Return-Path: Message-ID: <1330953167.3457.13.camel@pohly-mobl1.fritz.box> Subject: Re: [PATCH] bluetooth.h: fix compile issue when using in C++ From: Patrick Ohly To: Markus Rathgeb Cc: Marcel Holtmann , linux-bluetooth@vger.kernel.org Date: Mon, 05 Mar 2012 14:12:47 +0100 In-Reply-To: References: <1326708715.3360.135.camel@pohly-mobl1.fritz.box> <1330903638.3392.141.camel@aeonflux> <1330932819.4028.59.camel@pohly-mobl1.fritz.box> Content-Type: multipart/mixed; boundary="=-ySYURrvyH52A2W0DiFqT" Mime-Version: 1.0 List-ID: --=-ySYURrvyH52A2W0DiFqT Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit On Mon, 2012-03-05 at 09:31 +0100, Markus Rathgeb wrote: > Before you are applying the patch, could you also have a look at: > http://permalink.gmane.org/gmane.linux.bluez.kernel/22294 That's a second C++ problem with the header file. With typeof and -std=c ++0x I get an error, as you said. I'm fine with using __typeof__ instead of typeof. I verified that g++ 4.6.2 and clang++ 3.0 grok __typeof__, with and without -std=c++0x. I also checked that gcc accepts it without -std, with -std=gnu89, and with -std=c99. It rejects the header file with -std=c89 because of the inline keyword. Updated patch attached. Note that Debian seems to have picked the older http://marc.info/?l=linux-bluetooth&m=132644289619172&w=2 patch, the one which removes __attribute__((packed)) and replaces the (void *) cast with (struct __s *). I think that shows that it is important that upstream includes a solution, because otherwise distros will pick one randomly. -- Best Regards, Patrick Ohly The content of this message is my personal opinion only and although I am an employee of Intel, the statements I make here in no way represent Intel's position on the issue, nor am I authorized to speak on behalf of Intel on this matter. --=-ySYURrvyH52A2W0DiFqT Content-Disposition: attachment; filename*0=0001-bluetooth.h-fix-typecast-and-typeof-compile-issue-wh.pat; filename*1=ch Content-Type: text/x-patch; name="0001-bluetooth.h-fix-typecast-and-typeof-compile-issue-wh.patch"; charset="UTF-8" Content-Transfer-Encoding: 8bit >From 51f8b4d8343454b04e7ed83b7770185d718d6203 Mon Sep 17 00:00:00 2001 From: Patrick Ohly Date: Mon, 16 Jan 2012 10:58:44 +0100 Subject: [PATCH] bluetooth.h: fix typecast and typeof compile issue when used in C++ MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The compiler error for the typecast is: /usr/include/bluetooth/bluetooth.h::131:9: error: invalid conversion from 'void*' to 'bt_get_le64(void*)::*' ... The reason is that C++, in contrast to C, does not allow conversion of void * to anything, and this code gets compiled as C++ when the app is written in C++. The macro with the assignment itself is older, but only recent Bluez starts to use it in inline functions, thus triggering the problem. Another issue in combination with -std=c++0x is the use of typeof, which is not a standard C++ feature and thus gets rejected in strict mode. This patch keeps the "struct __attribute__((packed))" magic and merely changes the typecast so that it works in C and C++. typeof gets replaced with __typeof__. g++ 4.6.2 and clang++ 3.0-5 accept the modified header file, with and without -std=c++0x. gcc 4.6.2 accepts it without -std, with -std=gnu89, and with -std=c99. It rejects the header file with -std=c89 because of the inline keyword. Signed-off-by: Patrick Ohly --- lib/bluetooth.h | 8 ++++---- 1 files changed, 4 insertions(+), 4 deletions(-) diff --git a/lib/bluetooth.h b/lib/bluetooth.h index 5bd4f03..297d52d 100644 --- a/lib/bluetooth.h +++ b/lib/bluetooth.h @@ -112,16 +112,16 @@ enum { #define bt_get_unaligned(ptr) \ ({ \ struct __attribute__((packed)) { \ - typeof(*(ptr)) __v; \ - } *__p = (void *) (ptr); \ + __typeof__(*(ptr)) __v; \ + } *__p = (__typeof__(__p)) (ptr); \ __p->__v; \ }) #define bt_put_unaligned(val, ptr) \ do { \ struct __attribute__((packed)) { \ - typeof(*(ptr)) __v; \ - } *__p = (void *) (ptr); \ + __typeof__(*(ptr)) __v; \ + } *__p = (__typeof__(__p)) (ptr); \ __p->__v = (val); \ } while(0) -- 1.7.9 --=-ySYURrvyH52A2W0DiFqT--