+++ /dev/null
-// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
-// file at the top-level directory of this distribution and at
-// http://rust-lang.org/COPYRIGHT.
-//
-// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
-// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
-// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
-// option. This file may not be copied, modified, or distributed
-// except according to those terms.
-
-// This compiler pass detects constants that refer to themselves
-// recursively.
-
-use rustc::hir::map as hir_map;
-use rustc::session::Session;
-use rustc::hir::def::{Def, CtorKind};
-use rustc::util::common::ErrorReported;
-use rustc::util::nodemap::{NodeMap, NodeSet};
-
-use syntax::ast;
-use syntax_pos::Span;
-use rustc::hir::intravisit::{self, Visitor, NestedVisitorMap};
-use rustc::hir;
-
-struct CheckCrateVisitor<'a, 'hir: 'a> {
- sess: &'a Session,
- hir_map: &'a hir_map::Map<'hir>,
- // `discriminant_map` is a cache that associates the `NodeId`s of local
- // variant definitions with the discriminant expression that applies to
- // each one. If the variant uses the default values (starting from `0`),
- // then `None` is stored.
- discriminant_map: NodeMap<Option<hir::BodyId>>,
- detected_recursive_ids: NodeSet,
-}
-
-impl<'a, 'hir: 'a> Visitor<'hir> for CheckCrateVisitor<'a, 'hir> {
- fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'hir> {
- NestedVisitorMap::None
- }
-
- fn visit_item(&mut self, it: &'hir hir::Item) {
- match it.node {
- hir::ItemStatic(..) |
- hir::ItemConst(..) => {
- let mut recursion_visitor = CheckItemRecursionVisitor::new(self);
- recursion_visitor.visit_item(it);
- }
- hir::ItemEnum(ref enum_def, ref generics) => {
- // We could process the whole enum, but handling the variants
- // with discriminant expressions one by one gives more specific,
- // less redundant output.
- for variant in &enum_def.variants {
- if let Some(_) = variant.node.disr_expr {
- let mut recursion_visitor = CheckItemRecursionVisitor::new(self);
- recursion_visitor.populate_enum_discriminants(enum_def);
- recursion_visitor.visit_variant(variant, generics, it.id);
- }
- }
- }
- _ => {}
- }
- intravisit::walk_item(self, it)
- }
-
- fn visit_trait_item(&mut self, ti: &'hir hir::TraitItem) {
- match ti.node {
- hir::TraitItemKind::Const(_, ref default) => {
- if let Some(_) = *default {
- let mut recursion_visitor = CheckItemRecursionVisitor::new(self);
- recursion_visitor.visit_trait_item(ti);
- }
- }
- _ => {}
- }
- intravisit::walk_trait_item(self, ti)
- }
-
- fn visit_impl_item(&mut self, ii: &'hir hir::ImplItem) {
- match ii.node {
- hir::ImplItemKind::Const(..) => {
- let mut recursion_visitor = CheckItemRecursionVisitor::new(self);
- recursion_visitor.visit_impl_item(ii);
- }
- _ => {}
- }
- intravisit::walk_impl_item(self, ii)
- }
-}
-
-pub fn check_crate<'hir>(sess: &Session, hir_map: &hir_map::Map<'hir>)
- -> Result<(), ErrorReported>
-{
- let mut visitor = CheckCrateVisitor {
- sess,
- hir_map,
- discriminant_map: NodeMap(),
- detected_recursive_ids: NodeSet(),
- };
- sess.track_errors(|| {
- // FIXME(#37712) could use ItemLikeVisitor if trait items were item-like
- hir_map.krate().visit_all_item_likes(&mut visitor.as_deep_visitor());
- })
-}
-
-struct CheckItemRecursionVisitor<'a, 'b: 'a, 'hir: 'b> {
- sess: &'b Session,
- hir_map: &'b hir_map::Map<'hir>,
- discriminant_map: &'a mut NodeMap<Option<hir::BodyId>>,
- idstack: Vec<ast::NodeId>,
- detected_recursive_ids: &'a mut NodeSet,
-}
-
-impl<'a, 'b: 'a, 'hir: 'b> CheckItemRecursionVisitor<'a, 'b, 'hir> {
- fn new(v: &'a mut CheckCrateVisitor<'b, 'hir>) -> Self {
- CheckItemRecursionVisitor {
- sess: v.sess,
- hir_map: v.hir_map,
- discriminant_map: &mut v.discriminant_map,
- idstack: Vec::new(),
- detected_recursive_ids: &mut v.detected_recursive_ids,
- }
- }
- fn with_item_id_pushed<F>(&mut self, id: ast::NodeId, f: F, span: Span)
- where F: Fn(&mut Self)
- {
- if self.idstack.iter().any(|&x| x == id) {
- if self.detected_recursive_ids.contains(&id) {
- return;
- }
- self.detected_recursive_ids.insert(id);
- let any_static = self.idstack.iter().any(|&x| {
- if let hir_map::NodeItem(item) = self.hir_map.get(x) {
- if let hir::ItemStatic(..) = item.node {
- true
- } else {
- false
- }
- } else {
- false
- }
- });
- if !any_static {
- struct_span_err!(self.sess, span, E0265, "recursive constant")
- .span_label(span, "recursion not allowed in constant")
- .emit();
- }
- return;
- }
- self.idstack.push(id);
- f(self);
- self.idstack.pop();
- }
- // If a variant has an expression specifying its discriminant, then it needs
- // to be checked just like a static or constant. However, if there are more
- // variants with no explicitly specified discriminant, those variants will
- // increment the same expression to get their values.
- //
- // So for every variant, we need to track whether there is an expression
- // somewhere in the enum definition that controls its discriminant. We do
- // this by starting from the end and searching backward.
- fn populate_enum_discriminants(&mut self, enum_definition: &'hir hir::EnumDef) {
- // Get the map, and return if we already processed this enum or if it
- // has no variants.
- match enum_definition.variants.first() {
- None => {
- return;
- }
- Some(variant) if self.discriminant_map.contains_key(&variant.node.data.id()) => {
- return;
- }
- _ => {}
- }
-
- // Go through all the variants.
- let mut variant_stack: Vec<ast::NodeId> = Vec::new();
- for variant in enum_definition.variants.iter().rev() {
- variant_stack.push(variant.node.data.id());
- // When we find an expression, every variant currently on the stack
- // is affected by that expression.
- if let Some(expr) = variant.node.disr_expr {
- for id in &variant_stack {
- self.discriminant_map.insert(*id, Some(expr));
- }
- variant_stack.clear()
- }
- }
- // If we are at the top, that always starts at 0, so any variant on the
- // stack has a default value and does not need to be checked.
- for id in &variant_stack {
- self.discriminant_map.insert(*id, None);
- }
- }
-}
-
-impl<'a, 'b: 'a, 'hir: 'b> Visitor<'hir> for CheckItemRecursionVisitor<'a, 'b, 'hir> {
- fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'hir> {
- NestedVisitorMap::OnlyBodies(&self.hir_map)
- }
- fn visit_item(&mut self, it: &'hir hir::Item) {
- self.with_item_id_pushed(it.id, |v| intravisit::walk_item(v, it), it.span);
- }
-
- fn visit_enum_def(&mut self,
- enum_definition: &'hir hir::EnumDef,
- generics: &'hir hir::Generics,
- item_id: ast::NodeId,
- _: Span) {
- self.populate_enum_discriminants(enum_definition);
- intravisit::walk_enum_def(self, enum_definition, generics, item_id);
- }
-
- fn visit_variant(&mut self,
- variant: &'hir hir::Variant,
- _: &'hir hir::Generics,
- _: ast::NodeId) {
- let variant_id = variant.node.data.id();
- let maybe_expr = *self.discriminant_map.get(&variant_id).unwrap_or_else(|| {
- span_bug!(variant.span,
- "`check_static_recursion` attempted to visit \
- variant with unknown discriminant")
- });
- // If `maybe_expr` is `None`, that's because no discriminant is
- // specified that affects this variant. Thus, no risk of recursion.
- if let Some(expr) = maybe_expr {
- let expr = &self.hir_map.body(expr).value;
- self.with_item_id_pushed(expr.id, |v| intravisit::walk_expr(v, expr), expr.span);
- }
- }
-
- fn visit_trait_item(&mut self, ti: &'hir hir::TraitItem) {
- self.with_item_id_pushed(ti.id, |v| intravisit::walk_trait_item(v, ti), ti.span);
- }
-
- fn visit_impl_item(&mut self, ii: &'hir hir::ImplItem) {
- self.with_item_id_pushed(ii.id, |v| intravisit::walk_impl_item(v, ii), ii.span);
- }
-
- fn visit_path(&mut self, path: &'hir hir::Path, _: ast::NodeId) {
- match path.def {
- Def::Static(def_id, _) |
- Def::AssociatedConst(def_id) |
- Def::Const(def_id) => {
- if let Some(node_id) = self.hir_map.as_local_node_id(def_id) {
- match self.hir_map.get(node_id) {
- hir_map::NodeItem(item) => self.visit_item(item),
- hir_map::NodeTraitItem(item) => self.visit_trait_item(item),
- hir_map::NodeImplItem(item) => self.visit_impl_item(item),
- hir_map::NodeForeignItem(_) => {}
- _ => {
- span_bug!(path.span,
- "expected item, found {}",
- self.hir_map.node_to_string(node_id));
- }
- }
- }
- }
- // For variants, we only want to check expressions that
- // affect the specific variant used, but we need to check
- // the whole enum definition to see what expression that
- // might be (if any).
- Def::VariantCtor(variant_id, CtorKind::Const) => {
- if let Some(variant_id) = self.hir_map.as_local_node_id(variant_id) {
- let variant = self.hir_map.expect_variant(variant_id);
- let enum_id = self.hir_map.get_parent(variant_id);
- let enum_item = self.hir_map.expect_item(enum_id);
- if let hir::ItemEnum(ref enum_def, ref generics) = enum_item.node {
- self.populate_enum_discriminants(enum_def);
- self.visit_variant(variant, generics, enum_id);
- } else {
- span_bug!(path.span,
- "`check_static_recursion` found \
- non-enum in Def::VariantCtor");
- }
- }
- }
- _ => (),
- }
- intravisit::walk_path(self, path);
- }
-}
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