Path: ...!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!eternal-september.org!.POSTED!not-for-mail
From: Kaz Kylheku <643-408-1753@kylheku.com>
Newsgroups: comp.lang.c
Subject: Re: do { quit; } else { }
Date: Thu, 10 Apr 2025 00:20:29 -0000 (UTC)
Organization: A noiseless patient Spider
Lines: 57
Message-ID: <20250409170901.947@kylheku.com>
References: <vspbjh$8dvd$1@dont-email.me> <8634enhcui.fsf@linuxsc.com>
 <vsph6b$ce6m$5@dont-email.me> <86ldsdfocs.fsf@linuxsc.com>
 <20250406161323.00005809@yahoo.com> <86ecy5fjin.fsf@linuxsc.com>
 <20250406190321.000001dc@yahoo.com> <86plhodtsw.fsf@linuxsc.com>
 <20250407210248.00006457@yahoo.com> <vt15lq$bjs0$3@dont-email.me>
 <vt2lp6$1qtjd$1@dont-email.me> <vt31m5$2513i$1@dont-email.me>
 <vt3d4g$2djqe$1@dont-email.me> <vt3iqh$2ka99$1@dont-email.me>
 <868qoaeezc.fsf@linuxsc.com> <vt3oeo$2oq3p$1@dont-email.me>
 <86mscqcpy1.fsf@linuxsc.com> <vt48go$35hh3$2@dont-email.me>
 <86iknecjz8.fsf@linuxsc.com> <vt4del$3a9sk$1@dont-email.me>
 <86o6x5at05.fsf@linuxsc.com> <vt712u$1m84p$1@dont-email.me>
Injection-Date: Thu, 10 Apr 2025 02:20:29 +0200 (CEST)
Injection-Info: dont-email.me; posting-host="e3007b402d1419a454483462709f55b6";
	logging-data="1850192"; mail-complaints-to="abuse@eternal-september.org";	posting-account="U2FsdGVkX18oyTqn50kzzPy11p0tp8f0tp/HuKUzwQs="
User-Agent: slrn/pre1.0.4-9 (Linux)
Cancel-Lock: sha1:8pYZ/0dxyQbYs6ieR+y5OXC17rw=
Bytes: 3548

On 2025-04-09, bart <bc@freeuk.com> wrote:
> I'm not sure what your gripe is other than maybe I picked up on 
> something you got wrong. The discussion was about two struct types like 
> this:
>
>     typedef struct tag1 {...} T1;
>     typedef struct tag2 {...} T2;
>
> and whether T1 and T2 were compatible or not. You said:
>
> "and those types are not compatible, because the two struct tags are 
> different."
>
> In this case the tags would be "tag1" and "tag2". I then said:
>
> "I get an incompatible error (from the example you snipped) even when I
> remove both struct tags."

When you remove the tag from a struct definition, the implementation
behaves as if it were implementing a unique tag which is different
from any other such tag, and any tag that can possibly be written
using textual syntax.

How did you implement tagless struct declarations in your compiler?

> That means removing "tag1" and "tag2" so the example above looks like this:
>
>     typedef struct {...} T1;
>     typedef struct {...} T2;
>
> Here, you can't say the struct tags are different, as they are not 
> visible!

So if you close your eyes, two things that were different are now
no longer different, since they are invisible?

The tag is a property of the type, not of printed type declaration.

A struct type has a tag. If the declaration doesn't show one,
that doesn't mean it doesn't have a tag.

If a "Simulation" object has a "gravity" member, do you conclude
that a given simulation has no gravity, because the constructor
omitted specifying it?

  Simulation s = new Simulation(windSpeed = 35.7)

> As I concluded, your assertion about compatibility being based on tags 
> being the same or not didn't seem right.)

Or, you know, you could stop caring about what someone wrote in
comp.lang.c, be they right or wrong, and ... look it up?

-- 
TXR Programming Language: http://nongnu.org/txr
Cygnal: Cygwin Native Application Library: http://kylheku.com/cygnal
Mastodon: @Kazinator@mstdn.ca