If time domains differ, it is necessary to first convert the argument duration into a duration
at the position of "this", in the correct time domain. Then we recursively call the operator
again, but this time we will use the fast path that just adds two timepos_t values.
pbd/i18n.h MUST NEVER be included from header files and always be
the last include. This is because `_` is declared other headers
notably boost and some apple headers.
leading to issues like
../libs/pbd/gettext.h:58:27: error: expected unqualified-id before ‘const’
58 | # define gettext(Msgid) ((const char *) (Msgid))
It turned out that 'boost::intrusive::list_base_hook<>' won't compile if its parent class is declared using '__declspec(dllexport)' - so rather than exporting each entire class, let's use the alternative approach and export the various class members individually.
list_member_hook<> is very troublesome in MSVC and is known to cause problems in other compilers when used inside a class which has a virtual base class.
When switching backends, the effective sample-rate is zero.
This only affects the butler thread (the only active thread when
stopped). The actual issue here is the butler calling
"non-realtime-stop" without a backend. However fixing 0/0
generally seems appropriate.
```
#0 in int_div_round<long>(long, long) (x=0, y=0) at ../libs/pbd/pbd/integer_division.h:36
#1 in Temporal::samples_to_superclock(int64_t, int) (samples=0, sr=0) at ../libs/temporal/temporal/superclock.h:39
#2 in Temporal::timepos_t::timepos_t(long) (this=0x7f94bc0a5890, s=0) at ../libs/temporal/temporal/timeline.h:55
#3 in ARDOUR::Automatable::non_realtime_locate(long) (this=0x55a12a980cc8, now=0) at ../libs/ardour/automatable.cc:421
#4 in ARDOUR::Route::non_realtime_locate(long) (this=0x55a12a980ae0, pos=0) at ../libs/ardour/route.cc:5462
#5 in ARDOUR::Session::non_realtime_stop(bool, int, bool&) (this=0x55a12e0cd000, abort=false, on_entry=1, finished=@0x7f94bc0a5e0f: true) at ../libs/ardour/session_transport.cc:1487
#6 in ARDOUR::Session::butler_transport_work(bool) (this=0x55a12e0cd000, have_process_lock=false) at ../libs/ardour/session_transport.cc:1153
#7 in ARDOUR::Butler::thread_work() (this=0x55a12f3b7000) at ../libs/ardour/butler.cc:222
#8 in ARDOUR::Butler::_thread_work(void*) (arg=0x55a12f3b7000) at ../libs/ardour/butler.cc:16
```
Whenever a variable gets declared using 'thread_local' MSVC requires that it should not be compiled with DLL linkage (i.e. it mustn't be exportable). So for Temporal::TempoMap we'll need to export the required members individually, rather than exporting the entire class.
Later I'll need to push some extra changes (to support 'tempo_map_p' and 'boost::intrusive::list' etc) but these initial ones (hopefully!) won't cause any issues for the other builds.
