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From: Keith Thompson <kst-u@mib.org>
Newsgroups: comp.lang.c
Subject: Re: Future of C
Date: Tue, 13 Mar 2018 14:36:31 -0700
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bartc <bc@freeuk.com> writes:
[...]
> A longer example is given below. Results are as follows:
>
>                Compiles?   Runs? (using fred(10))
>
> Pelles C      No          ---
> Lccwin        Yes         Crashes (or bad results without copy test)
> DMC           No          ---
> Tiny C        Yes         Crashes
> MSVC          No          ---
> gcc 5.1.0     Yes         Yes
> clang         No          ---    (via rextester.com)
> mcc           No          ---    (my product)
>
>
> So only one compiler out of 7 or 8 fully supports a feature that you say 
> is so easy to implement; funny, that.
>
> Or rather, 'not difficult' (so what /is/ difficult in your opinion?)
>
> (Here, I've hardly got started with the complexities of VLAs, like 
> multiple-dimensional VLAs of my VLA D type and allocating them in loops.)
>
> -------------------------------------
>
>   void fred(int n){
>       typedef struct {int A[n],B[n/2],C[n*2];} D;
[SNIP]
>   }

N1570 6.7.2.1p9:
    A member of a structure or union may have any complete object type
    other than a variably modified type.

Apparently gcc supports VLA members as an extension.  clang does not.

You could have avoided this error if you know how to invoke compilers in
conforming mode.

-- 
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"