For clang-cl, we should follow cl's model of selecting a standard. Before C++17, this was "use newest language the compiler knows about" (keyed off -fmsc-version; clang-cl detects the system msvc version by default if that's not passed in). After C++17, there's an explicit language flag, and we use the same default as cl.
Last I checked (which was a while ago), libstdc++ didn't parse with -std=c++14, at least at some version. I don't remember which version of libstdc++ I tried (maybe 4.9?). Should that factor into the decision? Not parsing standard library headers by default on Linux seems like a somewhat suboptimal user experience. On Wed, Jun 29, 2016 at 3:09 PM, Richard Smith via cfe-commits < cfe-commits@lists.llvm.org> wrote: > Hi all! > > I'd like to establish a policy for Clang's default language standard (if > none is specified with -std), as follows: > > Clang defaults to the most recent published standard for the selected > language that it fully implements. > > The practical impact of this is that clang++ will default to C++14 for C++ > compilations (for version 3.9 onwards) and will default to C++17 once our > implementation support is complete and the standard is published (whichever > happens later). > > I'd suggest that we apply the same policy for clang-cl, but if it's > important that we enable a not-yet-fully-implemented standard for cl > compatibility, that seems reasonable. > > The question of whether the default mode for the GCC-compatible driver > should be -std=gnuXXX or -std=cXXX is separate, but also likely worth > discussing. Enabling GNU keywords by default is a very odd choice, and if > we believe we can change our defaults without breaking the world then this > seems like a good time to do so. > > I also intend to make explicit in our documentation that our -std=XXX flag > enables the selected standard, *plus all relevant issues in Defect Report > status from the relevant language committee* (it doesn't make sense to > support a language without its bugfixes). > > Thoughts? > > _______________________________________________ > cfe-commits mailing list > cfe-commits@lists.llvm.org > http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits > >
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