RE: cin and read(*,*) not waiting for kbd input in gdb

["Rockefeller, Harry" <Harry dot Rockefeller at flightsafety dot com>]

[snip]
>>>I'm not able to reproduce this problem.  Perhaps you can provide a similar transcript showing the steps to reproduce?
[snip]
>>Test code:
 > >    program test
  >>    implicit none
   >>   real    cycle_time_preset /0.0/ ! (seconds)
    >>  real    cycle_length /0.0/      ! (seconds)
     >> do
      >>   if (cycle_time_preset.le.0.0) then
       >>     write(*,*)'Supply the equivalent of run time in seconds.'
        >>    write(*,"('(Note: a negative run time will stop run): ',$)")
         >>   read(*,*) cycle_length
         >>else
          >>  cycle_length = cycle_time_preset
         >>end if
         >>if (cycle_length .lt. 0.0) stop 'normal termination'
      >>end do
      >>stop
      >>end

>>$ /usr/bin/gfortran   -g -ffree-form -ffree-line-length-none -Wunused -ffpe-trap=invalid,zero,overflow -o test.exe test.f
[snip]
>Following your test I do not have cin wait for kbd input whenever a breakpoint is set.
>In fact, if I run 'disa 1' to disable the breakpoint and then just 'run'
>(to restart the program from the beginning) then the program does pause for my keyboard input.
>This happens in both my Win 7 and Win 7 - RTX OS boots.
>This happens in both gdb 8.2.1-1 and 8.3.1-1.  It does not happen with Gdb version 8.1.1-1.
[snip]

I don't know if this is a gdb or a Cygwin implementation of gdb that is a problem.
Since I can go back to gdb version 8.1.1-1 this is not a problem for me now.
Here is a test case using the Fortran source above:

$ gfortran -g test1.f -o test1.exe

harryr@HARRYR-PC ~/d62sim/Excel
$ gdb test1
GNU gdb (GDB) (Cygwin 8.3.1-1) 8.3.1
Copyright (C) 2019 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
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Reading symbols from test1...
(gdb) b test1.f:9
Breakpoint 1 at 0x100401140: file test1.f, line 9.
(gdb) r
Starting program: /cygdrive/c/Users/harryr/d62sim/Excel/test1
[New Thread 7696.0x2a9c]
[New Thread 7696.0xf0c]
[New Thread 7696.0x22f8]
 Supply the equivalent of real time test in seconds.
(Note: a negative test length will stop run):
Thread 1 "test1" hit Breakpoint 1, test1 () at test1.f:9
9                read(*,*) cycle_length
(gdb) b unix.c:271
Breakpoint 2 at 0x3df9bb3c0: file /usr/src/debug/gcc-7.4.0-1/libgfortran/io/unix.c, line 272.
(gdb) c
Continuing.

Thread 1 "test1" hit Breakpoint 2, _gfortrani_flush_if_preconnected (s=0x80004e300) at /usr/src/debug/gcc-7.4.0-1/libgfortran/io/unix.c:272
272     {
(gdb) s
275       fd = ((unix_stream *) s)->fd;
(gdb)
276       if (fd == STDIN_FILENO)
(gdb)
277         fflush (stdin);
(gdb)
__getreent () at /usr/src/debug/cygwin-3.1.2-1/winsup/cygwin/thread.cc:89
89        return &_my_tls.local_clib;
(gdb)
NtCurrentTeb () at /usr/src/debug/cygwin-3.1.2-1/winsup/cygwin/thread.cc:89
89        return &_my_tls.local_clib;
(gdb)
__readgsqword (Offset=48) at /usr/x86_64-pc-cygwin/sys-root/usr/include/w32api/psdk_inc/intrin-impl.h:714
714     /usr/x86_64-pc-cygwin/sys-root/usr/include/w32api/psdk_inc/intrin-impl.h: No such file or directory.
(gdb)
__getreent () at /usr/src/debug/cygwin-3.1.2-1/winsup/cygwin/thread.cc:89
89        return &_my_tls.local_clib;
(gdb)
90      }
(gdb)
_gfortrani_flush_if_preconnected (s=<optimized out>) at /usr/src/debug/gcc-7.4.0-1/libgfortran/io/unix.c:282
282     }
(gdb)
277         fflush (stdin);
(gdb)
/wip/cygport-git/gdb/gdb-8.3.1-1.x86_64/src/gdb-8.3.1/gdb/infrun.c:2602: internal-error: void resume_1(gdb_signal): Assertion `pc_in_thread_step_range (pc, tp)' failed.
A problem internal to GDB has been detected,
further debugging may prove unreliable.
Quit this debugging session? (y or n)y

This is a bug, please report it.  For instructions, see:
<http://www.gnu.org/software/gdb/bugs/>.

/wip/cygport-git/gdb/gdb-8.3.1-1.x86_64/src/gdb-8.3.1/gdb/infrun.c:2602: internal-error: void resume_1(gdb_signal): Assertion `pc_in_thread_step_range (pc, tp)' failed.
A problem internal to GDB has been detected,
further debugging may prove unreliable.
Create a core file of GDB? (y or n) y
Aborted (core dumped)

Attachment: gdb.exe.stackdump
Description: gdb.exe.stackdump

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