840 lines
29 KiB
Rust
840 lines
29 KiB
Rust
// Copyright 2012 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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use core::prelude::*;
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use middle::const_eval::{compare_const_vals, lookup_const_by_id};
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use middle::const_eval::{eval_const_expr, const_val, const_int, const_bool};
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use middle::pat_util::*;
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use middle::ty::*;
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use middle::ty;
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use middle::typeck::method_map;
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use middle::moves;
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use util::ppaux::ty_to_str;
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use core::cmp;
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use core::option;
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use core::uint;
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use core::vec;
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use std::oldmap::HashMap;
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use std::sort;
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use syntax::ast::*;
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use syntax::ast_util::{variant_def_ids, unguarded_pat, walk_pat};
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use syntax::codemap::{span, dummy_sp, spanned};
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use syntax::print::pprust::pat_to_str;
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use syntax::visit;
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pub struct MatchCheckCtxt {
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tcx: ty::ctxt,
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method_map: method_map,
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moves_map: moves::MovesMap
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}
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pub fn check_crate(tcx: ty::ctxt,
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method_map: method_map,
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moves_map: moves::MovesMap,
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crate: @crate) {
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let cx = @MatchCheckCtxt {tcx: tcx,
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method_map: method_map,
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moves_map: moves_map};
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visit::visit_crate(*crate, (), visit::mk_vt(@visit::Visitor {
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visit_expr: |a,b,c| check_expr(cx, a, b, c),
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visit_local: |a,b,c| check_local(cx, a, b, c),
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visit_fn: |kind, decl, body, sp, id, e, v|
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check_fn(cx, kind, decl, body, sp, id, e, v),
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.. *visit::default_visitor::<()>()
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}));
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tcx.sess.abort_if_errors();
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}
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pub fn expr_is_non_moving_lvalue(cx: @MatchCheckCtxt, expr: @expr) -> bool {
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if !ty::expr_is_lval(cx.tcx, cx.method_map, expr) {
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return false;
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}
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!cx.moves_map.contains_key(&expr.id)
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}
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pub fn check_expr(cx: @MatchCheckCtxt, ex: @expr, &&s: (), v: visit::vt<()>) {
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visit::visit_expr(ex, s, v);
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match ex.node {
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expr_match(scrut, ref arms) => {
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// First, check legality of move bindings.
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let is_non_moving_lvalue = expr_is_non_moving_lvalue(cx, ex);
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for arms.each |arm| {
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check_legality_of_move_bindings(cx,
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is_non_moving_lvalue,
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arm.guard.is_some(),
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arm.pats);
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}
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check_arms(cx, (/*bad*/copy *arms));
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/* Check for exhaustiveness */
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// Check for empty enum, because is_useful only works on inhabited
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// types.
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let pat_ty = node_id_to_type(cx.tcx, scrut.id);
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if (*arms).is_empty() {
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if !type_is_empty(cx.tcx, pat_ty) {
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// We know the type is inhabited, so this must be wrong
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cx.tcx.sess.span_err(ex.span, fmt!("non-exhaustive patterns: \
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type %s is non-empty",
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ty_to_str(cx.tcx, pat_ty)));
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}
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// If the type *is* empty, it's vacuously exhaustive
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return;
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}
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match ty::get(pat_ty).sty {
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ty_enum(did, _) => {
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if (*enum_variants(cx.tcx, did)).is_empty() &&
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(*arms).is_empty() {
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return;
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}
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}
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_ => { /* We assume only enum types can be uninhabited */ }
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}
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let arms = vec::concat(arms.filter_mapped(unguarded_pat));
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check_exhaustive(cx, ex.span, arms);
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}
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_ => ()
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}
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}
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// Check for unreachable patterns
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pub fn check_arms(cx: @MatchCheckCtxt, arms: ~[arm]) {
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let mut seen = ~[];
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for arms.each |arm| {
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for arm.pats.each |pat| {
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let v = ~[*pat];
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match is_useful(cx, copy seen, v) {
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not_useful => {
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cx.tcx.sess.span_err(pat.span, ~"unreachable pattern");
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}
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_ => ()
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}
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if arm.guard.is_none() { seen.push(v); }
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}
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}
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}
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pub fn raw_pat(p: @pat) -> @pat {
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match p.node {
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pat_ident(_, _, Some(s)) => { raw_pat(s) }
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_ => { p }
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}
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}
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pub fn check_exhaustive(cx: @MatchCheckCtxt, sp: span, pats: ~[@pat]) {
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assert(!pats.is_empty());
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let ext = match is_useful(cx, vec::map(pats, |p| ~[*p]), ~[wild()]) {
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not_useful => return, // This is good, wildcard pattern isn't reachable
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useful_ => None,
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useful(ty, ref ctor) => {
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match ty::get(ty).sty {
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ty::ty_bool => {
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match (*ctor) {
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val(const_bool(true)) => Some(~"true"),
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val(const_bool(false)) => Some(~"false"),
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_ => None
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}
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}
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ty::ty_enum(id, _) => {
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let vid = match (*ctor) { variant(id) => id,
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_ => fail!(~"check_exhaustive: non-variant ctor") };
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match vec::find(*ty::enum_variants(cx.tcx, id),
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|v| v.id == vid) {
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Some(v) => Some(cx.tcx.sess.str_of(v.name)),
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None => fail!(~"check_exhaustive: bad variant in ctor")
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}
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}
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ty::ty_unboxed_vec(*) | ty::ty_evec(*) => {
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match (*ctor) {
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vec(n) => Some(fmt!("vectors of length %u", n)),
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_ => None
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}
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}
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_ => None
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}
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}
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};
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let msg = ~"non-exhaustive patterns" + match ext {
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Some(ref s) => ~": " + (*s) + ~" not covered",
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None => ~""
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};
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cx.tcx.sess.span_err(sp, msg);
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}
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pub type matrix = ~[~[@pat]];
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pub enum useful { useful(ty::t, ctor), useful_, not_useful }
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#[deriving_eq]
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pub enum ctor {
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single,
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variant(def_id),
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val(const_val),
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range(const_val, const_val),
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vec(uint)
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}
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// Algorithm from http://moscova.inria.fr/~maranget/papers/warn/index.html
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//
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// Whether a vector `v` of patterns is 'useful' in relation to a set of such
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// vectors `m` is defined as there being a set of inputs that will match `v`
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// but not any of the sets in `m`.
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//
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// This is used both for reachability checking (if a pattern isn't useful in
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// relation to preceding patterns, it is not reachable) and exhaustiveness
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// checking (if a wildcard pattern is useful in relation to a matrix, the
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// matrix isn't exhaustive).
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// Note: is_useful doesn't work on empty types, as the paper notes.
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// So it assumes that v is non-empty.
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pub fn is_useful(cx: @MatchCheckCtxt, +m: matrix, +v: &[@pat]) -> useful {
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if m.len() == 0u { return useful_; }
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if m[0].len() == 0u { return not_useful; }
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let real_pat = match vec::find(m, |r| r[0].id != 0) {
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Some(r) => r[0], None => v[0]
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};
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let left_ty = if real_pat.id == 0 { ty::mk_nil(cx.tcx) }
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else { ty::node_id_to_type(cx.tcx, real_pat.id) };
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match pat_ctor_id(cx, v[0]) {
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None => {
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match missing_ctor(cx, m, left_ty) {
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None => {
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match ty::get(left_ty).sty {
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ty::ty_bool => {
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match is_useful_specialized(cx, m, v,
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val(const_bool(true)),
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0u, left_ty){
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not_useful => {
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is_useful_specialized(cx, m, v,
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val(const_bool(false)),
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0u, left_ty)
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}
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ref u => (/*bad*/copy *u)
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}
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}
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ty::ty_enum(eid, _) => {
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for (*ty::enum_variants(cx.tcx, eid)).each |va| {
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match is_useful_specialized(cx, m, v, variant(va.id),
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va.args.len(), left_ty) {
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not_useful => (),
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ref u => return (/*bad*/copy *u)
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}
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}
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not_useful
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}
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ty::ty_unboxed_vec(*) | ty::ty_evec(*) => {
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let max_len = do m.foldr(0) |r, max_len| {
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match /*bad*/copy r[0].node {
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pat_vec(elems, _) => uint::max(elems.len(), max_len),
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_ => max_len
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}
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};
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for uint::range(0, max_len + 1) |n| {
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match is_useful_specialized(cx, m, v, vec(n), n, left_ty) {
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not_useful => (),
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ref u => return (/*bad*/copy *u)
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}
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}
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not_useful
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}
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_ => {
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let arity = ctor_arity(cx, single, left_ty);
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is_useful_specialized(cx, m, v, single, arity, left_ty)
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}
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}
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}
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Some(ref ctor) => {
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match is_useful(cx,
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vec::filter_map(m, |r| default(cx, r)),
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vec::tail(v)) {
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useful_ => useful(left_ty, (/*bad*/copy *ctor)),
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ref u => (/*bad*/copy *u)
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}
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}
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}
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}
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Some(ref v0_ctor) => {
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let arity = ctor_arity(cx, (*v0_ctor), left_ty);
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is_useful_specialized(cx, m, v, /*bad*/copy *v0_ctor, arity, left_ty)
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}
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}
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}
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pub fn is_useful_specialized(cx: @MatchCheckCtxt,
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m: matrix,
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+v: &[@pat],
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+ctor: ctor,
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arity: uint,
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lty: ty::t)
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-> useful {
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let ms = m.filter_mapped(|r| specialize(cx, *r, ctor, arity, lty));
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let could_be_useful = is_useful(
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cx, ms, specialize(cx, v, ctor, arity, lty).get());
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match could_be_useful {
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useful_ => useful(lty, ctor),
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ref u => (/*bad*/copy *u)
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}
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}
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pub fn pat_ctor_id(cx: @MatchCheckCtxt, p: @pat) -> Option<ctor> {
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let pat = raw_pat(p);
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match /*bad*/copy pat.node {
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pat_wild => { None }
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pat_ident(_, _, _) | pat_enum(_, _) => {
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match cx.tcx.def_map.find(&pat.id) {
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Some(def_variant(_, id)) => Some(variant(id)),
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Some(def_const(did)) => {
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let const_expr = lookup_const_by_id(cx.tcx, did).get();
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Some(val(eval_const_expr(cx.tcx, const_expr)))
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}
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_ => None
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}
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}
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pat_lit(expr) => { Some(val(eval_const_expr(cx.tcx, expr))) }
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pat_range(lo, hi) => {
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Some(range(eval_const_expr(cx.tcx, lo), eval_const_expr(cx.tcx, hi)))
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}
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pat_struct(*) => {
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match cx.tcx.def_map.find(&pat.id) {
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Some(def_variant(_, id)) => Some(variant(id)),
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_ => Some(single)
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}
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}
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pat_box(_) | pat_uniq(_) | pat_rec(_, _) | pat_tup(_) |
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pat_region(*) => {
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Some(single)
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}
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pat_vec(elems, tail) => {
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match tail {
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Some(_) => None,
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None => Some(vec(elems.len()))
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}
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}
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}
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}
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pub fn is_wild(cx: @MatchCheckCtxt, p: @pat) -> bool {
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let pat = raw_pat(p);
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match pat.node {
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pat_wild => { true }
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pat_ident(_, _, _) => {
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match cx.tcx.def_map.find(&pat.id) {
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Some(def_variant(_, _)) | Some(def_const(*)) => { false }
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_ => { true }
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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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pub fn missing_ctor(cx: @MatchCheckCtxt,
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m: matrix,
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left_ty: ty::t)
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-> Option<ctor> {
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match ty::get(left_ty).sty {
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ty::ty_box(_) | ty::ty_uniq(_) | ty::ty_rptr(*) | ty::ty_tup(_) |
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ty::ty_rec(_) | ty::ty_struct(*) => {
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for m.each |r| {
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if !is_wild(cx, r[0]) { return None; }
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}
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return Some(single);
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}
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ty::ty_enum(eid, _) => {
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let mut found = ~[];
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for m.each |r| {
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do option::iter(&pat_ctor_id(cx, r[0])) |id| {
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if !vec::contains(found, id) {
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found.push(/*bad*/copy *id);
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}
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}
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}
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let variants = ty::enum_variants(cx.tcx, eid);
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if found.len() != (*variants).len() {
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for vec::each(*variants) |v| {
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if !found.contains(&(variant(v.id))) {
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return Some(variant(v.id));
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}
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}
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fail!();
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} else { None }
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}
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ty::ty_nil => None,
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ty::ty_bool => {
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let mut true_found = false, false_found = false;
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for m.each |r| {
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match pat_ctor_id(cx, r[0]) {
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None => (),
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Some(val(const_bool(true))) => true_found = true,
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Some(val(const_bool(false))) => false_found = true,
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_ => fail!(~"impossible case")
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}
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}
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if true_found && false_found { None }
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else if true_found { Some(val(const_bool(false))) }
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else { Some(val(const_bool(true))) }
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}
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ty::ty_unboxed_vec(*) | ty::ty_evec(*) => {
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// Find the lengths and tails of all vector patterns.
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let vec_pat_lens = do m.filter_mapped |r| {
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match r[0].node {
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pat_vec(ref elems, ref tail) => {
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Some((elems.len(), tail.is_some()))
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}
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_ => None
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}
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};
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// Sort them by length such that for patterns of the same length,
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// those with a destructured tail come first.
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let mut sorted_vec_lens = sort::merge_sort(vec_pat_lens,
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|&(len1, tail1), &(len2, tail2)| {
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if len1 == len2 {
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tail1 > tail2
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} else {
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len1 <= len2
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}
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}
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);
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vec::dedup(&mut sorted_vec_lens);
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let mut found_tail = false;
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let mut next = 0;
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let mut missing = None;
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for sorted_vec_lens.each |&(length, tail)| {
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if length != next {
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missing = Some(next);
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break;
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}
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if tail {
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found_tail = true;
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break;
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}
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next += 1;
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}
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// We found patterns of all lengths within <0, next), yet there was no
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// pattern with a tail - therefore, we report vec(next) as missing.
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if !found_tail {
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missing = Some(next);
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}
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match missing {
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Some(k) => Some(vec(k)),
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None => None
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}
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}
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_ => Some(single)
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}
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}
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pub fn ctor_arity(cx: @MatchCheckCtxt, ctor: ctor, ty: ty::t) -> uint {
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match /*bad*/copy ty::get(ty).sty {
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ty::ty_tup(fs) => fs.len(),
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ty::ty_rec(fs) => fs.len(),
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ty::ty_box(_) | ty::ty_uniq(_) | ty::ty_rptr(*) => 1u,
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ty::ty_enum(eid, _) => {
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let id = match ctor { variant(id) => id,
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_ => fail!(~"impossible case") };
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match vec::find(*ty::enum_variants(cx.tcx, eid), |v| v.id == id ) {
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Some(v) => v.args.len(),
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None => fail!(~"impossible case")
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}
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}
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ty::ty_struct(cid, _) => ty::lookup_struct_fields(cx.tcx, cid).len(),
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ty::ty_unboxed_vec(*) | ty::ty_evec(*) => {
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match ctor {
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vec(n) => n,
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_ => 0u
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}
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}
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_ => 0u
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}
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}
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pub fn wild() -> @pat {
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@pat {id: 0, node: pat_wild, span: dummy_sp()}
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}
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pub fn specialize(cx: @MatchCheckCtxt,
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+r: &[@pat],
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ctor_id: ctor,
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arity: uint,
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left_ty: ty::t)
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-> Option<~[@pat]> {
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// Sad, but I can't get rid of this easily
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let mut r0 = copy *raw_pat(r[0]);
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match r0 {
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pat{id: pat_id, node: n, span: pat_span} =>
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match n {
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pat_wild => Some(vec::append(vec::from_elem(arity, wild()),
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vec::tail(r))),
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pat_ident(_, _, _) => {
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match cx.tcx.def_map.find(&pat_id) {
|
|
Some(def_variant(_, id)) => {
|
|
if variant(id) == ctor_id { Some(vec::tail(r)) }
|
|
else { None }
|
|
}
|
|
Some(def_const(did)) => {
|
|
let const_expr =
|
|
lookup_const_by_id(cx.tcx, did).get();
|
|
let e_v = eval_const_expr(cx.tcx, const_expr);
|
|
let match_ = match ctor_id {
|
|
val(ref v) => compare_const_vals(e_v, (*v)) == 0,
|
|
range(ref c_lo, ref c_hi) => {
|
|
compare_const_vals((*c_lo), e_v) >= 0 &&
|
|
compare_const_vals((*c_hi), e_v) <= 0
|
|
}
|
|
single => true,
|
|
_ => fail!(~"type error")
|
|
};
|
|
if match_ { Some(vec::tail(r)) } else { None }
|
|
}
|
|
_ => Some(vec::append(vec::from_elem(arity, wild()),
|
|
vec::tail(r)))
|
|
}
|
|
}
|
|
pat_enum(_, args) => {
|
|
match cx.tcx.def_map.get(&pat_id) {
|
|
def_variant(_, id) if variant(id) == ctor_id => {
|
|
let args = match args {
|
|
Some(args) => args,
|
|
None => vec::from_elem(arity, wild())
|
|
};
|
|
Some(vec::append(args, vec::tail(r)))
|
|
}
|
|
def_variant(_, _) => None,
|
|
def_struct(*) => {
|
|
// FIXME #4731: Is this right? --pcw
|
|
let new_args;
|
|
match args {
|
|
Some(args) => new_args = args,
|
|
None => new_args = vec::from_elem(arity, wild())
|
|
}
|
|
Some(vec::append(new_args, vec::tail(r)))
|
|
}
|
|
_ => None
|
|
}
|
|
}
|
|
pat_rec(ref flds, _) => {
|
|
let ty_flds = match /*bad*/copy ty::get(left_ty).sty {
|
|
ty::ty_rec(flds) => flds,
|
|
_ => fail!(~"bad type for pat_rec")
|
|
};
|
|
let args = vec::map(ty_flds, |ty_fld| {
|
|
match flds.find(|f| f.ident == ty_fld.ident) {
|
|
Some(f) => f.pat,
|
|
_ => wild()
|
|
}
|
|
});
|
|
Some(vec::append(args, vec::tail(r)))
|
|
}
|
|
pat_struct(_, ref flds, _) => {
|
|
// Is this a struct or an enum variant?
|
|
match cx.tcx.def_map.get(&pat_id) {
|
|
def_variant(_, variant_id) => {
|
|
if variant(variant_id) == ctor_id {
|
|
// FIXME #4731: Is this right? --pcw
|
|
let args = flds.map(|ty_field| {
|
|
match flds.find(|f|
|
|
f.ident == ty_field.ident) {
|
|
Some(f) => f.pat,
|
|
_ => wild()
|
|
}
|
|
});
|
|
Some(vec::append(args, vec::tail(r)))
|
|
} else {
|
|
None
|
|
}
|
|
}
|
|
_ => {
|
|
// Grab the class data that we care about.
|
|
let class_fields, class_id;
|
|
match ty::get(left_ty).sty {
|
|
ty::ty_struct(cid, _) => {
|
|
class_id = cid;
|
|
class_fields =
|
|
ty::lookup_struct_fields(cx.tcx,
|
|
class_id);
|
|
}
|
|
_ => {
|
|
cx.tcx.sess.span_bug(pat_span,
|
|
~"struct pattern didn't resolve to a struct");
|
|
}
|
|
}
|
|
let args = vec::map(class_fields, |class_field| {
|
|
match flds.find(|f|
|
|
f.ident == class_field.ident) {
|
|
Some(f) => f.pat,
|
|
_ => wild()
|
|
}
|
|
});
|
|
Some(vec::append(args, vec::tail(r)))
|
|
}
|
|
}
|
|
}
|
|
pat_tup(args) => Some(vec::append(args, vec::tail(r))),
|
|
pat_box(a) | pat_uniq(a) | pat_region(a) =>
|
|
Some(vec::append(~[a], vec::tail(r))),
|
|
pat_lit(expr) => {
|
|
let e_v = eval_const_expr(cx.tcx, expr);
|
|
let match_ = match ctor_id {
|
|
val(ref v) => compare_const_vals(e_v, (*v)) == 0,
|
|
range(ref c_lo, ref c_hi) => {
|
|
compare_const_vals((*c_lo), e_v) >= 0 &&
|
|
compare_const_vals((*c_hi), e_v) <= 0
|
|
}
|
|
single => true,
|
|
_ => fail!(~"type error")
|
|
};
|
|
if match_ { Some(vec::tail(r)) } else { None }
|
|
}
|
|
pat_range(lo, hi) => {
|
|
let (c_lo, c_hi) = match ctor_id {
|
|
val(ref v) => ((/*bad*/copy *v), (/*bad*/copy *v)),
|
|
range(ref lo, ref hi) =>
|
|
((/*bad*/copy *lo), (/*bad*/copy *hi)),
|
|
single => return Some(vec::tail(r)),
|
|
_ => fail!(~"type error")
|
|
};
|
|
let v_lo = eval_const_expr(cx.tcx, lo),
|
|
v_hi = eval_const_expr(cx.tcx, hi);
|
|
let match_ = compare_const_vals(c_lo, v_lo) >= 0 &&
|
|
compare_const_vals(c_hi, v_hi) <= 0;
|
|
if match_ { Some(vec::tail(r)) } else { None }
|
|
}
|
|
pat_vec(elems, tail) => {
|
|
match ctor_id {
|
|
vec(_) => {
|
|
let num_elements = elems.len();
|
|
if num_elements < arity && tail.is_some() {
|
|
Some(vec::append(
|
|
vec::append(elems, vec::from_elem(
|
|
arity - num_elements, wild()
|
|
)),
|
|
vec::tail(r)
|
|
))
|
|
} else if num_elements == arity {
|
|
Some(vec::append(elems, vec::tail(r)))
|
|
} else {
|
|
None
|
|
}
|
|
}
|
|
_ => None
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
pub fn default(cx: @MatchCheckCtxt, r: ~[@pat]) -> Option<~[@pat]> {
|
|
if is_wild(cx, r[0]) { Some(vec::tail(r)) }
|
|
else { None }
|
|
}
|
|
|
|
pub fn check_local(cx: @MatchCheckCtxt,
|
|
loc: @local,
|
|
&&s: (),
|
|
v: visit::vt<()>) {
|
|
visit::visit_local(loc, s, v);
|
|
if is_refutable(cx, loc.node.pat) {
|
|
cx.tcx.sess.span_err(loc.node.pat.span,
|
|
~"refutable pattern in local binding");
|
|
}
|
|
|
|
// Check legality of move bindings.
|
|
let is_lvalue = match loc.node.init {
|
|
Some(init) => expr_is_non_moving_lvalue(cx, init),
|
|
None => true
|
|
};
|
|
check_legality_of_move_bindings(cx, is_lvalue, false, [ loc.node.pat ]);
|
|
}
|
|
|
|
pub fn check_fn(cx: @MatchCheckCtxt,
|
|
kind: visit::fn_kind,
|
|
decl: fn_decl,
|
|
body: blk,
|
|
sp: span,
|
|
id: node_id,
|
|
&&s: (),
|
|
v: visit::vt<()>) {
|
|
visit::visit_fn(kind, decl, body, sp, id, s, v);
|
|
for decl.inputs.each |input| {
|
|
if is_refutable(cx, input.pat) {
|
|
cx.tcx.sess.span_err(input.pat.span,
|
|
~"refutable pattern in function argument");
|
|
}
|
|
}
|
|
}
|
|
|
|
pub fn is_refutable(cx: @MatchCheckCtxt, pat: &pat) -> bool {
|
|
match cx.tcx.def_map.find(&pat.id) {
|
|
Some(def_variant(enum_id, _)) => {
|
|
if vec::len(*ty::enum_variants(cx.tcx, enum_id)) != 1u {
|
|
return true;
|
|
}
|
|
}
|
|
Some(def_const(*)) => return true,
|
|
_ => ()
|
|
}
|
|
|
|
match /*bad*/copy pat.node {
|
|
pat_box(sub) | pat_uniq(sub) | pat_region(sub) |
|
|
pat_ident(_, _, Some(sub)) => {
|
|
is_refutable(cx, sub)
|
|
}
|
|
pat_wild | pat_ident(_, _, None) => { false }
|
|
pat_lit(@expr {node: expr_lit(@spanned { node: lit_nil, _}), _}) => {
|
|
// "()"
|
|
false
|
|
}
|
|
pat_lit(_) | pat_range(_, _) => { true }
|
|
pat_rec(fields, _) => {
|
|
fields.any(|f| is_refutable(cx, f.pat))
|
|
}
|
|
pat_struct(_, fields, _) => {
|
|
fields.any(|f| is_refutable(cx, f.pat))
|
|
}
|
|
pat_tup(elts) => {
|
|
elts.any(|elt| is_refutable(cx, *elt))
|
|
}
|
|
pat_enum(_, Some(args)) => {
|
|
args.any(|a| is_refutable(cx, *a))
|
|
}
|
|
pat_enum(_,_) => { false }
|
|
pat_vec(*) => { true }
|
|
}
|
|
}
|
|
|
|
// Legality of move bindings checking
|
|
|
|
pub fn check_legality_of_move_bindings(cx: @MatchCheckCtxt,
|
|
is_lvalue: bool,
|
|
has_guard: bool,
|
|
pats: &[@pat]) {
|
|
let tcx = cx.tcx;
|
|
let def_map = tcx.def_map;
|
|
let mut by_ref_span = None;
|
|
let mut any_by_move = false;
|
|
for pats.each |pat| {
|
|
do pat_bindings(def_map, *pat) |bm, id, span, _path| {
|
|
match bm {
|
|
bind_by_copy => {}
|
|
bind_by_ref(_) => {
|
|
by_ref_span = Some(span);
|
|
}
|
|
bind_infer => {
|
|
if cx.moves_map.contains_key(&id) {
|
|
any_by_move = true;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
let check_move: &fn(@pat, Option<@pat>) = |p, sub| {
|
|
// check legality of moving out of the enum
|
|
if sub.is_some() {
|
|
tcx.sess.span_err(
|
|
p.span,
|
|
~"cannot bind by-move with sub-bindings");
|
|
} else if has_guard {
|
|
tcx.sess.span_err(
|
|
p.span,
|
|
~"cannot bind by-move into a pattern guard");
|
|
} else if by_ref_span.is_some() {
|
|
tcx.sess.span_err(
|
|
p.span,
|
|
~"cannot bind by-move and by-ref \
|
|
in the same pattern");
|
|
tcx.sess.span_note(
|
|
by_ref_span.get(),
|
|
~"by-ref binding occurs here");
|
|
} else if is_lvalue {
|
|
tcx.sess.span_err(
|
|
p.span,
|
|
~"cannot bind by-move when \
|
|
matching an lvalue");
|
|
}
|
|
};
|
|
|
|
if !any_by_move { return; } // pointless micro-optimization
|
|
for pats.each |pat| {
|
|
do walk_pat(*pat) |p| {
|
|
if pat_is_binding(def_map, p) {
|
|
match p.node {
|
|
pat_ident(_, _, sub) => {
|
|
if cx.moves_map.contains_key(&p.id) {
|
|
check_move(p, sub);
|
|
}
|
|
}
|
|
_ => {
|
|
cx.tcx.sess.span_bug(
|
|
p.span,
|
|
fmt!("Binding pattern %d is \
|
|
not an identifier: %?",
|
|
p.id, p.node));
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
// Now check to ensure that any move binding is not behind an @ or &.
|
|
// This is always illegal.
|
|
let vt = visit::mk_vt(@visit::Visitor {
|
|
visit_pat: |pat, behind_bad_pointer: bool, v| {
|
|
match pat.node {
|
|
pat_ident(_, _, sub) => {
|
|
debug!("(check legality of move) checking pat \
|
|
ident with behind_bad_pointer %?",
|
|
behind_bad_pointer);
|
|
|
|
if behind_bad_pointer &&
|
|
cx.moves_map.contains_key(&pat.id)
|
|
{
|
|
cx.tcx.sess.span_err(
|
|
pat.span,
|
|
~"by-move pattern \
|
|
bindings may not occur \
|
|
behind @ or & bindings");
|
|
}
|
|
|
|
match sub {
|
|
None => {}
|
|
Some(subpat) => {
|
|
(v.visit_pat)(subpat, behind_bad_pointer, v);
|
|
}
|
|
}
|
|
}
|
|
|
|
pat_box(subpat) | pat_region(subpat) => {
|
|
(v.visit_pat)(subpat, true, v);
|
|
}
|
|
|
|
_ => visit::visit_pat(pat, behind_bad_pointer, v)
|
|
}
|
|
},
|
|
.. *visit::default_visitor::<bool>()
|
|
});
|
|
(vt.visit_pat)(*pat, false, vt);
|
|
}
|
|
}
|
|
|
|
// Local Variables:
|
|
// mode: rust
|
|
// fill-column: 78;
|
|
// indent-tabs-mode: nil
|
|
// c-basic-offset: 4
|
|
// buffer-file-coding-system: utf-8-unix
|
|
// End:
|