[Bug fortran/77504] New: "is used uninitialized" with allocatable string and array constructors

[tkoenig at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77504

            Bug ID: 77504
           Summary: "is used uninitialized" with allocatable string and
                    array constructors
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: tkoenig at gcc dot gnu.org
  Target Milestone: ---

Original bug report from John Urban, from

https://gcc.gnu.org/ml/fortran/2016-09/msg00015.html

program testit
implicit none
character(len=:),allocatable :: help_text(:)
integer                      :: i
   help_text=[ CHARACTER(LEN=80) :: &
   'defines length and size with different length expressions. Yeah!',&
   '   aaaaaaaaaaaaa',&
   '   bbbbbbbbbbbbbbbbb',&
   '   ddddddddddddddddddddd',&
   '']
   write(*,'(a)')repeat('=',len(help_text(1))) !assumed at least size one
   write(*,'(a)')(trim(help_text(i)),i=1,size(help_text))
   write(*,'(a)')repeat('=',len(help_text(1))) !assumed at least size one
end program testit

yields:

fortran -Wuninitialized a.f90
a.f90:3:0:

 character(len=:),allocatable :: help_text(:)

Warning: '.help_text' is used uninitialized in this function [-Wuninitialized]

with a current trunk.

Valgrind does not complain, so it might be spurious