One thing that was supported on PCC for many years was the ability to generate GE/Honeywell 6-bit character constants, using the back quote (`) character. I remember trying it in the late 80's on a shipping Sun machine and seeing that it was still present in the grammar, and, as nearly as I could remember, still produced the correct answer.

Steve

----- Original Message -----
From:
"Lars Brinkhoff" <lars@nocrew.org>

To:
"Warner Losh" <imp@bsdimp.com>
Cc:
"Steve Johnson" <scj@yaccman.com>, "The Eunuchs Hysterical Society" <tuhs@tuhs.org>
Sent:
Tue, 30 Oct 2018 08:16:17 +0000
Subject:
Re: [TUHS] Archaic yacc C grammar

Warner Losh wrote:
> Steve Johnson wrote:
> We actually had a pretty good system for making changes like
> that. First, we would change the compiler to accept both the old and
> the new. Then we would produce a warning that on a particular date
> the old would no longer work. Then we made the old an error and
> printed a message about how to fix it.
>
> How long a transition period did you typically have?

I heard the V7 compiler still supports old B style initialization
"int x 42;". So in some cases, a really long time.