With the scheme used to translate 'else if' currently the if expression is
translated in a new (else) scope context. If that if expression wants to
result in a value that requires refcounting then it will need to drop the
refcount in the cleanups of the else block.
Blocks return in a copy of the result of their ending expression, not the
direct result of the ending expression, as that may be a local variable which
gets zeroed by drop_slot.
get_os and get_arch were failing to return a value in the error
case; they were also assuming that strings are indexed from 1. No
idea how they ever worked, but anyway, fixed.
* Reorganized typestate into several modules.
* Made typestate check that any function with a non-nil return type
returns a value. For now, the check is a warning and not an error
(see next item).
* Added a "bot" type (prettyprinted as _|_), for constructs like be, ret, break, cont, and
fail that don't locally return a value that can be inspected. "bot"
is distinct from "nil". There is no concrete syntax for _|_, while
the concrete syntax for the nil type is ().
* Added support to the parser for a ! annotation on functions whose
result type is _|_. Such a function is required to have either a
fail or a call to another ! function that is reached in all control
flow paths. The point of this annotation is to mark functions like
unimpl() and span_err(), so that an alt with a call to err() in one
case isn't a false positive for the return-value checker. I haven't
actually annotated anything with it yet.
* Random bugfixes:
* * Fixed bug in trans::trans_binary that was throwing away the
cleanups for nested subexpressions of an and or or
(tests: box-inside-if and box-inside-if2).
** In typeck, unify the expected type arguments of a tag with the
actual specified arguments.
The verifier was not liking this when generating unoptimized bitcode. Per LLVM
docs it is not valid for function declarations to be marked internal, but
their implementations may be.
