Date: Wed, 2 Sep 2020 15:58:15 +0100 From: Bob Eager <rde@tavi.co.uk> To: freebsd-ports@freebsd.org Subject: Re: pkg-fallout: duplicate symbols? Message-ID: <20200902155815.62588c0d@raksha.tavi.co.uk> In-Reply-To: <slrnrkvbuk.1lm.naddy@lorvorc.mips.inka.de> References: <slrnrk29h7.2oqq.naddy@lorvorc.mips.inka.de> <9A44A7E3-B911-4D40-B34F-FC1A9E844D31@FreeBSD.org> <slrnrkvbuk.1lm.naddy@lorvorc.mips.inka.de>
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On Wed, 2 Sep 2020 14:44:36 -0000 (UTC) Christian Weisgerber <naddy@mips.inka.de> wrote: > On 2020-08-22, Dimitry Andric <dim@FreeBSD.org> wrote: > > > It can be worked around by adding -fcommon to the compilation > > flags, but in most cases it should not be too difficult to get rid > > of the multiply defined symbols. > > Right. > In C, a global is _defined_ in one object file and _declared_ when > it is referenced from elsewhere. See Kernighan & Ritchie. Commons > are a linker artifact that was never part of the C language, as far > as I can tell. > > Most instances turned up by -fno-common are accidental double > definitions of the same global, so you only need to turn the extra > definitions into declarations. However, in some cases they were > actually intended as separate variables and have been merged by > accident. In those cases, they should be renamed or made local > with "static". In some cases, it is deliberate. An initialised, but declared, global is used as a 'weak' global that can be overridden by checking its value. I maintain one port that does this!
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