rust/src/librustc_resolve/resolve_imports.rs
2016-02-03 23:39:16 +00:00

951 lines
41 KiB
Rust

// 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.
use self::ImportDirectiveSubclass::*;
use DefModifiers;
use DefOrModule;
use Module;
use Namespace::{self, TypeNS, ValueNS};
use NameBinding;
use ResolveResult;
use ResolveResult::*;
use Resolver;
use UseLexicalScopeFlag;
use {names_to_string, module_to_string};
use {resolve_error, ResolutionError};
use build_reduced_graph;
use rustc::lint;
use rustc::middle::def::*;
use rustc::middle::def_id::DefId;
use rustc::middle::privacy::*;
use syntax::ast::{NodeId, Name};
use syntax::attr::AttrMetaMethods;
use syntax::codemap::Span;
use syntax::util::lev_distance::find_best_match_for_name;
use std::mem::replace;
/// Contains data for specific types of import directives.
#[derive(Copy, Clone,Debug)]
pub enum ImportDirectiveSubclass {
SingleImport(Name /* target */, Name /* source */),
GlobImport,
}
/// Whether an import can be shadowed by another import.
#[derive(Debug,PartialEq,Clone,Copy)]
pub enum Shadowable {
Always,
Never,
}
/// One import directive.
#[derive(Debug,Clone)]
pub struct ImportDirective {
pub module_path: Vec<Name>,
pub subclass: ImportDirectiveSubclass,
pub span: Span,
pub id: NodeId,
pub is_public: bool, // see note in ImportResolutionPerNamespace about how to use this
pub shadowable: Shadowable,
}
impl ImportDirective {
pub fn new(module_path: Vec<Name>,
subclass: ImportDirectiveSubclass,
span: Span,
id: NodeId,
is_public: bool,
shadowable: Shadowable)
-> ImportDirective {
ImportDirective {
module_path: module_path,
subclass: subclass,
span: span,
id: id,
is_public: is_public,
shadowable: shadowable,
}
}
}
/// The item that an import resolves to.
#[derive(Clone,Debug)]
pub struct Target<'a> {
pub target_module: Module<'a>,
pub binding: NameBinding<'a>,
pub shadowable: Shadowable,
}
impl<'a> Target<'a> {
pub fn new(target_module: Module<'a>, binding: NameBinding<'a>, shadowable: Shadowable)
-> Self {
Target {
target_module: target_module,
binding: binding,
shadowable: shadowable,
}
}
}
#[derive(Debug)]
/// An ImportResolution records what we know about an imported name in a given namespace.
/// More specifically, it records the number of unresolved `use` directives that import the name,
/// the `use` directive importing the name in the namespace, and the `NameBinding` to which the
/// name in the namespace resolves (if applicable).
/// Different `use` directives may import the same name in different namespaces.
pub struct ImportResolution<'a> {
// When outstanding_references reaches zero, outside modules can count on the targets being
// correct. Before then, all bets are off; future `use` directives could override the name.
// Since shadowing is forbidden, the only way outstanding_references > 1 in a legal program
// is if the name is imported by exactly two `use` directives, one of which resolves to a
// value and the other of which resolves to a type.
pub outstanding_references: usize,
/// Whether this resolution came from a `use` or a `pub use`.
pub is_public: bool,
/// Resolution of the name in the namespace
pub target: Option<Target<'a>>,
/// The source node of the `use` directive
pub id: NodeId,
}
impl<'a> ImportResolution<'a> {
pub fn new(id: NodeId, is_public: bool) -> Self {
ImportResolution {
outstanding_references: 0,
id: id,
target: None,
is_public: is_public,
}
}
pub fn shadowable(&self) -> Shadowable {
match self.target {
Some(ref target) => target.shadowable,
None => Shadowable::Always,
}
}
}
struct ImportResolvingError<'a> {
/// Module where the error happened
source_module: Module<'a>,
import_directive: ImportDirective,
span: Span,
help: String,
}
struct ImportResolver<'a, 'b: 'a, 'tcx: 'b> {
resolver: &'a mut Resolver<'b, 'tcx>,
}
impl<'a, 'b:'a, 'tcx:'b> ImportResolver<'a, 'b, 'tcx> {
// Import resolution
//
// This is a fixed-point algorithm. We resolve imports until our efforts
// are stymied by an unresolved import; then we bail out of the current
// module and continue. We terminate successfully once no more imports
// remain or unsuccessfully when no forward progress in resolving imports
// is made.
/// Resolves all imports for the crate. This method performs the fixed-
/// point iteration.
fn resolve_imports(&mut self) {
let mut i = 0;
let mut prev_unresolved_imports = 0;
loop {
debug!("(resolving imports) iteration {}, {} imports left",
i,
self.resolver.unresolved_imports);
let module_root = self.resolver.graph_root;
let errors = self.resolve_imports_for_module_subtree(module_root);
if self.resolver.unresolved_imports == 0 {
debug!("(resolving imports) success");
break;
}
if self.resolver.unresolved_imports == prev_unresolved_imports {
// resolving failed
if errors.len() > 0 {
for e in errors {
self.import_resolving_error(e)
}
} else {
// Report unresolved imports only if no hard error was already reported
// to avoid generating multiple errors on the same import.
// Imports that are still indeterminate at this point are actually blocked
// by errored imports, so there is no point reporting them.
self.resolver.report_unresolved_imports(module_root);
}
break;
}
i += 1;
prev_unresolved_imports = self.resolver.unresolved_imports;
}
}
/// Resolves an `ImportResolvingError` into the correct enum discriminant
/// and passes that on to `resolve_error`.
fn import_resolving_error(&self, e: ImportResolvingError) {
// If it's a single failed import then create a "fake" import
// resolution for it so that later resolve stages won't complain.
if let SingleImport(target, _) = e.import_directive.subclass {
let mut import_resolutions = e.source_module.import_resolutions.borrow_mut();
let resolution = import_resolutions.entry((target, ValueNS)).or_insert_with(|| {
debug!("(resolving import error) adding import resolution for `{}`",
target);
ImportResolution::new(e.import_directive.id,
e.import_directive.is_public)
});
if resolution.target.is_none() {
debug!("(resolving import error) adding fake target to import resolution of `{}`",
target);
let name_binding = NameBinding {
modifiers: DefModifiers::IMPORTABLE,
def_or_module: DefOrModule::Def(Def::Err),
span: None,
};
// Create a fake target pointing to a fake name binding in our
// own module
let target = Target::new(e.source_module,
name_binding,
Shadowable::Always);
resolution.target = Some(target);
}
}
let path = import_path_to_string(&e.import_directive.module_path,
e.import_directive.subclass);
resolve_error(self.resolver,
e.span,
ResolutionError::UnresolvedImport(Some((&path, &e.help))));
}
/// Attempts to resolve imports for the given module and all of its
/// submodules.
fn resolve_imports_for_module_subtree(&mut self,
module_: Module<'b>)
-> Vec<ImportResolvingError<'b>> {
let mut errors = Vec::new();
debug!("(resolving imports for module subtree) resolving {}",
module_to_string(&*module_));
let orig_module = replace(&mut self.resolver.current_module, module_);
errors.extend(self.resolve_imports_for_module(module_));
self.resolver.current_module = orig_module;
build_reduced_graph::populate_module_if_necessary(self.resolver, &module_);
module_.for_each_local_child(|_, _, child_node| {
match child_node.module() {
None => {
// Nothing to do.
}
Some(child_module) => {
errors.extend(self.resolve_imports_for_module_subtree(child_module));
}
}
});
for (_, child_module) in module_.anonymous_children.borrow().iter() {
errors.extend(self.resolve_imports_for_module_subtree(child_module));
}
errors
}
/// Attempts to resolve imports for the given module only.
fn resolve_imports_for_module(&mut self, module: Module<'b>) -> Vec<ImportResolvingError<'b>> {
let mut errors = Vec::new();
if module.all_imports_resolved() {
debug!("(resolving imports for module) all imports resolved for {}",
module_to_string(&*module));
return errors;
}
let mut imports = module.imports.borrow_mut();
let import_count = imports.len();
let mut indeterminate_imports = Vec::new();
while module.resolved_import_count.get() + indeterminate_imports.len() < import_count {
let import_index = module.resolved_import_count.get();
match self.resolve_import_for_module(module, &imports[import_index]) {
ResolveResult::Failed(err) => {
let import_directive = &imports[import_index];
let (span, help) = match err {
Some((span, msg)) => (span, format!(". {}", msg)),
None => (import_directive.span, String::new()),
};
errors.push(ImportResolvingError {
source_module: module,
import_directive: import_directive.clone(),
span: span,
help: help,
});
}
ResolveResult::Indeterminate => {}
ResolveResult::Success(()) => {
// count success
module.resolved_import_count
.set(module.resolved_import_count.get() + 1);
continue;
}
}
// This resolution was not successful, keep it for later
indeterminate_imports.push(imports.swap_remove(import_index));
}
imports.extend(indeterminate_imports);
errors
}
/// Attempts to resolve the given import. The return value indicates
/// failure if we're certain the name does not exist, indeterminate if we
/// don't know whether the name exists at the moment due to other
/// currently-unresolved imports, or success if we know the name exists.
/// If successful, the resolved bindings are written into the module.
fn resolve_import_for_module(&mut self,
module_: Module<'b>,
import_directive: &ImportDirective)
-> ResolveResult<()> {
debug!("(resolving import for module) resolving import `{}::...` in `{}`",
names_to_string(&import_directive.module_path),
module_to_string(&*module_));
self.resolver
.resolve_module_path(module_,
&import_directive.module_path,
UseLexicalScopeFlag::DontUseLexicalScope,
import_directive.span)
.and_then(|(containing_module, lp)| {
// We found the module that the target is contained
// within. Attempt to resolve the import within it.
if let SingleImport(target, source) = import_directive.subclass {
self.resolve_single_import(&module_,
containing_module,
target,
source,
import_directive,
lp)
} else {
self.resolve_glob_import(&module_, containing_module, import_directive, lp)
}
})
.and_then(|()| {
// Decrement the count of unresolved imports.
assert!(self.resolver.unresolved_imports >= 1);
self.resolver.unresolved_imports -= 1;
if let GlobImport = import_directive.subclass {
module_.dec_glob_count();
if import_directive.is_public {
module_.dec_pub_glob_count();
}
}
if import_directive.is_public {
module_.dec_pub_count();
}
Success(())
})
}
/// Resolves the name in the namespace of the module because it is being imported by
/// importing_module. Returns the module in which the name was defined (as opposed to imported),
/// the name bindings defining the name, and whether or not the name was imported into `module`.
fn resolve_name_in_module(&mut self,
module: Module<'b>, // Module containing the name
name: Name,
ns: Namespace,
importing_module: Module<'b>) // Module importing the name
-> (ResolveResult<(Module<'b>, NameBinding<'b>)>, bool) {
build_reduced_graph::populate_module_if_necessary(self.resolver, module);
if let Some(name_binding) = module.get_child(name, ns) {
if name_binding.is_extern_crate() {
// track the extern crate as used.
if let Some(DefId { krate, .. }) = name_binding.module().unwrap().def_id() {
self.resolver.used_crates.insert(krate);
}
}
return (Success((module, name_binding)), false)
}
// If there is an unresolved glob at this point in the containing module, bail out.
// We don't know enough to be able to resolve the name.
if module.pub_glob_count.get() > 0 {
return (Indeterminate, false);
}
match module.import_resolutions.borrow().get(&(name, ns)) {
// The containing module definitely doesn't have an exported import with the
// name in question. We can therefore accurately report that names are unbound.
None => (Failed(None), false),
// The name is an import which has been fully resolved, so we just follow it.
Some(resolution) if resolution.outstanding_references == 0 => {
// Import resolutions must be declared with "pub" in order to be exported.
if !resolution.is_public {
return (Failed(None), false);
}
let target = resolution.target.clone();
if let Some(Target { target_module, binding, shadowable: _ }) = target {
self.resolver.record_import_use(name, ns, &resolution);
(Success((target_module, binding)), true)
} else {
(Failed(None), false)
}
}
// If module is the same module whose import we are resolving and
// it has an unresolved import with the same name as `name`, then the user
// is actually trying to import an item that is declared in the same scope
//
// e.g
// use self::submodule;
// pub mod submodule;
//
// In this case we continue as if we resolved the import and let
// check_for_conflicts_between_imports_and_items handle the conflict
Some(_) => match (importing_module.def_id(), module.def_id()) {
(Some(id1), Some(id2)) if id1 == id2 => (Failed(None), false),
_ => (Indeterminate, false)
},
}
}
fn resolve_single_import(&mut self,
module_: Module<'b>,
target_module: Module<'b>,
target: Name,
source: Name,
directive: &ImportDirective,
lp: LastPrivate)
-> ResolveResult<()> {
debug!("(resolving single import) resolving `{}` = `{}::{}` from `{}` id {}, last \
private {:?}",
target,
module_to_string(&*target_module),
source,
module_to_string(module_),
directive.id,
lp);
let lp = match lp {
LastMod(lp) => lp,
LastImport {..} => {
self.resolver
.session
.span_bug(directive.span, "not expecting Import here, must be LastMod")
}
};
// We need to resolve both namespaces for this to succeed.
let (value_result, value_used_reexport) =
self.resolve_name_in_module(&target_module, source, ValueNS, module_);
let (type_result, type_used_reexport) =
self.resolve_name_in_module(&target_module, source, TypeNS, module_);
match (&value_result, &type_result) {
(&Success((_, ref name_binding)), _) if !value_used_reexport &&
directive.is_public &&
!name_binding.is_public() => {
let msg = format!("`{}` is private, and cannot be reexported", source);
let note_msg = format!("Consider marking `{}` as `pub` in the imported module",
source);
struct_span_err!(self.resolver.session, directive.span, E0364, "{}", &msg)
.span_note(directive.span, &note_msg)
.emit();
}
(_, &Success((_, ref name_binding))) if !type_used_reexport &&
directive.is_public => {
if !name_binding.is_public() {
let msg = format!("`{}` is private, and cannot be reexported", source);
let note_msg =
format!("Consider declaring type or module `{}` with `pub`", source);
struct_span_err!(self.resolver.session, directive.span, E0365, "{}", &msg)
.span_note(directive.span, &note_msg)
.emit();
} else if name_binding.defined_with(DefModifiers::PRIVATE_VARIANT) {
let msg = format!("variant `{}` is private, and cannot be reexported \
(error E0364), consider declaring its enum as `pub`",
source);
self.resolver.session.add_lint(lint::builtin::PRIVATE_IN_PUBLIC,
directive.id,
directive.span,
msg);
}
}
_ => {}
}
let mut lev_suggestion = "".to_owned();
match (&value_result, &type_result) {
(&Indeterminate, _) | (_, &Indeterminate) => return Indeterminate,
(&Failed(_), &Failed(_)) => {
let children = target_module.children.borrow();
let names = children.keys().map(|&(ref name, _)| name);
if let Some(name) = find_best_match_for_name(names, &source.as_str(), None) {
lev_suggestion = format!(". Did you mean to use `{}`?", name);
} else {
let resolutions = target_module.import_resolutions.borrow();
let names = resolutions.keys().map(|&(ref name, _)| name);
if let Some(name) = find_best_match_for_name(names,
&source.as_str(),
None) {
lev_suggestion =
format!(". Did you mean to use the re-exported import `{}`?", name);
}
}
}
_ => (),
}
let mut value_used_public = false;
let mut type_used_public = false;
// We've successfully resolved the import. Write the results in.
let mut import_resolutions = module_.import_resolutions.borrow_mut();
{
let mut check_and_write_import = |namespace, result, used_public: &mut bool| {
let result: &ResolveResult<(Module<'b>, NameBinding)> = result;
let import_resolution = import_resolutions.get_mut(&(target, namespace)).unwrap();
let namespace_name = match namespace {
TypeNS => "type",
ValueNS => "value",
};
match *result {
Success((ref target_module, ref name_binding)) => {
debug!("(resolving single import) found {:?} target: {:?}",
namespace_name,
name_binding.def());
self.check_for_conflicting_import(&import_resolution,
directive.span,
target,
namespace);
self.check_that_import_is_importable(&name_binding,
directive.span,
target);
import_resolution.target = Some(Target::new(target_module,
name_binding.clone(),
directive.shadowable));
import_resolution.id = directive.id;
import_resolution.is_public = directive.is_public;
self.add_export(module_, target, &import_resolution);
*used_public = name_binding.is_public();
}
Failed(_) => {
// Continue.
}
Indeterminate => {
panic!("{:?} result should be known at this point", namespace_name);
}
}
self.check_for_conflicts_between_imports_and_items(module_,
import_resolution,
directive.span,
(target, namespace));
};
check_and_write_import(ValueNS, &value_result, &mut value_used_public);
check_and_write_import(TypeNS, &type_result, &mut type_used_public);
}
if let (&Failed(_), &Failed(_)) = (&value_result, &type_result) {
let msg = format!("There is no `{}` in `{}`{}",
source,
module_to_string(&target_module), lev_suggestion);
return Failed(Some((directive.span, msg)));
}
let value_used_public = value_used_reexport || value_used_public;
let type_used_public = type_used_reexport || type_used_public;
let value_def_and_priv = {
let import_resolution_value = import_resolutions.get_mut(&(target, ValueNS)).unwrap();
assert!(import_resolution_value.outstanding_references >= 1);
import_resolution_value.outstanding_references -= 1;
// Record what this import resolves to for later uses in documentation,
// this may resolve to either a value or a type, but for documentation
// purposes it's good enough to just favor one over the other.
import_resolution_value.target.as_ref().map(|target| {
let def = target.binding.def().unwrap();
let last_private = if value_used_public { lp } else { DependsOn(def.def_id()) };
(def, last_private)
})
};
let type_def_and_priv = {
let import_resolution_type = import_resolutions.get_mut(&(target, TypeNS)).unwrap();
assert!(import_resolution_type.outstanding_references >= 1);
import_resolution_type.outstanding_references -= 1;
import_resolution_type.target.as_ref().map(|target| {
let def = target.binding.def().unwrap();
let last_private = if type_used_public { lp } else { DependsOn(def.def_id()) };
(def, last_private)
})
};
let import_lp = LastImport {
value_priv: value_def_and_priv.map(|(_, p)| p),
value_used: Used,
type_priv: type_def_and_priv.map(|(_, p)| p),
type_used: Used,
};
if let Some((def, _)) = value_def_and_priv {
self.resolver.def_map.borrow_mut().insert(directive.id,
PathResolution {
base_def: def,
last_private: import_lp,
depth: 0,
});
}
if let Some((def, _)) = type_def_and_priv {
self.resolver.def_map.borrow_mut().insert(directive.id,
PathResolution {
base_def: def,
last_private: import_lp,
depth: 0,
});
}
debug!("(resolving single import) successfully resolved import");
return Success(());
}
// Resolves a glob import. Note that this function cannot fail; it either
// succeeds or bails out (as importing * from an empty module or a module
// that exports nothing is valid). target_module is the module we are
// actually importing, i.e., `foo` in `use foo::*`.
fn resolve_glob_import(&mut self,
module_: Module<'b>,
target_module: Module<'b>,
import_directive: &ImportDirective,
lp: LastPrivate)
-> ResolveResult<()> {
let id = import_directive.id;
let is_public = import_directive.is_public;
// This function works in a highly imperative manner; it eagerly adds
// everything it can to the list of import resolutions of the module
// node.
debug!("(resolving glob import) resolving glob import {}", id);
// We must bail out if the node has unresolved imports of any kind
// (including globs).
if (*target_module).pub_count.get() > 0 {
debug!("(resolving glob import) target module has unresolved pub imports; bailing out");
return ResolveResult::Indeterminate;
}
// Add all resolved imports from the containing module.
let import_resolutions = target_module.import_resolutions.borrow();
if module_.import_resolutions.borrow_state() != ::std::cell::BorrowState::Unused {
// In this case, target_module == module_
// This means we are trying to glob import a module into itself,
// and it is a no-go
debug!("(resolving glob imports) target module is current module; giving up");
return ResolveResult::Failed(Some((import_directive.span,
"Cannot glob-import a module into itself.".into())));
}
for (&(name, ns), target_import_resolution) in import_resolutions.iter() {
debug!("(resolving glob import) writing module resolution {} into `{}`",
name,
module_to_string(module_));
// Here we merge two import resolutions.
let mut import_resolutions = module_.import_resolutions.borrow_mut();
let mut dest_import_resolution =
import_resolutions.entry((name, ns))
.or_insert_with(|| ImportResolution::new(id, is_public));
match target_import_resolution.target {
Some(ref target) if target_import_resolution.is_public => {
self.check_for_conflicting_import(&dest_import_resolution,
import_directive.span,
name,
ns);
dest_import_resolution.id = id;
dest_import_resolution.is_public = is_public;
dest_import_resolution.target = Some(target.clone());
self.add_export(module_, name, &dest_import_resolution);
}
_ => {}
}
}
// Add all children from the containing module.
build_reduced_graph::populate_module_if_necessary(self.resolver, &target_module);
target_module.for_each_local_child(|name, ns, name_binding| {
self.merge_import_resolution(module_,
target_module,
import_directive,
(name, ns),
name_binding.clone());
});
// Record the destination of this import
if let Some(did) = target_module.def_id() {
self.resolver.def_map.borrow_mut().insert(id,
PathResolution {
base_def: Def::Mod(did),
last_private: lp,
depth: 0,
});
}
debug!("(resolving glob import) successfully resolved import");
return ResolveResult::Success(());
}
fn merge_import_resolution(&mut self,
module_: Module<'b>,
containing_module: Module<'b>,
import_directive: &ImportDirective,
(name, ns): (Name, Namespace),
name_binding: NameBinding<'b>) {
let id = import_directive.id;
let is_public = import_directive.is_public;
let mut import_resolutions = module_.import_resolutions.borrow_mut();
let dest_import_resolution = import_resolutions.entry((name, ns)).or_insert_with(|| {
ImportResolution::new(id, is_public)
});
debug!("(resolving glob import) writing resolution `{}` in `{}` to `{}`",
name,
module_to_string(&*containing_module),
module_to_string(module_));
// Merge the child item into the import resolution.
let modifier = DefModifiers::IMPORTABLE | DefModifiers::PUBLIC;
if ns == TypeNS && is_public && name_binding.defined_with(DefModifiers::PRIVATE_VARIANT) {
let msg = format!("variant `{}` is private, and cannot be reexported (error \
E0364), consider declaring its enum as `pub`", name);
self.resolver.session.add_lint(lint::builtin::PRIVATE_IN_PUBLIC,
import_directive.id,
import_directive.span,
msg);
}
if name_binding.defined_with(modifier) {
let namespace_name = match ns {
TypeNS => "type",
ValueNS => "value",
};
debug!("(resolving glob import) ... for {} target", namespace_name);
if dest_import_resolution.shadowable() == Shadowable::Never {
let msg = format!("a {} named `{}` has already been imported in this module",
namespace_name,
name);
span_err!(self.resolver.session, import_directive.span, E0251, "{}", msg);
} else {
let target = Target::new(containing_module,
name_binding.clone(),
import_directive.shadowable);
dest_import_resolution.target = Some(target);
dest_import_resolution.id = id;
dest_import_resolution.is_public = is_public;
self.add_export(module_, name, &dest_import_resolution);
}
}
self.check_for_conflicts_between_imports_and_items(module_,
dest_import_resolution,
import_directive.span,
(name, ns));
}
fn add_export(&mut self, module: Module<'b>, name: Name, resolution: &ImportResolution<'b>) {
if !resolution.is_public { return }
let node_id = match module.def_id() {
Some(def_id) => self.resolver.ast_map.as_local_node_id(def_id).unwrap(),
None => return,
};
let export = match resolution.target.as_ref().unwrap().binding.def() {
Some(def) => Export { name: name, def_id: def.def_id() },
None => return,
};
self.resolver.export_map.entry(node_id).or_insert(Vec::new()).push(export);
}
/// Checks that imported names and items don't have the same name.
fn check_for_conflicting_import(&mut self,
import_resolution: &ImportResolution,
import_span: Span,
name: Name,
namespace: Namespace) {
let target = &import_resolution.target;
debug!("check_for_conflicting_import: {}; target exists: {}",
name,
target.is_some());
match *target {
Some(ref target) if target.shadowable != Shadowable::Always => {
let ns_word = match namespace {
TypeNS => {
match target.binding.module() {
Some(ref module) if module.is_normal() => "module",
Some(ref module) if module.is_trait() => "trait",
_ => "type",
}
}
ValueNS => "value",
};
let use_id = import_resolution.id;
let item = self.resolver.ast_map.expect_item(use_id);
let mut err = struct_span_err!(self.resolver.session,
import_span,
E0252,
"a {} named `{}` has already been imported \
in this module",
ns_word,
name);
span_note!(&mut err,
item.span,
"previous import of `{}` here",
name);
err.emit();
}
Some(_) | None => {}
}
}
/// Checks that an import is actually importable
fn check_that_import_is_importable(&mut self,
name_binding: &NameBinding,
import_span: Span,
name: Name) {
if !name_binding.defined_with(DefModifiers::IMPORTABLE) {
let msg = format!("`{}` is not directly importable", name);
span_err!(self.resolver.session, import_span, E0253, "{}", &msg[..]);
}
}
/// Checks that imported names and items don't have the same name.
fn check_for_conflicts_between_imports_and_items(&mut self,
module: Module<'b>,
import: &ImportResolution<'b>,
import_span: Span,
(name, ns): (Name, Namespace)) {
// Check for item conflicts.
let name_binding = match module.get_child(name, ns) {
None => {
// There can't be any conflicts.
return;
}
Some(name_binding) => name_binding,
};
if ns == ValueNS {
match import.target {
Some(ref target) if target.shadowable != Shadowable::Always => {
let mut err = struct_span_err!(self.resolver.session,
import_span,
E0255,
"import `{}` conflicts with \
value in this module",
name);
if let Some(span) = name_binding.span {
err.span_note(span, "conflicting value here");
}
err.emit();
}
Some(_) | None => {}
}
} else {
match import.target {
Some(ref target) if target.shadowable != Shadowable::Always => {
if name_binding.is_extern_crate() {
let msg = format!("import `{0}` conflicts with imported crate \
in this module (maybe you meant `use {0}::*`?)",
name);
span_err!(self.resolver.session, import_span, E0254, "{}", &msg[..]);
return;
}
let (what, note) = match name_binding.module() {
Some(ref module) if module.is_normal() =>
("existing submodule", "note conflicting module here"),
Some(ref module) if module.is_trait() =>
("trait in this module", "note conflicting trait here"),
_ => ("type in this module", "note conflicting type here"),
};
let mut err = struct_span_err!(self.resolver.session,
import_span,
E0256,
"import `{}` conflicts with {}",
name,
what);
if let Some(span) = name_binding.span {
err.span_note(span, note);
}
err.emit();
}
Some(_) | None => {}
}
}
}
}
fn import_path_to_string(names: &[Name], subclass: ImportDirectiveSubclass) -> String {
if names.is_empty() {
import_directive_subclass_to_string(subclass)
} else {
(format!("{}::{}",
names_to_string(names),
import_directive_subclass_to_string(subclass)))
.to_string()
}
}
fn import_directive_subclass_to_string(subclass: ImportDirectiveSubclass) -> String {
match subclass {
SingleImport(_, source) => source.to_string(),
GlobImport => "*".to_string(),
}
}
pub fn resolve_imports(resolver: &mut Resolver) {
let mut import_resolver = ImportResolver { resolver: resolver };
import_resolver.resolve_imports();
}