[Bug fortran/114618] New: Format produces incorrect output when contains 1x, ok when uses " "

[urbanjost at comcast dot net via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114618

            Bug ID: 114618
           Summary: Format produces incorrect output when contains 1x, ok
                    when uses " "
           Product: gcc
           Version: 13.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: urbanjost at comcast dot net
  Target Milestone: ---

The format gen2 does what I would expect the format gen1 does,
but get very strange output when use 1x (in gen1)  instead of space character
(in gen2).

program tryit
   implicit none
   integer, parameter :: wp = kind(0d0)
   real(kind=wp) :: pi  =
3.14159265358979323846264338327950288419716939937510582097494459230_wp
   character(len=*), parameter:: gen1 = '(19("."),t1,g0,1x,t21,g0)'
   character(len=*), parameter:: gen2 = '(19("."),t1,g0," ",t21,g0)'
   character(len=:), allocatable :: fmt
   integer :: i, j
   do i=1,2
      select case(i)
      case(1); fmt=gen1
      case(2); fmt=gen2
      end select
      do j=1,2
         write (*, fmt) 'PI', pi
         write (*, fmt) 'REAL(PI)', real(pi)
         write (*, fmt) 'DBLE(PI)', dble(pi)
         write (*, fmt) 'RADIX', radix(pi)
         write (*, fmt) 'RANGE', range(pi)
         write (*, fmt) 'PRECISION', precision(pi)
         write (*,'(80("-"))')
      enddo
   enddo
end program tryit

PI.................^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@ 3.1415926535897931
REAL(PI)...........^@^@^@^@^@^@^@^@^@^@^@ 3.14159274
DBLE(PI)...........^@^@^@^@^@^@^@^@^@^@^@ 3.1415926535897931
RADIX..............^@^@^@^@^@^@^@^@^@^@^@ 3. 2
RANGE..............^@^@^@^@^@^@^@^@^@^@^@ 3. 307
PRECISION..........^@^@^@^@^@^@^@^@^@^@ 15
--------------------------------------------------------------------------------
PI.................----------------- 3.1415926535897931
REAL(PI)...........----------- 3.14159274
DBLE(PI)...........----------- 3.1415926535897931
RADIX..............----------- 3. 2
RANGE..............----------- 3. 307
PRECISION..........---------- 15
--------------------------------------------------------------------------------
PI ................ 3.1415926535897931
REAL(PI) .......... 3.14159274
DBLE(PI) .......... 3.1415926535897931
RADIX ............. 2
RANGE ............. 307
PRECISION ......... 15
--------------------------------------------------------------------------------
PI ................ 3.1415926535897931
REAL(PI) .......... 3.14159274
DBLE(PI) .......... 3.1415926535897931
RADIX ............. 2
RANGE ............. 307
PRECISION ......... 15
--------------------------------------------------------------------------------