440 lines
16 KiB
Rust
440 lines
16 KiB
Rust
import syntax::{visit, ast_util};
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import syntax::ast::*;
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import syntax::codemap::span;
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import ty::{kind, kind_sendable, kind_copyable, kind_noncopyable, kind_const,
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operators};
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import driver::session::session;
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import std::map::hashmap;
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import util::ppaux::{ty_to_str, tys_to_str};
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import syntax::print::pprust::expr_to_str;
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import freevars::freevar_entry;
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import dvec::extensions;
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import lint::{non_implicitly_copyable_typarams,implicit_copies};
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// Kind analysis pass.
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//
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// There are several kinds defined by various operations. The most restrictive
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// kind is noncopyable. The noncopyable kind can be extended with any number
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// of the following attributes.
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//
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// send: Things that can be sent on channels or included in spawned closures.
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// copy: Things that can be copied.
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// const: Things thare are deeply immutable. They are guaranteed never to
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// change, and can be safely shared without copying between tasks.
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//
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// Send includes scalar types as well as classes and unique types containing
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// only sendable types.
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//
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// Copy includes boxes, closure and unique types containing copyable types.
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//
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// Const include scalar types, things without non-const fields, and pointers
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// to const things.
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//
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// This pass ensures that type parameters are only instantiated with types
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// whose kinds are equal or less general than the way the type parameter was
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// annotated (with the `send`, `copy` or `const` keyword).
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//
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// It also verifies that noncopyable kinds are not copied. Sendability is not
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// applied, since none of our language primitives send. Instead, the sending
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// primitives in the stdlib are explicitly annotated to only take sendable
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// types.
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fn kind_to_str(k: kind) -> str {
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let mut kinds = []/~;
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if ty::kind_lteq(kind_const(), k) {
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vec::push(kinds, "const");
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}
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if ty::kind_can_be_copied(k) {
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vec::push(kinds, "copy");
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}
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if ty::kind_can_be_sent(k) {
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vec::push(kinds, "send");
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}
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str::connect(kinds, " ")
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}
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type rval_map = std::map::hashmap<node_id, ()>;
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type ctx = {tcx: ty::ctxt,
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method_map: typeck::method_map,
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last_use_map: liveness::last_use_map,
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current_item: node_id};
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fn check_crate(tcx: ty::ctxt,
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method_map: typeck::method_map,
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last_use_map: liveness::last_use_map,
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crate: @crate) {
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let ctx = {tcx: tcx,
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method_map: method_map,
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last_use_map: last_use_map,
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current_item: -1};
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let visit = visit::mk_vt(@{
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visit_expr: check_expr,
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visit_stmt: check_stmt,
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visit_block: check_block,
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visit_fn: check_fn,
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visit_ty: check_ty,
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visit_item: fn@(i: @item, cx: ctx, v: visit::vt<ctx>) {
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visit::visit_item(i, {current_item: i.id with cx}, v);
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}
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with *visit::default_visitor()
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});
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visit::visit_crate(*crate, ctx, visit);
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tcx.sess.abort_if_errors();
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}
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type check_fn = fn@(ctx, node_id, option<@freevar_entry>,
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bool, ty::t, sp: span);
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// Yields the appropriate function to check the kind of closed over
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// variables. `id` is the node_id for some expression that creates the
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// closure.
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fn with_appropriate_checker(cx: ctx, id: node_id, b: fn(check_fn)) {
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fn check_for_uniq(cx: ctx, id: node_id, fv: option<@freevar_entry>,
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is_move: bool, var_t: ty::t, sp: span) {
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// all captured data must be sendable, regardless of whether it is
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// moved in or copied in
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check_send(cx, var_t, sp);
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// copied in data must be copyable, but moved in data can be anything
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let is_implicit = fv.is_some();
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if !is_move { check_copy(cx, id, var_t, sp, is_implicit); }
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// check that only immutable variables are implicitly copied in
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for fv.each { |fv|
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check_imm_free_var(cx, fv.def, fv.span);
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}
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}
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fn check_for_box(cx: ctx, id: node_id, fv: option<@freevar_entry>,
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is_move: bool, var_t: ty::t, sp: span) {
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// copied in data must be copyable, but moved in data can be anything
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let is_implicit = fv.is_some();
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if !is_move { check_copy(cx, id, var_t, sp, is_implicit); }
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// check that only immutable variables are implicitly copied in
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for fv.each { |fv|
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check_imm_free_var(cx, fv.def, fv.span);
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}
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}
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fn check_for_block(cx: ctx, _id: node_id, fv: option<@freevar_entry>,
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_is_move: bool, _var_t: ty::t, sp: span) {
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// only restriction: no capture clauses (we would have to take
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// ownership of the moved/copied in data).
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if fv.is_none() {
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cx.tcx.sess.span_err(
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sp,
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"cannot capture values explicitly with a block closure");
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}
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}
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fn check_for_bare(cx: ctx, _id: node_id, _fv: option<@freevar_entry>,
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_is_move: bool,_var_t: ty::t, sp: span) {
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cx.tcx.sess.span_err(sp, "attempted dynamic environment capture");
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}
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let fty = ty::node_id_to_type(cx.tcx, id);
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alt ty::ty_fn_proto(fty) {
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proto_uniq { b(check_for_uniq) }
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proto_box { b(check_for_box) }
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proto_bare { b(check_for_bare) }
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proto_any | proto_block { b(check_for_block) }
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}
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}
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// Check that the free variables used in a shared/sendable closure conform
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// to the copy/move kind bounds. Then recursively check the function body.
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fn check_fn(fk: visit::fn_kind, decl: fn_decl, body: blk, sp: span,
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fn_id: node_id, cx: ctx, v: visit::vt<ctx>) {
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// Find the check function that enforces the appropriate bounds for this
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// kind of function:
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with_appropriate_checker(cx, fn_id) { |chk|
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// Begin by checking the variables in the capture clause, if any.
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// Here we slightly abuse the map function to both check and report
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// errors and produce a list of the def id's for all capture
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// variables. This list is used below to avoid checking and reporting
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// on a given variable twice.
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let cap_clause = alt fk {
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visit::fk_anon(_, cc) | visit::fk_fn_block(cc) { cc }
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visit::fk_item_fn(*) | visit::fk_method(*) |
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visit::fk_ctor(*) | visit::fk_dtor(*) { @[]/~ }
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};
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let captured_vars = (*cap_clause).map { |cap_item|
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let cap_def = cx.tcx.def_map.get(cap_item.id);
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let cap_def_id = ast_util::def_id_of_def(cap_def).node;
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let ty = ty::node_id_to_type(cx.tcx, cap_def_id);
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chk(cx, fn_id, none, cap_item.is_move, ty, cap_item.span);
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cap_def_id
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};
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// Iterate over any free variables that may not have appeared in the
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// capture list. Ensure that they too are of the appropriate kind.
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for vec::each(*freevars::get_freevars(cx.tcx, fn_id)) {|fv|
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let id = ast_util::def_id_of_def(fv.def).node;
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// skip over free variables that appear in the cap clause
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if captured_vars.contains(id) { cont; }
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// if this is the last use of the variable, then it will be
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// a move and not a copy
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let is_move = {
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alt check cx.last_use_map.find(fn_id) {
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some(vars) {(*vars).contains(id)}
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none {false}
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}
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};
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let ty = ty::node_id_to_type(cx.tcx, id);
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chk(cx, fn_id, some(fv), is_move, ty, fv.span);
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}
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}
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visit::visit_fn(fk, decl, body, sp, fn_id, cx, v);
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}
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fn check_block(b: blk, cx: ctx, v: visit::vt<ctx>) {
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alt b.node.expr {
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some(ex) { maybe_copy(cx, ex); }
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_ {}
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}
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visit::visit_block(b, cx, v);
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}
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fn check_expr(e: @expr, cx: ctx, v: visit::vt<ctx>) {
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#debug["kind::check_expr(%s)", expr_to_str(e)];
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alt e.node {
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expr_assign(_, ex) |
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expr_unary(box(_), ex) | expr_unary(uniq(_), ex) |
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expr_ret(some(ex)) | expr_cast(ex, _) { maybe_copy(cx, ex); }
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expr_copy(expr) { check_copy_ex(cx, expr, false); }
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// Vector add copies, but not "implicitly"
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expr_assign_op(_, _, ex) { check_copy_ex(cx, ex, false) }
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expr_binary(add, ls, rs) {
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check_copy_ex(cx, ls, false);
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check_copy_ex(cx, rs, false);
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}
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expr_rec(fields, def) {
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for fields.each {|field| maybe_copy(cx, field.node.expr); }
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alt def {
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some(ex) {
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// All noncopyable fields must be overridden
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let t = ty::expr_ty(cx.tcx, ex);
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let ty_fields = alt ty::get(t).struct {
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ty::ty_rec(f) { f }
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_ { cx.tcx.sess.span_bug(ex.span, "bad expr type in record"); }
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};
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for ty_fields.each {|tf|
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if !vec::any(fields, {|f| f.node.ident == tf.ident}) &&
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!ty::kind_can_be_copied(ty::type_kind(cx.tcx, tf.mt.ty)) {
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cx.tcx.sess.span_err(ex.span,
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"copying a noncopyable value");
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}
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}
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}
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_ {}
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}
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}
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expr_tup(exprs) | expr_vec(exprs, _) {
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for exprs.each {|expr| maybe_copy(cx, expr); }
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}
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expr_call(f, args, _) {
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let mut i = 0u;
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for ty::ty_fn_args(ty::expr_ty(cx.tcx, f)).each {|arg_t|
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alt ty::arg_mode(cx.tcx, arg_t) {
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by_copy { maybe_copy(cx, args[i]); }
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by_ref | by_val | by_mutbl_ref | by_move { }
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}
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i += 1u;
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}
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}
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expr_path(_) | expr_field(_, _, _) {
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option::iter(cx.tcx.node_type_substs.find(e.id)) {|ts|
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let bounds = alt check e.node {
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expr_path(_) {
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let did = ast_util::def_id_of_def(cx.tcx.def_map.get(e.id));
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ty::lookup_item_type(cx.tcx, did).bounds
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}
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expr_field(base, _, _) {
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alt cx.method_map.get(e.id).origin {
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typeck::method_static(did) {
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// n.b.: When we encode class/impl methods, the bounds
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// that we encode include both the class/impl bounds
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// and then the method bounds themselves...
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ty::lookup_item_type(cx.tcx, did).bounds
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}
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typeck::method_param({iface_id:ifce_id,
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method_num:n_mth, _}) |
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typeck::method_iface(ifce_id, n_mth) {
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// ...iface methods bounds, in contrast, include only the
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// method bounds, so we must preprend the tps from the
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// iface itself. This ought to be harmonized.
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let ifce_bounds =
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ty::lookup_item_type(cx.tcx, ifce_id).bounds;
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let mth = ty::iface_methods(cx.tcx, ifce_id)[n_mth];
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@(vec::append(*ifce_bounds, *mth.tps))
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}
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}
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}
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};
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if vec::len(ts) != vec::len(*bounds) {
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// Fail earlier to make debugging easier
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fail #fmt("Internal error: in kind::check_expr, length \
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mismatch between actual and declared bounds: actual = \
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%s (%u tys), declared = %? (%u tys)",
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tys_to_str(cx.tcx, ts), ts.len(), *bounds, (*bounds).len());
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}
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vec::iter2(ts, *bounds) {|ty, bound|
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check_bounds(cx, e.id, e.span, ty, bound)
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}
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}
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}
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_ { }
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}
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visit::visit_expr(e, cx, v);
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}
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fn check_stmt(stmt: @stmt, cx: ctx, v: visit::vt<ctx>) {
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alt stmt.node {
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stmt_decl(@{node: decl_local(locals), _}, _) {
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for locals.each {|local|
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alt local.node.init {
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some({op: init_assign, expr}) { maybe_copy(cx, expr); }
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_ {}
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}
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}
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}
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_ {}
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}
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visit::visit_stmt(stmt, cx, v);
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}
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fn check_ty(aty: @ty, cx: ctx, v: visit::vt<ctx>) {
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alt aty.node {
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ty_path(_, id) {
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option::iter(cx.tcx.node_type_substs.find(id)) {|ts|
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let did = ast_util::def_id_of_def(cx.tcx.def_map.get(id));
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let bounds = ty::lookup_item_type(cx.tcx, did).bounds;
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vec::iter2(ts, *bounds) {|ty, bound|
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check_bounds(cx, aty.id, aty.span, ty, bound)
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}
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}
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}
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_ {}
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}
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visit::visit_ty(aty, cx, v);
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}
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fn check_bounds(cx: ctx, id: node_id, sp: span,
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ty: ty::t, bounds: ty::param_bounds) {
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let kind = ty::type_kind(cx.tcx, ty);
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let p_kind = ty::param_bounds_to_kind(bounds);
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if !ty::kind_lteq(p_kind, kind) {
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// If the only reason the kind check fails is because the
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// argument type isn't implicitly copyable, consult the warning
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// settings to figure out what to do.
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let implicit = ty::kind_implicitly_copyable() - ty::kind_copyable();
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if ty::kind_lteq(p_kind, kind | implicit) {
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cx.tcx.sess.span_lint(
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non_implicitly_copyable_typarams,
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id, cx.current_item, sp,
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"instantiating copy type parameter with a \
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not implicitly copyable type");
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} else {
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cx.tcx.sess.span_err(
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sp,
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"instantiating a type parameter with an incompatible type " +
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"(needs `" + kind_to_str(p_kind) +
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"`, got `" + kind_to_str(kind) +
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"`, missing `" + kind_to_str(p_kind - kind) + "`)");
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}
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}
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}
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fn maybe_copy(cx: ctx, ex: @expr) {
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check_copy_ex(cx, ex, true);
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}
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fn is_nullary_variant(cx: ctx, ex: @expr) -> bool {
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alt ex.node {
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expr_path(_) {
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alt cx.tcx.def_map.get(ex.id) {
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def_variant(edid, vdid) {
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vec::len(ty::enum_variant_with_id(cx.tcx, edid, vdid).args) == 0u
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}
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_ { false }
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}
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}
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_ { false }
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}
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}
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fn check_copy_ex(cx: ctx, ex: @expr, implicit_copy: bool) {
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if ty::expr_is_lval(cx.method_map, ex) &&
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!cx.last_use_map.contains_key(ex.id) &&
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!is_nullary_variant(cx, ex) {
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let ty = ty::expr_ty(cx.tcx, ex);
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check_copy(cx, ex.id, ty, ex.span, implicit_copy);
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}
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}
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fn check_imm_free_var(cx: ctx, def: def, sp: span) {
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let msg = "mutable variables cannot be implicitly captured; \
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use a capture clause";
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alt def {
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def_local(_, is_mutbl) {
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if is_mutbl {
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cx.tcx.sess.span_err(sp, msg);
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}
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}
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def_arg(_, mode) {
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alt ty::resolved_mode(cx.tcx, mode) {
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by_ref | by_val | by_move | by_copy { /* ok */ }
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by_mutbl_ref {
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cx.tcx.sess.span_err(sp, msg);
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}
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}
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}
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def_upvar(_, def1, _) {
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check_imm_free_var(cx, *def1, sp);
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}
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def_binding(*) | def_self(*) { /*ok*/ }
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_ {
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cx.tcx.sess.span_bug(
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sp,
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#fmt["unknown def for free variable: %?", def]);
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}
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}
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}
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fn check_copy(cx: ctx, id: node_id, ty: ty::t, sp: span,
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implicit_copy: bool) {
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let k = ty::type_kind(cx.tcx, ty);
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if !ty::kind_can_be_copied(k) {
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cx.tcx.sess.span_err(sp, "copying a noncopyable value");
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} else if implicit_copy && !ty::kind_can_be_implicitly_copied(k) {
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cx.tcx.sess.span_lint(
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implicit_copies, id, cx.current_item,
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sp,
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"implicitly copying a non-implicitly-copyable value");
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}
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}
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fn check_send(cx: ctx, ty: ty::t, sp: span) {
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if !ty::kind_can_be_sent(ty::type_kind(cx.tcx, ty)) {
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cx.tcx.sess.span_err(sp, "not a sendable value");
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}
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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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// indent-tabs-mode: nil
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// c-basic-offset: 4
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// buffer-file-coding-system: utf-8-unix
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// End:
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//
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