[Bug fortran/126530] New: Option -Wundefined-vars doesn't catch functions returning without defining their result

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=126530

            Bug ID: 126530
           Summary: Option -Wundefined-vars doesn't catch functions
                    returning without defining their result
           Product: gcc
           Version: 17.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: mikael at gcc dot gnu.org
  Target Milestone: ---

In the example below, the compiler could warn for every function except `i1'
and `i2'.  But -Wundefined-vars catches nothing here.

module m
  implicit none
contains
  function f1()
    integer :: f1
  end function
  function f2() result(r)
    integer :: r
  end function
  function g1()
    integer, allocatable :: g1
  end function
  function g2() result(r)
    integer, allocatable :: r
  end function
  function h1()
    integer, allocatable :: h1
    allocate(h1)
  end function
  function h2() result(r)
    integer, allocatable :: r
    allocate(r)
  end function
  ! No warning expected for this one
  function i1()
    integer, allocatable :: i1
    allocate(i1)
    i1 = 2
  end function
  ! No warning expected for this one
  function i2() result(r)
    integer, allocatable :: r
    allocate(r)
    r = 2
  end function
  function j1()
    integer, pointer :: j1
  end function
  function j2() result(r)
    integer, pointer :: r
  end function
  function k1()
    integer, pointer :: k1
    allocate(k1)
  end function
  function k2() result(r)
    integer, pointer :: r
    allocate(r)
  end function
end module