fmt was updated during the clang-format update, which breaks the previous implementation of FmtLogMessage
Changes were:
* Move definition of FmtLogMessage into log.h to use variadic templates as FMT_VARIADIC was removed
To supplement the change above:
* Move Entry and CreateEntry into log.h
* Add LogEntry in backend.cpp
* Uses PopWait to reduce the amount of busy waiting if there aren't many
new logs
* Opens the log file as shared on windows, letting other programs read
the logs, but not write to them while citra is running
* Flushes the logs to disk if a log >= error arrives
* Change the logging backend to support multiple sinks through the
Backend Interface
* Add a new set of logging macros to use fmtlib instead.
* Qt: Compile as GUI application on windows to make the console hidden by
default. Add filter configuration and a button to open log location.
* SDL: Migrate to the new logging macros
It provided a large increase in complexity of the logging system while
having a negligible performance impact: the usage patterns of the ring
buffer meant that each log contended with the logging thread, causing
it to effectively act as a synchronous extra buffering.
Also removed some broken code related to filtering of subclasses which
was broken since it was introduced. (Which means no one ever used that
feature anyway, since, 8 months later, no one ever complained.)
