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Rollup merge of #64623 - matthewjasper:underscore-imports, r=petrochenkov

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Remove last uses of gensyms

Underscore bindings now use unique `SyntaxContext`s to avoid collisions. This was the last use of gensyms in the compiler, so this PR also removes them.

closes #49300
cc #60869

r? @petrochenkov
This commit is contained in:
Tyler Mandry 2019-10-15 16:07:41 -07:00 committed by GitHub
commit af3d9e57e7
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GPG key ID: 4AEE18F83AFDEB23
12 changed files with 247 additions and 154 deletions
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2
src/librustc/ty/print/pretty.rs
View file

@ -1483,7 +1483,7 @@ impl<F: fmt::Write> FmtPrinter<'_, 'tcx, F> {
}
// Replace any anonymous late-bound regions with named
// variants, using gensym'd identifiers, so that we can
// variants, using new unique identifiers, so that we can
// clearly differentiate between named and unnamed regions in
// the output. We'll probably want to tweak this over time to
// decide just how much information to give.

16
src/librustc_resolve/build_reduced_graph.rs
View file

@ -94,7 +94,8 @@ impl<'a> Resolver<'a> {
where T: ToNameBinding<'a>,
{
let binding = def.to_name_binding(self.arenas);
if let Err(old_binding) = self.try_define(parent, ident, ns, binding) {
let key = self.new_key(ident, ns);
if let Err(old_binding) = self.try_define(parent, key, binding) {
self.report_conflict(parent, ident, ns, old_binding, &binding);
}
}
@ -349,9 +350,12 @@ impl<'a, 'b> BuildReducedGraphVisitor<'a, 'b> {
self.r.indeterminate_imports.push(directive);
match directive.subclass {
// Don't add unresolved underscore imports to modules
SingleImport { target: Ident { name: kw::Underscore, .. }, .. } => {}
SingleImport { target, type_ns_only, .. } => {
self.r.per_ns(|this, ns| if !type_ns_only || ns == TypeNS {
let mut resolution = this.resolution(current_module, target, ns).borrow_mut();
let key = this.new_key(target, ns);
let mut resolution = this.resolution(current_module, key).borrow_mut();
resolution.add_single_import(directive);
});
}
@ -407,7 +411,7 @@ impl<'a, 'b> BuildReducedGraphVisitor<'a, 'b> {
};
match use_tree.kind {
ast::UseTreeKind::Simple(rename, ..) => {
let mut ident = use_tree.ident().gensym_if_underscore();
let mut ident = use_tree.ident();
let mut module_path = prefix;
let mut source = module_path.pop().unwrap();
let mut type_ns_only = false;
@ -585,7 +589,7 @@ impl<'a, 'b> BuildReducedGraphVisitor<'a, 'b> {
let parent_scope = &self.parent_scope;
let parent = parent_scope.module;
let expansion = parent_scope.expansion;
let ident = item.ident.gensym_if_underscore();
let ident = item.ident;
let sp = item.span;
let vis = self.resolve_visibility(&item.vis);
@ -851,10 +855,6 @@ impl<'a, 'b> BuildReducedGraphVisitor<'a, 'b> {
fn build_reduced_graph_for_external_crate_res(&mut self, child: Export<NodeId>) {
let parent = self.parent_scope.module;
let Export { ident, res, vis, span } = child;
// FIXME: We shouldn't create the gensym here, it should come from metadata,
// but metadata cannot encode gensyms currently, so we create it here.
// This is only a guess, two equivalent idents may incorrectly get different gensyms here.
let ident = ident.gensym_if_underscore();
let expansion = ExpnId::root(); // FIXME(jseyfried) intercrate hygiene
// Record primary definitions.
match res {

6
src/librustc_resolve/diagnostics.rs
View file

@ -80,11 +80,11 @@ impl<'a> Resolver<'a> {
names: &mut Vec<TypoSuggestion>,
filter_fn: &impl Fn(Res) -> bool,
) {
for (&(ident, _), resolution) in self.resolutions(module).borrow().iter() {
for (key, resolution) in self.resolutions(module).borrow().iter() {
if let Some(binding) = resolution.borrow().binding {
let res = binding.res();
if filter_fn(res) {
names.push(TypoSuggestion::from_res(ident.name, res));
names.push(TypoSuggestion::from_res(key.ident.name, res));
}
}
}
@ -849,7 +849,7 @@ impl<'a, 'b> ImportResolver<'a, 'b> {
}
let resolutions = self.r.resolutions(crate_module).borrow();
let resolution = resolutions.get(&(ident, MacroNS))?;
let resolution = resolutions.get(&self.r.new_key(ident, MacroNS))?;
let binding = resolution.borrow().binding()?;
if let Res::Def(DefKind::Macro(MacroKind::Bang), _) = binding.res() {
let module_name = crate_module.kind.name().unwrap();

38
src/librustc_resolve/lib.rs
View file

@ -432,7 +432,22 @@ impl ModuleKind {
}
}
type Resolutions<'a> = RefCell<FxIndexMap<(Ident, Namespace), &'a RefCell<NameResolution<'a>>>>;
/// A key that identifies a binding in a given `Module`.
///
/// Multiple bindings in the same module can have the same key (in a valid
/// program) if all but one of them come from glob imports.
#[derive(Copy, Clone, PartialEq, Eq, Hash)]
struct BindingKey {
/// The identifier for the binding, aways the `modern` version of the
/// identifier.
ident: Ident,
ns: Namespace,
/// 0 if ident is not `_`, otherwise a value that's unique to the specific
/// `_` in the expanded AST that introduced this binding.
disambiguator: u32,
}
type Resolutions<'a> = RefCell<FxIndexMap<BindingKey, &'a RefCell<NameResolution<'a>>>>;
/// One node in the tree of modules.
pub struct ModuleData<'a> {
@ -492,8 +507,8 @@ impl<'a> ModuleData<'a> {
fn for_each_child<R, F>(&'a self, resolver: &mut R, mut f: F)
where R: AsMut<Resolver<'a>>, F: FnMut(&mut R, Ident, Namespace, &'a NameBinding<'a>)
{
for (&(ident, ns), name_resolution) in resolver.as_mut().resolutions(self).borrow().iter() {
name_resolution.borrow().binding.map(|binding| f(resolver, ident, ns, binding));
for (key, name_resolution) in resolver.as_mut().resolutions(self).borrow().iter() {
name_resolution.borrow().binding.map(|binding| f(resolver, key.ident, key.ns, binding));
}
}
@ -882,6 +897,7 @@ pub struct Resolver<'a> {
module_map: FxHashMap<DefId, Module<'a>>,
extern_module_map: FxHashMap<DefId, Module<'a>>,
binding_parent_modules: FxHashMap<PtrKey<'a, NameBinding<'a>>, Module<'a>>,
underscore_disambiguator: u32,
/// Maps glob imports to the names of items actually imported.
pub glob_map: GlobMap,
@ -1160,6 +1176,7 @@ impl<'a> Resolver<'a> {
extern_crate_map: Default::default(),
export_map: FxHashMap::default(),
trait_map: Default::default(),
underscore_disambiguator: 0,
empty_module,
module_map,
block_map: Default::default(),
@ -1284,6 +1301,17 @@ impl<'a> Resolver<'a> {
self.arenas.alloc_module(module)
}
fn new_key(&mut self, ident: Ident, ns: Namespace) -> BindingKey {
let ident = ident.modern();
let disambiguator = if ident.name == kw::Underscore {
self.underscore_disambiguator += 1;
self.underscore_disambiguator
} else {
0
};
BindingKey { ident, ns, disambiguator }
}
fn resolutions(&mut self, module: Module<'a>) -> &'a Resolutions<'a> {
if module.populate_on_access.get() {
module.populate_on_access.set(false);
@ -1292,9 +1320,9 @@ impl<'a> Resolver<'a> {
&module.lazy_resolutions
}
fn resolution(&mut self, module: Module<'a>, ident: Ident, ns: Namespace)
fn resolution(&mut self, module: Module<'a>, key: BindingKey)
-> &'a RefCell<NameResolution<'a>> {
*self.resolutions(module).borrow_mut().entry((ident.modern(), ns))
*self.resolutions(module).borrow_mut().entry(key)
.or_insert_with(|| self.arenas.alloc_name_resolution())
}

94
src/librustc_resolve/resolve_imports.rs
View file

@ -7,7 +7,7 @@ use crate::{CrateLint, Module, ModuleOrUniformRoot, PerNS, ScopeSet, ParentScope
use crate::Determinacy::{self, *};
use crate::Namespace::{self, TypeNS, MacroNS};
use crate::{NameBinding, NameBindingKind, ToNameBinding, PathResult, PrivacyError};
use crate::{Resolver, ResolutionError, Segment, ModuleKind};
use crate::{Resolver, ResolutionError, BindingKey, Segment, ModuleKind};
use crate::{names_to_string, module_to_string};
use crate::diagnostics::Suggestion;
@ -235,7 +235,8 @@ impl<'a> Resolver<'a> {
}
};
let resolution = self.resolution(module, ident, ns)
let key = self.new_key(ident, ns);
let resolution = self.resolution(module, key)
.try_borrow_mut()
.map_err(|_| (Determined, Weak::No))?; // This happens when there is a cycle of imports.
@ -447,17 +448,16 @@ impl<'a> Resolver<'a> {
}
// Define the name or return the existing binding if there is a collision.
pub fn try_define(
crate fn try_define(
&mut self,
module: Module<'a>,
ident: Ident,
ns: Namespace,
key: BindingKey,
binding: &'a NameBinding<'a>,
) -> Result<(), &'a NameBinding<'a>> {
let res = binding.res();
self.check_reserved_macro_name(ident, res);
self.check_reserved_macro_name(key.ident, res);
self.set_binding_parent_module(binding, module);
self.update_resolution(module, ident, ns, |this, resolution| {
self.update_resolution(module, key, |this, resolution| {
if let Some(old_binding) = resolution.binding {
if res == Res::Err {
// Do not override real bindings with `Res::Err`s from error recovery.
@ -479,8 +479,9 @@ impl<'a> Resolver<'a> {
} else {
(binding, old_binding)
};
if glob_binding.res() != nonglob_binding.res() &&
ns == MacroNS && nonglob_binding.expansion != ExpnId::root() {
if glob_binding.res() != nonglob_binding.res()
&& key.ns == MacroNS && nonglob_binding.expansion != ExpnId::root()
{
resolution.binding = Some(this.ambiguity(
AmbiguityKind::GlobVsExpanded,
nonglob_binding,
@ -499,9 +500,9 @@ impl<'a> Resolver<'a> {
DUPLICATE_MACRO_EXPORTS,
CRATE_NODE_ID,
binding.span,
&format!("a macro named `{}` has already been exported", ident),
&format!("a macro named `{}` has already been exported", key.ident),
BuiltinLintDiagnostics::DuplicatedMacroExports(
ident, old_binding.span, binding.span));
key.ident, old_binding.span, binding.span));
resolution.binding = Some(binding);
} else {
@ -531,9 +532,9 @@ impl<'a> Resolver<'a> {
// Use `f` to mutate the resolution of the name in the module.
// If the resolution becomes a success, define it in the module's glob importers.
fn update_resolution<T, F>(
&mut self, module: Module<'a>,
ident: Ident,
ns: Namespace,
&mut self,
module: Module<'a>,
key: BindingKey,
f: F,
) -> T
where F: FnOnce(&mut Resolver<'a>, &mut NameResolution<'a>) -> T
@ -541,7 +542,7 @@ impl<'a> Resolver<'a> {
// Ensure that `resolution` isn't borrowed when defining in the module's glob importers,
// during which the resolution might end up getting re-defined via a glob cycle.
let (binding, t) = {
let resolution = &mut *self.resolution(module, ident, ns).borrow_mut();
let resolution = &mut *self.resolution(module, key).borrow_mut();
let old_binding = resolution.binding();
let t = f(self, resolution);
@ -558,7 +559,7 @@ impl<'a> Resolver<'a> {
// Define `binding` in `module`s glob importers.
for directive in module.glob_importers.borrow_mut().iter() {
let mut ident = ident.modern();
let mut ident = key.ident;
let scope = match ident.span.reverse_glob_adjust(module.expansion, directive.span) {
Some(Some(def)) => self.macro_def_scope(def),
Some(None) => directive.parent_scope.module,
@ -566,7 +567,8 @@ impl<'a> Resolver<'a> {
};
if self.is_accessible_from(binding.vis, scope) {
let imported_binding = self.import(binding, directive);
let _ = self.try_define(directive.parent_scope.module, ident, ns, imported_binding);
let key = BindingKey { ident, ..key };
let _ = self.try_define(directive.parent_scope.module, key, imported_binding);
}
}
@ -580,7 +582,8 @@ impl<'a> Resolver<'a> {
let dummy_binding = self.dummy_binding;
let dummy_binding = self.import(dummy_binding, directive);
self.per_ns(|this, ns| {
let _ = this.try_define(directive.parent_scope.module, target, ns, dummy_binding);
let key = this.new_key(target, ns);
let _ = this.try_define(directive.parent_scope.module, key, dummy_binding);
// Consider erroneous imports used to avoid duplicate diagnostics.
this.record_use(target, ns, dummy_binding, false);
});
@ -820,8 +823,11 @@ impl<'a, 'b> ImportResolver<'a, 'b> {
let parent = directive.parent_scope.module;
match source_bindings[ns].get() {
Err(Undetermined) => indeterminate = true,
// Don't update the resolution, because it was never added.
Err(Determined) if target.name == kw::Underscore => {}
Err(Determined) => {
this.update_resolution(parent, target, ns, |_, resolution| {
let key = this.new_key(target, ns);
this.update_resolution(parent, key, |_, resolution| {
resolution.single_imports.remove(&PtrKey(directive));
});
}
@ -1052,7 +1058,7 @@ impl<'a, 'b> ImportResolver<'a, 'b> {
_ => None,
};
let resolutions = resolutions.as_ref().into_iter().flat_map(|r| r.iter());
let names = resolutions.filter_map(|(&(ref i, _), resolution)| {
let names = resolutions.filter_map(|(BindingKey { ident: i, .. }, resolution)| {
if *i == ident { return None; } // Never suggest the same name
match *resolution.borrow() {
NameResolution { binding: Some(name_binding), .. } => {
@ -1301,19 +1307,18 @@ impl<'a, 'b> ImportResolver<'a, 'b> {
// Ensure that `resolutions` isn't borrowed during `try_define`,
// since it might get updated via a glob cycle.
let bindings = self.r.resolutions(module).borrow().iter().filter_map(|(ident, resolution)| {
resolution.borrow().binding().map(|binding| (*ident, binding))
let bindings = self.r.resolutions(module).borrow().iter().filter_map(|(key, resolution)| {
resolution.borrow().binding().map(|binding| (*key, binding))
}).collect::<Vec<_>>();
for ((mut ident, ns), binding) in bindings {
let scope = match ident.span.reverse_glob_adjust(module.expansion, directive.span) {
for (mut key, binding) in bindings {
let scope = match key.ident.span.reverse_glob_adjust(module.expansion, directive.span) {
Some(Some(def)) => self.r.macro_def_scope(def),
Some(None) => directive.parent_scope.module,
None => continue,
};
if self.r.is_accessible_from(binding.pseudo_vis(), scope) {
let imported_binding = self.r.import(binding, directive);
let _ =
self.r.try_define(directive.parent_scope.module, ident, ns, imported_binding);
let _ = self.r.try_define(directive.parent_scope.module, key, imported_binding);
}
}
@ -1329,29 +1334,23 @@ impl<'a, 'b> ImportResolver<'a, 'b> {
let mut reexports = Vec::new();
for (&(ident, ns), resolution) in self.r.resolutions(module).borrow().iter() {
let resolution = &mut *resolution.borrow_mut();
let binding = match resolution.binding {
Some(binding) => binding,
None => continue,
};
module.for_each_child(self.r, |this, ident, ns, binding| {
// Filter away ambiguous imports and anything that has def-site
// hygiene.
// FIXME: Implement actual cross-crate hygiene.
let is_good_import = binding.is_import() && !binding.is_ambiguity()
&& !ident.span.modern().from_expansion();
&& !ident.span.from_expansion();
if is_good_import || binding.is_macro_def() {
let res = binding.res();
if res != Res::Err {
if let Some(def_id) = res.opt_def_id() {
if !def_id.is_local() {
self.r.cstore.export_macros_untracked(def_id.krate);
this.cstore.export_macros_untracked(def_id.krate);
}
}
reexports.push(Export {
ident: ident.modern(),
res: res,
ident,
res,
span: binding.span,
vis: binding.vis,
});
@ -1360,7 +1359,7 @@ impl<'a, 'b> ImportResolver<'a, 'b> {
if let NameBindingKind::Import { binding: orig_binding, directive, .. } = binding.kind {
if ns == TypeNS && orig_binding.is_variant() &&
!orig_binding.vis.is_at_least(binding.vis, &*self) {
!orig_binding.vis.is_at_least(binding.vis, &*this) {
let msg = match directive.subclass {
ImportDirectiveSubclass::SingleImport { .. } => {
format!("variant `{}` is private and cannot be re-exported",
@ -1372,33 +1371,34 @@ impl<'a, 'b> ImportResolver<'a, 'b> {
let error_id = (DiagnosticMessageId::ErrorId(0), // no code?!
Some(binding.span),
msg.clone());
let fresh = self.r.session.one_time_diagnostics
let fresh = this.session.one_time_diagnostics
.borrow_mut().insert(error_id);
if !fresh {
continue;
return;
}
msg
},
ref s @ _ => bug!("unexpected import subclass {:?}", s)
};
let mut err = self.r.session.struct_span_err(binding.span, &msg);
let mut err = this.session.struct_span_err(binding.span, &msg);
let imported_module = match directive.imported_module.get() {
Some(ModuleOrUniformRoot::Module(module)) => module,
_ => bug!("module should exist"),
};
let parent_module = imported_module.parent.expect("parent should exist");
let resolutions = self.r.resolutions(parent_module).borrow();
let resolutions = this.resolutions(parent_module).borrow();
let enum_path_segment_index = directive.module_path.len() - 1;
let enum_ident = directive.module_path[enum_path_segment_index].ident;
let enum_resolution = resolutions.get(&(enum_ident, TypeNS))
let key = this.new_key(enum_ident, TypeNS);
let enum_resolution = resolutions.get(&key)
.expect("resolution should exist");
let enum_span = enum_resolution.borrow()
.binding.expect("binding should exist")
.span;
let enum_def_span = self.r.session.source_map().def_span(enum_span);
let enum_def_snippet = self.r.session.source_map()
let enum_def_span = this.session.source_map().def_span(enum_span);
let enum_def_snippet = this.session.source_map()
.span_to_snippet(enum_def_span).expect("snippet should exist");
// potentially need to strip extant `crate`/`pub(path)` for suggestion
let after_vis_index = enum_def_snippet.find("enum")
@ -1406,7 +1406,7 @@ impl<'a, 'b> ImportResolver<'a, 'b> {
let suggestion = format!("pub {}",
&enum_def_snippet[after_vis_index..]);
self.r.session
this.session
.diag_span_suggestion_once(&mut err,
DiagnosticMessageId::ErrorId(0),
enum_def_span,
@ -1415,7 +1415,7 @@ impl<'a, 'b> ImportResolver<'a, 'b> {
err.emit();
}
}
}
});
if reexports.len() > 0 {
if let Some(def_id) = module.def_id() {

3
src/libsyntax/ext/proc_macro_server.rs
View file

@ -334,8 +334,7 @@ impl Ident {
if !Self::is_valid(&string) {
panic!("`{:?}` is not a valid identifier", string)
}
// Get rid of gensyms to conservatively check rawness on the string contents only.
if is_raw && !sym.as_interned_str().as_symbol().can_be_raw() {
if is_raw && !sym.can_be_raw() {
panic!("`{}` cannot be a raw identifier", string);
}
Ident { sym, is_raw, span }

90
src/libsyntax_pos/symbol.rs
View file

@ -808,25 +808,13 @@ impl Ident {
Ident::new(self.name, self.span.modern_and_legacy())
}
/// Transforms an underscore identifier into one with the same name, but
/// gensymed. Leaves non-underscore identifiers unchanged.
pub fn gensym_if_underscore(self) -> Ident {
if self.name == kw::Underscore {
let name = with_interner(|interner| interner.gensymed(self.name));
Ident::new(name, self.span)
} else {
self
}
}
/// Convert the name to a `LocalInternedString`. This is a slowish
/// operation because it requires locking the symbol interner.
pub fn as_str(self) -> LocalInternedString {
self.name.as_str()
}
/// Convert the name to an `InternedString`. This is a slowish operation
/// because it requires locking the symbol interner.
/// Convert the name to an `InternedString`.
pub fn as_interned_str(self) -> InternedString {
self.name.as_interned_str()
}
@ -881,26 +869,9 @@ impl UseSpecializedDecodable for Ident {
}
}
/// A symbol is an interned or gensymed string. A gensym is a symbol that is
/// never equal to any other symbol.
/// An interned string.
///
/// Conceptually, a gensym can be thought of as a normal symbol with an
/// invisible unique suffix. Gensyms are useful when creating new identifiers
/// that must not match any existing identifiers, e.g. during macro expansion
/// and syntax desugaring. Because gensyms should always be identifiers, all
/// gensym operations are on `Ident` rather than `Symbol`. (Indeed, in the
/// future the gensym-ness may be moved from `Symbol` to hygiene data.)
///
/// Examples:
/// ```
/// assert_eq!(Ident::from_str("_"), Ident::from_str("_"))
/// assert_ne!(Ident::from_str("_").gensym_if_underscore(), Ident::from_str("_"))
/// assert_ne!(
/// Ident::from_str("_").gensym_if_underscore(),
/// Ident::from_str("_").gensym_if_underscore(),
/// )
/// ```
/// Internally, a symbol is implemented as an index, and all operations
/// Internally, a `Symbol` is implemented as an index, and all operations
/// (including hashing, equality, and ordering) operate on that index. The use
/// of `rustc_index::newtype_index!` means that `Option<Symbol>` only takes up 4 bytes,
/// because `rustc_index::newtype_index!` reserves the last 256 values for tagging purposes.
@ -951,12 +922,9 @@ impl Symbol {
})
}
/// Convert to an `InternedString`. This is a slowish operation because it
/// requires locking the symbol interner.
/// Convert to an `InternedString`.
pub fn as_interned_str(self) -> InternedString {
with_interner(|interner| InternedString {
symbol: interner.interned(self)
})
InternedString { symbol: self }
}
pub fn as_u32(self) -> u32 {
@ -966,12 +934,7 @@ impl Symbol {
impl fmt::Debug for Symbol {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
let is_gensymed = with_interner(|interner| interner.is_gensymed(*self));
if is_gensymed {
write!(f, "{}({:?})", self, self.0)
} else {
write!(f, "{}", self)
}
fmt::Display::fmt(self, f)
}
}
@ -994,15 +957,11 @@ impl Decodable for Symbol {
}
// The `&'static str`s in this type actually point into the arena.
//
// Note that normal symbols are indexed upward from 0, and gensyms are indexed
// downward from SymbolIndex::MAX_AS_U32.
#[derive(Default)]
pub struct Interner {
arena: DroplessArena,
names: FxHashMap<&'static str, Symbol>,
strings: Vec<&'static str>,
gensyms: Vec<Symbol>,
}
impl Interner {
@ -1035,34 +994,10 @@ impl Interner {
self.names.insert(string, name);
name
}
fn interned(&self, symbol: Symbol) -> Symbol {
if (symbol.0.as_usize()) < self.strings.len() {
symbol
} else {
self.gensyms[(SymbolIndex::MAX_AS_U32 - symbol.0.as_u32()) as usize]
}
}
fn gensymed(&mut self, symbol: Symbol) -> Symbol {
self.gensyms.push(symbol);
Symbol::new(SymbolIndex::MAX_AS_U32 - self.gensyms.len() as u32 + 1)
}
fn is_gensymed(&mut self, symbol: Symbol) -> bool {
symbol.0.as_usize() >= self.strings.len()
}
// Get the symbol as a string. `Symbol::as_str()` should be used in
// preference to this function.
pub fn get(&self, symbol: Symbol) -> &str {
match self.strings.get(symbol.0.as_usize()) {
Some(string) => string,
None => {
let symbol = self.gensyms[(SymbolIndex::MAX_AS_U32 - symbol.0.as_u32()) as usize];
self.strings[symbol.0.as_usize()]
}
}
self.strings[symbol.0.as_usize()]
}
}
@ -1223,19 +1158,12 @@ impl fmt::Display for LocalInternedString {
}
}
/// An alternative to `Symbol` that is focused on string contents. It has two
/// main differences to `Symbol`.
/// An alternative to `Symbol` that is focused on string contents.
///
/// First, its implementations of `Hash`, `PartialOrd` and `Ord` work with the
/// Its implementations of `Hash`, `PartialOrd` and `Ord` work with the
/// string chars rather than the symbol integer. This is useful when hash
/// stability is required across compile sessions, or a guaranteed sort
/// ordering is required.
///
/// Second, gensym-ness is irrelevant. E.g.:
/// ```
/// assert_ne!(Symbol::gensym("x"), Symbol::gensym("x"))
/// assert_eq!(Symbol::gensym("x").as_interned_str(), Symbol::gensym("x").as_interned_str())
/// ```
#[derive(Clone, Copy, PartialEq, Eq)]
pub struct InternedString {
symbol: Symbol,

7
src/libsyntax_pos/symbol/tests.rs
View file

@ -14,13 +14,6 @@ fn interner_tests() {
assert_eq!(i.intern("cat"), Symbol::new(1));
// dog is still at zero
assert_eq!(i.intern("dog"), Symbol::new(0));
let z = i.intern("zebra");
assert_eq!(i.gensymed(z), Symbol::new(SymbolIndex::MAX_AS_U32));
// gensym of same string gets new number:
assert_eq!(i.gensymed(z), Symbol::new(SymbolIndex::MAX_AS_U32 - 1));
// gensym of *existing* string gets new number:
let d = i.intern("dog");
assert_eq!(i.gensymed(d), Symbol::new(SymbolIndex::MAX_AS_U32 - 2));
}
#[test]

33
src/test/ui/underscore-imports/hygiene-2.rs Normal file
View file

@ -0,0 +1,33 @@
// Make sure that underscore imports with different contexts can exist in the
// same scope.
// check-pass
#![feature(decl_macro)]
mod x {
pub use std::ops::Deref as _;
}
macro n() {
pub use crate::x::*;
}
#[macro_export]
macro_rules! p {
() => { pub use crate::x::*; }
}
macro m($y:ident) {
mod $y {
crate::n!(); // Reexport of `Deref` should not be imported in `main`
crate::p!(); // Reexport of `Deref` should be imported into `main`
}
}
m!(y);
fn main() {
use crate::y::*;
(&()).deref();
}

40
src/test/ui/underscore-imports/hygiene.rs Normal file
View file

@ -0,0 +1,40 @@
// Make sure that underscore imports have the same hygiene considerations as
// other imports.
#![feature(decl_macro)]
mod x {
pub use std::ops::Deref as _;
}
macro glob_import() {
pub use crate::x::*;
}
macro underscore_import() {
use std::ops::DerefMut as _;
}
mod y {
crate::glob_import!();
crate::underscore_import!();
}
macro create_module($y:ident) {
mod $y {
crate::glob_import!();
crate::underscore_import!();
}
}
create_module!(z);
fn main() {
use crate::y::*;
use crate::z::*;
glob_import!();
underscore_import!();
(&()).deref(); //~ ERROR no method named `deref`
(&mut ()).deref_mut(); //~ ERROR no method named `deref_mut`
}

27
src/test/ui/underscore-imports/hygiene.stderr Normal file
View file

@ -0,0 +1,27 @@
error[E0599]: no method named `deref` found for type `&()` in the current scope
--> $DIR/hygiene.rs:38:11
|
LL | (&()).deref();
| ^^^^^ method not found in `&()`
|
= help: items from traits can only be used if the trait is in scope
help: the following trait is implemented but not in scope; perhaps add a `use` for it:
|
LL | use std::ops::Deref;
|
error[E0599]: no method named `deref_mut` found for type `&mut ()` in the current scope
--> $DIR/hygiene.rs:39:15
|
LL | (&mut ()).deref_mut();
| ^^^^^^^^^ method not found in `&mut ()`
|
= help: items from traits can only be used if the trait is in scope
help: the following trait is implemented but not in scope; perhaps add a `use` for it:
|
LL | use std::ops::DerefMut;
|
error: aborting due to 2 previous errors
For more information about this error, try `rustc --explain E0599`.

45
src/test/ui/underscore-imports/macro-expanded.rs Normal file
View file

@ -0,0 +1,45 @@
// Check that macro expanded underscore imports behave as expected
// check-pass
#![feature(decl_macro, rustc_attrs)]
mod x {
pub use std::ops::Not as _;
}
macro m() {
mod w {
mod y {
pub use std::ops::Deref as _;
}
use crate::x::*;
use self::y::*;
use std::ops::DerefMut as _;
fn f() {
false.not();
(&()).deref();
(&mut ()).deref_mut();
}
}
}
#[rustc_macro_transparency = "transparent"]
macro n() {
mod z {
pub use std::ops::Deref as _;
}
use crate::x::*;
use crate::z::*;
use std::ops::DerefMut as _;
fn f() {
false.not();
(&()).deref();
(&mut ()).deref_mut();
}
}
m!();
n!();
fn main() {}