This makes it easier for the caller to optimize the take/drop away for
temporary values, and opens up new possibilities for alias handling.
Breaks tail calls.
You can now say
let {bcx, val} = some_result_returner();
Similar for loop variables. Assigning to such variables is not safe
yet. Function arguments also remain a TODO.
This adds parser support and most of the machinery for
auto x = 10, y = 20;
However, the above still goes wrong somewhere in typestate, causing
the state checker to believe only the last variable in the list is
initialized after the statement.
Tim, if you have a moment, could you go over the changes to the tstate
code in this patch and see where I'm going wrong?
Multi-var-decls without the typestate extension
Add a loop
You can now say
expr_move(?dst, ?src) | expr_assign(?dst, ?src) { ... }
to match both expr_move and expr_assign. The names, types, and number
of bound names have to match in all the patterns.
Closes#449.
src/comp/syntax is currently just a sub-module of rustc, but it will,
in the near future, be its own crate. This includes:
- The AST data structure
- The parser
- The pretty-printer
- Visit, walk, and fold
- The syntax extension system
- Some utility stuff that should be in the stdlib*
*) Stdlib extensions currently require a snapshot before they can be
used, and the win build is very broken right now. This is temporary
and will be cleaned up when one of those problems goes away.
A lot of code was moved by this patch, mostly towards a more organized
layout. Some package paths did get longer, and I guess the new layout
will take some getting used to. Sorry about that!
Please try not to re-introduce any dependencies in syntax/ on any of
the other src/comp/ subdirs.
(Using the * operator.)
This makes tags more useful as nominal 'newtype' types, since you no
longer have to copy out their contents (or construct a cumbersome
boilerplate alt) to access them.
I could have gone with a scheme where you could dereference individual
arguments of an n-ary variant with ._0, ._1, etc, but opted not to,
since we plan to move to a system where all variants are unary (or, I
guess, nullary).
This is important since we are going to be making functions noncopyable
soon, which means we'll be seeing a lot of boxed functions.
(*f)(...) is really just too heavyweight.
Doing the autodereferencing was a very little bit tricky since
trans_call works with an *lval* of the function whereas existing
autoderef code was not for lvals.
