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Re: C language declaration "bugs"

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Thiago Adams <thiago.adams@gmail.com> writes:

> Off course this is not a bug. 
> But I think it s strange that I cannot use the same 
> syntax for declarations in structs and functions.
>
> For instance:
>
> struct X
> {
>   int * a[]; //ERROR
>   int b[]; //ERROR
> };

The second one is not an error -- it's a flexible array member (or would
be if there were at least one valid struct member preceding it).  It
does not say what you want, I agree, but it's not an error.

> void f(int * a[]) { } //Ok
> void f2(int b[]) { } //Ok

Another way of looking at is that it's a shame C permits the special
case of empty []s to mean * in a parameter declaration.  It's a
hang-over from very early C and is no more than an anomaly.  What's
more, you can even put a number in there for no purpose at all.

But now the []s in that position have acquired a new set of meanings:

  void f(int n, int a[n]);       // variably modified parameter
  void f(int n, int a[*]);       // alternative for (prototypes only)
  void f(int a[static 3]);       // pointer to at least 3 ints
  void f(int a[const static 3]); // const pointer to at least 3 ints

and more besides.

The fact that type qualifiers (like const) in that position modify the
pointer is reasonable (since the pointed-to type can be qualified
anyway) but unfortunate.  I.e.

  void f(int a[const]);

is just a silly way to write

  void f(int *const s);

<snip>
> when I do out of function scope
>
> //warning: array 'i' assumed to have one element 
> int i[];
>
> So here is one more language suggestion:
>
> make empty array syntax the same of  "pointer" syntax.
>
> int i[]; the same of int *i;

C's desire not to break existing code both its strength and its
weakness.  It has resulted in all sorts of oddities because the ISO C
committee is very conservative about changes to the meaning of currently
valid code.  Some would say it's been too conservative and some would
say not conservative enough.

-- 
Ben.

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C language declaration "bugs" Thiago Adams <thiago.adams@gmail.com> - 2016-10-11 05:17 -0700
  Re: C language declaration "bugs" Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-10-11 13:58 +0100
    Re: C language declaration "bugs" Thiago Adams <thiago.adams@gmail.com> - 2016-10-11 06:47 -0700
      Re: C language declaration "bugs" Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-10-11 15:03 +0100
        Re: C language declaration "bugs" Thiago Adams <thiago.adams@gmail.com> - 2016-10-11 07:41 -0700
          Re: C language declaration "bugs" BartC <bc@freeuk.com> - 2016-10-11 16:31 +0100
        Re: C language declaration "bugs" Keith Thompson <kst-u@mib.org> - 2016-10-11 10:01 -0700
          Re: C language declaration "bugs" Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-10-11 19:10 +0100
  Re: C language declaration "bugs" BartC <bc@freeuk.com> - 2016-10-11 14:14 +0100

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