rmaprath added inline comments. ================ Comment at: include/__threading_support:201 @@ +200,3 @@ +// Mutex +#define _LIBCPP_MUTEX_INITIALIZER nullptr +struct __libcpp_platform_mutex_t; ---------------- bcraig wrote: > I'm not sure I like taking the freedom to define _LIBCPP_MUTEX_INITIALIZER > away from implementers. > > Would it be too terrible to replace this entire #elif block with something > like the following? > > ``` > #if !defined(__has_include) || __has_include(<os_provided_thread.h>) > #include <os_provided_thread.h> > #else > #error "_LIBCPP_THREAD_API_EXTERNAL requires the implementer to provide > <os_provided_thread.h> in the include path" > #endif > ``` > > The problem is that, `std::mutex` constructor needs to be `constexpr` (as you pointed out earlier). And since `__libcpp_mutex_t` is a pointer type (for this externally threaded variant), sensible definitions for `_LIBCPP_MUTEX_INITIALIZER` are limited.
Other than `nullptr`, one may be able to define `_LIBCPP_MUTEX_INITIALIZER` to be a pointer to some constant mutex (presuming that make it `constexpr` OK?) but I'm not convinced if such a setup would be very useful. Hope that sounds sensible? http://reviews.llvm.org/D20328 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
