[Bug fortran/84093] New: Invalid nested derived type constructor not rejected

[neil.n.carlson at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84093

            Bug ID: 84093
           Summary: Invalid nested derived type constructor not rejected
           Product: gcc
           Version: 8.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: neil.n.carlson at gmail dot com
  Target Milestone: ---

Gfortran allows invalid nested derived type constructors. Consider this
example:

type parent
  integer :: a, b
end type

type, extends(parent) :: child
  real :: x
end type

type(child) :: foo
foo = child(parent(1,2),3.0)

end

Note 4.59 and the preceding paragraphs (in F08 or F15 standard) are clear
that in this example parent(1,2) corresponds to the first component of
child, which is a, and gfortran should reject this illegal code.

The correct constructor must use keywords if one wants to use the parent
constructor:

foo = child(parent=parent(1,2), x=3.0)

Note that the extends_2.f03 testsuite program contains this error.