Date: Mon, 30 Jul 2012 11:12:09 +0400 From: Lev Serebryakov <lev@FreeBSD.org> To: Arnaud Lacombe <lacombar@gmail.com> Cc: "Bjoern A. Zeeb" <bzeeb-lists@lists.zabbadoz.net>, Luigi Rizzo <rizzo@iet.unipi.it>, current@freebsd.org, David Chisnall <theraven@freebsd.org> Subject: Re: RFC: libkern version of inet_ntoa_r Message-ID: <492266872.20120730111209@serebryakov.spb.ru> In-Reply-To: <CACqU3MUZJH2FcWbYL0UBNwhztQRtY%2Bsk-ZGxywgg43pFe4ZyRw@mail.gmail.com> References: <20120725155211.GA33971@onelab2.iet.unipi.it> <alpine.BSF.2.00.1207282213171.4474@ai.fobar.qr> <20120729095833.GB80946@onelab2.iet.unipi.it> <CBCC6E24-8D03-422E-B571-1B62FB7667E6@FreeBSD.org> <20120729191958.GB85015@onelab2.iet.unipi.it> <CACqU3MVNCOdde7atRVT7xaYH1qHjm=4uS0Eih8EgG3=DDaOGCw@mail.gmail.com> <20120729204721.GA87481@onelab2.iet.unipi.it> <1119098728.20120730003000@serebryakov.spb.ru> <CACqU3MUZJH2FcWbYL0UBNwhztQRtY%2Bsk-ZGxywgg43pFe4ZyRw@mail.gmail.com>
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Hello, Arnaud.
You wrote 30 =D0=B8=D1=8E=D0=BB=D1=8F 2012 =D0=B3., 2:30:21:
>> It looks very gcc-ish.
AL> could you back your point with a technical argument, please ? This
AL> sounds rather FUD'ish so far.
AL> The ({ ... }) is nothing more than a primary-expression enclosing a
AL> compound-statement;
And how will it return value? It is completely illegal for compound
statement to return value. And to be a part of primary expression, too.
Here is simple test:
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
1 #include <stdlib.h>
2 #include <stdio.h>
3
4 int fn(int x, int y) { return x + y; }
5
6 #define fn(x) ({ fn(x, 42); })
7
8 int main(int argc, char *argv[]) {
9 printf("%d\n", fn(10));
10 return 0;
11 }
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
gcc compiles it and prints "52", but MSVC++ 10.0 cannot compile this
at all, and it is in its own right:
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
D:\home\lev\test>cl test.c
Microsoft (R) 32-bit C/C++ Optimizing Compiler Version 16.00.40219.01 for 8=
0x86
Copyright (C) Microsoft Corporation. All rights reserved.
test.c
test.c(9) : error C2059: syntax error : '{'
test.c(9) : error C2059: syntax error : ')'
test.c(9) : error C2059: syntax error : ')'
test.c(10) : error C2059: syntax error : 'return'
test.c(11) : error C2059: syntax error : '}'
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
See http://gcc.gnu.org/onlinedocs/gcc/Statement-Exprs.html -- it is
clearly marked as "GNU C" construct, not ANSI/ISO C/C++ one.
And even more:
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
> gcc -Wall -ansi -pedantic -std=3Dc99 test.c
test.c: In function 'main':
test.c:9: warning: ISO C forbids braced-groups within expressions
>
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
--=20
// Black Lion AKA Lev Serebryakov <lev@FreeBSD.org>
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