On Tue, Oct 2, 2018 at 10:33 AM Christof Douma <christof.do...@arm.com> wrote:
> Hi Marshall. > > I think that this patch breaks backwards compatibility. Assumes that the > header file "version" is used by C++ projects that use a C++ standard that > did not specify a 'version' header. Many toolchains will put search paths > specified with -I in front of the system search path. The result is that > the application header file is included whenever a standard header file is > included. That is unexpected and can break builds. > > Do you agree this is an issue or do you consider this an issue with the > way toolchains handle include search paths? Christof - I've been thinking about this the last few days. We can ameliorate this in libc++, (See Richard's suggestion on __version) but anything we do will be a short-term solution. The first time someone includes another header file that #include <version>, they're back to square one. That header is supposed to be "the place to go" for information about your standard library, and people are going to use it. For example, I expect that Boost.Config will start using it soon (if it doesn't already) A better solution (and not just because it would require other people to do the work) would be to have the build systems either: * Stop using VERSION as a file name - use something like VERSION.STAMP instead. * Use '-iquote' instead of '-I' to manage the list of include directories. I agree that it's annoying for people's builds to be broken when they upgrade their development tools, and especially when they didn't do anything "wrong". -- Marshall
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