285 lines
9.2 KiB
Rust
285 lines
9.2 KiB
Rust
// Copyright 2012-2013 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 driver::session::Session;
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use middle::resolve;
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use middle::ty;
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use middle::typeck;
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use util::ppaux;
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use std::cell::RefCell;
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use syntax::ast::*;
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use syntax::codemap;
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use syntax::{ast_util, ast_map};
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use syntax::visit::Visitor;
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use syntax::visit;
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struct CheckCrateVisitor {
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sess: Session,
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ast_map: ast_map::map,
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def_map: resolve::DefMap,
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method_map: typeck::method_map,
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tcx: ty::ctxt,
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}
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impl Visitor<bool> for CheckCrateVisitor {
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fn visit_item(&mut self, i:@item, env:bool) {
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check_item(self, self.sess, self.ast_map, self.def_map, i, env);
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}
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fn visit_pat(&mut self, p:&Pat, env:bool) {
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check_pat(self, p, env);
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}
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fn visit_expr(&mut self, ex:@Expr, env:bool) {
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check_expr(self, self.sess, self.def_map, self.method_map,
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self.tcx, ex, env);
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}
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}
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pub fn check_crate(sess: Session,
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crate: &Crate,
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ast_map: ast_map::map,
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def_map: resolve::DefMap,
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method_map: typeck::method_map,
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tcx: ty::ctxt) {
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let mut v = CheckCrateVisitor {
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sess: sess,
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ast_map: ast_map,
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def_map: def_map,
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method_map: method_map,
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tcx: tcx,
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};
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visit::walk_crate(&mut v, crate, false);
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sess.abort_if_errors();
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}
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pub fn check_item(v: &mut CheckCrateVisitor,
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sess: Session,
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ast_map: ast_map::map,
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def_map: resolve::DefMap,
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it: @item,
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_is_const: bool) {
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match it.node {
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item_static(_, _, ex) => {
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v.visit_expr(ex, true);
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check_item_recursion(sess, ast_map, def_map, it);
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}
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item_enum(ref enum_definition, _) => {
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for var in (*enum_definition).variants.iter() {
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for ex in var.node.disr_expr.iter() {
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v.visit_expr(*ex, true);
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}
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}
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}
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_ => visit::walk_item(v, it, false)
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}
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}
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pub fn check_pat(v: &mut CheckCrateVisitor, p: &Pat, _is_const: bool) {
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fn is_str(e: @Expr) -> bool {
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match e.node {
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ExprVstore(
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@Expr { node: ExprLit(@codemap::Spanned {
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node: lit_str(..),
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..}),
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.. },
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ExprVstoreUniq
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) => true,
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_ => false
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}
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}
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match p.node {
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// Let through plain ~-string literals here
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PatLit(a) => if !is_str(a) { v.visit_expr(a, true); },
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PatRange(a, b) => {
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if !is_str(a) { v.visit_expr(a, true); }
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if !is_str(b) { v.visit_expr(b, true); }
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}
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_ => visit::walk_pat(v, p, false)
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}
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}
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pub fn check_expr(v: &mut CheckCrateVisitor,
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sess: Session,
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def_map: resolve::DefMap,
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method_map: typeck::method_map,
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tcx: ty::ctxt,
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e: @Expr,
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is_const: bool) {
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if is_const {
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match e.node {
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ExprUnary(_, UnDeref, _) => { }
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ExprUnary(_, UnBox, _) | ExprUnary(_, UnUniq, _) => {
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sess.span_err(e.span,
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"cannot do allocations in constant expressions");
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return;
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}
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ExprLit(@codemap::Spanned {node: lit_str(..), ..}) => { }
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ExprBinary(..) | ExprUnary(..) => {
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let method_map = method_map.borrow();
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if method_map.get().contains_key(&e.id) {
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sess.span_err(e.span, "user-defined operators are not \
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allowed in constant expressions");
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}
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}
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ExprLit(_) => (),
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ExprCast(_, _) => {
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let ety = ty::expr_ty(tcx, e);
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if !ty::type_is_numeric(ety) && !ty::type_is_unsafe_ptr(ety) {
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sess.span_err(e.span, ~"can not cast to `" +
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ppaux::ty_to_str(tcx, ety) +
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"` in a constant expression");
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}
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}
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ExprPath(ref pth) => {
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// NB: In the future you might wish to relax this slightly
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// to handle on-demand instantiation of functions via
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// foo::<bar> in a const. Currently that is only done on
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// a path in trans::callee that only works in block contexts.
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if !pth.segments.iter().all(|segment| segment.types.is_empty()) {
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sess.span_err(
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e.span, "paths in constants may only refer to \
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items without type parameters");
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}
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let def_map = def_map.borrow();
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match def_map.get().find(&e.id) {
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Some(&DefStatic(..)) |
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Some(&DefFn(_, _)) |
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Some(&DefVariant(_, _, _)) |
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Some(&DefStruct(_)) => { }
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Some(&def) => {
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debug!("(checking const) found bad def: {:?}", def);
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sess.span_err(
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e.span,
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"paths in constants may only refer to \
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constants or functions");
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}
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None => {
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sess.span_bug(e.span, "unbound path in const?!");
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}
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}
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}
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ExprCall(callee, _, NoSugar) => {
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let def_map = def_map.borrow();
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match def_map.get().find(&callee.id) {
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Some(&DefStruct(..)) => {} // OK.
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Some(&DefVariant(..)) => {} // OK.
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_ => {
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sess.span_err(
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e.span,
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"function calls in constants are limited to \
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struct and enum constructors");
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}
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}
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}
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ExprParen(e) => { check_expr(v, sess, def_map, method_map,
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tcx, e, is_const); }
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ExprVstore(_, ExprVstoreSlice) |
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ExprVec(_, MutImmutable) |
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ExprAddrOf(MutImmutable, _) |
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ExprField(..) |
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ExprIndex(..) |
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ExprTup(..) |
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ExprRepeat(..) |
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ExprStruct(..) => { }
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ExprAddrOf(..) => {
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sess.span_err(
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e.span,
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"borrowed pointers in constants may only refer to \
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immutable values");
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},
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ExprVstore(_, ExprVstoreUniq) |
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ExprVstore(_, ExprVstoreBox) => {
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sess.span_err(e.span, "cannot allocate vectors in constant expressions")
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},
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_ => {
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sess.span_err(e.span,
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"constant contains unimplemented expression type");
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return;
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}
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}
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}
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visit::walk_expr(v, e, is_const);
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}
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#[deriving(Clone)]
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struct env {
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root_it: @item,
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sess: Session,
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ast_map: ast_map::map,
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def_map: resolve::DefMap,
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idstack: @RefCell<~[NodeId]>,
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}
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struct CheckItemRecursionVisitor {
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env: env,
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}
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// Make sure a const item doesn't recursively refer to itself
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// FIXME: Should use the dependency graph when it's available (#1356)
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pub fn check_item_recursion(sess: Session,
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ast_map: ast_map::map,
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def_map: resolve::DefMap,
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it: @item) {
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let env = env {
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root_it: it,
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sess: sess,
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ast_map: ast_map,
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def_map: def_map,
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idstack: @RefCell::new(~[]),
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};
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let mut visitor = CheckItemRecursionVisitor { env: env };
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visitor.visit_item(it, ());
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}
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impl Visitor<()> for CheckItemRecursionVisitor {
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fn visit_item(&mut self, it: @item, _: ()) {
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{
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let mut idstack = self.env.idstack.borrow_mut();
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if idstack.get().iter().any(|x| x == &(it.id)) {
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self.env.sess.span_fatal(self.env.root_it.span,
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"recursive constant");
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}
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idstack.get().push(it.id);
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}
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visit::walk_item(self, it, ());
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{
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let mut idstack = self.env.idstack.borrow_mut();
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idstack.get().pop();
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}
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}
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fn visit_expr(&mut self, e: @Expr, _: ()) {
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match e.node {
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ExprPath(..) => {
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let def_map = self.env.def_map.borrow();
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match def_map.get().find(&e.id) {
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Some(&DefStatic(def_id, _)) if
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ast_util::is_local(def_id) => {
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let ast_map = self.env.ast_map.borrow();
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match ast_map.get().get_copy(&def_id.node) {
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ast_map::node_item(it, _) => {
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self.visit_item(it, ());
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}
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_ => fail!("const not bound to an item")
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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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}
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visit::walk_expr(self, e, ());
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}
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}
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