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Date: Mon, 27 Apr 2020 14:19:23 +0100
From: Tony Finch <dot@dotat.at>
To: The Eunuchs Hysterical Society <tuhs@tuhs.org>
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Subject: Re: [TUHS] v7 K&R C
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Rob Pike <robpike@gmail.com> wrote:

> The ability to call a function pointer fp with the syntax fp() rather than
> (*fp)() came rather late, I think at Bjarne's suggestion or example. Pretty
> sure it was not in v7 C, as you observe.

I've seen some interesting discussion about Dave Horsfall's favourite
retro-C definition of abort():

	int abort 4;
	...
		abort();

https://minnie.tuhs.org/pipermail/tuhs/2020-March/020680.html

In particular a lot of people didn't know that function pointers could not
be called like abort() so they didn't realise that 4 was the machine code
contents of the function, not the address of the function. (Extra
confusing since branching to address 4 was also a plausible way to crash
the program...)

But that made me wonder what 7th-and-earlier C would do if you tried to
call a local variable. I guess that would lead to the compiler saying

		error("Call of non-function");

Tony.
-- 
f.anthony.n.finch  <dot@dotat.at>  http://dotat.at/
Hebrides, Bailey, Fair Isle, Faeroes: Northeasterly 4 to 6, occasionally 7 at
first in north Fair Isle. Moderate or rough. Showers. Good, occasionally
moderate.