Date: Fri, 17 Jun 2016 12:03:00 +0930 From: Shane Ambler <FreeBSD@ShaneWare.Biz> To: john drake <diewolfsschanze@yahoo.com>, questions@freebsd.org Subject: Re: gcc-4.8.4_3 Message-ID: <5763615C.70900@ShaneWare.Biz> In-Reply-To: <78CEDABA-2A7F-4361-B626-D05CB2F966A0@yahoo.com> References: <78CEDABA-2A7F-4361-B626-D05CB2F966A0@yahoo.com>
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On 17/06/2016 09:05, john drake via freebsd-questions wrote: > Am running FreeBSD 10.2 and installed gcc-4.8.4_3 > > After installation received the following message from bcc: > for linking use -Wl, > -rparh=/usr/local/lib/gcc48 > > For ports leveraging USE_GCC, > USES=compiler, or > USES=fortran, > this happens transparently. Firstly this only applies to using the FreeBSD ports system. For a project that you manually compile within your home folder this will not help. See the porters handbook for help creating a port - https://www.freebsd.org/doc/en/books/porters-handbook/ > (1). What does this mean, and how do I make it happen transparently? > How do I actually implement the USE approach? In a port's Makefile you can add USE_GCC=4.8+ and the port will be built using gcc v4.8 or higher. The ports infrastructure adds the relevant settings to environment variables for this to work. See /usr/ports/Mk/bsd.gcc.mk There is also USE=compiler:ARGS for a more flexible approach. This allows a port to specify it needs a compiler that supports C++11 and a version of gcc or clang that supports c++11 will be chosen. See /usr/ports/Mk/Uses/compiler To work, both of these options rely on the projects build system respecting environment variables such as CC CXX CFLAGS CXXFLAGS... patches sometimes need to be applied otherwise. USE=fortran is similar but only applies to using gcc or ifort as the compiler when the project uses fortran. > (2). Can I make this transparent by altering the path command by > adding /usr/local/lib/gcc48? In most cases, adding one of the above options to a port's Makefile is all that is needed. > (3) Please supply me with answers to both approaches and their > relative advantages/disadvantages? USE_GCC - specifies that only gcc can be used on this project. USE=compiler - is more flexible as gcc or clang may be used as long as it supports the features you need for the project. The USE=compiler also allows a user to set FAVORITE_COMPILER in their make.conf to influence the compiler chosen. > (4). Also, supply me with the best approach. That's a matter of opinion with some dependency on the way the project is compiled. I would say USE=compiler is a better option but some projects will only compile with gcc so need to have USE_GCC -- FreeBSD - the place to B...Software Developing Shane Ambler
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