaN                      
NaN
 c=   0.0000000000000000        0.0000000000000000        0.0000000000000000    

Clearly, the allocatable c and the automatic array a are not initialized by the
compiler option.

1. Consider this an enhancement request - a colleague of mine was severely
   hampered in his search for a bug.

2. Consider this a bug report with respect to our documentation, which doesn't
   mention this exceptions at all.