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This is a closure based API for creating switches that obey ownership
convensions. The way you use it with objects is as follows:
SwitchEnumBuilder S(...);
S.addCase(Decl, Block, [](ManagedValue Arg) -> void {
...
});
S.addCase(Decl, Block, [](ManagedValue Arg) -> void {
...
});
S.addDefaultCase(Block, [](ManagedValue Arg) -> void {
...
});
std::move(S).emit();
What is important is that it sets up the switch_enum destination blocks with the
proper cleanups for code emitted into the destination block and also provides
the default error with the passed in value with the appropriate cleanups.
It does not handle exits from the switch_enum on purpose since diamond
switch_enum APIs form a subset of APIs. It also expects the closure to create
terminators if appropriate.
In the switch_enum_addr case you have to do a bit more work, but it is still a
nicer API than doing it by hand as we do today.
rdar://29791263