Once again a situation where the combined and compute do the exact same
thing as far as Sema/AST/etc is concerned, so this patch adds tests and
enables it.
This is another clause where the parsing does all the required
enforcement besides the construct it appertains to, so this patch
removes the restriction and adds sufficient test coverage for combined
constructs.
This is another pair of clauses where the work is already done from
previous constructs, so this just has to allow them and include tests
for them. This patch adds testing, does a few little cleanup bits on the
clause checking, and enables these.
This clause takes one of two fixed values, and can apply to all three of
the combined constructs. Tests/etc are all exactly like the compute
constructs, so committing them all here.
This clause is pretty small/doesn't do much semantic-analysis-wise, , other than
have two spellings and disallow certain clauses after it. However, as
most of those aren't implemented yet, the diagnostic is left as a TODO.
