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use crate::{CrateLint, Module, ModuleKind, ModuleOrUniformRoot};
use crate::{PathResult, PathSource, Segment};
use crate::path_names_to_string;
use crate::diagnostics::{add_typo_suggestion, ImportSuggestion, TypoSuggestion};
use crate::late::{LateResolutionVisitor, RibKind};
use errors::{Applicability, DiagnosticBuilder, DiagnosticId};
use log::debug;
use rustc::hir::def::{self, DefKind, CtorKind};
use rustc::hir::def::Namespace::{self, *};
use rustc::hir::def_id::{CRATE_DEF_INDEX, DefId};
use rustc::hir::PrimTy;
use rustc::session::config::nightly_options;
use rustc::util::nodemap::FxHashSet;
use syntax::ast::{self, Expr, ExprKind, Ident, NodeId, Path, Ty, TyKind};
use syntax::ext::base::MacroKind;
use syntax::symbol::kw;
use syntax::util::lev_distance::find_best_match_for_name;
use syntax_pos::Span;
type Res = def::Res<ast::NodeId>;
/// A field or associated item from self type suggested in case of resolution failure.
enum AssocSuggestion {
Field,
MethodWithSelf,
AssocItem,
}
fn is_self_type(path: &[Segment], namespace: Namespace) -> bool {
namespace == TypeNS && path.len() == 1 && path[0].ident.name == kw::SelfUpper
}
fn is_self_value(path: &[Segment], namespace: Namespace) -> bool {
namespace == ValueNS && path.len() == 1 && path[0].ident.name == kw::SelfLower
}
/// Gets the stringified path for an enum from an `ImportSuggestion` for an enum variant.
fn import_candidate_to_enum_paths(suggestion: &ImportSuggestion) -> (String, String) {
let variant_path = &suggestion.path;
let variant_path_string = path_names_to_string(variant_path);
let path_len = suggestion.path.segments.len();
let enum_path = ast::Path {
span: suggestion.path.span,
segments: suggestion.path.segments[0..path_len - 1].to_vec(),
};
let enum_path_string = path_names_to_string(&enum_path);
(variant_path_string, enum_path_string)
}
impl<'a> LateResolutionVisitor<'a, '_> {
/// Handles error reporting for `smart_resolve_path_fragment` function.
/// Creates base error and amends it with one short label and possibly some longer helps/notes.
pub(crate) fn smart_resolve_report_errors(
&mut self,
path: &[Segment],
span: Span,
source: PathSource<'_>,
res: Option<Res>,
) -> (DiagnosticBuilder<'a>, Vec<ImportSuggestion>) {
let ident_span = path.last().map_or(span, |ident| ident.ident.span);
let ns = source.namespace();
let is_expected = &|res| source.is_expected(res);
let is_enum_variant = &|res| {
if let Res::Def(DefKind::Variant, _) = res { true } else { false }
};
// Make the base error.
let expected = source.descr_expected();
let path_str = Segment::names_to_string(path);
let item_str = path.last().unwrap().ident;
let code = source.error_code(res.is_some());
let (base_msg, fallback_label, base_span) = if let Some(res) = res {
(format!("expected {}, found {} `{}`", expected, res.descr(), path_str),
format!("not a {}", expected),
span)
} else {
let item_span = path.last().unwrap().ident.span;
let (mod_prefix, mod_str) = if path.len() == 1 {
(String::new(), "this scope".to_string())
} else if path.len() == 2 && path[0].ident.name == kw::PathRoot {
(String::new(), "the crate root".to_string())
} else {
let mod_path = &path[..path.len() - 1];
let mod_prefix = match self.resolve_path(
mod_path, Some(TypeNS), false, span, CrateLint::No
) {
PathResult::Module(ModuleOrUniformRoot::Module(module)) => module.res(),
_ => None,
}.map_or(String::new(), |res| format!("{} ", res.descr()));
(mod_prefix, format!("`{}`", Segment::names_to_string(mod_path)))
};
(format!("cannot find {} `{}` in {}{}", expected, item_str, mod_prefix, mod_str),
format!("not found in {}", mod_str),
item_span)
};
let code = DiagnosticId::Error(code.into());
let mut err = self.r.session.struct_span_err_with_code(base_span, &base_msg, code);
// Emit help message for fake-self from other languages (e.g., `this` in Javascript).
if ["this", "my"].contains(&&*item_str.as_str())
&& self.self_value_is_available(path[0].ident.span, span) {
err.span_suggestion(
span,
"did you mean",
"self".to_string(),
Applicability::MaybeIncorrect,
);
}
// Emit special messages for unresolved `Self` and `self`.
if is_self_type(path, ns) {
syntax::diagnostic_used!(E0411);
err.code(DiagnosticId::Error("E0411".into()));
err.span_label(span, format!("`Self` is only available in impls, traits, \
and type definitions"));
return (err, Vec::new());
}
if is_self_value(path, ns) {
debug!("smart_resolve_path_fragment: E0424, source={:?}", source);
syntax::diagnostic_used!(E0424);
err.code(DiagnosticId::Error("E0424".into()));
err.span_label(span, match source {
PathSource::Pat => {
format!("`self` value is a keyword \
and may not be bound to \
variables or shadowed")
}
_ => {
format!("`self` value is a keyword \
only available in methods \
with `self` parameter")
}
});
return (err, Vec::new());
}
// Try to lookup name in more relaxed fashion for better error reporting.
let ident = path.last().unwrap().ident;
let candidates = self.r.lookup_import_candidates(ident, ns, is_expected)
.drain(..)
.filter(|ImportSuggestion { did, .. }| {
match (did, res.and_then(|res| res.opt_def_id())) {
(Some(suggestion_did), Some(actual_did)) => *suggestion_did != actual_did,
_ => true,
}
})
.collect::<Vec<_>>();
let crate_def_id = DefId::local(CRATE_DEF_INDEX);
if candidates.is_empty() && is_expected(Res::Def(DefKind::Enum, crate_def_id)) {
let enum_candidates =
self.r.lookup_import_candidates(ident, ns, is_enum_variant);
let mut enum_candidates = enum_candidates.iter()
.map(|suggestion| {
import_candidate_to_enum_paths(&suggestion)
}).collect::<Vec<_>>();
enum_candidates.sort();
if !enum_candidates.is_empty() {
// Contextualize for E0412 "cannot find type", but don't belabor the point
// (that it's a variant) for E0573 "expected type, found variant".
let preamble = if res.is_none() {
let others = match enum_candidates.len() {
1 => String::new(),
2 => " and 1 other".to_owned(),
n => format!(" and {} others", n)
};
format!("there is an enum variant `{}`{}; ",
enum_candidates[0].0, others)
} else {
String::new()
};
let msg = format!("{}try using the variant's enum", preamble);
err.span_suggestions(
span,
&msg,
enum_candidates.into_iter()
.map(|(_variant_path, enum_ty_path)| enum_ty_path)
// Variants re-exported in prelude doesn't mean `prelude::v1` is the
// type name!
// FIXME: is there a more principled way to do this that
// would work for other re-exports?
.filter(|enum_ty_path| enum_ty_path != "std::prelude::v1")
// Also write `Option` rather than `std::prelude::v1::Option`.
.map(|enum_ty_path| {
// FIXME #56861: DRY-er prelude filtering.
enum_ty_path.trim_start_matches("std::prelude::v1::").to_owned()
}),
Applicability::MachineApplicable,
);
}
}
if path.len() == 1 && self.self_type_is_available(span) {
if let Some(candidate) = self.lookup_assoc_candidate(ident, ns, is_expected) {
let self_is_available = self.self_value_is_available(path[0].ident.span, span);
match candidate {
AssocSuggestion::Field => {
if self_is_available {
err.span_suggestion(
span,
"you might have meant to use the available field",
format!("self.{}", path_str),
Applicability::MachineApplicable,
);
} else {
err.span_label(
span,
"a field by this name exists in `Self`",
);
}
}
AssocSuggestion::MethodWithSelf if self_is_available => {
err.span_suggestion(
span,
"try",
format!("self.{}", path_str),
Applicability::MachineApplicable,
);
}
AssocSuggestion::MethodWithSelf | AssocSuggestion::AssocItem => {
err.span_suggestion(
span,
"try",
format!("Self::{}", path_str),
Applicability::MachineApplicable,
);
}
}
return (err, candidates);
}
}
// Try Levenshtein algorithm.
let levenshtein_worked = add_typo_suggestion(
&mut err, self.lookup_typo_candidate(path, ns, is_expected, span), ident_span
);
// Try context-dependent help if relaxed lookup didn't work.
if let Some(res) = res {
if self.smart_resolve_context_dependent_help(&mut err,
span,
source,
res,
&path_str,
&fallback_label) {
return (err, candidates);
}
}
// Fallback label.
if !levenshtein_worked {
err.span_label(base_span, fallback_label);
self.type_ascription_suggestion(&mut err, base_span);
}
(err, candidates)
}
fn followed_by_brace(&self, span: Span) -> (bool, Option<(Span, String)>) {
// HACK(estebank): find a better way to figure out that this was a
// parser issue where a struct literal is being used on an expression
// where a brace being opened means a block is being started. Look
// ahead for the next text to see if `span` is followed by a `{`.
let sm = self.r.session.source_map();
let mut sp = span;
loop {
sp = sm.next_point(sp);
match sm.span_to_snippet(sp) {
Ok(ref snippet) => {
if snippet.chars().any(|c| { !c.is_whitespace() }) {
break;
}
}
_ => break,
}
}
let followed_by_brace = match sm.span_to_snippet(sp) {
Ok(ref snippet) if snippet == "{" => true,
_ => false,
};
// In case this could be a struct literal that needs to be surrounded
// by parenthesis, find the appropriate span.
let mut i = 0;
let mut closing_brace = None;
loop {
sp = sm.next_point(sp);
match sm.span_to_snippet(sp) {
Ok(ref snippet) => {
if snippet == "}" {
let sp = span.to(sp);
if let Ok(snippet) = sm.span_to_snippet(sp) {
closing_brace = Some((sp, snippet));
}
break;
}
}
_ => break,
}
i += 1;
// The bigger the span, the more likely we're incorrect --
// bound it to 100 chars long.
if i > 100 {
break;
}
}
return (followed_by_brace, closing_brace)
}
/// Provides context-dependent help for errors reported by the `smart_resolve_path_fragment`
/// function.
/// Returns `true` if able to provide context-dependent help.
fn smart_resolve_context_dependent_help(
&mut self,
err: &mut DiagnosticBuilder<'a>,
span: Span,
source: PathSource<'_>,
res: Res,
path_str: &str,
fallback_label: &str,
) -> bool {
let ns = source.namespace();
let is_expected = &|res| source.is_expected(res);
let path_sep = |err: &mut DiagnosticBuilder<'_>, expr: &Expr| match expr.node {
ExprKind::Field(_, ident) => {
err.span_suggestion(
expr.span,
"use the path separator to refer to an item",
format!("{}::{}", path_str, ident),
Applicability::MaybeIncorrect,
);
true
}
ExprKind::MethodCall(ref segment, ..) => {
let span = expr.span.with_hi(segment.ident.span.hi());
err.span_suggestion(
span,
"use the path separator to refer to an item",
format!("{}::{}", path_str, segment.ident),
Applicability::MaybeIncorrect,
);
true
}
_ => false,
};
let mut bad_struct_syntax_suggestion = || {
let (followed_by_brace, closing_brace) = self.followed_by_brace(span);
let mut suggested = false;
match source {
PathSource::Expr(Some(parent)) => {
suggested = path_sep(err, &parent);
}
PathSource::Expr(None) if followed_by_brace == true => {
if let Some((sp, snippet)) = closing_brace {
err.span_suggestion(
sp,
"surround the struct literal with parenthesis",
format!("({})", snippet),
Applicability::MaybeIncorrect,
);
} else {
err.span_label(
span, // Note the parenthesis surrounding the suggestion below
format!("did you mean `({} {{ /* fields */ }})`?", path_str),
);
}
suggested = true;
},
_ => {}
}
if !suggested {
err.span_label(
span,
format!("did you mean `{} {{ /* fields */ }}`?", path_str),
);
}
};
match (res, source) {
(Res::Def(DefKind::Macro(MacroKind::Bang), _), _) => {
err.span_suggestion(
span,
"use `!` to invoke the macro",
format!("{}!", path_str),
Applicability::MaybeIncorrect,
);
if path_str == "try" && span.rust_2015() {
err.note("if you want the `try` keyword, you need to be in the 2018 edition");
}
}
(Res::Def(DefKind::TyAlias, _), PathSource::Trait(_)) => {
err.span_label(span, "type aliases cannot be used as traits");
if nightly_options::is_nightly_build() {
err.note("did you mean to use a trait alias?");
}
}
(Res::Def(DefKind::Mod, _), PathSource::Expr(Some(parent))) => {
if !path_sep(err, &parent) {
return false;
}
}
(Res::Def(DefKind::Enum, def_id), PathSource::TupleStruct)
| (Res::Def(DefKind::Enum, def_id), PathSource::Expr(..)) => {
if let Some(variants) = self.collect_enum_variants(def_id) {
if !variants.is_empty() {
let msg = if variants.len() == 1 {
"try using the enum's variant"
} else {
"try using one of the enum's variants"
};
err.span_suggestions(
span,
msg,
variants.iter().map(path_names_to_string),
Applicability::MaybeIncorrect,
);
}
} else {
err.note("did you mean to use one of the enum's variants?");
}
},
(Res::Def(DefKind::Struct, def_id), _) if ns == ValueNS => {
if let Some((ctor_def, ctor_vis))
= self.r.struct_constructors.get(&def_id).cloned() {
let accessible_ctor =
self.r.is_accessible_from(ctor_vis, self.parent_scope.module);
if is_expected(ctor_def) && !accessible_ctor {
err.span_label(
span,
format!("constructor is not visible here due to private fields"),
);
}
} else {
bad_struct_syntax_suggestion();
}
}
(Res::Def(DefKind::Union, _), _) |
(Res::Def(DefKind::Variant, _), _) |
(Res::Def(DefKind::Ctor(_, CtorKind::Fictive), _), _) if ns == ValueNS => {
bad_struct_syntax_suggestion();
}
(Res::SelfTy(..), _) if ns == ValueNS => {
err.span_label(span, fallback_label);
err.note("can't use `Self` as a constructor, you must use the implemented struct");
}
(Res::Def(DefKind::TyAlias, _), _)
| (Res::Def(DefKind::AssocTy, _), _) if ns == ValueNS => {
err.note("can't use a type alias as a constructor");
}
_ => return false,
}
true
}
fn lookup_assoc_candidate<FilterFn>(&mut self,
ident: Ident,
ns: Namespace,
filter_fn: FilterFn)
-> Option<AssocSuggestion>
where FilterFn: Fn(Res) -> bool
{
fn extract_node_id(t: &Ty) -> Option<NodeId> {
match t.node {
TyKind::Path(None, _) => Some(t.id),
TyKind::Rptr(_, ref mut_ty) => extract_node_id(&mut_ty.ty),
// This doesn't handle the remaining `Ty` variants as they are not
// that commonly the self_type, it might be interesting to provide
// support for those in future.
_ => None,
}
}
// Fields are generally expected in the same contexts as locals.
if filter_fn(Res::Local(ast::DUMMY_NODE_ID)) {
if let Some(node_id) = self.current_self_type.as_ref().and_then(extract_node_id) {
// Look for a field with the same name in the current self_type.
if let Some(resolution) = self.r.partial_res_map.get(&node_id) {
match resolution.base_res() {
Res::Def(DefKind::Struct, did) | Res::Def(DefKind::Union, did)
if resolution.unresolved_segments() == 0 => {
if let Some(field_names) = self.r.field_names.get(&did) {
if field_names.iter().any(|&field_name| ident.name == field_name) {
return Some(AssocSuggestion::Field);
}
}
}
_ => {}
}
}
}
}
for assoc_type_ident in &self.current_trait_assoc_types {
if *assoc_type_ident == ident {
return Some(AssocSuggestion::AssocItem);
}
}
// Look for associated items in the current trait.
if let Some((module, _)) = self.current_trait_ref {
if let Ok(binding) = self.r.resolve_ident_in_module(
ModuleOrUniformRoot::Module(module),
ident,
ns,
&self.parent_scope,
false,
module.span,
) {
let res = binding.res();
if filter_fn(res) {
return Some(if self.r.has_self.contains(&res.def_id()) {
AssocSuggestion::MethodWithSelf
} else {
AssocSuggestion::AssocItem
});
}
}
}
None
}
fn lookup_typo_candidate(
&mut self,
path: &[Segment],
ns: Namespace,
filter_fn: &impl Fn(Res) -> bool,
span: Span,
) -> Option<TypoSuggestion> {
let mut names = Vec::new();
if path.len() == 1 {
// Search in lexical scope.
// Walk backwards up the ribs in scope and collect candidates.
for rib in self.ribs[ns].iter().rev() {
// Locals and type parameters
for (ident, &res) in &rib.bindings {
if filter_fn(res) {
names.push(TypoSuggestion::from_res(ident.name, res));
}
}
// Items in scope
if let RibKind::ModuleRibKind(module) = rib.kind {
// Items from this module
self.r.add_module_candidates(module, &mut names, &filter_fn);
if let ModuleKind::Block(..) = module.kind {
// We can see through blocks
} else {
// Items from the prelude
if !module.no_implicit_prelude {
let extern_prelude = self.r.extern_prelude.clone();
names.extend(extern_prelude.iter().flat_map(|(ident, _)| {
self.r.crate_loader
.maybe_process_path_extern(ident.name, ident.span)
.and_then(|crate_id| {
let crate_mod = Res::Def(
DefKind::Mod,
DefId {
krate: crate_id,
index: CRATE_DEF_INDEX,
},
);
if filter_fn(crate_mod) {
Some(TypoSuggestion::from_res(ident.name, crate_mod))
} else {
None
}
})
}));
if let Some(prelude) = self.r.prelude {
self.r.add_module_candidates(prelude, &mut names, &filter_fn);
}
}
break;
}
}
}
// Add primitive types to the mix
if filter_fn(Res::PrimTy(PrimTy::Bool)) {
names.extend(
self.r.primitive_type_table.primitive_types.iter().map(|(name, prim_ty)| {
TypoSuggestion::from_res(*name, Res::PrimTy(*prim_ty))
})
)
}
} else {
// Search in module.
let mod_path = &path[..path.len() - 1];
if let PathResult::Module(module) = self.resolve_path(
mod_path, Some(TypeNS), false, span, CrateLint::No
) {
if let ModuleOrUniformRoot::Module(module) = module {
self.r.add_module_candidates(module, &mut names, &filter_fn);
}
}
}
let name = path[path.len() - 1].ident.name;
// Make sure error reporting is deterministic.
names.sort_by_cached_key(|suggestion| suggestion.candidate.as_str());
match find_best_match_for_name(
names.iter().map(|suggestion| &suggestion.candidate),
&name.as_str(),
None,
) {
Some(found) if found != name => names
.into_iter()
.find(|suggestion| suggestion.candidate == found),
_ => None,
}
}
/// Only used in a specific case of type ascription suggestions
fn get_colon_suggestion_span(&self, start: Span) -> Span {
let cm = self.r.session.source_map();
start.to(cm.next_point(start))
}
fn type_ascription_suggestion(
&self,
err: &mut DiagnosticBuilder<'_>,
base_span: Span,
) {
debug!("type_ascription_suggetion {:?}", base_span);
let cm = self.r.session.source_map();
let base_snippet = cm.span_to_snippet(base_span);
debug!("self.current_type_ascription {:?}", self.current_type_ascription);
if let Some(sp) = self.current_type_ascription.last() {
let mut sp = *sp;
loop {
// Try to find the `:`; bail on first non-':' / non-whitespace.
sp = cm.next_point(sp);
if let Ok(snippet) = cm.span_to_snippet(sp.to(cm.next_point(sp))) {
let line_sp = cm.lookup_char_pos(sp.hi()).line;
let line_base_sp = cm.lookup_char_pos(base_span.lo()).line;
if snippet == ":" {
let mut show_label = true;
if line_sp != line_base_sp {
err.span_suggestion_short(
sp,
"did you mean to use `;` here instead?",
";".to_string(),
Applicability::MaybeIncorrect,
);
} else {
let colon_sp = self.get_colon_suggestion_span(sp);
let after_colon_sp = self.get_colon_suggestion_span(
colon_sp.shrink_to_hi(),
);
if !cm.span_to_snippet(after_colon_sp).map(|s| s == " ")
.unwrap_or(false)
{
err.span_suggestion(
colon_sp,
"maybe you meant to write a path separator here",
"::".to_string(),
Applicability::MaybeIncorrect,
);
show_label = false;
}
if let Ok(base_snippet) = base_snippet {
let mut sp = after_colon_sp;
for _ in 0..100 {
// Try to find an assignment
sp = cm.next_point(sp);
let snippet = cm.span_to_snippet(sp.to(cm.next_point(sp)));
match snippet {
Ok(ref x) if x.as_str() == "=" => {
err.span_suggestion(
base_span,
"maybe you meant to write an assignment here",
format!("let {}", base_snippet),
Applicability::MaybeIncorrect,
);
show_label = false;
break;
}
Ok(ref x) if x.as_str() == "\n" => break,
Err(_) => break,
Ok(_) => {}
}
}
}
}
if show_label {
err.span_label(base_span,
"expecting a type here because of type ascription");
}
break;
} else if !snippet.trim().is_empty() {
debug!("tried to find type ascription `:` token, couldn't find it");
break;
}
} else {
break;
}
}
}
}
fn find_module(&mut self, def_id: DefId) -> Option<(Module<'a>, ImportSuggestion)> {
let mut result = None;
let mut seen_modules = FxHashSet::default();
let mut worklist = vec![(self.r.graph_root, Vec::new())];
while let Some((in_module, path_segments)) = worklist.pop() {
// abort if the module is already found
if result.is_some() { break; }
in_module.for_each_child_stable(self.r, |_, ident, _, name_binding| {
// abort if the module is already found or if name_binding is private external
if result.is_some() || !name_binding.vis.is_visible_locally() {
return
}
if let Some(module) = name_binding.module() {
// form the path
let mut path_segments = path_segments.clone();
path_segments.push(ast::PathSegment::from_ident(ident));
let module_def_id = module.def_id().unwrap();
if module_def_id == def_id {
let path = Path {
span: name_binding.span,
segments: path_segments,
};
result = Some((module, ImportSuggestion { did: Some(def_id), path }));
} else {
// add the module to the lookup
if seen_modules.insert(module_def_id) {
worklist.push((module, path_segments));
}
}
}
});
}
result
}
fn collect_enum_variants(&mut self, def_id: DefId) -> Option<Vec<Path>> {
self.find_module(def_id).map(|(enum_module, enum_import_suggestion)| {
let mut variants = Vec::new();
enum_module.for_each_child_stable(self.r, |_, ident, _, name_binding| {
if let Res::Def(DefKind::Variant, _) = name_binding.res() {
let mut segms = enum_import_suggestion.path.segments.clone();
segms.push(ast::PathSegment::from_ident(ident));
variants.push(Path {
span: name_binding.span,
segments: segms,
});
}
});
variants
})
}
}
You can’t perform that action at this time.