Other handles can only be used within the loop itself, but Async is intended
to be used from another thread. This introduces the possibility of a race
condition between the loop being destroyed and the Async being destroyed.
Change Async to keep a weak reference to a loop and check it before performing
libuv operations.
This allows the called function to pass along the promise to another
asynchronous callback.
To avoid memory allocations, add a home-rolled, simplified, non-allocating
version of std::promise and std::future as wpi::promise and wpi::future.
This is a breaking change as it makes Async a template (e.g. Async<> must
be used instead of just Async). When data parameters are provided, an
internal mutex and vector is used to hold the parameter packs until the loop
runs.
Also change header guards to WPI header guards.
Remove StringRef::c_str() customization, replacing the handful of uses with Twine or SmallString.
TCPStream: Include errno.h and make Windows includes lowercase for consistency.
Upstream LLVM version: eb4186cca7924fb1706357545311a2fa3de40c59
During shared library loading, a different libLLVM can be pulled in, causing
llvm symbols from dependent libraries to resolve to that library instead of
this one. This has been seen in the wild with the Mesa OpenGL implementation
in JavaFX applications (see wpilibsuite/shuffleboard#361).
This is clearly a very breaking change. For some level of backwards
compatibility, a namespace alias from llvm to wpi is performed in the "llvm"
headers. Unfortunately, forward declarations of llvm classes will still break,
but compilers seem to generate clear error messages in those cases
("namespace alias 'llvm' not allowed here, assuming 'wpi'").
This change also moves all the wpiutil headers to a single "wpi" subdirectory
from the previously split "llvm", "support", "tcpsockets", and "udpsockets".
Shim headers will be added for backwards compatibility in a later commit.
