Re: toolchain/53023: config(1) behavior change with new gcc6

[Valery Ushakov <uwe%stderr.spb.ru@localhost>]

The following reply was made to PR toolchain/53023; it has been noted by GNATS.

From: Valery Ushakov <uwe%stderr.spb.ru@localhost>
To: gnats-bugs%NetBSD.org@localhost
Cc: 
Subject: Re: toolchain/53023: config(1) behavior change with new gcc6
Date: Tue, 13 Feb 2018 16:13:38 +0300

 On Tue, Feb 13, 2018 at 07:20:00 +0000, paul%whooppee.com@localhost wrote:
 
 > With previous gcc5, if you added "dbcool* at i2c? addr 0xxx" to the amd64
 > GENERIC config file, it would create an ioconf.c file that includes the
 > following text:
 > 
 > 	static const struct cfiattrdata dbcoolcf_iattrdata = {
 > 		"dbcool", 0, {
 > 			{ NULL, NULL, 0 },
 > 		}
 > 	};
 > 
 > However, with the newly introduced gcc6, these lines do not get generated.
 > As a result, the eventual compilation of ioconf.c -> .o fails with the
 > message
 > 
 > 	error: 'dbcoolcf_iattrdata' defined but not used
 
 I can't seem to parse it.  If "these lines do NOT get GENERATED" now
 then how compiling it can fail with "DEFINED but not used"?
 
 That variable IS generated with both new and old configs, but the new
 gcc fails with (and you have trimmed the relevant part):
 
 ioconf.c:436:33: error: 'dbcoolcf_iattrdata' defined but not used [-Werror=unused-const-variable=]
 
 which is new in gcc6, i guess.  A bit of background:
 
   https://gcc.gnu.org/ml/gcc-patches/2015-09/msg00847.html
 
 -uwe