Path: csiph.com!eternal-september.org!feeder.eternal-september.org!reader02.eternal-september.org!.POSTED!not-for-mail
From: Keith Thompson <kst-u@mib.org>
Newsgroups: comp.lang.c
Subject: Re: Future of C
Date: Mon, 12 Mar 2018 16:24:43 -0700
Organization: None to speak of
Lines: 31
Message-ID: <lnina0c1xg.fsf@kst-u.example.com>
References: <0231327b-9e28-46e4-9178-46c881a8dd91@googlegroups.com> <p7rm8f$1oj3$1@gioia.aioe.org> <20180310180016.eda9bc36e1a3b182bc2563a8@gmail.com> <p81ie9$1pc8$1@gioia.aioe.org> <20180311000302.8e7cd15242a818ab75eb2e98@gmail.com> <83527acf-abed-4f8f-878c-7d4db9cd5ac1@googlegroups.com> <c7g9add2d3mgc6ksk4c4f4500ivubjuog9@4ax.com> <20180311161525.ac591de531b83d6b14b2cd43@gmail.com> <90236828-48d7-4ee5-9b86-4cedd0e29b5f@googlegroups.com> <hwhpC.902622$F74.120435@fx47.am4> <d9d91c28-fb38-400b-8b92-ce7ce7d2b9cd@googlegroups.com> <3r7jne-t3h.ln1@gangtai.grep.be> <8e201938-ada4-42d9-8ae6-13b1047306e2@googlegroups.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Injection-Info: reader02.eternal-september.org; posting-host="877122f47cb3293e34ad9ed0b03f90bc"; logging-data="13764"; mail-complaints-to="abuse@eternal-september.org";	posting-account="U2FsdGVkX182e3HtCV3oLL/etdbWcEkM"
User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.1 (gnu/linux)
Cancel-Lock: sha1:SniOP+QSGPHR96sxNEsxZK1NOyo= sha1:cZjHpOu84UjnE8IoocXoTdP4xek=
Xref: csiph.com comp.lang.c:127720

supercat@casperkitty.com writes:
[...]
> At present the semantics of creating an object of VLA type (as opposed
> to merely defining such a type and then creating a pointer to one) seem
> a bit too vague to really be useful.  From the point of view of the
> Standard, would a conforming implementation ever be required to actually
> allocate a meaningful amount of space for a VLA?  The Standard offers
> no guidance whatsoever about what sizes of requests implementations should
> be expected to handle, nor about what implementations should do if a
> request would be too big.  How are programmers supposed to judge whether a
> VLA declaration of a given size would be reasonable?

Take the above paragraph and replace each occurrence of VLA by
constant-length array.

    #define SOME_BIG_NUMBER /*...*/

    void func1(void) {
        int fixed_array[SOME_BIG_NUMBER];
    }

    void func2(void) {
        size_t var = SOME_BIG_NUMBER;
        int vla[var];
    }

-- 
Keith Thompson (The_Other_Keith) kst-u@mib.org  <http://www.ghoti.net/~kst>
Working, but not speaking, for JetHead Development, Inc.
"We must do something.  This is something.  Therefore, we must do this."
    -- Antony Jay and Jonathan Lynn, "Yes Minister"