[libc++][RFC] Always define internal feature test macros (#89178)
Currently, the library-internal feature test macros are only defined if
the feature is not available, and always have the prefix
`_LIBCPP_HAS_NO_`. This patch changes that, so that they are always
defined and have the prefix `_LIBCPP_HAS_` instead. This changes the
canonical use of these macros to `#if _LIBCPP_HAS_FEATURE`, which means
that using an undefined macro (e.g. due to a missing include) is
diagnosed now. While this is rather unlikely currently, a similar change
in `<__configuration/availability.h>` caught a few bugs. This also
improves readability, since it removes the double-negation of `#ifndef
_LIBCPP_HAS_NO_FEATURE`.
The current patch only touches the macros defined in `<__config>`. If
people are happy with this approach, I'll make a follow-up PR to also
change the macros defined in `<__config_site>`.
diff --git a/libcxx/src/future.cpp b/libcxx/src/future.cpp
index e2c14c8..04e6fb8 100644
--- a/libcxx/src/future.cpp
+++ b/libcxx/src/future.cpp
@@ -142,10 +142,10 @@
promise<void>::~promise() {
if (__state_) {
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#if _LIBCPP_HAS_EXCEPTIONS
if (!__state_->__has_value() && __state_->use_count() > 1)
__state_->set_exception(make_exception_ptr(future_error(future_errc::broken_promise)));
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#endif // _LIBCPP_HAS_EXCEPTIONS
__state_->__release_shared();
}
}
