Gentoo Archives: gentoo-dev

From: "C. Bergström" <cbergstrom@×××××××××.com>
To: gentoo-dev@l.g.o
Cc: Kent Fredric <kentfredric@×××××.com>
Subject: Re: [gentoo-dev] How to support C++11 in libraries?
Date: Wed, 18 Dec 2013 17:57:30
Message-Id: 52B1E1CF.504@pathscale.com
In Reply to: Re: [gentoo-dev] How to support C++11 in libraries? by Kent Fredric
1 On 12/19/13 12:47 AM, Kent Fredric wrote:
2 > On 19 December 2013 06:33, Jan Kundrát <jkt@g.o> wrote:
3 >> I'm worried by the cost of such a policy, though, because we would suddenly
4 >> have to patch some unknown amount of software
5 >
6 > Given the nature that changing that CXX Flag globally for all users
7 > could cause many packages to spontaneously fail to build, wouldn't
8 > that imply that changing that flag would essentially be de-stabilizing
9 > the whole tree, and a package being (arch) would no longer be an
10 > indication of sane, tested behaviour?
11 >
12 > This is really the perk of the USE driven process, the granular
13 > piecemeal approach that does only as much as necessary, without
14 > changing things that are already stable.
15 In practice wouldn't that mean you'd have to add c++11 USE flag to every
16 C++11 application and lib?
17
18 I just sent an email with some crazy thoughts - Your point is totally
19 correct - this "migration" needs to happen while not breaking the whole
20 tree. Logistically - what's the best way to maintain both those "ABI" at
21 the same time?
22
23 "Best case" both build and you end up with a linker problem (can be
24 worked around with compiler patches)
25 /usr/lib64/libboost.so
26 /usr/lib64-c++11/libboost.so
27
28 Worst case only 1 builds
29 this breaks down into generally 2 cases
30 1. Programs/libs which have intentionally adopted c++11 and don't
31 care about C++03 (clang/llvm/lldb)
32 2. Programs/libs which can't be compiles with c++11 mode
33
34
35 /usr/lib64/libfoo.so

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