When calling NullCheckedInvocation::invoke with a capture-less lambda,
GCC 9.3 determines that the expression
std::declval<TheLambda>() != nullptr
is well-formed, and uses the version of invoke containing a nullptr
check. However, the compiler is also able to determine that this
expression can never be false, and emits a warning.
With this patch applied, the DemoRunner should build under MinGW, and be
(nearly) feature-complete compared to the MSVC build.
Specifically, when building with MinGW:
- Adds support for accessibility
- Fixes build issues in the juce_video module
- Fixes a link issue in the VST3 wrapper when VST3_CAN_REPLACE_VST2 is
defined
- Adds support for the new-style native FileChooser
- Tidies up some other low-severity warnings
Known issues:
- Direct2D rendering is still not supported when building with MinGW due
to ABI compatibilities.
The Apple threading documentation [^1] says the following:
> The second argument to pthread_setschedparam is the desired policy,
which can currently be one of SCHED_FIFO (first in, first out),
SCHED_RR (round-robin), or SCHED_OTHER. The SCHED_OTHER policy is
generally used for extra policies that are specific to a given
operating system, and should thus be avoided when writing portable
code.
This appears to differ from the policy semantics on Linux and BSD, where
FIFO and RR are both explicitly real-time policies.
Therefore, on Linux/BSD we only enable the RR policy if the requested
priority is 8 or higher. Meanwhile, on macOS, we map all thread
priorities (0 - 10) onto the RR policy with an appropriate priority.
[^1]: https://developer.apple.com/library/archive/documentation/Darwin/Conceptual/KernelProgramming/scheduler/scheduler.html
