To: J3                                                     J3/15-192
From: Steve Lionel and Dan Nagle
Subject: Control of message and exception warning for STOP/ERROR STOP
Keywords: STOP, ERROR STOP
Date: 2015 August 04

Reference: 15-007r1

Introduction
------------

This item arose from discussion of UK-23.

The standard currently says that for the STOP and ERROR STOP statements
that the stop code "is made available in a processor-dependent manner."
A common implementation of this is to display a message on the standard
error output unit such as "FORTRAN STOP 1234". Many users have requested
the ability to suppress display of this message, especially as the
standard also encourages implementations to return integer stop codes as
the program's exit status.

Users have also requested the ability to suppress the standard's required
"warning" indicating which exceptions are currently signaling. Some
implementations provide a mechanism, such as environment variables, to
suppress display of these messages; standard syntax for this option is
desireable.

Specification
-------------
Add syntax to the STOP and ERROR STOP statements that allow programmer
individual, execution-time control of the display of the stop code
message and the exception warning.

[During initial discussion it was suggested that supplying a blank
string as a stop code could be an indication to suppress the message,
but this would not allow for setting the program exit status with an
integer stop code.]

Syntax
------

The following syntax is proposed:

STOP [(stop-opt-list)] stop-code
ERROR STOP [(stop-opt-list)] stop-code

stop-opt   is  STOPMSG = scalar-logical-expression
           or  SUMMARY = scalar-logical-expression

No stop-opt shall appear more than once in a stop-opt-list

If any stop-opt is omitted, the default value is .TRUE..

If STOPMSG is .TRUE., the stop code is made available in a processor-
dependent manner (formatted output to ERROR_UNIT recommended); if
.FALSE. it is not. The recommendation that an integer stop code be
supplied as the process exit status is not affected by the value of
STOPMSG.

If SUMMARY is .TRUE., a summary of currently signaling exceptions is
output to the unit identified by ERROR_UNIT; if .FALSE. the summary
is not output.

Edits
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TBS