Why do you consider an I/O error a "should not occur" situation rather than an 
expected exception? Why can't HLASM provide footprints for the error routine to 
use for a context message?


--
Shmuel (Seymour J.) Metz
http://mason.gmu.edu/~smetz3

________________________________________
From: IBM Mainframe Assembler List <[email protected]> on behalf 
of Jonathan Scott <[email protected]>
Sent: Monday, April 15, 2019 11:01 AM
To: [email protected]
Subject: Re: Lousy error from HLASM in USS

Ref:  Your note of Mon, 15 Apr 2019 14:57:34 +0000

Shmuel (Seymour J.) Metz writes:
> That's how it's coded, not how it has to be coded. There's no reason that
> the common error routine couldn't produce an equivalent of ASMA435I .

The reason is that it would add unnecessary complexity and risk
to a piece of code which is already having to handle a "should
not occur" situation and hence has to be very cautious about
what it can assume.

The common SYNAD routine merely obtains the SYNAD information
and terminates HLASM with the corresponding message. It also
picks out the DDNAME from the message buffer. The abort routine
has some logic to check whether SYSPRINT or SYSTERM is available
for writing out the message and if not it uses WTO.

The abort routine has no awareness of what was being done when
the I/O error occurred, which could be before the start of the
assembly, during the first pass, the interlude or the second
pass, after the end, or anywhere else.  If an I/O error occurs,
control does not return to the I/O caller, as that would require
I/O handling logic on every type of I/O function. It would
obviously be theoretically possible to establish progress flags
to enable a more specific diagnostic, but I wouldn't vote for
that as a sensible use of development resources.

> BTW, does HLASM display the second line of SYNADAF when the "S" indicator is
> there?

HLASM has had code to check for the 'S' indicator at +127 and
issue the additional message since about 1998.  I hope it works!

Jonathan Scott, HLASM
IBM Hursley, UK

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