Implement checking of alias safety in tail calls.
This commit is contained in:
Marijn Haverbeke
parent
b2b8002fd3
commit
9b5ebe726c
@ -77,12 +77,18 @@ fn visit_item(@ctx cx, &@ast::item i, &scope sc, &vt[scope] v) {
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}
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fn visit_expr(@ctx cx, &@ast::expr ex, &scope sc, &vt[scope] v) {
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auto handled = false;
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auto handled = true;
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alt (ex.node) {
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case (ast::expr_call(?f, ?args, _)) { check_call(*cx, f, args, sc); }
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case (ast::expr_call(?f, ?args, _)) {
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check_call(*cx, f, args, sc);
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handled = false;
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}
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case (ast::expr_be(?cl, _)) {
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check_tail_call(*cx, cl);
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visit::visit_expr(cl, sc, v);
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}
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case (ast::expr_alt(?input, ?arms, _)) {
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check_alt(*cx, input, arms, sc, v);
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handled = true;
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}
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case (ast::expr_put(?val, _)) {
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alt (val) {
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@ -97,32 +103,27 @@ fn visit_expr(@ctx cx, &@ast::expr ex, &scope sc, &vt[scope] v) {
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}
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case (_) { }
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}
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handled = true;
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}
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case (ast::expr_for_each(?decl, ?call, ?block, _)) {
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check_for_each(*cx, decl, call, block, sc, v);
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handled = true;
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}
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case (ast::expr_for(?decl, ?seq, ?block, _)) {
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check_for(*cx, decl, seq, block, sc, v);
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handled = true;
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}
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case (ast::expr_path(?pt, ?ann)) {
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check_var(*cx, ex, pt, ann, false, sc);
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handled = false;
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}
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case (ast::expr_move(?dest, ?src, _)) {
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check_assign(cx, dest, src, sc, v);
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handled = true;
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}
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case (ast::expr_assign(?dest, ?src, _)) {
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check_assign(cx, dest, src, sc, v);
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handled = true;
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}
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case (ast::expr_assign_op(_, ?dest, ?src, _)) {
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check_assign(cx, dest, src, sc, v);
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handled = true;
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}
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case (_) { }
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case (_) { handled = false; }
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}
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if (!handled) { visit::visit_expr(ex, sc, v); }
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}
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@ -130,11 +131,8 @@ fn visit_expr(@ctx cx, &@ast::expr ex, &scope sc, &vt[scope] v) {
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fn check_call(&ctx cx, &@ast::expr f, &vec[@ast::expr] args, &scope sc) ->
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rec(vec[def_num] root_vars, vec[ty::t] unsafe_ts) {
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auto fty = ty::expr_ty(*cx.tcx, f);
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auto arg_ts =
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alt (ty::struct(*cx.tcx, fty)) {
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case (ty::ty_fn(_, ?args, _, _, _)) { args }
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case (ty::ty_native_fn(_, ?args, _)) { args }
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};
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auto arg_ts = fty_args(cx, fty);
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let vec[def_num] roots = [];
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let vec[tup(uint, def_num)] mut_roots = [];
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let vec[ty::t] unsafe_ts = [];
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@ -175,11 +173,11 @@ fn check_call(&ctx cx, &@ast::expr f, &vec[@ast::expr] args, &scope sc) ->
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if (vec::len(unsafe_ts) > 0u) {
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alt (f.node) {
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case (ast::expr_path(_, ?ann)) {
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if (def_is_local(cx.dm.get(ann.id))) {
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cx.tcx.sess.span_err(f.span,
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#fmt("function may alias with \
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argument %u, which is not immutably rooted",
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unsafe_t_offsets.(0)));
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if (def_is_local(cx.dm.get(ann.id), true)) {
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cx.tcx.sess.span_err
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(f.span, #fmt("function may alias with argument \
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%u, which is not immutably rooted",
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unsafe_t_offsets.(0)));
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}
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}
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case (_) { }
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@ -221,8 +219,47 @@ fn check_call(&ctx cx, &@ast::expr f, &vec[@ast::expr] args, &scope sc) ->
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ret rec(root_vars=roots, unsafe_ts=unsafe_ts);
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}
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fn check_alt(&ctx cx, &@ast::expr input, &vec[ast::arm] arms, &scope sc,
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&vt[scope] v) {
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fn check_tail_call(&ctx cx, &@ast::expr call) {
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auto args;
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auto f = alt (call.node) {
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case (ast::expr_call(?f, ?args_, _)) { args = args_; f }
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};
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auto i = 0u;
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for (ty::arg arg_t in fty_args(cx, ty::expr_ty(*cx.tcx, f))) {
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if (arg_t.mode != ty::mo_val) {
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auto mut_a = arg_t.mode == ty::mo_alias(true);
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auto ok = true;
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alt (args.(i).node) {
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case (ast::expr_path(_, ?ann)) {
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auto def = cx.dm.get(ann.id);
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auto dnum = ast::def_id_of_def(def)._1;
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alt (cx.local_map.find(dnum)) {
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case (some(arg(ast::alias(?mut)))) {
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if (mut_a && !mut) {
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cx.tcx.sess.span_warn
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(args.(i).span, "passing an immutable \
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alias by mutable alias");
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}
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}
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case (_) {
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ok = !def_is_local(def, false);
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}
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}
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}
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case (_) { ok = false; }
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}
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if (!ok) {
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cx.tcx.sess.span_warn
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(args.(i).span, "can not pass a local value by alias to \
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a tail call");
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}
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}
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i += 1u;
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}
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}
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fn check_alt(&ctx cx, &@ast::expr input, &vec[ast::arm] arms,
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&scope sc, &vt[scope] v) {
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visit::visit_expr(input, sc, v);
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auto root = expr_root(cx, input, true);
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auto roots =
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@ -317,7 +354,7 @@ fn check_for(&ctx cx, &@ast::local local, &@ast::expr seq, &ast::block block,
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fn check_var(&ctx cx, &@ast::expr ex, &ast::path p, ast::ann ann, bool assign,
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&scope sc) {
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auto def = cx.dm.get(ann.id);
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if (!def_is_local(def)) { ret; }
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if (!def_is_local(def, true)) { ret; }
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auto my_defnum = ast::def_id_of_def(def)._1;
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auto var_t = ty::expr_ty(*cx.tcx, ex);
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for (restrict r in sc) {
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@ -594,15 +631,23 @@ fn ty_can_unsafely_include(&ctx cx, ty::t needle, ty::t haystack, bool mut) ->
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ret helper(*cx.tcx, needle, haystack, mut);
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}
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fn def_is_local(&ast::def d) -> bool {
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fn def_is_local(&ast::def d, bool objfields_count) -> bool {
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ret alt (d) {
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case (ast::def_local(_)) { true }
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case (ast::def_arg(_)) { true }
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case (ast::def_obj_field(_)) { true }
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case (ast::def_binding(_)) { true }
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case (_) { false }
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};
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case (ast::def_local(_)) { true }
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case (ast::def_arg(_)) { true }
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case (ast::def_obj_field(_)) { objfields_count }
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case (ast::def_binding(_)) { true }
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case (_) { false }
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};
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}
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fn fty_args(&ctx cx, ty::t fty) -> vec[ty::arg] {
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ret alt (ty::struct(*cx.tcx, fty)) {
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case (ty::ty_fn(_, ?args, _, _, _)) { args }
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case (ty::ty_native_fn(_, ?args, _)) { args }
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};
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}
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// Local Variables:
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// mode: rust
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// fill-column: 78;
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