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chromium / external / github.com / rust-lang / rust / f668999153d78903658b6937a099819e0b634a06 / . / src / librustc / hir / lowering.rs
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// Copyright 2015 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.
//! Lowers the AST to the HIR.
//!
//! Since the AST and HIR are fairly similar, this is mostly a simple procedure,
//! much like a fold. Where lowering involves a bit more work things get more
//! interesting and there are some invariants you should know about. These mostly
//! concern spans and ids.
//!
//! Spans are assigned to AST nodes during parsing and then are modified during
//! expansion to indicate the origin of a node and the process it went through
//! being expanded. Ids are assigned to AST nodes just before lowering.
//!
//! For the simpler lowering steps, ids and spans should be preserved. Unlike
//! expansion we do not preserve the process of lowering in the spans, so spans
//! should not be modified here. When creating a new node (as opposed to
//! 'folding' an existing one), then you create a new id using `next_id()`.
//!
//! You must ensure that ids are unique. That means that you should only use the
//! id from an AST node in a single HIR node (you can assume that AST node ids
//! are unique). Every new node must have a unique id. Avoid cloning HIR nodes.
//! If you do, you must then set the new node's id to a fresh one.
//!
//! Spans are used for error messages and for tools to map semantics back to
//! source code. It is therefore not as important with spans as ids to be strict
//! about use (you can't break the compiler by screwing up a span). Obviously, a
//! HIR node can only have a single span. But multiple nodes can have the same
//! span and spans don't need to be kept in order, etc. Where code is preserved
//! by lowering, it should have the same span as in the AST. Where HIR nodes are
//! new it is probably best to give a span for the whole AST node being lowered.
//! All nodes should have real spans, don't use dummy spans. Tools are likely to
//! get confused if the spans from leaf AST nodes occur in multiple places
//! in the HIR, especially for multiple identifiers.
use hir;
use hir::map::{Definitions, DefKey, REGULAR_SPACE};
use hir::map::definitions::DefPathData;
use hir::def_id::{DefIndex, DefId, CRATE_DEF_INDEX};
use hir::def::{Def, PathResolution};
use rustc_data_structures::indexed_vec::IndexVec;
use session::Session;
use util::nodemap::{DefIdMap, FxHashMap, NodeMap};
use std::collections::BTreeMap;
use std::fmt::Debug;
use std::iter;
use std::mem;
use syntax::attr;
use syntax::ast::*;
use syntax::errors;
use syntax::ext::hygiene::{Mark, SyntaxContext};
use syntax::ptr::P;
use syntax::codemap::{self, respan, Spanned};
use syntax::std_inject;
use syntax::symbol::{Symbol, keywords};
use syntax::util::small_vector::SmallVector;
use syntax::visit::{self, Visitor};
use syntax_pos::Span;
const HIR_ID_COUNTER_LOCKED: u32 = 0xFFFFFFFF;
pub struct LoweringContext<'a> {
crate_root: Option<&'static str>,
// Use to assign ids to hir nodes that do not directly correspond to an ast node
sess: &'a Session,
// As we walk the AST we must keep track of the current 'parent' def id (in
// the form of a DefIndex) so that if we create a new node which introduces
// a definition, then we can properly create the def id.
parent_def: Option<DefIndex>,
resolver: &'a mut Resolver,
name_map: FxHashMap<Ident, Name>,
/// The items being lowered are collected here.
items: BTreeMap<NodeId, hir::Item>,
trait_items: BTreeMap<hir::TraitItemId, hir::TraitItem>,
impl_items: BTreeMap<hir::ImplItemId, hir::ImplItem>,
bodies: BTreeMap<hir::BodyId, hir::Body>,
exported_macros: Vec<hir::MacroDef>,
trait_impls: BTreeMap<DefId, Vec<NodeId>>,
trait_default_impl: BTreeMap<DefId, NodeId>,
catch_scopes: Vec<NodeId>,
loop_scopes: Vec<NodeId>,
is_in_loop_condition: bool,
type_def_lifetime_params: DefIdMap<usize>,
current_hir_id_owner: Vec<(DefIndex, u32)>,
item_local_id_counters: NodeMap<u32>,
node_id_to_hir_id: IndexVec<NodeId, hir::HirId>,
}
pub trait Resolver {
/// Resolve a hir path generated by the lowerer when expanding `for`, `if let`, etc.
fn resolve_hir_path(&mut self, path: &mut hir::Path, is_value: bool);
/// Obtain the resolution for a node id
fn get_resolution(&mut self, id: NodeId) -> Option<PathResolution>;
/// We must keep the set of definitions up to date as we add nodes that weren't in the AST.
/// This should only return `None` during testing.
fn definitions(&mut self) -> &mut Definitions;
}
pub fn lower_crate(sess: &Session,
krate: &Crate,
resolver: &mut Resolver)
-> hir::Crate {
// We're constructing the HIR here; we don't care what we will
// read, since we haven't even constructed the *input* to
// incr. comp. yet.
let _ignore = sess.dep_graph.in_ignore();
LoweringContext {
crate_root: std_inject::injected_crate_name(krate),
sess,
parent_def: None,
resolver,
name_map: FxHashMap(),
items: BTreeMap::new(),
trait_items: BTreeMap::new(),
impl_items: BTreeMap::new(),
bodies: BTreeMap::new(),
trait_impls: BTreeMap::new(),
trait_default_impl: BTreeMap::new(),
exported_macros: Vec::new(),
catch_scopes: Vec::new(),
loop_scopes: Vec::new(),
is_in_loop_condition: false,
type_def_lifetime_params: DefIdMap(),
current_hir_id_owner: vec![(CRATE_DEF_INDEX, 0)],
item_local_id_counters: NodeMap(),
node_id_to_hir_id: IndexVec::new(),
}.lower_crate(krate)
}
#[derive(Copy, Clone, PartialEq, Eq)]
enum ParamMode {
/// Any path in a type context.
Explicit,
/// The `module::Type` in `module::Type::method` in an expression.
Optional
}
impl<'a> LoweringContext<'a> {
fn lower_crate(mut self, c: &Crate) -> hir::Crate {
/// Full-crate AST visitor that inserts into a fresh
/// `LoweringContext` any information that may be
/// needed from arbitrary locations in the crate.
/// E.g. The number of lifetime generic parameters
/// declared for every type and trait definition.
struct MiscCollector<'lcx, 'interner: 'lcx> {
lctx: &'lcx mut LoweringContext<'interner>,
}
impl<'lcx, 'interner> Visitor<'lcx> for MiscCollector<'lcx, 'interner> {
fn visit_item(&mut self, item: &'lcx Item) {
self.lctx.allocate_hir_id_counter(item.id, item);
match item.node {
ItemKind::Struct(_, ref generics) |
ItemKind::Union(_, ref generics) |
ItemKind::Enum(_, ref generics) |
ItemKind::Ty(_, ref generics) |
ItemKind::Trait(_, ref generics, ..) => {
let def_id = self.lctx.resolver.definitions().local_def_id(item.id);
let count = generics.lifetimes.len();
self.lctx.type_def_lifetime_params.insert(def_id, count);
}
_ => {}
}
visit::walk_item(self, item);
}
fn visit_trait_item(&mut self, item: &'lcx TraitItem) {
self.lctx.allocate_hir_id_counter(item.id, item);
visit::walk_trait_item(self, item);
}
fn visit_impl_item(&mut self, item: &'lcx ImplItem) {
self.lctx.allocate_hir_id_counter(item.id, item);
visit::walk_impl_item(self, item);
}
}
struct ItemLowerer<'lcx, 'interner: 'lcx> {
lctx: &'lcx mut LoweringContext<'interner>,
}
impl<'lcx, 'interner> Visitor<'lcx> for ItemLowerer<'lcx, 'interner> {
fn visit_item(&mut self, item: &'lcx Item) {
let mut item_lowered = true;
self.lctx.with_hir_id_owner(item.id, |lctx| {
if let Some(hir_item) = lctx.lower_item(item) {
lctx.items.insert(item.id, hir_item);
} else {
item_lowered = false;
}
});
if item_lowered {
visit::walk_item(self, item);
}
}
fn visit_trait_item(&mut self, item: &'lcx TraitItem) {
self.lctx.with_hir_id_owner(item.id, |lctx| {
let id = hir::TraitItemId { node_id: item.id };
let hir_item = lctx.lower_trait_item(item);
lctx.trait_items.insert(id, hir_item);
});
visit::walk_trait_item(self, item);
}
fn visit_impl_item(&mut self, item: &'lcx ImplItem) {
self.lctx.with_hir_id_owner(item.id, |lctx| {
let id = hir::ImplItemId { node_id: item.id };
let hir_item = lctx.lower_impl_item(item);
lctx.impl_items.insert(id, hir_item);
});
visit::walk_impl_item(self, item);
}
}
self.lower_node_id(CRATE_NODE_ID);
debug_assert!(self.node_id_to_hir_id[CRATE_NODE_ID] == hir::CRATE_HIR_ID);
visit::walk_crate(&mut MiscCollector { lctx: &mut self }, c);
visit::walk_crate(&mut ItemLowerer { lctx: &mut self }, c);
let module = self.lower_mod(&c.module);
let attrs = self.lower_attrs(&c.attrs);
let body_ids = body_ids(&self.bodies);
self.resolver
.definitions()
.init_node_id_to_hir_id_mapping(self.node_id_to_hir_id);
hir::Crate {
module,
attrs,
span: c.span,
exported_macros: hir::HirVec::from(self.exported_macros),
items: self.items,
trait_items: self.trait_items,
impl_items: self.impl_items,
bodies: self.bodies,
body_ids,
trait_impls: self.trait_impls,
trait_default_impl: self.trait_default_impl,
}
}
fn allocate_hir_id_counter<T: Debug>(&mut self,
owner: NodeId,
debug: &T) {
if self.item_local_id_counters.insert(owner, 0).is_some() {
bug!("Tried to allocate item_local_id_counter for {:?} twice", debug);
}
// Always allocate the first HirId for the owner itself
self.lower_node_id_with_owner(owner, owner);
}
fn lower_node_id_generic<F>(&mut self,
ast_node_id: NodeId,
alloc_hir_id: F)
-> NodeId
where F: FnOnce(&mut Self) -> hir::HirId
{
if ast_node_id == DUMMY_NODE_ID {
return ast_node_id;
}
let min_size = ast_node_id.as_usize() + 1;
if min_size > self.node_id_to_hir_id.len() {
self.node_id_to_hir_id.resize(min_size, hir::DUMMY_HIR_ID);
}
if self.node_id_to_hir_id[ast_node_id] == hir::DUMMY_HIR_ID {
// Generate a new HirId
self.node_id_to_hir_id[ast_node_id] = alloc_hir_id(self);
}
ast_node_id
}
fn with_hir_id_owner<F>(&mut self, owner: NodeId, f: F)
where F: FnOnce(&mut Self)
{
let counter = self.item_local_id_counters
.insert(owner, HIR_ID_COUNTER_LOCKED)
.unwrap();
let def_index = self.resolver.definitions().opt_def_index(owner).unwrap();
self.current_hir_id_owner.push((def_index, counter));
f(self);
let (new_def_index, new_counter) = self.current_hir_id_owner.pop().unwrap();
debug_assert!(def_index == new_def_index);
debug_assert!(new_counter >= counter);
let prev = self.item_local_id_counters.insert(owner, new_counter).unwrap();
debug_assert!(prev == HIR_ID_COUNTER_LOCKED);
}
/// This method allocates a new HirId for the given NodeId and stores it in
/// the LoweringContext's NodeId => HirId map.
/// Take care not to call this method if the resulting HirId is then not
/// actually used in the HIR, as that would trigger an assertion in the
/// HirIdValidator later on, which makes sure that all NodeIds got mapped
/// properly. Calling the method twice with the same NodeId is fine though.
fn lower_node_id(&mut self, ast_node_id: NodeId) -> NodeId {
self.lower_node_id_generic(ast_node_id, |this| {
let &mut (def_index, ref mut local_id_counter) = this.current_hir_id_owner
.last_mut()
.unwrap();
let local_id = *local_id_counter;
*local_id_counter += 1;
hir::HirId {
owner: def_index,
local_id: hir::ItemLocalId(local_id),
}
})
}
fn lower_node_id_with_owner(&mut self,
ast_node_id: NodeId,
owner: NodeId)
-> NodeId {
self.lower_node_id_generic(ast_node_id, |this| {
let local_id_counter = this.item_local_id_counters
.get_mut(&owner)
.unwrap();
let local_id = *local_id_counter;
// We want to be sure not to modify the counter in the map while it
// is also on the stack. Otherwise we'll get lost updates when writing
// back from the stack to the map.
debug_assert!(local_id != HIR_ID_COUNTER_LOCKED);
*local_id_counter += 1;
let def_index = this.resolver.definitions().opt_def_index(owner).unwrap();
hir::HirId {
owner: def_index,
local_id: hir::ItemLocalId(local_id),
}
})
}
fn record_body(&mut self, value: hir::Expr, decl: Option<&FnDecl>)
-> hir::BodyId {
let body = hir::Body {
arguments: decl.map_or(hir_vec![], |decl| {
decl.inputs.iter().map(|x| self.lower_arg(x)).collect()
}),
value,
};
let id = body.id();
self.bodies.insert(id, body);
id
}
fn next_id(&mut self) -> NodeId {
self.lower_node_id(self.sess.next_node_id())
}
fn expect_full_def(&mut self, id: NodeId) -> Def {
self.resolver.get_resolution(id).map_or(Def::Err, |pr| {
if pr.unresolved_segments() != 0 {
bug!("path not fully resolved: {:?}", pr);
}
pr.base_def()
})
}
fn diagnostic(&self) -> &errors::Handler {
self.sess.diagnostic()
}
fn str_to_ident(&self, s: &'static str) -> Name {
Symbol::gensym(s)
}
fn allow_internal_unstable(&self, reason: &'static str, mut span: Span) -> Span {
let mark = Mark::fresh(Mark::root());
mark.set_expn_info(codemap::ExpnInfo {
call_site: span,
callee: codemap::NameAndSpan {
format: codemap::CompilerDesugaring(Symbol::intern(reason)),
span: Some(span),
allow_internal_unstable: true,
},
});
span.ctxt = SyntaxContext::empty().apply_mark(mark);
span
}
fn with_catch_scope<T, F>(&mut self, catch_id: NodeId, f: F) -> T
where F: FnOnce(&mut LoweringContext) -> T
{
let len = self.catch_scopes.len();
self.catch_scopes.push(catch_id);
let result = f(self);
assert_eq!(len + 1, self.catch_scopes.len(),
"catch scopes should be added and removed in stack order");
self.catch_scopes.pop().unwrap();
result
}
fn with_loop_scope<T, F>(&mut self, loop_id: NodeId, f: F) -> T
where F: FnOnce(&mut LoweringContext) -> T
{
// We're no longer in the base loop's condition; we're in another loop.
let was_in_loop_condition = self.is_in_loop_condition;
self.is_in_loop_condition = false;
let len = self.loop_scopes.len();
self.loop_scopes.push(loop_id);
let result = f(self);
assert_eq!(len + 1, self.loop_scopes.len(),
"Loop scopes should be added and removed in stack order");
self.loop_scopes.pop().unwrap();
self.is_in_loop_condition = was_in_loop_condition;
result
}
fn with_loop_condition_scope<T, F>(&mut self, f: F) -> T
where F: FnOnce(&mut LoweringContext) -> T
{
let was_in_loop_condition = self.is_in_loop_condition;
self.is_in_loop_condition = true;
let result = f(self);
self.is_in_loop_condition = was_in_loop_condition;
result
}
fn with_new_scopes<T, F>(&mut self, f: F) -> T
where F: FnOnce(&mut LoweringContext) -> T
{
let was_in_loop_condition = self.is_in_loop_condition;
self.is_in_loop_condition = false;
let catch_scopes = mem::replace(&mut self.catch_scopes, Vec::new());
let loop_scopes = mem::replace(&mut self.loop_scopes, Vec::new());
let result = f(self);
self.catch_scopes = catch_scopes;
self.loop_scopes = loop_scopes;
self.is_in_loop_condition = was_in_loop_condition;
result
}
fn with_parent_def<T, F>(&mut self, parent_id: NodeId, f: F) -> T
where F: FnOnce(&mut LoweringContext) -> T
{
let old_def = self.parent_def;
self.parent_def = {
let defs = self.resolver.definitions();
Some(defs.opt_def_index(parent_id).unwrap())
};
let result = f(self);
self.parent_def = old_def;
result
}
fn def_key(&mut self, id: DefId) -> DefKey {
if id.is_local() {
self.resolver.definitions().def_key(id.index)
} else {
self.sess.cstore.def_key(id)
}
}
fn lower_ident(&mut self, ident: Ident) -> Name {
let ident = ident.modern();
if ident.ctxt == SyntaxContext::empty() {
return ident.name;
}
*self.name_map.entry(ident).or_insert_with(|| Symbol::from_ident(ident))
}
fn lower_opt_sp_ident(&mut self, o_id: Option<Spanned<Ident>>) -> Option<Spanned<Name>> {
o_id.map(|sp_ident| respan(sp_ident.span, sp_ident.node.name))
}
fn lower_loop_destination(&mut self, destination: Option<(NodeId, Spanned<Ident>)>)
-> hir::Destination
{
match destination {
Some((id, label_ident)) => {
let target = if let Def::Label(loop_id) = self.expect_full_def(id) {
hir::LoopIdResult::Ok(self.lower_node_id(loop_id))
} else {
hir::LoopIdResult::Err(hir::LoopIdError::UnresolvedLabel)
};
hir::Destination {
ident: Some(label_ident),
target_id: hir::ScopeTarget::Loop(target),
}
},
None => {
let loop_id = self.loop_scopes
.last()
.map(|innermost_loop_id| *innermost_loop_id);
hir::Destination {
ident: None,
target_id: hir::ScopeTarget::Loop(
loop_id.map(|id| Ok(self.lower_node_id(id)))
.unwrap_or(Err(hir::LoopIdError::OutsideLoopScope))
.into())
}
}
}
}
fn lower_attrs(&mut self, attrs: &Vec<Attribute>) -> hir::HirVec<Attribute> {
attrs.clone().into()
}
fn lower_arm(&mut self, arm: &Arm) -> hir::Arm {
hir::Arm {
attrs: self.lower_attrs(&arm.attrs),
pats: arm.pats.iter().map(|x| self.lower_pat(x)).collect(),
guard: arm.guard.as_ref().map(|ref x| P(self.lower_expr(x))),
body: P(self.lower_expr(&arm.body)),
}
}
fn lower_ty_binding(&mut self, b: &TypeBinding) -> hir::TypeBinding {
hir::TypeBinding {
id: self.lower_node_id(b.id),
name: self.lower_ident(b.ident),
ty: self.lower_ty(&b.ty),
span: b.span,
}
}
fn lower_ty(&mut self, t: &Ty) -> P<hir::Ty> {
let kind = match t.node {
TyKind::Infer => hir::TyInfer,
TyKind::Err => hir::TyErr,
TyKind::Slice(ref ty) => hir::TySlice(self.lower_ty(ty)),
TyKind::Ptr(ref mt) => hir::TyPtr(self.lower_mt(mt)),
TyKind::Rptr(ref region, ref mt) => {
let span = Span { hi: t.span.lo, ..t.span };
let lifetime = match *region {
Some(ref lt) => self.lower_lifetime(lt),
None => self.elided_lifetime(span)
};
hir::TyRptr(lifetime, self.lower_mt(mt))
}
TyKind::BareFn(ref f) => {
hir::TyBareFn(P(hir::BareFnTy {
lifetimes: self.lower_lifetime_defs(&f.lifetimes),
unsafety: self.lower_unsafety(f.unsafety),
abi: f.abi,
decl: self.lower_fn_decl(&f.decl),
}))
}
TyKind::Never => hir::TyNever,
TyKind::Tup(ref tys) => {
hir::TyTup(tys.iter().map(|ty| self.lower_ty(ty)).collect())
}
TyKind::Paren(ref ty) => {
return self.lower_ty(ty);
}
TyKind::Path(ref qself, ref path) => {
let id = self.lower_node_id(t.id);
let qpath = self.lower_qpath(t.id, qself, path, ParamMode::Explicit);
return self.ty_path(id, t.span, qpath);
}
TyKind::ImplicitSelf => {
hir::TyPath(hir::QPath::Resolved(None, P(hir::Path {
def: self.expect_full_def(t.id),
segments: hir_vec![hir::PathSegment {
name: keywords::SelfType.name(),
parameters: hir::PathParameters::none()
}],
span: t.span,
})))
}
TyKind::Array(ref ty, ref length) => {
let length = self.lower_expr(length);
hir::TyArray(self.lower_ty(ty),
self.record_body(length, None))
}
TyKind::Typeof(ref expr) => {
let expr = self.lower_expr(expr);
hir::TyTypeof(self.record_body(expr, None))
}
TyKind::TraitObject(ref bounds) => {
let mut lifetime_bound = None;
let bounds = bounds.iter().filter_map(|bound| {
match *bound {
TraitTyParamBound(ref ty, TraitBoundModifier::None) => {
Some(self.lower_poly_trait_ref(ty))
}
TraitTyParamBound(_, TraitBoundModifier::Maybe) => None,
RegionTyParamBound(ref lifetime) => {
if lifetime_bound.is_none() {
lifetime_bound = Some(self.lower_lifetime(lifetime));
}
None
}
}
}).collect();
let lifetime_bound = lifetime_bound.unwrap_or_else(|| {
self.elided_lifetime(t.span)
});
hir::TyTraitObject(bounds, lifetime_bound)
}
TyKind::ImplTrait(ref bounds) => {
hir::TyImplTrait(self.lower_bounds(bounds))
}
TyKind::Mac(_) => panic!("TyMac should have been expanded by now."),
};
P(hir::Ty {
id: self.lower_node_id(t.id),
node: kind,
span: t.span,
})
}
fn lower_foreign_mod(&mut self, fm: &ForeignMod) -> hir::ForeignMod {
hir::ForeignMod {
abi: fm.abi,
items: fm.items.iter().map(|x| self.lower_foreign_item(x)).collect(),
}
}
fn lower_global_asm(&mut self, ga: &GlobalAsm) -> P<hir::GlobalAsm> {
P(hir::GlobalAsm {
asm: ga.asm,
ctxt: ga.ctxt,
})
}
fn lower_variant(&mut self, v: &Variant) -> hir::Variant {
Spanned {
node: hir::Variant_ {
name: v.node.name.name,
attrs: self.lower_attrs(&v.node.attrs),
data: self.lower_variant_data(&v.node.data),
disr_expr: v.node.disr_expr.as_ref().map(|e| {
let e = self.lower_expr(e);
self.record_body(e, None)
}),
},
span: v.span,
}
}
fn lower_qpath(&mut self,
id: NodeId,
qself: &Option<QSelf>,
p: &Path,
param_mode: ParamMode)
-> hir::QPath {
let qself_position = qself.as_ref().map(|q| q.position);
let qself = qself.as_ref().map(|q| self.lower_ty(&q.ty));
let resolution = self.resolver.get_resolution(id)
.unwrap_or(PathResolution::new(Def::Err));
let proj_start = p.segments.len() - resolution.unresolved_segments();
let path = P(hir::Path {
def: resolution.base_def(),
segments: p.segments[..proj_start].iter().enumerate().map(|(i, segment)| {
let param_mode = match (qself_position, param_mode) {
(Some(j), ParamMode::Optional) if i < j => {
// This segment is part of the trait path in a
// qualified path - one of `a`, `b` or `Trait`
// in `<X as a::b::Trait>::T::U::method`.
ParamMode::Explicit
}
_ => param_mode
};
// Figure out if this is a type/trait segment,
// which may need lifetime elision performed.
let parent_def_id = |this: &mut Self, def_id: DefId| {
DefId {
krate: def_id.krate,
index: this.def_key(def_id).parent.expect("missing parent")
}
};
let type_def_id = match resolution.base_def() {
Def::AssociatedTy(def_id) if i + 2 == proj_start => {
Some(parent_def_id(self, def_id))
}
Def::Variant(def_id) if i + 1 == proj_start => {
Some(parent_def_id(self, def_id))
}
Def::Struct(def_id) |
Def::Union(def_id) |
Def::Enum(def_id) |
Def::TyAlias(def_id) |
Def::Trait(def_id) if i + 1 == proj_start => Some(def_id),
_ => None
};
let num_lifetimes = type_def_id.map_or(0, |def_id| {
if let Some(&n) = self.type_def_lifetime_params.get(&def_id) {
return n;
}
assert!(!def_id.is_local());
let n = self.sess.cstore.item_generics_cloned(def_id).regions.len();
self.type_def_lifetime_params.insert(def_id, n);
n
});
self.lower_path_segment(p.span, segment, param_mode, num_lifetimes)
}).collect(),
span: p.span,
});
// Simple case, either no projections, or only fully-qualified.
// E.g. `std::mem::size_of` or `<I as Iterator>::Item`.
if resolution.unresolved_segments() == 0 {
return hir::QPath::Resolved(qself, path);
}
// Create the innermost type that we're projecting from.
let mut ty = if path.segments.is_empty() {
// If the base path is empty that means there exists a
// syntactical `Self`, e.g. `&i32` in `<&i32>::clone`.
qself.expect("missing QSelf for <T>::...")
} else {
// Otherwise, the base path is an implicit `Self` type path,
// e.g. `Vec` in `Vec::new` or `<I as Iterator>::Item` in
// `<I as Iterator>::Item::default`.
let new_id = self.next_id();
self.ty_path(new_id, p.span, hir::QPath::Resolved(qself, path))
};
// Anything after the base path are associated "extensions",
// out of which all but the last one are associated types,
// e.g. for `std::vec::Vec::<T>::IntoIter::Item::clone`:
// * base path is `std::vec::Vec<T>`
// * "extensions" are `IntoIter`, `Item` and `clone`
// * type nodes are:
// 1. `std::vec::Vec<T>` (created above)
// 2. `<std::vec::Vec<T>>::IntoIter`
// 3. `<<std::vec::Vec<T>>::IntoIter>::Item`
// * final path is `<<<std::vec::Vec<T>>::IntoIter>::Item>::clone`
for (i, segment) in p.segments.iter().enumerate().skip(proj_start) {
let segment = P(self.lower_path_segment(p.span, segment, param_mode, 0));
let qpath = hir::QPath::TypeRelative(ty, segment);
// It's finished, return the extension of the right node type.
if i == p.segments.len() - 1 {
return qpath;
}
// Wrap the associated extension in another type node.
let new_id = self.next_id();
ty = self.ty_path(new_id, p.span, qpath);
}
// Should've returned in the for loop above.
span_bug!(p.span, "lower_qpath: no final extension segment in {}..{}",
proj_start, p.segments.len())
}
fn lower_path_extra(&mut self,
id: NodeId,
p: &Path,
name: Option<Name>,
param_mode: ParamMode,
defaults_to_global: bool)
-> hir::Path {
let mut segments = p.segments.iter();
if defaults_to_global && p.is_global() {
segments.next();
}
hir::Path {
def: self.expect_full_def(id),
segments: segments.map(|segment| {
self.lower_path_segment(p.span, segment, param_mode, 0)
}).chain(name.map(|name| {
hir::PathSegment {
name,
parameters: hir::PathParameters::none()
}
})).collect(),
span: p.span,
}
}
fn lower_path(&mut self,
id: NodeId,
p: &Path,
param_mode: ParamMode,
defaults_to_global: bool)
-> hir::Path {
self.lower_path_extra(id, p, None, param_mode, defaults_to_global)
}
fn lower_path_segment(&mut self,
path_span: Span,
segment: &PathSegment,
param_mode: ParamMode,
expected_lifetimes: usize)
-> hir::PathSegment {
let mut parameters = if let Some(ref parameters) = segment.parameters {
match **parameters {
PathParameters::AngleBracketed(ref data) => {
let data = self.lower_angle_bracketed_parameter_data(data, param_mode);
hir::AngleBracketedParameters(data)
}
PathParameters::Parenthesized(ref data) => {
hir::ParenthesizedParameters(self.lower_parenthesized_parameter_data(data))
}
}
} else {
let data = self.lower_angle_bracketed_parameter_data(&Default::default(), param_mode);
hir::AngleBracketedParameters(data)
};
if let hir::AngleBracketedParameters(ref mut data) = parameters {
if data.lifetimes.is_empty() {
data.lifetimes = (0..expected_lifetimes).map(|_| {
self.elided_lifetime(path_span)
}).collect();
}
}
hir::PathSegment {
name: self.lower_ident(segment.identifier),
parameters,
}
}
fn lower_angle_bracketed_parameter_data(&mut self,
data: &AngleBracketedParameterData,
param_mode: ParamMode)
-> hir::AngleBracketedParameterData {
let &AngleBracketedParameterData { ref lifetimes, ref types, ref bindings } = data;
hir::AngleBracketedParameterData {
lifetimes: self.lower_lifetimes(lifetimes),
types: types.iter().map(|ty| self.lower_ty(ty)).collect(),
infer_types: types.is_empty() && param_mode == ParamMode::Optional,
bindings: bindings.iter().map(|b| self.lower_ty_binding(b)).collect(),
}
}
fn lower_parenthesized_parameter_data(&mut self,
data: &ParenthesizedParameterData)
-> hir::ParenthesizedParameterData {
let &ParenthesizedParameterData { ref inputs, ref output, span } = data;
hir::ParenthesizedParameterData {
inputs: inputs.iter().map(|ty| self.lower_ty(ty)).collect(),
output: output.as_ref().map(|ty| self.lower_ty(ty)),
span,
}
}
fn lower_local(&mut self, l: &Local) -> P<hir::Local> {
P(hir::Local {
id: self.lower_node_id(l.id),
ty: l.ty.as_ref().map(|t| self.lower_ty(t)),
pat: self.lower_pat(&l.pat),
init: l.init.as_ref().map(|e| P(self.lower_expr(e))),
span: l.span,
attrs: l.attrs.clone(),
source: hir::LocalSource::Normal,
})
}
fn lower_mutability(&mut self, m: Mutability) -> hir::Mutability {
match m {
Mutability::Mutable => hir::MutMutable,
Mutability::Immutable => hir::MutImmutable,
}
}
fn lower_arg(&mut self, arg: &Arg) -> hir::Arg {
hir::Arg {
id: self.lower_node_id(arg.id),
pat: self.lower_pat(&arg.pat),
}
}
fn lower_fn_args_to_names(&mut self, decl: &FnDecl)
-> hir::HirVec<Spanned<Name>> {
decl.inputs.iter().map(|arg| {
match arg.pat.node {
PatKind::Ident(_, ident, None) => {
respan(ident.span, ident.node.name)
}
_ => respan(arg.pat.span, keywords::Invalid.name()),
}
}).collect()
}
fn lower_fn_decl(&mut self, decl: &FnDecl) -> P<hir::FnDecl> {
P(hir::FnDecl {
inputs: decl.inputs.iter().map(|arg| self.lower_ty(&arg.ty)).collect(),
output: match decl.output {
FunctionRetTy::Ty(ref ty) => hir::Return(self.lower_ty(ty)),
FunctionRetTy::Default(span) => hir::DefaultReturn(span),
},
variadic: decl.variadic,
has_implicit_self: decl.inputs.get(0).map_or(false, |arg| {
match arg.ty.node {
TyKind::ImplicitSelf => true,
TyKind::Rptr(_, ref mt) => mt.ty.node == TyKind::ImplicitSelf,
_ => false
}
})
})
}
fn lower_ty_param_bound(&mut self, tpb: &TyParamBound) -> hir::TyParamBound {
match *tpb {
TraitTyParamBound(ref ty, modifier) => {
hir::TraitTyParamBound(self.lower_poly_trait_ref(ty),
self.lower_trait_bound_modifier(modifier))
}
RegionTyParamBound(ref lifetime) => {
hir::RegionTyParamBound(self.lower_lifetime(lifetime))
}
}
}
fn lower_ty_param(&mut self, tp: &TyParam, add_bounds: &[TyParamBound]) -> hir::TyParam {
let mut name = self.lower_ident(tp.ident);
// Don't expose `Self` (recovered "keyword used as ident" parse error).
// `rustc::ty` expects `Self` to be only used for a trait's `Self`.
// Instead, use gensym("Self") to create a distinct name that looks the same.
if name == keywords::SelfType.name() {
name = Symbol::gensym("Self");
}
let mut bounds = self.lower_bounds(&tp.bounds);
if !add_bounds.is_empty() {
bounds = bounds.into_iter().chain(self.lower_bounds(add_bounds).into_iter()).collect();
}
hir::TyParam {
id: self.lower_node_id(tp.id),
name,
bounds,
default: tp.default.as_ref().map(|x| self.lower_ty(x)),
span: tp.span,
pure_wrt_drop: tp.attrs.iter().any(|attr| attr.check_name("may_dangle")),
}
}
fn lower_ty_params(&mut self, tps: &Vec<TyParam>, add_bounds: &NodeMap<Vec<TyParamBound>>)
-> hir::HirVec<hir::TyParam> {
tps.iter().map(|tp| {
self.lower_ty_param(tp, add_bounds.get(&tp.id).map_or(&[][..], |x| &x))
}).collect()
}
fn lower_lifetime(&mut self, l: &Lifetime) -> hir::Lifetime {
hir::Lifetime {
id: self.lower_node_id(l.id),
name: self.lower_ident(l.ident),
span: l.span,
}
}
fn lower_lifetime_def(&mut self, l: &LifetimeDef) -> hir::LifetimeDef {
hir::LifetimeDef {
lifetime: self.lower_lifetime(&l.lifetime),
bounds: self.lower_lifetimes(&l.bounds),
pure_wrt_drop: l.attrs.iter().any(|attr| attr.check_name("may_dangle")),
}
}
fn lower_lifetimes(&mut self, lts: &Vec<Lifetime>) -> hir::HirVec<hir::Lifetime> {
lts.iter().map(|l| self.lower_lifetime(l)).collect()
}
fn lower_lifetime_defs(&mut self, lts: &Vec<LifetimeDef>) -> hir::HirVec<hir::LifetimeDef> {
lts.iter().map(|l| self.lower_lifetime_def(l)).collect()
}
fn lower_generics(&mut self, g: &Generics) -> hir::Generics {
// Collect `?Trait` bounds in where clause and move them to parameter definitions.
let mut add_bounds = NodeMap();
for pred in &g.where_clause.predicates {
if let WherePredicate::BoundPredicate(ref bound_pred) = *pred {
'next_bound: for bound in &bound_pred.bounds {
if let TraitTyParamBound(_, TraitBoundModifier::Maybe) = *bound {
let report_error = |this: &mut Self| {
this.diagnostic().span_err(bound_pred.bounded_ty.span,
"`?Trait` bounds are only permitted at the \
point where a type parameter is declared");
};
// Check if the where clause type is a plain type parameter.
match bound_pred.bounded_ty.node {
TyKind::Path(None, ref path)
if path.segments.len() == 1 &&
bound_pred.bound_lifetimes.is_empty() => {
if let Some(Def::TyParam(def_id)) =
self.resolver.get_resolution(bound_pred.bounded_ty.id)
.map(|d| d.base_def()) {
if let Some(node_id) =
self.resolver.definitions().as_local_node_id(def_id) {
for ty_param in &g.ty_params {
if node_id == ty_param.id {
add_bounds.entry(ty_param.id).or_insert(Vec::new())
.push(bound.clone());
continue 'next_bound;
}
}
}
}
report_error(self)
}
_ => report_error(self)
}
}
}
}
}
hir::Generics {
ty_params: self.lower_ty_params(&g.ty_params, &add_bounds),
lifetimes: self.lower_lifetime_defs(&g.lifetimes),
where_clause: self.lower_where_clause(&g.where_clause),
span: g.span,
}
}
fn lower_where_clause(&mut self, wc: &WhereClause) -> hir::WhereClause {
hir::WhereClause {
id: self.lower_node_id(wc.id),
predicates: wc.predicates
.iter()
.map(|predicate| self.lower_where_predicate(predicate))
.collect(),
}
}
fn lower_where_predicate(&mut self, pred: &WherePredicate) -> hir::WherePredicate {
match *pred {
WherePredicate::BoundPredicate(WhereBoundPredicate{ ref bound_lifetimes,
ref bounded_ty,
ref bounds,
span}) => {
hir::WherePredicate::BoundPredicate(hir::WhereBoundPredicate {
bound_lifetimes: self.lower_lifetime_defs(bound_lifetimes),
bounded_ty: self.lower_ty(bounded_ty),
bounds: bounds.iter().filter_map(|bound| match *bound {
// Ignore `?Trait` bounds, they were copied into type parameters already.
TraitTyParamBound(_, TraitBoundModifier::Maybe) => None,
_ => Some(self.lower_ty_param_bound(bound))
}).collect(),
span,
})
}
WherePredicate::RegionPredicate(WhereRegionPredicate{ ref lifetime,
ref bounds,
span}) => {
hir::WherePredicate::RegionPredicate(hir::WhereRegionPredicate {
span,
lifetime: self.lower_lifetime(lifetime),
bounds: bounds.iter().map(|bound| self.lower_lifetime(bound)).collect(),
})
}
WherePredicate::EqPredicate(WhereEqPredicate{ id,
ref lhs_ty,
ref rhs_ty,
span}) => {
hir::WherePredicate::EqPredicate(hir::WhereEqPredicate {
id: self.lower_node_id(id),
lhs_ty: self.lower_ty(lhs_ty),
rhs_ty: self.lower_ty(rhs_ty),
span,
})
}
}
}
fn lower_variant_data(&mut self, vdata: &VariantData) -> hir::VariantData {
match *vdata {
VariantData::Struct(ref fields, id) => {
hir::VariantData::Struct(fields.iter()
.enumerate()
.map(|f| self.lower_struct_field(f))
.collect(),
self.lower_node_id(id))
}
VariantData::Tuple(ref fields, id) => {
hir::VariantData::Tuple(fields.iter()
.enumerate()
.map(|f| self.lower_struct_field(f))
.collect(),
self.lower_node_id(id))
}
VariantData::Unit(id) => hir::VariantData::Unit(self.lower_node_id(id)),
}
}
fn lower_trait_ref(&mut self, p: &TraitRef) -> hir::TraitRef {
let path = match self.lower_qpath(p.ref_id, &None, &p.path, ParamMode::Explicit) {
hir::QPath::Resolved(None, path) => path.and_then(|path| path),
qpath => bug!("lower_trait_ref: unexpected QPath `{:?}`", qpath)
};
hir::TraitRef {
path,
ref_id: self.lower_node_id(p.ref_id),
}
}
fn lower_poly_trait_ref(&mut self, p: &PolyTraitRef) -> hir::PolyTraitRef {
hir::PolyTraitRef {
bound_lifetimes: self.lower_lifetime_defs(&p.bound_lifetimes),
trait_ref: self.lower_trait_ref(&p.trait_ref),
span: p.span,
}
}
fn lower_struct_field(&mut self, (index, f): (usize, &StructField)) -> hir::StructField {
hir::StructField {
span: f.span,
id: self.lower_node_id(f.id),
name: self.lower_ident(match f.ident {
Some(ident) => ident,
// FIXME(jseyfried) positional field hygiene
None => Ident { name: Symbol::intern(&index.to_string()), ctxt: f.span.ctxt },
}),
vis: self.lower_visibility(&f.vis, None),
ty: self.lower_ty(&f.ty),
attrs: self.lower_attrs(&f.attrs),
}
}
fn lower_field(&mut self, f: &Field) -> hir::Field {
hir::Field {
name: respan(f.ident.span, self.lower_ident(f.ident.node)),
expr: P(self.lower_expr(&f.expr)),
span: f.span,
is_shorthand: f.is_shorthand,
}
}
fn lower_mt(&mut self, mt: &MutTy) -> hir::MutTy {
hir::MutTy {
ty: self.lower_ty(&mt.ty),
mutbl: self.lower_mutability(mt.mutbl),
}
}
fn lower_bounds(&mut self, bounds: &[TyParamBound]) -> hir::TyParamBounds {
bounds.iter().map(|bound| self.lower_ty_param_bound(bound)).collect()
}
fn lower_block(&mut self, b: &Block, targeted_by_break: bool) -> P<hir::Block> {
let mut expr = None;
let mut stmts = vec![];
for (index, stmt) in b.stmts.iter().enumerate() {
if index == b.stmts.len() - 1 {
if let StmtKind::Expr(ref e) = stmt.node {
expr = Some(P(self.lower_expr(e)));
} else {
stmts.extend(self.lower_stmt(stmt));
}
} else {
stmts.extend(self.lower_stmt(stmt));
}
}
P(hir::Block {
id: self.lower_node_id(b.id),
stmts: stmts.into(),
expr,
rules: self.lower_block_check_mode(&b.rules),
span: b.span,
targeted_by_break,
})
}
fn lower_item_kind(&mut self,
id: NodeId,
name: &mut Name,
attrs: &hir::HirVec<Attribute>,
vis: &mut hir::Visibility,
i: &ItemKind)
-> hir::Item_ {
match *i {
ItemKind::ExternCrate(string) => hir::ItemExternCrate(string),
ItemKind::Use(ref view_path) => {
let path = match view_path.node {
ViewPathSimple(_, ref path) => path,
ViewPathGlob(ref path) => path,
ViewPathList(ref path, ref path_list_idents) => {
for &Spanned { node: ref import, span } in path_list_idents {
// `use a::{self as x, b as y};` lowers to
// `use a as x; use a::b as y;`
let mut ident = import.name;
let suffix = if ident.name == keywords::SelfValue.name() {
if let Some(last) = path.segments.last() {
ident = last.identifier;
}
None
} else {
Some(ident.name)
};
let mut path = self.lower_path_extra(import.id, path, suffix,
ParamMode::Explicit, true);
path.span = span;
self.allocate_hir_id_counter(import.id, import);
self.with_hir_id_owner(import.id, |this| {
let vis = match *vis {
hir::Visibility::Public => hir::Visibility::Public,
hir::Visibility::Crate => hir::Visibility::Crate,
hir::Visibility::Inherited => hir::Visibility::Inherited,
hir::Visibility::Restricted { ref path, id: _ } => {
hir::Visibility::Restricted {
path: path.clone(),
// We are allocating a new NodeId here
id: this.next_id(),
}
}
};
this.items.insert(import.id, hir::Item {
id: import.id,
name: import.rename.unwrap_or(ident).name,
attrs: attrs.clone(),
node: hir::ItemUse(P(path), hir::UseKind::Single),
vis,
span,
});
});
}
path
}
};
let path = P(self.lower_path(id, path, ParamMode::Explicit, true));
let kind = match view_path.node {
ViewPathSimple(ident, _) => {
*name = ident.name;
hir::UseKind::Single
}
ViewPathGlob(_) => {
hir::UseKind::Glob
}
ViewPathList(..) => {
// Privatize the degenerate import base, used only to check
// the stability of `use a::{};`, to avoid it showing up as
// a reexport by accident when `pub`, e.g. in documentation.
*vis = hir::Inherited;
hir::UseKind::ListStem
}
};
hir::ItemUse(path, kind)
}
ItemKind::Static(ref t, m, ref e) => {
let value = self.lower_expr(e);
hir::ItemStatic(self.lower_ty(t),
self.lower_mutability(m),
self.record_body(value, None))
}
ItemKind::Const(ref t, ref e) => {
let value = self.lower_expr(e);
hir::ItemConst(self.lower_ty(t),
self.record_body(value, None))
}
ItemKind::Fn(ref decl, unsafety, constness, abi, ref generics, ref body) => {
self.with_new_scopes(|this| {
let body = this.lower_block(body, false);
let body = this.expr_block(body, ThinVec::new());
let body_id = this.record_body(body, Some(decl));
hir::ItemFn(this.lower_fn_decl(decl),
this.lower_unsafety(unsafety),
this.lower_constness(constness),
abi,
this.lower_generics(generics),
body_id)
})
}
ItemKind::Mod(ref m) => hir::ItemMod(self.lower_mod(m)),
ItemKind::ForeignMod(ref nm) => hir::ItemForeignMod(self.lower_foreign_mod(nm)),
ItemKind::GlobalAsm(ref ga) => hir::ItemGlobalAsm(self.lower_global_asm(ga)),
ItemKind::Ty(ref t, ref generics) => {
hir::ItemTy(self.lower_ty(t), self.lower_generics(generics))
}
ItemKind::Enum(ref enum_definition, ref generics) => {
hir::ItemEnum(hir::EnumDef {
variants: enum_definition.variants
.iter()
.map(|x| self.lower_variant(x))
.collect(),
},
self.lower_generics(generics))
}
ItemKind::Struct(ref struct_def, ref generics) => {
let struct_def = self.lower_variant_data(struct_def);
hir::ItemStruct(struct_def, self.lower_generics(generics))
}
ItemKind::Union(ref vdata, ref generics) => {
let vdata = self.lower_variant_data(vdata);
hir::ItemUnion(vdata, self.lower_generics(generics))
}
ItemKind::DefaultImpl(unsafety, ref trait_ref) => {
let trait_ref = self.lower_trait_ref(trait_ref);
if let Def::Trait(def_id) = trait_ref.path.def {
self.trait_default_impl.insert(def_id, id);
}
hir::ItemDefaultImpl(self.lower_unsafety(unsafety),
trait_ref)
}
ItemKind::Impl(unsafety,
polarity,
defaultness,
ref generics,
ref ifce,
ref ty,
ref impl_items) => {
let new_impl_items = impl_items.iter()
.map(|item| self.lower_impl_item_ref(item))
.collect();
let ifce = ifce.as_ref().map(|trait_ref| self.lower_trait_ref(trait_ref));
if let Some(ref trait_ref) = ifce {
if let Def::Trait(def_id) = trait_ref.path.def {
self.trait_impls.entry(def_id).or_insert(vec![]).push(id);
}
}
hir::ItemImpl(self.lower_unsafety(unsafety),
self.lower_impl_polarity(polarity),
self.lower_defaultness(defaultness, true /* [1] */),
self.lower_generics(generics),
ifce,
self.lower_ty(ty),
new_impl_items)
}
ItemKind::Trait(unsafety, ref generics, ref bounds, ref items) => {
let bounds = self.lower_bounds(bounds);
let items = items.iter().map(|item| self.lower_trait_item_ref(item)).collect();
hir::ItemTrait(self.lower_unsafety(unsafety),
self.lower_generics(generics),
bounds,
items)
}
ItemKind::MacroDef(..) | ItemKind::Mac(..) => panic!("Shouldn't still be around"),
}
// [1] `defaultness.has_value()` is never called for an `impl`, always `true` in order to
// not cause an assertion failure inside the `lower_defaultness` function
}
fn lower_trait_item(&mut self, i: &TraitItem) -> hir::TraitItem {
self.with_parent_def(i.id, |this| {
hir::TraitItem {
id: this.lower_node_id(i.id),
name: this.lower_ident(i.ident),
attrs: this.lower_attrs(&i.attrs),
node: match i.node {
TraitItemKind::Const(ref ty, ref default) => {
hir::TraitItemKind::Const(this.lower_ty(ty),
default.as_ref().map(|x| {
let value = this.lower_expr(x);
this.record_body(value, None)
}))
}
TraitItemKind::Method(ref sig, None) => {
let names = this.lower_fn_args_to_names(&sig.decl);
hir::TraitItemKind::Method(this.lower_method_sig(sig),
hir::TraitMethod::Required(names))
}
TraitItemKind::Method(ref sig, Some(ref body)) => {
let body = this.lower_block(body, false);
let expr = this.expr_block(body, ThinVec::new());
let body_id = this.record_body(expr, Some(&sig.decl));
hir::TraitItemKind::Method(this.lower_method_sig(sig),
hir::TraitMethod::Provided(body_id))
}
TraitItemKind::Type(ref bounds, ref default) => {
hir::TraitItemKind::Type(this.lower_bounds(bounds),
default.as_ref().map(|x| this.lower_ty(x)))
}
TraitItemKind::Macro(..) => panic!("Shouldn't exist any more"),
},
span: i.span,
}
})
}
fn lower_trait_item_ref(&mut self, i: &TraitItem) -> hir::TraitItemRef {
let (kind, has_default) = match i.node {
TraitItemKind::Const(_, ref default) => {
(hir::AssociatedItemKind::Const, default.is_some())
}
TraitItemKind::Type(_, ref default) => {
(hir::AssociatedItemKind::Type, default.is_some())
}
TraitItemKind::Method(ref sig, ref default) => {
(hir::AssociatedItemKind::Method {
has_self: sig.decl.has_self(),
}, default.is_some())
}
TraitItemKind::Macro(..) => unimplemented!(),
};
hir::TraitItemRef {
id: hir::TraitItemId { node_id: i.id },
name: self.lower_ident(i.ident),
span: i.span,
defaultness: self.lower_defaultness(Defaultness::Default, has_default),
kind,
}
}
fn lower_impl_item(&mut self, i: &ImplItem) -> hir::ImplItem {
self.with_parent_def(i.id, |this| {
hir::ImplItem {
id: this.lower_node_id(i.id),
name: this.lower_ident(i.ident),
attrs: this.lower_attrs(&i.attrs),
vis: this.lower_visibility(&i.vis, None),
defaultness: this.lower_defaultness(i.defaultness, true /* [1] */),
node: match i.node {
ImplItemKind::Const(ref ty, ref expr) => {
let value = this.lower_expr(expr);
let body_id = this.record_body(value, None);
hir::ImplItemKind::Const(this.lower_ty(ty), body_id)
}
ImplItemKind::Method(ref sig, ref body) => {
let body = this.lower_block(body, false);
let expr = this.expr_block(body, ThinVec::new());
let body_id = this.record_body(expr, Some(&sig.decl));
hir::ImplItemKind::Method(this.lower_method_sig(sig), body_id)
}
ImplItemKind::Type(ref ty) => hir::ImplItemKind::Type(this.lower_ty(ty)),
ImplItemKind::Macro(..) => panic!("Shouldn't exist any more"),
},
span: i.span,
}
})
// [1] since `default impl` is not yet implemented, this is always true in impls
}
fn lower_impl_item_ref(&mut self, i: &ImplItem) -> hir::ImplItemRef {
hir::ImplItemRef {
id: hir::ImplItemId { node_id: i.id },
name: self.lower_ident(i.ident),
span: i.span,
vis: self.lower_visibility(&i.vis, Some(i.id)),
defaultness: self.lower_defaultness(i.defaultness, true /* [1] */),
kind: match i.node {
ImplItemKind::Const(..) => hir::AssociatedItemKind::Const,
ImplItemKind::Type(..) => hir::AssociatedItemKind::Type,
ImplItemKind::Method(ref sig, _) => hir::AssociatedItemKind::Method {
has_self: sig.decl.has_self(),
},
ImplItemKind::Macro(..) => unimplemented!(),
},
}
// [1] since `default impl` is not yet implemented, this is always true in impls
}
fn lower_mod(&mut self, m: &Mod) -> hir::Mod {
hir::Mod {
inner: m.inner,
item_ids: m.items.iter().flat_map(|x| self.lower_item_id(x)).collect(),
}
}
fn lower_item_id(&mut self, i: &Item) -> SmallVector<hir::ItemId> {
match i.node {
ItemKind::Use(ref view_path) => {
if let ViewPathList(_, ref imports) = view_path.node {
return iter::once(i.id).chain(imports.iter().map(|import| import.node.id))
.map(|id| hir::ItemId { id: id }).collect();
}
}
ItemKind::MacroDef(..) => return SmallVector::new(),
_ => {}
}
SmallVector::one(hir::ItemId { id: i.id })
}
pub fn lower_item(&mut self, i: &Item) -> Option<hir::Item> {
let mut name = i.ident.name;
let mut vis = self.lower_visibility(&i.vis, None);
let attrs = self.lower_attrs(&i.attrs);
if let ItemKind::MacroDef(ref def) = i.node {
if !def.legacy || i.attrs.iter().any(|attr| attr.path == "macro_export") {
self.exported_macros.push(hir::MacroDef {
name,
vis,
attrs,
id: i.id,
span: i.span,
body: def.stream(),
legacy: def.legacy,
});
}
return None;
}
let node = self.with_parent_def(i.id, |this| {
this.lower_item_kind(i.id, &mut name, &attrs, &mut vis, &i.node)
});
Some(hir::Item {
id: self.lower_node_id(i.id),
name,
attrs,
node,
vis,
span: i.span,
})
}
fn lower_foreign_item(&mut self, i: &ForeignItem) -> hir::ForeignItem {
self.with_parent_def(i.id, |this| {
hir::ForeignItem {
id: this.lower_node_id(i.id),
name: i.ident.name,
attrs: this.lower_attrs(&i.attrs),
node: match i.node {
ForeignItemKind::Fn(ref fdec, ref generics) => {
hir::ForeignItemFn(this.lower_fn_decl(fdec),
this.lower_fn_args_to_names(fdec),
this.lower_generics(generics))
}
ForeignItemKind::Static(ref t, m) => {
hir::ForeignItemStatic(this.lower_ty(t), m)
}
},
vis: this.lower_visibility(&i.vis, None),
span: i.span,
}
})
}
fn lower_method_sig(&mut self, sig: &MethodSig) -> hir::MethodSig {
hir::MethodSig {
generics: self.lower_generics(&sig.generics),
abi: sig.abi,
unsafety: self.lower_unsafety(sig.unsafety),
constness: self.lower_constness(sig.constness),
decl: self.lower_fn_decl(&sig.decl),
}
}
fn lower_unsafety(&mut self, u: Unsafety) -> hir::Unsafety {
match u {
Unsafety::Unsafe => hir::Unsafety::Unsafe,
Unsafety::Normal => hir::Unsafety::Normal,
}
}
fn lower_constness(&mut self, c: Spanned<Constness>) -> hir::Constness {
match c.node {
Constness::Const => hir::Constness::Const,
Constness::NotConst => hir::Constness::NotConst,
}
}
fn lower_unop(&mut self, u: UnOp) -> hir::UnOp {
match u {
UnOp::Deref => hir::UnDeref,
UnOp::Not => hir::UnNot,
UnOp::Neg => hir::UnNeg,
}
}
fn lower_binop(&mut self, b: BinOp) -> hir::BinOp {
Spanned {
node: match b.node {
BinOpKind::Add => hir::BiAdd,
BinOpKind::Sub => hir::BiSub,
BinOpKind::Mul => hir::BiMul,
BinOpKind::Div => hir::BiDiv,
BinOpKind::Rem => hir::BiRem,
BinOpKind::And => hir::BiAnd,
BinOpKind::Or => hir::BiOr,
BinOpKind::BitXor => hir::BiBitXor,
BinOpKind::BitAnd => hir::BiBitAnd,
BinOpKind::BitOr => hir::BiBitOr,
BinOpKind::Shl => hir::BiShl,
BinOpKind::Shr => hir::BiShr,
BinOpKind::Eq => hir::BiEq,
BinOpKind::Lt => hir::BiLt,
BinOpKind::Le => hir::BiLe,
BinOpKind::Ne => hir::BiNe,
BinOpKind::Ge => hir::BiGe,
BinOpKind::Gt => hir::BiGt,
},
span: b.span,
}
}
fn lower_pat(&mut self, p: &Pat) -> P<hir::Pat> {
P(hir::Pat {
id: self.lower_node_id(p.id),
node: match p.node {
PatKind::Wild => hir::PatKind::Wild,
PatKind::Ident(ref binding_mode, pth1, ref sub) => {
self.with_parent_def(p.id, |this| {
match this.resolver.get_resolution(p.id).map(|d| d.base_def()) {
// `None` can occur in body-less function signatures
def @ None | def @ Some(Def::Local(_)) => {
let def_id = def.map(|d| d.def_id()).unwrap_or_else(|| {
this.resolver.definitions().local_def_id(p.id)
});
hir::PatKind::Binding(this.lower_binding_mode(binding_mode),
def_id,
respan(pth1.span, pth1.node.name),
sub.as_ref().map(|x| this.lower_pat(x)))
}
Some(def) => {
hir::PatKind::Path(hir::QPath::Resolved(None, P(hir::Path {
span: pth1.span,
def,
segments: hir_vec![
hir::PathSegment::from_name(pth1.node.name)
],
})))
}
}
})
}
PatKind::Lit(ref e) => hir::PatKind::Lit(P(self.lower_expr(e))),
PatKind::TupleStruct(ref path, ref pats, ddpos) => {
let qpath = self.lower_qpath(p.id, &None, path, ParamMode::Optional);
hir::PatKind::TupleStruct(qpath,
pats.iter().map(|x| self.lower_pat(x)).collect(),
ddpos)
}
PatKind::Path(ref qself, ref path) => {
hir::PatKind::Path(self.lower_qpath(p.id, qself, path, ParamMode::Optional))
}
PatKind::Struct(ref path, ref fields, etc) => {
let qpath = self.lower_qpath(p.id, &None, path, ParamMode::Optional);
let fs = fields.iter()
.map(|f| {
Spanned {
span: f.span,
node: hir::FieldPat {
name: self.lower_ident(f.node.ident),
pat: self.lower_pat(&f.node.pat),
is_shorthand: f.node.is_shorthand,
},
}
})
.collect();
hir::PatKind::Struct(qpath, fs, etc)
}
PatKind::Tuple(ref elts, ddpos) => {
hir::PatKind::Tuple(elts.iter().map(|x| self.lower_pat(x)).collect(), ddpos)
}
PatKind::Box(ref inner) => hir::PatKind::Box(self.lower_pat(inner)),
PatKind::Ref(ref inner, mutbl) => {
hir::PatKind::Ref(self.lower_pat(inner), self.lower_mutability(mutbl))
}
PatKind::Range(ref e1, ref e2, ref end) => {
hir::PatKind::Range(P(self.lower_expr(e1)),
P(self.lower_expr(e2)),
self.lower_range_end(end))
}
PatKind::Slice(ref before, ref slice, ref after) => {
hir::PatKind::Slice(before.iter().map(|x| self.lower_pat(x)).collect(),
slice.as_ref().map(|x| self.lower_pat(x)),
after.iter().map(|x| self.lower_pat(x)).collect())
}
PatKind::Mac(_) => panic!("Shouldn't exist here"),
},
span: p.span,
})
}
fn lower_range_end(&mut self, e: &RangeEnd) -> hir::RangeEnd {
match *e {
RangeEnd::Included => hir::RangeEnd::Included,
RangeEnd::Excluded => hir::RangeEnd::Excluded,
}
}
fn lower_expr(&mut self, e: &Expr) -> hir::Expr {
let kind = match e.node {
// Issue #22181:
// Eventually a desugaring for `box EXPR`
// (similar to the desugaring above for `in PLACE BLOCK`)
// should go here, desugaring
//
// to:
//
// let mut place = BoxPlace::make_place();
// let raw_place = Place::pointer(&mut place);
// let value = $value;
// unsafe {
// ::std::ptr::write(raw_place, value);
// Boxed::finalize(place)
// }
//
// But for now there are type-inference issues doing that.
ExprKind::Box(ref inner) => {
hir::ExprBox(P(self.lower_expr(inner)))
}
// Desugar ExprBox: `in (PLACE) EXPR`
ExprKind::InPlace(ref placer, ref value_expr) => {
// to:
//
// let p = PLACE;
// let mut place = Placer::make_place(p);
// let raw_place = Place::pointer(&mut place);
// push_unsafe!({
// std::intrinsics::move_val_init(raw_place, pop_unsafe!( EXPR ));
// InPlace::finalize(place)
// })
let placer_expr = P(self.lower_expr(placer));
let value_expr = P(self.lower_expr(value_expr));
let placer_ident = self.str_to_ident("placer");
let place_ident = self.str_to_ident("place");
let p_ptr_ident = self.str_to_ident("p_ptr");
let make_place = ["ops", "Placer", "make_place"];
let place_pointer = ["ops", "Place", "pointer"];
let move_val_init = ["intrinsics", "move_val_init"];
let inplace_finalize = ["ops", "InPlace", "finalize"];
let unstable_span = self.allow_internal_unstable("<-", e.span);
let make_call = |this: &mut LoweringContext, p, args| {
let path = P(this.expr_std_path(unstable_span, p, ThinVec::new()));
P(this.expr_call(e.span, path, args))
};
let mk_stmt_let = |this: &mut LoweringContext, bind, expr| {
this.stmt_let(e.span, false, bind, expr)
};
let mk_stmt_let_mut = |this: &mut LoweringContext, bind, expr| {
this.stmt_let(e.span, true, bind, expr)
};
// let placer = <placer_expr> ;
let (s1, placer_binding) = {
mk_stmt_let(self, placer_ident, placer_expr)
};
// let mut place = Placer::make_place(placer);
let (s2, place_binding) = {
let placer = self.expr_ident(e.span, placer_ident, placer_binding);
let call = make_call(self, &make_place, hir_vec![placer]);
mk_stmt_let_mut(self, place_ident, call)
};
// let p_ptr = Place::pointer(&mut place);
let (s3, p_ptr_binding) = {
let agent = P(self.expr_ident(e.span, place_ident, place_binding));
let args = hir_vec![self.expr_mut_addr_of(e.span, agent)];
let call = make_call(self, &place_pointer, args);
mk_stmt_let(self, p_ptr_ident, call)
};
// pop_unsafe!(EXPR));
let pop_unsafe_expr = {
self.signal_block_expr(hir_vec![],
value_expr,
e.span,
hir::PopUnsafeBlock(hir::CompilerGenerated),
ThinVec::new())
};
// push_unsafe!({
// std::intrinsics::move_val_init(raw_place, pop_unsafe!( EXPR ));
// InPlace::finalize(place)
// })
let expr = {
let ptr = self.expr_ident(e.span, p_ptr_ident, p_ptr_binding);
let call_move_val_init =
hir::StmtSemi(
make_call(self, &move_val_init, hir_vec![ptr, pop_unsafe_expr]),
self.next_id());
let call_move_val_init = respan(e.span, call_move_val_init);
let place = self.expr_ident(e.span, place_ident, place_binding);
let call = make_call(self, &inplace_finalize, hir_vec![place]);
P(self.signal_block_expr(hir_vec![call_move_val_init],
call,
e.span,
hir::PushUnsafeBlock(hir::CompilerGenerated),
ThinVec::new()))
};
let block = self.block_all(e.span, hir_vec![s1, s2, s3], Some(expr));
hir::ExprBlock(P(block))
}
ExprKind::Array(ref exprs) => {
hir::ExprArray(exprs.iter().map(|x| self.lower_expr(x)).collect())
}
ExprKind::Repeat(ref expr, ref count) => {
let expr = P(self.lower_expr(expr));
let count = self.lower_expr(count);
hir::ExprRepeat(expr, self.record_body(count, None))
}
ExprKind::Tup(ref elts) => {
hir::ExprTup(elts.iter().map(|x| self.lower_expr(x)).collect())
}
ExprKind::Call(ref f, ref args) => {
let f = P(self.lower_expr(f));
hir::ExprCall(f, args.iter().map(|x| self.lower_expr(x)).collect())
}
ExprKind::MethodCall(i, ref tps, ref args) => {
let tps = tps.iter().map(|x| self.lower_ty(x)).collect();
let args = args.iter().map(|x| self.lower_expr(x)).collect();
hir::ExprMethodCall(respan(i.span, self.lower_ident(i.node)), tps, args)
}
ExprKind::Binary(binop, ref lhs, ref rhs) => {
let binop = self.lower_binop(binop);
let lhs = P(self.lower_expr(lhs));
let rhs = P(self.lower_expr(rhs));
hir::ExprBinary(binop, lhs, rhs)
}
ExprKind::Unary(op, ref ohs) => {
let op = self.lower_unop(op);
let ohs = P(self.lower_expr(ohs));
hir::ExprUnary(op, ohs)
}
ExprKind::Lit(ref l) => hir::ExprLit(P((**l).clone())),
ExprKind::Cast(ref expr, ref ty) => {
let expr = P(self.lower_expr(expr));
hir::ExprCast(expr, self.lower_ty(ty))
}
ExprKind::Type(ref expr, ref ty) => {
let expr = P(self.lower_expr(expr));
hir::ExprType(expr, self.lower_ty(ty))
}
ExprKind::AddrOf(m, ref ohs) => {
let m = self.lower_mutability(m);
let ohs = P(self.lower_expr(ohs));
hir::ExprAddrOf(m, ohs)
}
// More complicated than you might expect because the else branch
// might be `if let`.
ExprKind::If(ref cond, ref blk, ref else_opt) => {
let else_opt = else_opt.as_ref().map(|els| {
match els.node {
ExprKind::IfLet(..) => {
// wrap the if-let expr in a block
let span = els.span;
let els = P(self.lower_expr(els));
let id = self.next_id();
let blk = P(hir::Block {
stmts: hir_vec![],
expr: Some(els),
id,
rules: hir::DefaultBlock,
span,
targeted_by_break: false,
});
P(self.expr_block(blk, ThinVec::new()))
}
_ => P(self.lower_expr(els)),
}
});
let then_blk = self.lower_block(blk, false);
let then_expr = self.expr_block(then_blk, ThinVec::new());
hir::ExprIf(P(self.lower_expr(cond)), P(then_expr), else_opt)
}
ExprKind::While(ref cond, ref body, opt_ident) => {
self.with_loop_scope(e.id, |this|
hir::ExprWhile(
this.with_loop_condition_scope(|this| P(this.lower_expr(cond))),
this.lower_block(body, false),
this.lower_opt_sp_ident(opt_ident)))
}
ExprKind::Loop(ref body, opt_ident) => {
self.with_loop_scope(e.id, |this|
hir::ExprLoop(this.lower_block(body, false),
this.lower_opt_sp_ident(opt_ident),
hir::LoopSource::Loop))
}
ExprKind::Catch(ref body) => {
self.with_catch_scope(body.id, |this|
hir::ExprBlock(this.lower_block(body, true)))
}
ExprKind::Match(ref expr, ref arms) => {
hir::ExprMatch(P(self.lower_expr(expr)),
arms.iter().map(|x| self.lower_arm(x)).collect(),
hir::MatchSource::Normal)
}
ExprKind::Closure(capture_clause, ref decl, ref body, fn_decl_span) => {
self.with_new_scopes(|this| {
this.with_parent_def(e.id, |this| {
let expr = this.lower_expr(body);
hir::ExprClosure(this.lower_capture_clause(capture_clause),
this.lower_fn_decl(decl),
this.record_body(expr, Some(decl)),
fn_decl_span)
})
})
}
ExprKind::Block(ref blk) => hir::ExprBlock(self.lower_block(blk, false)),
ExprKind::Assign(ref el, ref er) => {
hir::ExprAssign(P(self.lower_expr(el)), P(self.lower_expr(er)))
}
ExprKind::AssignOp(op, ref el, ref er) => {
hir::ExprAssignOp(self.lower_binop(op),
P(self.lower_expr(el)),
P(self.lower_expr(er)))
}
ExprKind::Field(ref el, ident) => {
hir::ExprField(P(self.lower_expr(el)),
respan(ident.span, self.lower_ident(ident.node)))
}
ExprKind::TupField(ref el, ident) => {
hir::ExprTupField(P(self.lower_expr(el)), ident)
}
ExprKind::Index(ref el, ref er) => {
hir::ExprIndex(P(self.lower_expr(el)), P(self.lower_expr(er)))
}
ExprKind::Range(ref e1, ref e2, lims) => {
use syntax::ast::RangeLimits::*;
let path = match (e1, e2, lims) {
(&None, &None, HalfOpen) => "RangeFull",
(&Some(..), &None, HalfOpen) => "RangeFrom",
(&None, &Some(..), HalfOpen) => "RangeTo",
(&Some(..), &Some(..), HalfOpen) => "Range",
(&None, &Some(..), Closed) => "RangeToInclusive",
(&Some(..), &Some(..), Closed) => "RangeInclusive",
(_, &None, Closed) =>
panic!(self.diagnostic().span_fatal(
e.span, "inclusive range with no end")),
};
let fields =
e1.iter().map(|e| ("start", e)).chain(e2.iter().map(|e| ("end", e)))
.map(|(s, e)| {
let expr = P(self.lower_expr(&e));
let unstable_span = self.allow_internal_unstable("...", e.span);
self.field(Symbol::intern(s), expr, unstable_span)
}).collect::<P<[hir::Field]>>();
let is_unit = fields.is_empty();
let unstable_span = self.allow_internal_unstable("...", e.span);
let struct_path =
iter::once("ops").chain(iter::once(path))
.collect::<Vec<_>>();
let struct_path = self.std_path(unstable_span, &struct_path, is_unit);
let struct_path = hir::QPath::Resolved(None, P(struct_path));
return hir::Expr {
id: self.lower_node_id(e.id),
node: if is_unit {
hir::ExprPath(struct_path)
} else {
hir::ExprStruct(struct_path, fields, None)
},
span: unstable_span,
attrs: e.attrs.clone(),
};
}
ExprKind::Path(ref qself, ref path) => {
hir::ExprPath(self.lower_qpath(e.id, qself, path, ParamMode::Optional))
}
ExprKind::Break(opt_ident, ref opt_expr) => {
let label_result = if self.is_in_loop_condition && opt_ident.is_none() {
hir::Destination {
ident: opt_ident,
target_id: hir::ScopeTarget::Loop(
Err(hir::LoopIdError::UnlabeledCfInWhileCondition).into()),
}
} else {
self.lower_loop_destination(opt_ident.map(|ident| (e.id, ident)))
};
hir::ExprBreak(
label_result,
opt_expr.as_ref().map(|x| P(self.lower_expr(x))))
}
ExprKind::Continue(opt_ident) =>
hir::ExprAgain(
if self.is_in_loop_condition && opt_ident.is_none() {
hir::Destination {
ident: opt_ident,
target_id: hir::ScopeTarget::Loop(Err(
hir::LoopIdError::UnlabeledCfInWhileCondition).into()),
}
} else {
self.lower_loop_destination(opt_ident.map( |ident| (e.id, ident)))
}),
ExprKind::Ret(ref e) => hir::ExprRet(e.as_ref().map(|x| P(self.lower_expr(x)))),
ExprKind::InlineAsm(ref asm) => {
let hir_asm = hir::InlineAsm {
inputs: asm.inputs.iter().map(|&(ref c, _)| c.clone()).collect(),
outputs: asm.outputs.iter().map(|out| {
hir::InlineAsmOutput {
constraint: out.constraint.clone(),
is_rw: out.is_rw,
is_indirect: out.is_indirect,
}
}).collect(),
asm: asm.asm.clone(),
asm_str_style: asm.asm_str_style,
clobbers: asm.clobbers.clone().into(),
volatile: asm.volatile,
alignstack: asm.alignstack,
dialect: asm.dialect,
ctxt: asm.ctxt,
};
let outputs =
asm.outputs.iter().map(|out| self.lower_expr(&out.expr)).collect();
let inputs =
asm.inputs.iter().map(|&(_, ref input)| self.lower_expr(input)).collect();
hir::ExprInlineAsm(P(hir_asm), outputs, inputs)
}
ExprKind::Struct(ref path, ref fields, ref maybe_expr) => {
hir::ExprStruct(self.lower_qpath(e.id, &None, path, ParamMode::Optional),
fields.iter().map(|x| self.lower_field(x)).collect(),
maybe_expr.as_ref().map(|x| P(self.lower_expr(x))))
}
ExprKind::Paren(ref ex) => {
let mut ex = self.lower_expr(ex);
// include parens in span, but only if it is a super-span.
if e.span.contains(ex.span) {
ex.span = e.span;
}
// merge attributes into the inner expression.
let mut attrs = e.attrs.clone();
attrs.extend::<Vec<_>>(ex.attrs.into());
ex.attrs = attrs;
return ex;
}
// Desugar ExprIfLet
// From: `if let <pat> = <sub_expr> <body> [<else_opt>]`
ExprKind::IfLet(ref pat, ref sub_expr, ref body, ref else_opt) => {
// to:
//
// match <sub_expr> {
// <pat> => <body>,
// _ => [<else_opt> | ()]
// }
let mut arms = vec![];
// `<pat> => <body>`
{
let body = self.lower_block(body, false);
let body_expr = P(self.expr_block(body, ThinVec::new()));
let pat = self.lower_pat(pat);
arms.push(self.arm(hir_vec![pat], body_expr));
}
// _ => [<else_opt>|()]
{
let wildcard_arm: Option<&Expr> = else_opt.as_ref().map(|p| &**p);
let wildcard_pattern = self.pat_wild(e.span);
let body = if let Some(else_expr) = wildcard_arm {
P(self.lower_expr(else_expr))
} else {
self.expr_tuple(e.span, hir_vec![])
};
arms.push(self.arm(hir_vec![wildcard_pattern], body));
}
let contains_else_clause = else_opt.is_some();
let sub_expr = P(self.lower_expr(sub_expr));
hir::ExprMatch(
sub_expr,
arms.into(),
hir::MatchSource::IfLetDesugar {
contains_else_clause,
})
}
// Desugar ExprWhileLet
// From: `[opt_ident]: while let <pat> = <sub_expr> <body>`
ExprKind::WhileLet(ref pat, ref sub_expr, ref body, opt_ident) => {
// to:
//
// [opt_ident]: loop {
// match <sub_expr> {
// <pat> => <body>,
// _ => break
// }
// }
// Note that the block AND the condition are evaluated in the loop scope.
// This is done to allow `break` from inside the condition of the loop.
let (body, break_expr, sub_expr) = self.with_loop_scope(e.id, |this| (
this.lower_block(body, false),
this.expr_break(e.span, ThinVec::new()),
this.with_loop_condition_scope(|this| P(this.lower_expr(sub_expr))),
));
// `<pat> => <body>`
let pat_arm = {
let body_expr = P(self.expr_block(body, ThinVec::new()));
let pat = self.lower_pat(pat);
self.arm(hir_vec![pat], body_expr)
};
// `_ => break`
let break_arm = {
let pat_under = self.pat_wild(e.span);
self.arm(hir_vec![pat_under], break_expr)
};
// `match <sub_expr> { ... }`
let arms = hir_vec![pat_arm, break_arm];
let match_expr = self.expr(e.span,
hir::ExprMatch(sub_expr,
arms,
hir::MatchSource::WhileLetDesugar),
ThinVec::new());
// `[opt_ident]: loop { ... }`
let loop_block = P(self.block_expr(P(match_expr)));
let loop_expr = hir::ExprLoop(loop_block, self.lower_opt_sp_ident(opt_ident),
hir::LoopSource::WhileLet);
// add attributes to the outer returned expr node
loop_expr
}
// Desugar ExprForLoop
// From: `[opt_ident]: for <pat> in <head> <body>`
ExprKind::ForLoop(ref pat, ref head, ref body, opt_ident) => {
// to:
//
// {
// let result = match ::std::iter::IntoIterator::into_iter(<head>) {
// mut iter => {
// [opt_ident]: loop {
// let mut __next;
// match ::std::iter::Iterator::next(&mut iter) {
// ::std::option::Option::Some(val) => __next = val,
// ::std::option::Option::None => break
// };
// let <pat> = __next;
// StmtExpr(<body>);
// }
// }
// };
// result
// }
// expand <head>
let head = self.lower_expr(head);
let iter = self.str_to_ident("iter");
let next_ident = self.str_to_ident("__next");
let next_pat = self.pat_ident_binding_mode(e.span,
next_ident,
hir::BindByValue(hir::MutMutable));
// `::std::option::Option::Some(val) => next = val`
let pat_arm = {
let val_ident = self.str_to_ident("val");
let val_pat = self.pat_ident(e.span, val_ident);
let val_expr = P(self.expr_ident(e.span, val_ident, val_pat.id));
let next_expr = P(self.expr_ident(e.span, next_ident, next_pat.id));
let assign = P(self.expr(e.span,
hir::ExprAssign(next_expr, val_expr),
ThinVec::new()));
let some_pat = self.pat_some(e.span, val_pat);
self.arm(hir_vec![some_pat], assign)
};
// `::std::option::Option::None => break`
let break_arm = {
let break_expr = self.with_loop_scope(e.id, |this|
this.expr_break(e.span, ThinVec::new()));
let pat = self.pat_none(e.span);
self.arm(hir_vec![pat], break_expr)
};
// `mut iter`
let iter_pat = self.pat_ident_binding_mode(e.span, iter,
hir::BindByValue(hir::MutMutable));
// `match ::std::iter::Iterator::next(&mut iter) { ... }`
let match_expr = {
let iter = P(self.expr_ident(e.span, iter, iter_pat.id));
let ref_mut_iter = self.expr_mut_addr_of(e.span, iter);
let next_path = &["iter", "Iterator", "next"];
let next_path = P(self.expr_std_path(e.span, next_path, ThinVec::new()));
let next_expr = P(self.expr_call(e.span, next_path,
hir_vec![ref_mut_iter]));
let arms = hir_vec![pat_arm, break_arm];
P(self.expr(e.span,
hir::ExprMatch(next_expr, arms,
hir::MatchSource::ForLoopDesugar),
ThinVec::new()))
};
let match_stmt = respan(e.span, hir::StmtExpr(match_expr, self.next_id()));
let next_expr = P(self.expr_ident(e.span, next_ident, next_pat.id));
// `let mut __next`
let next_let = self.stmt_let_pat(e.span,
None,
next_pat,
hir::LocalSource::ForLoopDesugar);
// `let <pat> = __next`
let pat = self.lower_pat(pat);
let pat_let = self.stmt_let_pat(e.span,
Some(next_expr),
pat,
hir::LocalSource::ForLoopDesugar);
let body_block = self.with_loop_scope(e.id,
|this| this.lower_block(body, false));
let body_expr = P(self.expr_block(body_block, ThinVec::new()));
let body_stmt = respan(e.span, hir::StmtExpr(body_expr, self.next_id()));
let loop_block = P(self.block_all(e.span,
hir_vec![next_let,
match_stmt,
pat_let,
body_stmt],
None));
// `[opt_ident]: loop { ... }`
let loop_expr = hir::ExprLoop(loop_block, self.lower_opt_sp_ident(opt_ident),
hir::LoopSource::ForLoop);
let loop_expr = P(hir::Expr {
id: self.lower_node_id(e.id),
node: loop_expr,
span: e.span,
attrs: ThinVec::new(),
});
// `mut iter => { ... }`
let iter_arm = self.arm(hir_vec![iter_pat], loop_expr);
// `match ::std::iter::IntoIterator::into_iter(<head>) { ... }`
let into_iter_expr = {
let into_iter_path = &["iter", "IntoIterator", "into_iter"];
let into_iter = P(self.expr_std_path(e.span, into_iter_path,
ThinVec::new()));
P(self.expr_call(e.span, into_iter, hir_vec![head]))
};
let match_expr = P(self.expr_match(e.span,
into_iter_expr,
hir_vec![iter_arm],
hir::MatchSource::ForLoopDesugar));
// `{ let _result = ...; _result }`
// underscore prevents an unused_variables lint if the head diverges
let result_ident = self.str_to_ident("_result");
let (let_stmt, let_stmt_binding) =
self.stmt_let(e.span, false, result_ident, match_expr);
let result = P(self.expr_ident(e.span, result_ident, let_stmt_binding));
let block = P(self.block_all(e.span, hir_vec![let_stmt], Some(result)));
// add the attributes to the outer returned expr node
return self.expr_block(block, e.attrs.clone());
}
// Desugar ExprKind::Try
// From: `<expr>?`
ExprKind::Try(ref sub_expr) => {
// to:
//
// match Try::into_result(<expr>) {
// Ok(val) => #[allow(unreachable_code)] val,
// Err(err) => #[allow(unreachable_code)]
// // If there is an enclosing `catch {...}`
// break 'catch_target Try::from_error(From::from(err)),
// // Otherwise
// return Try::from_error(From::from(err)),
// }
let unstable_span = self.allow_internal_unstable("?", e.span);
// Try::into_result(<expr>)
let discr = {
// expand <expr>
let sub_expr = self.lower_expr(sub_expr);
let path = &["ops", "Try", "into_result"];
let path = P(self.expr_std_path(unstable_span, path, ThinVec::new()));
P(self.expr_call(e.span, path, hir_vec![sub_expr]))
};
// #[allow(unreachable_code)]
let attr = {
// allow(unreachable_code)
let allow = {
let allow_ident = self.str_to_ident("allow");
let uc_ident = self.str_to_ident("unreachable_code");
let uc_meta_item = attr::mk_spanned_word_item(e.span, uc_ident);
let uc_nested = NestedMetaItemKind::MetaItem(uc_meta_item);
let uc_spanned = respan(e.span, uc_nested);
attr::mk_spanned_list_item(e.span, allow_ident, vec![uc_spanned])
};
attr::mk_spanned_attr_outer(e.span, attr::mk_attr_id(), allow)
};
let attrs = vec![attr];
// Ok(val) => #[allow(unreachable_code)] val,
let ok_arm = {
let val_ident = self.str_to_ident("val");
let val_pat = self.pat_ident(e.span, val_ident);
let val_expr = P(self.expr_ident_with_attrs(e.span,
val_ident,
val_pat.id,
ThinVec::from(attrs.clone())));
let ok_pat = self.pat_ok(e.span, val_pat);
self.arm(hir_vec![ok_pat], val_expr)
};
// Err(err) => #[allow(unreachable_code)]
// return Carrier::from_error(From::from(err)),
let err_arm = {
let err_ident = self.str_to_ident("err");
let err_local = self.pat_ident(e.span, err_ident);
let from_expr = {
let path = &["convert", "From", "from"];
let from = P(self.expr_std_path(e.span, path, ThinVec::new()));
let err_expr = self.expr_ident(e.span, err_ident, err_local.id);
self.expr_call(e.span, from, hir_vec![err_expr])
};
let from_err_expr = {
let path = &["ops", "Try", "from_error"];
let from_err = P(self.expr_std_path(unstable_span, path,
ThinVec::new()));
P(self.expr_call(e.span, from_err, hir_vec![from_expr]))
};
let thin_attrs = ThinVec::from(attrs);
let catch_scope = self.catch_scopes.last().map(|x| *x);
let ret_expr = if let Some(catch_node) = catch_scope {
P(self.expr(
e.span,
hir::ExprBreak(
hir::Destination {
ident: None,
target_id: hir::ScopeTarget::Block(catch_node),
},
Some(from_err_expr)
),
thin_attrs))
} else {
P(self.expr(e.span,
hir::Expr_::ExprRet(Some(from_err_expr)),
thin_attrs))
};
let err_pat = self.pat_err(e.span, err_local);
self.arm(hir_vec![err_pat], ret_expr)
};
hir::ExprMatch(discr,
hir_vec![err_arm, ok_arm],
hir::MatchSource::TryDesugar)
}
ExprKind::Mac(_) => panic!("Shouldn't exist here"),
};
hir::Expr {
id: self.lower_node_id(e.id),
node: kind,
span: e.span,
attrs: e.attrs.clone(),
}
}
fn lower_stmt(&mut self, s: &Stmt) -> SmallVector<hir::Stmt> {
SmallVector::one(match s.node {
StmtKind::Local(ref l) => Spanned {
node: hir::StmtDecl(P(Spanned {
node: hir::DeclLocal(self.lower_local(l)),
span: s.span,
}), self.lower_node_id(s.id)),
span: s.span,
},
StmtKind::Item(ref it) => {
// Can only use the ID once.
let mut id = Some(s.id);
return self.lower_item_id(it).into_iter().map(|item_id| Spanned {
node: hir::StmtDecl(P(Spanned {
node: hir::DeclItem(item_id),
span: s.span,
}), id.take()
.map(|id| self.lower_node_id(id))
.unwrap_or_else(|| self.next_id())),
span: s.span,
}).collect();
}
StmtKind::Expr(ref e) => {
Spanned {
node: hir::StmtExpr(P(self.lower_expr(e)),
self.lower_node_id(s.id)),
span: s.span,
}
}
StmtKind::Semi(ref e) => {
Spanned {
node: hir::StmtSemi(P(self.lower_expr(e)),
self.lower_node_id(s.id)),
span: s.span,
}
}
StmtKind::Mac(..) => panic!("Shouldn't exist here"),
})
}
fn lower_capture_clause(&mut self, c: CaptureBy) -> hir::CaptureClause {
match c {
CaptureBy::Value => hir::CaptureByValue,
CaptureBy::Ref => hir::CaptureByRef,
}
}
/// If an `explicit_owner` is given, this method allocates the `HirId` in
/// the address space of that item instead of the item currently being
/// lowered. This can happen during `lower_impl_item_ref()` where we need to
/// lower a `Visibility` value although we haven't lowered the owning
/// `ImplItem` in question yet.
fn lower_visibility(&mut self,
v: &Visibility,
explicit_owner: Option<NodeId>)
-> hir::Visibility {
match *v {
Visibility::Public => hir::Public,
Visibility::Crate(_) => hir::Visibility::Crate,
Visibility::Restricted { ref path, id } => {
hir::Visibility::Restricted {
path: P(self.lower_path(id, path, ParamMode::Explicit, true)),
id: if let Some(owner) = explicit_owner {
self.lower_node_id_with_owner(id, owner)
} else {
self.lower_node_id(id)
}
}
}
Visibility::Inherited => hir::Inherited,
}
}
fn lower_defaultness(&mut self, d: Defaultness, has_value: bool) -> hir::Defaultness {
match d {
Defaultness::Default => hir::Defaultness::Default { has_value: has_value },
Defaultness::Final => {
assert!(has_value);
hir::Defaultness::Final
}
}
}
fn lower_block_check_mode(&mut self, b: &BlockCheckMode) -> hir::BlockCheckMode {
match *b {
BlockCheckMode::Default => hir::DefaultBlock,
BlockCheckMode::Unsafe(u) => hir::UnsafeBlock(self.lower_unsafe_source(u)),
}
}
fn lower_binding_mode(&mut self, b: &BindingMode) -> hir::BindingMode {
match *b {
BindingMode::ByRef(m) => hir::BindByRef(self.lower_mutability(m)),
BindingMode::ByValue(m) => hir::BindByValue(self.lower_mutability(m)),
}
}
fn lower_unsafe_source(&mut self, u: UnsafeSource) -> hir::UnsafeSource {
match u {
CompilerGenerated => hir::CompilerGenerated,
UserProvided => hir::UserProvided,
}
}
fn lower_impl_polarity(&mut self, i: ImplPolarity) -> hir::ImplPolarity {
match i {
ImplPolarity::Positive => hir::ImplPolarity::Positive,
ImplPolarity::Negative => hir::ImplPolarity::Negative,
}
}
fn lower_trait_bound_modifier(&mut self, f: TraitBoundModifier) -> hir::TraitBoundModifier {
match f {
TraitBoundModifier::None => hir::TraitBoundModifier::None,
TraitBoundModifier::Maybe => hir::TraitBoundModifier::Maybe,
}
}
// Helper methods for building HIR.
fn arm(&mut self, pats: hir::HirVec<P<hir::Pat>>, expr: P<hir::Expr>) -> hir::Arm {
hir::Arm {
attrs: hir_vec![],
pats,
guard: None,
body: expr,
}
}
fn field(&mut self, name: Name, expr: P<hir::Expr>, span: Span) -> hir::Field {
hir::Field {
name: Spanned {
node: name,
span,
},
span,
expr,
is_shorthand: false,
}
}
fn expr_break(&mut self, span: Span, attrs: ThinVec<Attribute>) -> P<hir::Expr> {
let expr_break = hir::ExprBreak(self.lower_loop_destination(None), None);
P(self.expr(span, expr_break, attrs))
}
fn expr_call(&mut self, span: Span, e: P<hir::Expr>, args: hir::HirVec<hir::Expr>)
-> hir::Expr {
self.expr(span, hir::ExprCall(e, args), ThinVec::new())
}
fn expr_ident(&mut self, span: Span, id: Name, binding: NodeId) -> hir::Expr {
self.expr_ident_with_attrs(span, id, binding, ThinVec::new())
}
fn expr_ident_with_attrs(&mut self, span: Span,
id: Name,
binding: NodeId,
attrs: ThinVec<Attribute>) -> hir::Expr {
let def = {
let defs = self.resolver.definitions();
Def::Local(defs.local_def_id(binding))
};
let expr_path = hir::ExprPath(hir::QPath::Resolved(None, P(hir::Path {
span,
def,
segments: hir_vec![hir::PathSegment::from_name(id)],
})));
self.expr(span, expr_path, attrs)
}
fn expr_mut_addr_of(&mut self, span: Span, e: P<hir::Expr>) -> hir::Expr {
self.expr(span, hir::ExprAddrOf(hir::MutMutable, e), ThinVec::new())
}
fn expr_std_path(&mut self,
span: Span,
components: &[&str],
attrs: ThinVec<Attribute>)
-> hir::Expr {
let path = self.std_path(span, components, true);
self.expr(span, hir::ExprPath(hir::QPath::Resolved(None, P(path))), attrs)
}
fn expr_match(&mut self,
span: Span,
arg: P<hir::Expr>,
arms: hir::HirVec<hir::Arm>,
source: hir::MatchSource)
-> hir::Expr {
self.expr(span, hir::ExprMatch(arg, arms, source), ThinVec::new())
}
fn expr_block(&mut self, b: P<hir::Block>, attrs: ThinVec<Attribute>) -> hir::Expr {
self.expr(b.span, hir::ExprBlock(b), attrs)
}
fn expr_tuple(&mut self, sp: Span, exprs: hir::HirVec<hir::Expr>) -> P<hir::Expr> {
P(self.expr(sp, hir::ExprTup(exprs), ThinVec::new()))
}
fn expr(&mut self, span: Span, node: hir::Expr_, attrs: ThinVec<Attribute>) -> hir::Expr {
hir::Expr {
id: self.next_id(),
node,
span,
attrs,
}
}
fn stmt_let_pat(&mut self,
sp: Span,
ex: Option<P<hir::Expr>>,
pat: P<hir::Pat>,
source: hir::LocalSource)
-> hir::Stmt {
let local = P(hir::Local {
pat,
ty: None,
init: ex,
id: self.next_id(),
span: sp,
attrs: ThinVec::new(),
source,
});
let decl = respan(sp, hir::DeclLocal(local));
respan(sp, hir::StmtDecl(P(decl), self.next_id()))
}
fn stmt_let(&mut self, sp: Span, mutbl: bool, ident: Name, ex: P<hir::Expr>)
-> (hir::Stmt, NodeId) {
let pat = if mutbl {
self.pat_ident_binding_mode(sp, ident, hir::BindByValue(hir::MutMutable))
} else {
self.pat_ident(sp, ident)
};
let pat_id = pat.id;
(self.stmt_let_pat(sp, Some(ex), pat, hir::LocalSource::Normal), pat_id)
}
fn block_expr(&mut self, expr: P<hir::Expr>) -> hir::Block {
self.block_all(expr.span, hir::HirVec::new(), Some(expr))
}
fn block_all(&mut self, span: Span, stmts: hir::HirVec<hir::Stmt>, expr: Option<P<hir::Expr>>)
-> hir::Block {
hir::Block {
stmts,
expr,
id: self.next_id(),
rules: hir::DefaultBlock,
span,
targeted_by_break: false,
}
}
fn pat_ok(&mut self, span: Span, pat: P<hir::Pat>) -> P<hir::Pat> {
self.pat_std_enum(span, &["result", "Result", "Ok"], hir_vec![pat])
}
fn pat_err(&mut self, span: Span, pat: P<hir::Pat>) -> P<hir::Pat> {
self.pat_std_enum(span, &["result", "Result", "Err"], hir_vec![pat])
}
fn pat_some(&mut self, span: Span, pat: P<hir::Pat>) -> P<hir::Pat> {
self.pat_std_enum(span, &["option", "Option", "Some"], hir_vec![pat])
}
fn pat_none(&mut self, span: Span) -> P<hir::Pat> {
self.pat_std_enum(span, &["option", "Option", "None"], hir_vec![])
}
fn pat_std_enum(&mut self,
span: Span,
components: &[&str],
subpats: hir::HirVec<P<hir::Pat>>)
-> P<hir::Pat> {
let path = self.std_path(span, components, true);
let qpath = hir::QPath::Resolved(None, P(path));
let pt = if subpats.is_empty() {
hir::PatKind::Path(qpath)
} else {
hir::PatKind::TupleStruct(qpath, subpats, None)
};
self.pat(span, pt)
}
fn pat_ident(&mut self, span: Span, name: Name) -> P<hir::Pat> {
self.pat_ident_binding_mode(span, name, hir::BindByValue(hir::MutImmutable))
}
fn pat_ident_binding_mode(&mut self, span: Span, name: Name, bm: hir::BindingMode)
-> P<hir::Pat> {
let id = self.next_id();
let parent_def = self.parent_def.unwrap();
let def_id = {
let defs = self.resolver.definitions();
let def_path_data = DefPathData::Binding(name);
let def_index = defs
.create_def_with_parent(parent_def, id, def_path_data, REGULAR_SPACE, Mark::root());
DefId::local(def_index)
};
P(hir::Pat {
id,
node: hir::PatKind::Binding(bm,
def_id,
Spanned {
span,
node: name,
},
None),
span,
})
}
fn pat_wild(&mut self, span: Span) -> P<hir::Pat> {
self.pat(span, hir::PatKind::Wild)
}
fn pat(&mut self, span: Span, pat: hir::PatKind) -> P<hir::Pat> {
P(hir::Pat {
id: self.next_id(),
node: pat,
span,
})
}
/// Given suffix ["b","c","d"], returns path `::std::b::c::d` when
/// `fld.cx.use_std`, and `::core::b::c::d` otherwise.
/// The path is also resolved according to `is_value`.
fn std_path(&mut self, span: Span, components: &[&str], is_value: bool) -> hir::Path {
let mut path = hir::Path {
span,
def: Def::Err,
segments: iter::once(keywords::CrateRoot.name()).chain({
self.crate_root.into_iter().chain(components.iter().cloned()).map(Symbol::intern)
}).map(hir::PathSegment::from_name).collect(),
};
self.resolver.resolve_hir_path(&mut path, is_value);
path
}
fn signal_block_expr(&mut self,
stmts: hir::HirVec<hir::Stmt>,
expr: P<hir::Expr>,
span: Span,
rule: hir::BlockCheckMode,
attrs: ThinVec<Attribute>)
-> hir::Expr {
let id = self.next_id();
let block = P(hir::Block {
rules: rule,
span,
id,
stmts,
expr: Some(expr),
targeted_by_break: false,
});
self.expr_block(block, attrs)
}
fn ty_path(&mut self, id: NodeId, span: Span, qpath: hir::QPath) -> P<hir::Ty> {
let mut id = id;
let node = match qpath {
hir::QPath::Resolved(None, path) => {
// Turn trait object paths into `TyTraitObject` instead.
if let Def::Trait(_) = path.def {
let principal = hir::PolyTraitRef {
bound_lifetimes: hir_vec![],
trait_ref: hir::TraitRef {
path: path.and_then(|path| path),
ref_id: id,
},
span,
};
// The original ID is taken by the `PolyTraitRef`,
// so the `Ty` itself needs a different one.
id = self.next_id();
hir::TyTraitObject(hir_vec![principal], self.elided_lifetime(span))
} else {
hir::TyPath(hir::QPath::Resolved(None, path))
}
}
_ => hir::TyPath(qpath)
};
P(hir::Ty { id, node, span })
}
fn elided_lifetime(&mut self, span: Span) -> hir::Lifetime {
hir::Lifetime {
id: self.next_id(),
span,
name: keywords::Invalid.name()
}
}
}
fn body_ids(bodies: &BTreeMap<hir::BodyId, hir::Body>) -> Vec<hir::BodyId> {
// Sorting by span ensures that we get things in order within a
// file, and also puts the files in a sensible order.
let mut body_ids: Vec<_> = bodies.keys().cloned().collect();
body_ids.sort_by_key(|b| bodies[b].value.span);
body_ids
}