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// Copyright 2012-2015 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 {CrateLint, PathResult};
use std::collections::BTreeSet;
use syntax::ast::Ident;
use syntax::symbol::{keywords, Symbol};
use syntax_pos::Span;
use resolve_imports::ImportResolver;
impl<'a, 'b:'a, 'c: 'b> ImportResolver<'a, 'b, 'c> {
/// Add suggestions for a path that cannot be resolved.
pub(crate) fn make_path_suggestion(
&mut self,
span: Span,
path: Vec<Ident>
) -> Option<Vec<Ident>> {
debug!("make_path_suggestion: span={:?} path={:?}", span, path);
// If we don't have a path to suggest changes to, then return.
if path.is_empty() {
return None;
}
// Check whether a ident is a path segment that is not root.
let is_special = |ident: Ident| ident.is_path_segment_keyword() &&
ident.name != keywords::CrateRoot.name();
match (path.get(0), path.get(1)) {
// Make suggestions that require at least two non-special path segments.
(Some(fst), Some(snd)) if !is_special(*fst) && !is_special(*snd) => {
debug!("make_path_suggestion: fst={:?} snd={:?}", fst, snd);
self.make_missing_self_suggestion(span, path.clone())
.or_else(|| self.make_missing_crate_suggestion(span, path.clone()))
.or_else(|| self.make_missing_super_suggestion(span, path.clone()))
.or_else(|| self.make_external_crate_suggestion(span, path.clone()))
},
_ => None,
}
}
/// Suggest a missing `self::` if that resolves to an correct module.
///
/// ```
/// |
/// LL | use foo::Bar;
/// | ^^^ Did you mean `self::foo`?
/// ```
fn make_missing_self_suggestion(
&mut self,
span: Span,
mut path: Vec<Ident>
) -> Option<Vec<Ident>> {
// Replace first ident with `self` and check if that is valid.
path[0].name = keywords::SelfValue.name();
let result = self.resolve_path(None, &path, None, false, span, CrateLint::No);
debug!("make_missing_self_suggestion: path={:?} result={:?}", path, result);
if let PathResult::Module(..) = result {
Some(path)
} else {
None
}
}
/// Suggest a missing `crate::` if that resolves to an correct module.
///
/// ```
/// |
/// LL | use foo::Bar;
/// | ^^^ Did you mean `crate::foo`?
/// ```
fn make_missing_crate_suggestion(
&mut self,
span: Span,
mut path: Vec<Ident>
) -> Option<Vec<Ident>> {
// Replace first ident with `crate` and check if that is valid.
path[0].name = keywords::Crate.name();
let result = self.resolve_path(None, &path, None, false, span, CrateLint::No);
debug!("make_missing_crate_suggestion: path={:?} result={:?}", path, result);
if let PathResult::Module(..) = result {
Some(path)
} else {
None
}
}
/// Suggest a missing `super::` if that resolves to an correct module.
///
/// ```
/// |
/// LL | use foo::Bar;
/// | ^^^ Did you mean `super::foo`?
/// ```
fn make_missing_super_suggestion(
&mut self,
span: Span,
mut path: Vec<Ident>
) -> Option<Vec<Ident>> {
// Replace first ident with `crate` and check if that is valid.
path[0].name = keywords::Super.name();
let result = self.resolve_path(None, &path, None, false, span, CrateLint::No);
debug!("make_missing_super_suggestion: path={:?} result={:?}", path, result);
if let PathResult::Module(..) = result {
Some(path)
} else {
None
}
}
/// Suggest a missing external crate name if that resolves to an correct module.
///
/// ```
/// |
/// LL | use foobar::Baz;
/// | ^^^^^^ Did you mean `baz::foobar`?
/// ```
///
/// Used when importing a submodule of an external crate but missing that crate's
/// name as the first part of path.
fn make_external_crate_suggestion(
&mut self,
span: Span,
mut path: Vec<Ident>
) -> Option<Vec<Ident>> {
// Need to clone else we can't call `resolve_path` without a borrow error. We also store
// into a `BTreeMap` so we can get consistent ordering (and therefore the same diagnostic)
// each time.
let external_crate_names: BTreeSet<Symbol> = self.resolver.extern_prelude
.clone().drain().collect();
// Insert a new path segment that we can replace.
let new_path_segment = path[0].clone();
path.insert(1, new_path_segment);
// Iterate in reverse so that we start with crates at the end of the alphabet. This means
// that we'll always get `std` before `core`.
for name in external_crate_names.iter().rev() {
let ident = Ident::with_empty_ctxt(*name);
// Calling `maybe_process_path_extern` ensures that we're only running `resolve_path`
// on a crate name that won't ICE.
if let Some(_) = self.crate_loader.maybe_process_path_extern(*name, ident.span) {
// Replace the first after root (a placeholder we inserted) with a crate name
// and check if that is valid.
path[1].name = *name;
let result = self.resolve_path(None, &path, None, false, span, CrateLint::No);
debug!("make_external_crate_suggestion: name={:?} path={:?} result={:?}",
name, path, result);
if let PathResult::Module(..) = result {
return Some(path)
}
}
}
// Remove our placeholder segment.
path.remove(1);
None
}
}
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