rust/src/comp/middle/kind.rs

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import option::{some, none};
import syntax::{visit, ast_util};
import syntax::ast::*;
import syntax::codemap::span;
// Kind analysis pass. There are three kinds:
//
// sendable: scalar types, and unique types containing only sendable types
// copyable: boxes, objects, closures, and uniques containing copyable types
// noncopyable: resources, or unique types containing resources
//
// This pass ensures that type parameters are only instantiated with types
// whose kinds are equal or less general than the way the type parameter was
// annotated (with the `send` or `copy` keyword).
//
// It also verifies that noncopyable kinds are not copied. Sendability is not
// applied, since none of our language primitives send. Instead, the sending
// primitives in the stdlib are explicitly annotated to only take sendable
// types.
fn kind_to_str(k: kind) -> str {
alt k {
kind_sendable. { "sendable" }
kind_copyable. { "copyable" }
kind_noncopyable. { "noncopyable" }
}
}
type rval_map = std::map::hashmap<node_id, ()>;
type ctx = {tcx: ty::ctxt,
rval_map: rval_map,
last_uses: last_use::last_uses};
fn check_crate(tcx: ty::ctxt, last_uses: last_use::last_uses,
crate: @crate) -> rval_map {
let ctx = {tcx: tcx,
rval_map: std::map::new_int_hash(),
last_uses: last_uses};
let visit = visit::mk_vt(@{
visit_expr: check_expr,
visit_stmt: check_stmt
with *visit::default_visitor()
});
visit::visit_crate(*crate, ctx, visit);
tcx.sess.abort_if_errors();
ret ctx.rval_map;
}
fn check_expr(e: @expr, cx: ctx, v: visit::vt<ctx>) {
alt e.node {
expr_assign(_, ex) | expr_assign_op(_, _, ex) |
expr_block({node: {expr: some(ex), _}, _}) |
expr_unary(box(_), ex) | expr_unary(uniq(_), ex) { maybe_copy(cx, ex); }
expr_ret(some(ex)) { maybe_copy(cx, ex); }
expr_copy(expr) { check_copy_ex(cx, expr, false); }
// Vector add copies.
expr_binary(add., ls, rs) { maybe_copy(cx, ls); maybe_copy(cx, rs); }
expr_rec(fields, def) {
for field in fields { maybe_copy(cx, field.node.expr); }
alt def {
some(ex) {
// All noncopyable fields must be overridden
let t = ty::expr_ty(cx.tcx, ex);
let ty_fields = alt ty::struct(cx.tcx, t) { ty::ty_rec(f) { f } };
for tf in ty_fields {
if !vec::any({|f| f.node.ident == tf.ident}, fields) &&
ty::type_kind(cx.tcx, tf.mt.ty) == kind_noncopyable {
cx.tcx.sess.span_err(ex.span,
"copying a noncopyable value");
}
}
}
_ {}
}
}
expr_tup(exprs) | expr_vec(exprs, _) {
for expr in exprs { maybe_copy(cx, expr); }
}
expr_bind(_, args) {
for a in args { alt a { some(ex) { maybe_copy(cx, ex); } _ {} } }
}
expr_call(f, args, _) {
let i = 0u;
for arg_t in ty::ty_fn_args(cx.tcx, ty::expr_ty(cx.tcx, f)) {
alt arg_t.mode { by_copy. { maybe_copy(cx, args[i]); } _ {} }
i += 1u;
}
}
expr_path(_) {
let substs = ty::node_id_to_ty_param_substs_opt_and_ty(cx.tcx, e.id);
alt substs.substs {
some(ts) {
let did = ast_util::def_id_of_def(cx.tcx.def_map.get(e.id));
let kinds = ty::lookup_item_type(cx.tcx, did).kinds, i = 0u;
for ty in ts {
let kind = ty::type_kind(cx.tcx, ty);
if !ty::kind_lteq(kinds[i], kind) {
cx.tcx.sess.span_err(e.span, "instantiating a " +
kind_to_str(kinds[i]) +
" type parameter with a "
+ kind_to_str(kind) + " type");
}
i += 1u;
}
}
none. {}
}
}
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expr_fn({proto: proto_send, _}, captures) {
for free in *freevars::get_freevars(cx.tcx, e.id) {
let id = ast_util::def_id_of_def(free).node;
let ty = ty::node_id_to_type(cx.tcx, id);
check_copy(cx, ty, e.span);
}
}
expr_fn({proto: proto_shared(_), _}, captures) {
for free in *freevars::get_freevars(cx.tcx, e.id) {
let id = ast_util::def_id_of_def(free).node;
let ty = ty::node_id_to_type(cx.tcx, id);
check_copy(cx, ty, e.span);
}
}
expr_ternary(_, a, b) { maybe_copy(cx, a); maybe_copy(cx, b); }
_ { }
}
visit::visit_expr(e, cx, v);
}
fn check_stmt(stmt: @stmt, cx: ctx, v: visit::vt<ctx>) {
alt stmt.node {
stmt_decl(@{node: decl_local(locals), _}, _) {
for (_, local) in locals {
alt local.node.init {
some({op: init_assign., expr}) { maybe_copy(cx, expr); }
_ {}
}
}
}
_ {}
}
visit::visit_stmt(stmt, cx, v);
}
fn maybe_copy(cx: ctx, ex: @expr) {
check_copy_ex(cx, ex, true);
}
fn check_copy_ex(cx: ctx, ex: @expr, _warn: bool) {
if ty::expr_is_lval(cx.tcx, ex) && !cx.last_uses.contains_key(ex.id) {
let ty = ty::expr_ty(cx.tcx, ex);
check_copy(cx, ty, ex.span);
// FIXME turn this on again once vector types are no longer unique.
// Right now, it is too annoying to be useful.
/* if warn && ty::type_is_unique(cx.tcx, ty) {
cx.tcx.sess.span_warn(ex.span, "copying a unique value");
}*/
}
}
fn check_copy(cx: ctx, ty: ty::t, sp: span) {
if ty::type_kind(cx.tcx, ty) == kind_noncopyable {
cx.tcx.sess.span_err(sp, "copying a noncopyable value");
}
}
//
// Local Variables:
// mode: rust
// fill-column: 78;
// indent-tabs-mode: nil
// c-basic-offset: 4
// buffer-file-coding-system: utf-8-unix
// End:
//