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Overhaul alias-checking of blocks

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The set of active bindings has to be updated as by-reference locals are
encountered.

Issue #918
This commit is contained in:
Marijn Haverbeke 2011-09-15 15:34:50 +02:00
parent 87fa38910e
commit 75eee8b194
1 changed files with 27 additions and 34 deletions
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61
src/comp/middle/alias.rs
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@ -47,7 +47,6 @@ fn check_crate(tcx: ty::ctxt, crate: @ast::crate) -> copy_map {
copy_map: std::map::new_int_hash()};
let v = @{visit_fn: bind visit_fn(cx, _, _, _, _, _, _, _),
visit_expr: bind visit_expr(cx, _, _, _),
visit_decl: bind visit_decl(cx, _, _, _),
visit_block: bind visit_block(cx, _, _, _)
with *visit::default_visitor::<scope>()};
visit::visit_crate(*crate, {bs: [], ret_style: ast::return_val},
@ -132,46 +131,38 @@ fn visit_expr(cx: @ctx, ex: @ast::expr, sc: scope, v: vt<scope>) {
if !handled { visit::visit_expr(ex, sc, v); }
}
fn visit_decl(cx: @ctx, d: @ast::decl, sc: scope, v: vt<scope>) {
visit::visit_decl(d, sc, v);
alt d.node {
ast::decl_local(locs) {
for (_, loc) in locs {
alt loc.node.init {
some(init) {
if init.op == ast::init_move {
check_lval(cx, init.expr, sc, v);
}
}
none. { }
}
}
}
_ { }
}
}
fn visit_block(cx: @ctx, b: ast::blk, sc: scope, v: vt<scope>) {
let ref_locs = [];
let bs = sc.bs;
for stmt in b.node.stmts {
alt stmt.node {
ast::stmt_decl(@{node: ast::decl_local(ls), _}, _) {
for (st, loc) in ls {
ast::stmt_decl(@{node: ast::decl_item(it), _}, _) {
v.visit_item(it, sc, v);
}
ast::stmt_decl(@{node: ast::decl_local(locs), _}, _) {
for (st, loc) in locs {
if st == ast::let_ref {
ref_locs += [loc];
add_bindings_for_let(*cx, bs, loc);
sc = {bs: bs with sc};
}
alt loc.node.init {
some(init) {
if init.op == ast::init_move {
check_lval(cx, init.expr, sc, v);
}
}
none. { }
}
}
}
_ {}
ast::stmt_expr(ex, _) {
v.visit_expr(ex, sc, v);
}
ast::stmt_crate_directive(cd) {
visit::visit_crate_directive(cd, sc, v);
}
}
}
if vec::len(ref_locs) > 0u {
let bindings = sc.bs;
for loc in ref_locs { add_bindings_for_let(*cx, bindings, loc); }
visit::visit_block(b, {bs: bindings with sc}, v);
} else {
visit::visit_block(b, sc, v);
}
visit::visit_expr_opt(b.node.expr, sc, v);
}
fn add_bindings_for_let(cx: ctx, &bs: [binding], loc: @ast::local) {
@ -192,12 +183,14 @@ fn add_bindings_for_let(cx: ctx, &bs: [binding], loc: @ast::local) {
let ret_style = ty::ty_fn_ret_style(cx.tcx, fty);
if ast_util::ret_by_ref(ret_style) {
// FIXME pick right arg
let arg_root = expr_root(cx.tcx, args[0], false);
let arg = args[0];
let arg_root = expr_root(cx.tcx, arg, false);
root_var = path_def_id(cx, arg_root.ex);
if !is_none(root_var) {
is_temp = false;
if ret_style == ast::return_ref(true) {
outer_ds = [@{mut: true with *arg_root.ds[0]}];
outer_ds = [@{mut: true, kind: unbox,
outer_t: ty::expr_ty(cx.tcx, arg)}];
}
outer_ds = *arg_root.ds + outer_ds;
}