[Bug fortran/105371] New: The result of the merge function is different when it's type of parameters is the extensions type of derived type

[xudong.luo@compiler-dev.com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105371

            Bug ID: 105371
           Summary: The result of the merge function is different when
                    it's type of parameters  is the extensions type of
                    derived type
           Product: gcc
           Version: 11.3.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: xudong.luo@compiler-dev.com
  Target Milestone: ---

Created attachment 52862
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=52862&action=edit
output

Whether the mask is a constant or a variable causes inconsistent results of the
merge function when it's type of parameters  is the extensions type of derived
type.
1.The mask is constant
Program test00
  Type t
    Integer :: c
  End Type
  Type,Extends(t) :: t2
    Integer :: c2
  End Type
  Class(t),Allocatable :: x,y,r
  logical :: ok = .true.
  x = t2(1,-1)
  y = t2(2,-2)
  r = merge (x,y,.true.)
  Select Type (z=>r)
  Type Is (t)
    print *,z%c
  Type Is (t2)
    print *,z%c,z%c2
  End Select
End Program
2. The mask is variable
Program test01
  Type t
    Integer :: c
  End Type
  Type,Extends(t) :: t2
    Integer :: c2
  End Type
  Class(t),Allocatable :: x,y,r
  logical :: ok = .true.
  integer :: i = 1
  x = t2(1,-1)
  y = t2(2,-2)
  r = merge (x,y,i == 1)
  Select Type (z=>r)
  Type Is (t)
    print *,z%c
  Type Is (t2)
    print *,z%c,z%c2
  End Select
End Program