[Bug fortran/78033] Internal Compiler Error in enforce_single_undo_checkpoint

["sgk at troutmask dot apl.washington.edu" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78033

--- Comment #5 from Steve Kargl <sgk at troutmask dot apl.washington.edu> ---
On Wed, Oct 19, 2016 at 04:17:34AM +0000, kargl at gcc dot gnu.org wrote:
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78033
> 
> --- Comment #2 from kargl at gcc dot gnu.org ---
> (In reply to kargl from comment #1)
> > Reduced testcase.
> > 
> > function f(n, x)
> >    integer, intent(in) :: n 
> >    complex, intent(in) :: x(1:n)
> >    real :: f
> >    f = g([real(x(1:n)), aimag(x(1:n))])
> > end function f
> > 
> > If the array sections are removed in favor of the whole array,
> > the code compiles.
> 
> Even further reduction.
> 
> subroutine f(n, x)
>    integer, intent(in) :: n 
>    complex, intent(in) :: x(1:n)
>    real :: y(2*n)
>    y = [real(x(1:n), aimag(x(1:n))]
> end subroutine f
> 
> The constructor with array sections is going south.
> 

A even further reduced testcase.

subroutine f(n, x)
   integer, intent(in) :: n 
   complex, intent(in) :: x(1:n)
   real :: y(2*n)
   ! y = [ real(x)]      ! This works.
    y = [ real(x(1:n))]  ! This fails.
end subroutine f

The REAL in the array constructor is confusing the mechanism
for looking for a typespeci, e.g., [ REAL :: x(1:n)]