On Fri, Jul 1, 2016 at 4:37 PM, Eric Fiselier <e...@efcs.ca> wrote: > The attribute is ignored unless it is placed on the in-class declaration > of the member. It has no effect when applied to the explicit definition. >
Ugh, right, attributes added after the definition aren't well-treated. Seems reasonable to me for us to emit a strong definition of the variable (linkonce_odr -> weak_odr) if it has an out-of-line declaration, for compatibility with cases like this. That way you wouldn't need this change at all. > I would rather keep the workaround internal than make the change in the > headers. > Oh, sure, changing the header would definitely be the wrong thing. > On Fri, Jul 1, 2016 at 5:34 PM, Richard Smith <rich...@metafoo.co.uk> > wrote: > >> On Fri, Jul 1, 2016 at 4:22 PM, Eric Fiselier via cfe-commits < >> cfe-commits@lists.llvm.org> wrote: >> >>> Author: ericwf >>> Date: Fri Jul 1 18:22:25 2016 >>> New Revision: 274403 >>> >>> URL: http://llvm.org/viewvc/llvm-project?rev=274403&view=rev >>> Log: >>> Work around ABI break caused by C++17 inline variables. >>> >>> Modified: >>> libcxx/trunk/src/chrono.cpp >>> >>> Modified: libcxx/trunk/src/chrono.cpp >>> URL: >>> http://llvm.org/viewvc/llvm-project/libcxx/trunk/src/chrono.cpp?rev=274403&r1=274402&r2=274403&view=diff >>> >>> ============================================================================== >>> --- libcxx/trunk/src/chrono.cpp (original) >>> +++ libcxx/trunk/src/chrono.cpp Fri Jul 1 18:22:25 2016 >>> @@ -6,7 +6,7 @@ >>> // Source Licenses. See LICENSE.TXT for details. >>> // >>> >>> >>> //===----------------------------------------------------------------------===// >>> - >>> +#define _LIBCPP_BUILDING_CHRONO >>> #include "chrono" >>> #include "cerrno" // errno >>> #include "system_error" // __throw_system_error >>> @@ -32,6 +32,9 @@ namespace chrono >>> // system_clock >>> >>> const bool system_clock::is_steady; >>> >> >> Can you mark this as __attribute__((used)) instead of adding a separate >> use? >> >> >>> +// Make is_steady non-discardable in C++17 >>> +// See PR28395 (https://llvm.org/bugs/show_bug.cgi?id=28395) >>> +static const bool& __is_steady_force_use1 __attribute__((used)) = >>> system_clock::is_steady; >>> >>> system_clock::time_point >>> system_clock::now() _NOEXCEPT >>> @@ -68,6 +71,10 @@ system_clock::from_time_t(time_t t) _NOE >>> // instead. >>> >>> const bool steady_clock::is_steady; >>> +// Make is_steady non-discardable in C++17 >>> +// See PR28395 (https://llvm.org/bugs/show_bug.cgi?id=28395) >>> +static const bool& __is_steady_force_use2 __attribute__((used)) = >>> steady_clock::is_steady; >>> + >>> >>> #ifdef CLOCK_MONOTONIC >>> >>> >>> >>> _______________________________________________ >>> cfe-commits mailing list >>> cfe-commits@lists.llvm.org >>> http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits >>> >> >> >
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