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macros.rs
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macros.rs
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// Copyright 2016 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.
use {AmbiguityError, Resolver, ResolutionError, resolve_error};
use {Module, ModuleKind, NameBinding, NameBindingKind, PathResult};
use Namespace::{self, MacroNS};
use build_reduced_graph::BuildReducedGraphVisitor;
use resolve_imports::ImportResolver;
use rustc::hir::def_id::{DefId, BUILTIN_MACROS_CRATE, CRATE_DEF_INDEX, DefIndex};
use rustc::hir::def::{Def, Export};
use rustc::hir::map::{self, DefCollector};
use rustc::ty;
use std::cell::Cell;
use std::rc::Rc;
use syntax::ast::{self, Name, Ident};
use syntax::attr;
use syntax::errors::DiagnosticBuilder;
use syntax::ext::base::{self, Determinacy, MultiModifier, MultiDecorator};
use syntax::ext::base::{NormalTT, Resolver as SyntaxResolver, SyntaxExtension};
use syntax::ext::expand::{Expansion, mark_tts};
use syntax::ext::hygiene::Mark;
use syntax::ext::tt::macro_rules;
use syntax::feature_gate::{emit_feature_err, GateIssue};
use syntax::fold::Folder;
use syntax::ptr::P;
use syntax::symbol::keywords;
use syntax::util::lev_distance::find_best_match_for_name;
use syntax::visit::Visitor;
use syntax_pos::{Span, DUMMY_SP};
#[derive(Clone)]
pub struct InvocationData<'a> {
pub module: Cell<Module<'a>>,
pub def_index: DefIndex,
// True if this expansion is in a `const_integer` position, for example `[u32; m!()]`.
// c.f. `DefCollector::visit_ast_const_integer`.
pub const_integer: bool,
// The scope in which the invocation path is resolved.
pub legacy_scope: Cell<LegacyScope<'a>>,
// The smallest scope that includes this invocation's expansion,
// or `Empty` if this invocation has not been expanded yet.
pub expansion: Cell<LegacyScope<'a>>,
}
impl<'a> InvocationData<'a> {
pub fn root(graph_root: Module<'a>) -> Self {
InvocationData {
module: Cell::new(graph_root),
def_index: CRATE_DEF_INDEX,
const_integer: false,
legacy_scope: Cell::new(LegacyScope::Empty),
expansion: Cell::new(LegacyScope::Empty),
}
}
}
#[derive(Copy, Clone)]
pub enum LegacyScope<'a> {
Empty,
Invocation(&'a InvocationData<'a>), // The scope of the invocation, not including its expansion
Expansion(&'a InvocationData<'a>), // The scope of the invocation, including its expansion
Binding(&'a LegacyBinding<'a>),
}
pub struct LegacyBinding<'a> {
pub parent: Cell<LegacyScope<'a>>,
pub name: ast::Name,
ext: Rc<SyntaxExtension>,
pub span: Span,
}
pub enum MacroBinding<'a> {
Legacy(&'a LegacyBinding<'a>),
Modern(&'a NameBinding<'a>),
}
impl<'a> base::Resolver for Resolver<'a> {
fn next_node_id(&mut self) -> ast::NodeId {
self.session.next_node_id()
}
fn get_module_scope(&mut self, id: ast::NodeId) -> Mark {
let mark = Mark::fresh();
let module = self.module_map[&id];
self.invocations.insert(mark, self.arenas.alloc_invocation_data(InvocationData {
module: Cell::new(module),
def_index: module.def_id().unwrap().index,
const_integer: false,
legacy_scope: Cell::new(LegacyScope::Empty),
expansion: Cell::new(LegacyScope::Empty),
}));
mark
}
fn eliminate_crate_var(&mut self, item: P<ast::Item>) -> P<ast::Item> {
struct EliminateCrateVar<'b, 'a: 'b>(&'b mut Resolver<'a>);
impl<'a, 'b> Folder for EliminateCrateVar<'a, 'b> {
fn fold_path(&mut self, mut path: ast::Path) -> ast::Path {
let ident = path.segments[0].identifier;
if ident.name == "$crate" {
path.segments[0].identifier.name = keywords::CrateRoot.name();
let module = self.0.resolve_crate_var(ident.ctxt);
if !module.is_local() {
path.segments.insert(1, match module.kind {
ModuleKind::Def(_, name) => ast::Ident::with_empty_ctxt(name).into(),
_ => unreachable!(),
})
}
}
path
}
}
EliminateCrateVar(self).fold_item(item).expect_one("")
}
fn visit_expansion(&mut self, mark: Mark, expansion: &Expansion) {
let invocation = self.invocations[&mark];
self.collect_def_ids(invocation, expansion);
self.current_module = invocation.module.get();
self.current_module.unresolved_invocations.borrow_mut().remove(&mark);
let mut visitor = BuildReducedGraphVisitor {
resolver: self,
legacy_scope: LegacyScope::Invocation(invocation),
expansion: mark,
};
expansion.visit_with(&mut visitor);
self.current_module.unresolved_invocations.borrow_mut().remove(&mark);
invocation.expansion.set(visitor.legacy_scope);
}
fn add_ext(&mut self, ident: ast::Ident, ext: Rc<SyntaxExtension>) {
if let NormalTT(..) = *ext {
self.macro_names.insert(ident.name);
}
let def_id = DefId {
krate: BUILTIN_MACROS_CRATE,
index: DefIndex::new(self.macro_map.len()),
};
self.macro_map.insert(def_id, ext);
let binding = self.arenas.alloc_name_binding(NameBinding {
kind: NameBindingKind::Def(Def::Macro(def_id)),
span: DUMMY_SP,
vis: ty::Visibility::PrivateExternal,
expansion: Mark::root(),
});
self.builtin_macros.insert(ident.name, binding);
}
fn add_expansions_at_stmt(&mut self, id: ast::NodeId, macros: Vec<Mark>) {
self.macros_at_scope.insert(id, macros);
}
fn resolve_imports(&mut self) {
ImportResolver { resolver: self }.resolve_imports()
}
fn find_attr_invoc(&mut self, attrs: &mut Vec<ast::Attribute>) -> Option<ast::Attribute> {
for i in 0..attrs.len() {
match self.builtin_macros.get(&attrs[i].name()).cloned() {
Some(binding) => match *binding.get_macro(self) {
MultiModifier(..) | MultiDecorator(..) | SyntaxExtension::AttrProcMacro(..) => {
return Some(attrs.remove(i))
}
_ => {}
},
None => {}
}
}
None
}
fn resolve_macro(&mut self, scope: Mark, path: &ast::Path, force: bool)
-> Result<Rc<SyntaxExtension>, Determinacy> {
let ast::Path { ref segments, span } = *path;
if segments.iter().any(|segment| segment.parameters.is_some()) {
let kind =
if segments.last().unwrap().parameters.is_some() { "macro" } else { "module" };
let msg = format!("type parameters are not allowed on {}s", kind);
self.session.span_err(path.span, &msg);
return Err(Determinacy::Determined);
}
let path: Vec<_> = segments.iter().map(|seg| seg.identifier).collect();
let invocation = self.invocations[&scope];
self.current_module = invocation.module.get();
if path.len() > 1 {
if !self.use_extern_macros {
let msg = "non-ident macro paths are experimental";
let feature = "use_extern_macros";
emit_feature_err(&self.session.parse_sess, feature, span, GateIssue::Language, msg);
return Err(Determinacy::Determined);
}
let ext = match self.resolve_path(&path, Some(MacroNS), None) {
PathResult::NonModule(path_res) => match path_res.base_def {
Def::Err => Err(Determinacy::Determined),
def @ _ => Ok(self.get_macro(def)),
},
PathResult::Module(..) => unreachable!(),
PathResult::Indeterminate if !force => return Err(Determinacy::Undetermined),
_ => Err(Determinacy::Determined),
};
self.current_module.macro_resolutions.borrow_mut()
.push((path.into_boxed_slice(), span));
return ext;
}
let name = path[0].name;
let result = match self.resolve_legacy_scope(&invocation.legacy_scope, name, false) {
Some(MacroBinding::Legacy(binding)) => Ok(binding.ext.clone()),
Some(MacroBinding::Modern(binding)) => Ok(binding.get_macro(self)),
None => match self.resolve_lexical_macro_path_segment(path[0], MacroNS, None) {
Ok(binding) => Ok(binding.get_macro(self)),
Err(Determinacy::Undetermined) if !force => return Err(Determinacy::Undetermined),
_ => {
let msg = format!("macro undefined: '{}!'", name);
let mut err = self.session.struct_span_err(span, &msg);
self.suggest_macro_name(&name.as_str(), &mut err);
err.emit();
return Err(Determinacy::Determined);
},
},
};
if self.use_extern_macros {
self.current_module.legacy_macro_resolutions.borrow_mut().push((scope, path[0], span));
}
result
}
}
impl<'a> Resolver<'a> {
// Resolve the initial segment of a non-global macro path (e.g. `foo` in `foo::bar!();`)
pub fn resolve_lexical_macro_path_segment(&mut self,
ident: Ident,
ns: Namespace,
record_used: Option<Span>)
-> Result<&'a NameBinding<'a>, Determinacy> {
let mut module = self.current_module;
let mut potential_expanded_shadower: Option<&NameBinding> = None;
loop {
// Since expanded macros may not shadow the lexical scope (enforced below),
// we can ignore unresolved invocations (indicated by the penultimate argument).
match self.resolve_ident_in_module(module, ident, ns, true, record_used) {
Ok(binding) => {
let span = match record_used {
Some(span) => span,
None => return Ok(binding),
};
match potential_expanded_shadower {
Some(shadower) if shadower.def() != binding.def() => {
let name = ident.name;
self.ambiguity_errors.push(AmbiguityError {
span: span, name: name, b1: shadower, b2: binding, lexical: true,
legacy: false,
});
return Ok(shadower);
}
_ if binding.expansion == Mark::root() => return Ok(binding),
_ => potential_expanded_shadower = Some(binding),
}
},
Err(Determinacy::Undetermined) => return Err(Determinacy::Undetermined),
Err(Determinacy::Determined) => {}
}
match module.kind {
ModuleKind::Block(..) => module = module.parent.unwrap(),
ModuleKind::Def(..) => return match potential_expanded_shadower {
Some(binding) => Ok(binding),
None if record_used.is_some() => Err(Determinacy::Determined),
None => Err(Determinacy::Undetermined),
},
}
}
}
pub fn resolve_legacy_scope(&mut self,
mut scope: &'a Cell<LegacyScope<'a>>,
name: Name,
record_used: bool)
-> Option<MacroBinding<'a>> {
let mut possible_time_travel = None;
let mut relative_depth: u32 = 0;
let mut binding = None;
loop {
match scope.get() {
LegacyScope::Empty => break,
LegacyScope::Expansion(invocation) => {
match invocation.expansion.get() {
LegacyScope::Invocation(_) => scope.set(invocation.legacy_scope.get()),
LegacyScope::Empty => {
if possible_time_travel.is_none() {
possible_time_travel = Some(scope);
}
scope = &invocation.legacy_scope;
}
_ => {
relative_depth += 1;
scope = &invocation.expansion;
}
}
}
LegacyScope::Invocation(invocation) => {
relative_depth = relative_depth.saturating_sub(1);
scope = &invocation.legacy_scope;
}
LegacyScope::Binding(potential_binding) => {
if potential_binding.name == name {
if (!self.use_extern_macros || record_used) && relative_depth > 0 {
self.disallowed_shadowing.push(potential_binding);
}
binding = Some(potential_binding);
break
}
scope = &potential_binding.parent;
}
};
}
let binding = match binding {
Some(binding) => MacroBinding::Legacy(binding),
None => match self.builtin_macros.get(&name).cloned() {
Some(binding) => MacroBinding::Modern(binding),
None => return None,
},
};
if !self.use_extern_macros {
if let Some(scope) = possible_time_travel {
// Check for disallowed shadowing later
self.lexical_macro_resolutions.push((name, scope));
}
}
Some(binding)
}
pub fn finalize_current_module_macro_resolutions(&mut self) {
let module = self.current_module;
for &(ref path, span) in module.macro_resolutions.borrow().iter() {
match self.resolve_path(path, Some(MacroNS), Some(span)) {
PathResult::NonModule(_) => {},
PathResult::Failed(msg, _) => {
resolve_error(self, span, ResolutionError::FailedToResolve(&msg));
}
_ => unreachable!(),
}
}
for &(mark, ident, span) in module.legacy_macro_resolutions.borrow().iter() {
let legacy_scope = &self.invocations[&mark].legacy_scope;
let legacy_resolution = self.resolve_legacy_scope(legacy_scope, ident.name, true);
let resolution = self.resolve_lexical_macro_path_segment(ident, MacroNS, Some(span));
let (legacy_resolution, resolution) = match (legacy_resolution, resolution) {
(Some(legacy_resolution), Ok(resolution)) => (legacy_resolution, resolution),
_ => continue,
};
let (legacy_span, participle) = match legacy_resolution {
MacroBinding::Modern(binding) if binding.def() == resolution.def() => continue,
MacroBinding::Modern(binding) => (binding.span, "imported"),
MacroBinding::Legacy(binding) => (binding.span, "defined"),
};
let msg1 = format!("`{}` could resolve to the macro {} here", ident, participle);
let msg2 = format!("`{}` could also resolve to the macro imported here", ident);
self.session.struct_span_err(span, &format!("`{}` is ambiguous", ident))
.span_note(legacy_span, &msg1)
.span_note(resolution.span, &msg2)
.emit();
}
}
fn suggest_macro_name(&mut self, name: &str, err: &mut DiagnosticBuilder<'a>) {
if let Some(suggestion) = find_best_match_for_name(self.macro_names.iter(), name, None) {
if suggestion != name {
err.help(&format!("did you mean `{}!`?", suggestion));
} else {
err.help(&format!("have you added the `#[macro_use]` on the module/import?"));
}
}
}
fn collect_def_ids(&mut self, invocation: &'a InvocationData<'a>, expansion: &Expansion) {
let Resolver { ref mut invocations, arenas, graph_root, .. } = *self;
let InvocationData { def_index, const_integer, .. } = *invocation;
let visit_macro_invoc = &mut |invoc: map::MacroInvocationData| {
invocations.entry(invoc.mark).or_insert_with(|| {
arenas.alloc_invocation_data(InvocationData {
def_index: invoc.def_index,
const_integer: invoc.const_integer,
module: Cell::new(graph_root),
expansion: Cell::new(LegacyScope::Empty),
legacy_scope: Cell::new(LegacyScope::Empty),
})
});
};
let mut def_collector = DefCollector::new(&mut self.definitions);
def_collector.visit_macro_invoc = Some(visit_macro_invoc);
def_collector.with_parent(def_index, |def_collector| {
if const_integer {
if let Expansion::Expr(ref expr) = *expansion {
def_collector.visit_ast_const_integer(expr);
}
}
expansion.visit_with(def_collector)
});
}
pub fn define_macro(&mut self, item: &ast::Item, legacy_scope: &mut LegacyScope<'a>) {
let tts = match item.node {
ast::ItemKind::Mac(ref mac) => &mac.node.tts,
_ => unreachable!(),
};
if item.ident.name == "macro_rules" {
self.session.span_err(item.span, "user-defined macros may not be named `macro_rules`");
}
let mark = Mark::from_placeholder_id(item.id);
let invocation = self.invocations[&mark];
invocation.module.set(self.current_module);
let mut def = ast::MacroDef {
ident: item.ident,
attrs: item.attrs.clone(),
id: ast::DUMMY_NODE_ID,
span: item.span,
body: mark_tts(tts, mark),
};
*legacy_scope = LegacyScope::Binding(self.arenas.alloc_legacy_binding(LegacyBinding {
parent: Cell::new(*legacy_scope),
name: def.ident.name,
ext: Rc::new(macro_rules::compile(&self.session.parse_sess, &def)),
span: def.span,
}));
self.macro_names.insert(def.ident.name);
if attr::contains_name(&def.attrs, "macro_export") {
def.id = self.next_node_id();
DefCollector::new(&mut self.definitions).with_parent(CRATE_DEF_INDEX, |collector| {
collector.visit_macro_def(&def)
});
self.macro_exports.push(Export {
name: def.ident.name,
def: Def::Macro(self.definitions.local_def_id(def.id)),
});
self.exported_macros.push(def);
}
}
}