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.
Passing args to middle::fold::fold_expr_anon_obj by reference to be
consistent with the other folds; adding a dummy fold_expr_anon_obj to
typeck to be filled in later.
This prevents insane things like 'auto while = 2', which would parse
in the previous revision, but then break when you tried to mutate it
with 'while = 10'.
Keywords are now only recognized in contexts where they are valid. The
lexer no longer recognizes them, all words are lexed as IDENT tokens,
that get interpreted by the parser.
