This commit allows patterns like:
alt x { some(_) { ... } none { } }
without the '.' after none. The parser suspends judgment about
whether a bare ident is a tag or a new bound variable; instead,
the resolver disambiguates.
This means that any code after resolution that pattern-matches on
patterns needs to call pat_util::normalize_pat, which consults
an environment to do this disambiguation.
In addition, local variables are no longer allowed to shadow
tag names, so this required changing some code (e.g. renaming
variables named "mut", and renaming ast::sub to subtract).
The parser currently accepts patterns with and without the '.'.
Once the compiler and libraries are changed, it will no longer
accept the '.'.
Addresses issue #1393.
For now disallow disr. values unless all variants use nullary
contractors (i.e. "enum-like").
Disr. values are now encoded in the crate metadata, but only when it
will differ from the inferred value based on the order.
We should probalby warn when defining a method foo on {foo: int} etc.
This should reduce the amount of useless typevars that are allocated.
Issue #1227
See src/test/run-pass/nested-patterns.rs for some examples. The syntax is
boundvar@subpattern
Which will match the subpattern as usual, but also bind boundvar to the
whole matched value.
Closes#838
There's no good reason to force them to be spilled anymore. Some
pieces of trans become more elegant this way, and less stack allocs
and load/stores are needed.
Issue #1021
Local values that are not mutated, don't need to be cleaned up, and
are immediate, don't need to be spilled. (All immediate args, and
non-pointer immediate let locals.)
Issue #667
Wires in a basic framework for destination-passing style, with
backwards-compatibility to the old approach, so that expression types
can be moved over to it one at a time (by moving them from trans_expr
to trans_expr_dps).
The builder functions in trans_build now look at an 'unreachable' flag
in the block context and don't generate code (returning undefined
placeholder values) when this flag is set. Threading the unreachable
flag through context still requires some care, but this seems a more
sane approach than re-checking for terminated blocks throughout the
compiler.
When creating a block, if you use its closest dominator as parent, the
flag will be automatically passed through. If you can't do that,
because the dominator is a scope block that you're trying to get out
of, you'll have to do something like this to explicitly pass on the
flag:
if bcx.unreachable { Unreachable(next_cx); }
Closes#949. Closes#946. Closes#942. Closes#895. Closes#894.
Closes#892. Closes#957. Closes#958.
trans::type_of now has a constraint saying that its type argument
is statically sized. This eliminates the "impossible happened" case
in type_of. Yay!
I note that this change decreased translation time for stage2/rustc
from 16.1 s to 14.0 s. I also think many of the remaining checks
could be eliminated with some mildly clever use of constrained types
and further preconditions. Future work!
