[patch, fortran] PR80741 [Regression 7/8] DTIO wrong code causes incorrect behaviour of namelist READ

[Jerry DeLisle]

Hi all,

When I first looked at this I thought the minor front end bobble was the 
problem. That turns out to be unrelated but needed to be fixed in trans-io.c

The actual problem was that when I moved the last_char to the unit structure, 
needed for DTIO, the value saved there persists across I/O operations so in the 
case of the PR the REWIND was was working but the EOF character from the 
preceding read was passed on.

I conservatively have reset the last_char in several places out of concern for 
missing a code path on this.

Regression tested on x86_64.  New test case attached.

OK for trunk and then back port to 7 in about a week?

Regards,

Jerry

2017-05-16  Jerry DeLisle  <jvdelisle@gcc.gnu.org>

	PR fortran/80741
	* trans-io.c (transfer_namelist_element): Change check from
	NULL_TREE to null_pointer_node.

2017-05-16  Jerry DeLisle  <jvdelisle@gcc.gnu.org>

	PR libgfortran/80741
	* transfer.c (finalize_transfer): Reset last_char to 'empty'.
	* file_pos.c (formatted_backspace): Likewise.
	(st_endfile): Likewise.
	(st_rewind): Likewise.
	(st_flush): Likewise.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: pr80741.diff
Type: text/x-patch
Size: 2136 bytes
Desc: not available
URL: <http://gcc.gnu.org/pipermail/fortran/attachments/20170517/d20f183f/attachment.bin>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: read_4.f90
Type: text/x-fortran
Size: 713 bytes
Desc: not available
URL: <http://gcc.gnu.org/pipermail/fortran/attachments/20170517/d20f183f/attachment-0001.bin>