use crate::check::FnCtxt;
use rustc_ast::util::lev_distance;
use rustc_data_structures::fx::{FxHashMap, FxHashSet};
use rustc_errors::{pluralize, struct_span_err, Applicability, DiagnosticBuilder};
use rustc_hir as hir;
use rustc_hir::def::{DefKind, Namespace, Res};
use rustc_hir::def_id::{DefId, CRATE_DEF_INDEX, LOCAL_CRATE};
use rustc_hir::intravisit;
use rustc_hir::lang_items::LangItem;
use rustc_hir::{ExprKind, Node, QPath};
use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
use rustc_middle::hir::map as hir_map;
use rustc_middle::ty::print::with_crate_prefix;
use rustc_middle::ty::{
self, ToPolyTraitRef, ToPredicate, Ty, TyCtxt, TypeFoldable, WithConstness,
};
use rustc_span::symbol::{kw, sym, Ident};
use rustc_span::{source_map, FileName, Span};
use rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt;
use rustc_trait_selection::traits::Obligation;
use std::cmp::Ordering;
use super::probe::Mode;
use super::{CandidateSource, MethodError, NoMatchData};
impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
fn is_fn_ty(&self, ty: Ty<'tcx>, span: Span) -> bool {
let tcx = self.tcx;
match ty.kind() {
ty::Closure(..) | ty::FnDef(..) | ty::FnPtr(_) => true,
_ => {
let fn_once = match tcx.lang_items().require(LangItem::FnOnce) {
Ok(fn_once) => fn_once,
Err(..) => return false,
};
self.autoderef(span, ty).any(|(ty, _)| {
self.probe(|_| {
let fn_once_substs = tcx.mk_substs_trait(
ty,
&[self
.next_ty_var(TypeVariableOrigin {
kind: TypeVariableOriginKind::MiscVariable,
span,
})
.into()],
);
let trait_ref = ty::TraitRef::new(fn_once, fn_once_substs);
let poly_trait_ref = trait_ref.to_poly_trait_ref();
let obligation = Obligation::misc(
span,
self.body_id,
self.param_env,
poly_trait_ref.without_const().to_predicate(tcx),
);
self.predicate_may_hold(&obligation)
})
})
}
}
}
pub fn report_method_error<'b>(
&self,
span: Span,
rcvr_ty: Ty<'tcx>,
item_name: Ident,
source: SelfSource<'b>,
error: MethodError<'tcx>,
args: Option<&'tcx [hir::Expr<'tcx>]>,
) -> Option<DiagnosticBuilder<'_>> {
let orig_span = span;
let mut span = span;
if rcvr_ty.references_error() {
return None;
}
let report_candidates = |span: Span,
err: &mut DiagnosticBuilder<'_>,
mut sources: Vec<CandidateSource>,
sugg_span: Span| {
sources.sort();
sources.dedup();
let limit = if sources.len() == 5 { 5 } else { 4 };
for (idx, source) in sources.iter().take(limit).enumerate() {
match *source {
CandidateSource::ImplSource(impl_did) => {
let item = match self
.associated_item(impl_did, item_name, Namespace::ValueNS)
.or_else(|| {
let impl_trait_ref = self.tcx.impl_trait_ref(impl_did)?;
self.associated_item(
impl_trait_ref.def_id,
item_name,
Namespace::ValueNS,
)
}) {
Some(item) => item,
None => continue,
};
let note_span = self
.tcx
.hir()
.span_if_local(item.def_id)
.or_else(|| self.tcx.hir().span_if_local(impl_did));
let impl_ty = self.tcx.at(span).type_of(impl_did);
let insertion = match self.tcx.impl_trait_ref(impl_did) {
None => String::new(),
Some(trait_ref) => format!(
" of the trait `{}`",
self.tcx.def_path_str(trait_ref.def_id)
),
};
let (note_str, idx) = if sources.len() > 1 {
(
format!(
"candidate #{} is defined in an impl{} for the type `{}`",
idx + 1,
insertion,
impl_ty,
),
Some(idx + 1),
)
} else {
(
format!(
"the candidate is defined in an impl{} for the type `{}`",
insertion, impl_ty,
),
None,
)
};
if let Some(note_span) = note_span {
err.span_note(
self.tcx.sess.source_map().guess_head_span(note_span),
¬e_str,
);
} else {
err.note(¬e_str);
}
if let Some(trait_ref) = self.tcx.impl_trait_ref(impl_did) {
let path = self.tcx.def_path_str(trait_ref.def_id);
let ty = match item.kind {
ty::AssocKind::Const | ty::AssocKind::Type => rcvr_ty,
ty::AssocKind::Fn => self
.tcx
.fn_sig(item.def_id)
.inputs()
.skip_binder()
.get(0)
.filter(|ty| ty.is_region_ptr() && !rcvr_ty.is_region_ptr())
.copied()
.unwrap_or(rcvr_ty),
};
print_disambiguation_help(
item_name,
args,
err,
path,
ty,
item.kind,
item.def_id,
sugg_span,
idx,
self.tcx.sess.source_map(),
);
}
}
CandidateSource::TraitSource(trait_did) => {
let item =
match self.associated_item(trait_did, item_name, Namespace::ValueNS) {
Some(item) => item,
None => continue,
};
let item_span = self
.tcx
.sess
.source_map()
.guess_head_span(self.tcx.def_span(item.def_id));
let idx = if sources.len() > 1 {
let msg = &format!(
"candidate #{} is defined in the trait `{}`",
idx + 1,
self.tcx.def_path_str(trait_did)
);
err.span_note(item_span, msg);
Some(idx + 1)
} else {
let msg = &format!(
"the candidate is defined in the trait `{}`",
self.tcx.def_path_str(trait_did)
);
err.span_note(item_span, msg);
None
};
let path = self.tcx.def_path_str(trait_did);
print_disambiguation_help(
item_name,
args,
err,
path,
rcvr_ty,
item.kind,
item.def_id,
sugg_span,
idx,
self.tcx.sess.source_map(),
);
}
}
}
if sources.len() > limit {
err.note(&format!("and {} others", sources.len() - limit));
}
};
let sugg_span = if let SelfSource::MethodCall(expr) = source {
self.tcx.hir().expect_expr(self.tcx.hir().get_parent_node(expr.hir_id)).span
} else {
span
};
match error {
MethodError::NoMatch(NoMatchData {
static_candidates: static_sources,
unsatisfied_predicates,
out_of_scope_traits,
lev_candidate,
mode,
}) => {
let tcx = self.tcx;
let actual = self.resolve_vars_if_possible(rcvr_ty);
let ty_str = self.ty_to_string(actual);
let is_method = mode == Mode::MethodCall;
let item_kind = if is_method {
"method"
} else if actual.is_enum() {
"variant or associated item"
} else {
match (item_name.as_str().chars().next(), actual.is_fresh_ty()) {
(Some(name), false) if name.is_lowercase() => "function or associated item",
(Some(_), false) => "associated item",
(Some(_), true) | (None, false) => "variant or associated item",
(None, true) => "variant",
}
};
let mut err = if !actual.references_error() {
let mut candidates = all_traits(self.tcx).into_iter().filter_map(|info| {
self.associated_item(info.def_id, item_name, Namespace::ValueNS)
});
let fund_assoc = |opt_def_id: Option<DefId>| {
opt_def_id
.and_then(|id| self.associated_item(id, item_name, Namespace::ValueNS))
.is_some()
};
let lang_items = tcx.lang_items();
let found_candidate = candidates.next().is_some()
|| fund_assoc(lang_items.i8_impl())
|| fund_assoc(lang_items.i16_impl())
|| fund_assoc(lang_items.i32_impl())
|| fund_assoc(lang_items.i64_impl())
|| fund_assoc(lang_items.i128_impl())
|| fund_assoc(lang_items.u8_impl())
|| fund_assoc(lang_items.u16_impl())
|| fund_assoc(lang_items.u32_impl())
|| fund_assoc(lang_items.u64_impl())
|| fund_assoc(lang_items.u128_impl())
|| fund_assoc(lang_items.f32_impl())
|| fund_assoc(lang_items.f32_runtime_impl())
|| fund_assoc(lang_items.f64_impl())
|| fund_assoc(lang_items.f64_runtime_impl());
if let (true, false, SelfSource::MethodCall(expr), true) = (
actual.is_numeric(),
actual.has_concrete_skeleton(),
source,
found_candidate,
) {
let mut err = struct_span_err!(
tcx.sess,
span,
E0689,
"can't call {} `{}` on ambiguous numeric type `{}`",
item_kind,
item_name,
ty_str
);
let concrete_type = if actual.is_integral() { "i32" } else { "f32" };
match expr.kind {
ExprKind::Lit(ref lit) => {
let snippet = tcx
.sess
.source_map()
.span_to_snippet(lit.span)
.unwrap_or_else(|_| "<numeric literal>".to_owned());
err.span_suggestion(
lit.span,
&format!(
"you must specify a concrete type for \
this numeric value, like `{}`",
concrete_type
),
format!("{}_{}", snippet, concrete_type),
Applicability::MaybeIncorrect,
);
}
ExprKind::Path(ref qpath) => {
if let &QPath::Resolved(_, ref path) = &qpath {
if let hir::def::Res::Local(hir_id) = path.res {
let span = tcx.hir().span(hir_id);
let snippet = tcx.sess.source_map().span_to_snippet(span);
let filename = tcx.sess.source_map().span_to_filename(span);
let parent_node = self
.tcx
.hir()
.get(self.tcx.hir().get_parent_node(hir_id));
let msg = format!(
"you must specify a type for this binding, like `{}`",
concrete_type,
);
match (filename, parent_node, snippet) {
(
FileName::Real(_),
Node::Local(hir::Local {
source: hir::LocalSource::Normal,
ty,
..
}),
Ok(ref snippet),
) => {
err.span_suggestion(
span.to(ty
.as_ref()
.map(|ty| ty.span)
.unwrap_or(span)),
&msg,
format!("{}: {}", snippet, concrete_type),
Applicability::MaybeIncorrect,
);
}
_ => {
err.span_label(span, msg);
}
}
}
}
}
_ => {}
}
err.emit();
return None;
} else {
span = item_name.span;
let mut err = struct_span_err!(
tcx.sess,
span,
E0599,
"no {} named `{}` found for {} `{}` in the current scope",
item_kind,
item_name,
actual.prefix_string(),
ty_str,
);
if let Mode::MethodCall = mode {
if let SelfSource::MethodCall(call) = source {
self.suggest_await_before_method(
&mut err, item_name, actual, call, span,
);
}
}
if let Some(span) =
tcx.sess.confused_type_with_std_module.borrow().get(&span)
{
if let Ok(snippet) = tcx.sess.source_map().span_to_snippet(*span) {
err.span_suggestion(
*span,
"you are looking for the module in `std`, \
not the primitive type",
format!("std::{}", snippet),
Applicability::MachineApplicable,
);
}
}
if let ty::RawPtr(_) = &actual.kind() {
err.note(
"try using `<*const T>::as_ref()` to get a reference to the \
type behind the pointer: https://doc.rust-lang.org/std/\
primitive.pointer.html#method.as_ref",
);
err.note(
"using `<*const T>::as_ref()` on a pointer \
which is unaligned or points to invalid \
or uninitialized memory is undefined behavior",
);
}
err
}
} else {
tcx.sess.diagnostic().struct_dummy()
};
if let Some(def) = actual.ty_adt_def() {
if let Some(full_sp) = tcx.hir().span_if_local(def.did) {
let def_sp = tcx.sess.source_map().guess_head_span(full_sp);
err.span_label(
def_sp,
format!(
"{} `{}` not found {}",
item_kind,
item_name,
if def.is_enum() && !is_method { "here" } else { "for this" }
),
);
}
}
if let SelfSource::MethodCall(expr) = source {
let field_receiver =
self.autoderef(span, rcvr_ty).find_map(|(ty, _)| match ty.kind() {
ty::Adt(def, substs) if !def.is_enum() => {
let variant = &def.non_enum_variant();
self.tcx.find_field_index(item_name, variant).map(|index| {
let field = &variant.fields[index];
let field_ty = field.ty(tcx, substs);
(field, field_ty)
})
}
_ => None,
});
if let Some((field, field_ty)) = field_receiver {
let scope = self.tcx.parent_module(self.body_id).to_def_id();
let is_accessible = field.vis.is_accessible_from(scope, self.tcx);
if is_accessible {
if self.is_fn_ty(&field_ty, span) {
let expr_span = expr.span.to(item_name.span);
err.multipart_suggestion(
&format!(
"to call the function stored in `{}`, \
surround the field access with parentheses",
item_name,
),
vec![
(expr_span.shrink_to_lo(), '('.to_string()),
(expr_span.shrink_to_hi(), ')'.to_string()),
],
Applicability::MachineApplicable,
);
} else {
let call_expr = self
.tcx
.hir()
.expect_expr(self.tcx.hir().get_parent_node(expr.hir_id));
if let Some(span) = call_expr.span.trim_start(item_name.span) {
err.span_suggestion(
span,
"remove the arguments",
String::new(),
Applicability::MaybeIncorrect,
);
}
}
}
let field_kind = if is_accessible { "field" } else { "private field" };
err.span_label(item_name.span, format!("{}, not a method", field_kind));
} else if lev_candidate.is_none() && static_sources.is_empty() {
err.span_label(span, format!("{} not found in `{}`", item_kind, ty_str));
self.tcx.sess.trait_methods_not_found.borrow_mut().insert(orig_span);
}
} else {
err.span_label(span, format!("{} not found in `{}`", item_kind, ty_str));
self.tcx.sess.trait_methods_not_found.borrow_mut().insert(orig_span);
}
if self.is_fn_ty(&rcvr_ty, span) {
macro_rules! report_function {
($span:expr, $name:expr) => {
err.note(&format!(
"`{}` is a function, perhaps you wish to call it",
$name
));
};
}
if let SelfSource::MethodCall(expr) = source {
if let Ok(expr_string) = tcx.sess.source_map().span_to_snippet(expr.span) {
report_function!(expr.span, expr_string);
} else if let ExprKind::Path(QPath::Resolved(_, ref path)) = expr.kind {
if let Some(segment) = path.segments.last() {
report_function!(expr.span, segment.ident);
}
}
}
}
if !static_sources.is_empty() {
err.note(
"found the following associated functions; to be used as methods, \
functions must have a `self` parameter",
);
err.span_label(span, "this is an associated function, not a method");
}
if static_sources.len() == 1 {
let ty_str = if let Some(CandidateSource::ImplSource(impl_did)) =
static_sources.get(0)
{
let ty = tcx.at(span).type_of(*impl_did);
match (&ty.peel_refs().kind(), &actual.peel_refs().kind()) {
(ty::Adt(def, _), ty::Adt(def_actual, _)) if def == def_actual => {
self.ty_to_value_string(actual.peel_refs())
}
_ => self.ty_to_value_string(ty.peel_refs()),
}
} else {
self.ty_to_value_string(actual.peel_refs())
};
if let SelfSource::MethodCall(expr) = source {
err.span_suggestion(
expr.span.to(span),
"use associated function syntax instead",
format!("{}::{}", ty_str, item_name),
Applicability::MachineApplicable,
);
} else {
err.help(&format!("try with `{}::{}`", ty_str, item_name,));
}
report_candidates(span, &mut err, static_sources, sugg_span);
} else if static_sources.len() > 1 {
report_candidates(span, &mut err, static_sources, sugg_span);
}
let mut restrict_type_params = false;
if !unsatisfied_predicates.is_empty() {
let def_span = |def_id| {
self.tcx.sess.source_map().guess_head_span(self.tcx.def_span(def_id))
};
let mut type_params = FxHashMap::default();
let mut bound_spans = vec![];
let mut collect_type_param_suggestions =
|self_ty: Ty<'tcx>, parent_pred: &ty::Predicate<'tcx>, obligation: &str| {
if let (ty::Param(_), ty::PredicateAtom::Trait(p, _)) =
(self_ty.kind(), parent_pred.skip_binders())
{
if let ty::Adt(def, _) = p.trait_ref.self_ty().kind() {
let node = def.did.as_local().map(|def_id| {
self.tcx
.hir()
.get(self.tcx.hir().local_def_id_to_hir_id(def_id))
});
if let Some(hir::Node::Item(hir::Item { kind, .. })) = node {
if let Some(g) = kind.generics() {
let key = match &g.where_clause.predicates[..] {
[.., pred] => (pred.span().shrink_to_hi(), false),
[] => (
g.where_clause
.span_for_predicates_or_empty_place(),
true,
),
};
type_params
.entry(key)
.or_insert_with(FxHashSet::default)
.insert(obligation.to_owned());
}
}
}
}
};
let mut bound_span_label = |self_ty: Ty<'_>, obligation: &str, quiet: &str| {
let msg = format!(
"doesn't satisfy `{}`",
if obligation.len() > 50 { quiet } else { obligation }
);
match &self_ty.kind() {
ty::Adt(def, _) => bound_spans.push((def_span(def.did), msg)),
ty::Dynamic(preds, _) => {
for pred in preds.skip_binder() {
match pred {
ty::ExistentialPredicate::Trait(tr) => {
bound_spans.push((def_span(tr.def_id), msg.clone()))
}
ty::ExistentialPredicate::Projection(_)
| ty::ExistentialPredicate::AutoTrait(_) => {}
}
}
}
ty::Closure(def_id, _) => bound_spans
.push((def_span(*def_id), format!("doesn't satisfy `{}`", quiet))),
_ => {}
}
};
let mut format_pred = |pred: ty::Predicate<'tcx>| {
let bound_predicate = pred.bound_atom();
match bound_predicate.skip_binder() {
ty::PredicateAtom::Projection(pred) => {
let pred = bound_predicate.rebind(pred);
let trait_ref =
pred.skip_binder().projection_ty.trait_ref(self.tcx);
let assoc = self
.tcx
.associated_item(pred.skip_binder().projection_ty.item_def_id);
let ty = pred.skip_binder().ty;
let obligation = format!("{}::{} = {}", trait_ref, assoc.ident, ty);
let quiet = format!(
"<_ as {}>::{} = {}",
trait_ref.print_only_trait_path(),
assoc.ident,
ty
);
bound_span_label(trait_ref.self_ty(), &obligation, &quiet);
Some((obligation, trait_ref.self_ty()))
}
ty::PredicateAtom::Trait(poly_trait_ref, _) => {
let p = poly_trait_ref.trait_ref;
let self_ty = p.self_ty();
let path = p.print_only_trait_path();
let obligation = format!("{}: {}", self_ty, path);
let quiet = format!("_: {}", path);
bound_span_label(self_ty, &obligation, &quiet);
Some((obligation, self_ty))
}
_ => None,
}
};
let mut bound_list = unsatisfied_predicates
.iter()
.filter_map(|(pred, parent_pred)| {
format_pred(*pred).map(|(p, self_ty)| match parent_pred {
None => format!("`{}`", p),
Some(parent_pred) => match format_pred(*parent_pred) {
None => format!("`{}`", p),
Some((parent_p, _)) => {
collect_type_param_suggestions(self_ty, parent_pred, &p);
format!("`{}`\nwhich is required by `{}`", p, parent_p)
}
},
})
})
.enumerate()
.collect::<Vec<(usize, String)>>();
for ((span, empty_where), obligations) in type_params.into_iter() {
restrict_type_params = true;
let mut obligations = obligations.into_iter().collect::<Vec<_>>();
obligations.sort();
err.span_suggestion_verbose(
span,
&format!(
"consider restricting the type parameter{s} to satisfy the \
trait bound{s}",
s = pluralize!(obligations.len())
),
format!(
"{} {}",
if empty_where { " where" } else { "," },
obligations.join(", ")
),
Applicability::MaybeIncorrect,
);
}
bound_list.sort_by(|(_, a), (_, b)| a.cmp(&b));
bound_list.dedup_by(|(_, a), (_, b)| a == b);
bound_list.sort_by_key(|(pos, _)| *pos);
bound_spans.sort();
bound_spans.dedup();
for (span, msg) in bound_spans.into_iter() {
err.span_label(span, &msg);
}
if !bound_list.is_empty() {
let bound_list = bound_list
.into_iter()
.map(|(_, path)| path)
.collect::<Vec<_>>()
.join("\n");
err.note(&format!(
"the method `{}` exists but the following trait bounds were not \
satisfied:\n{}",
item_name, bound_list
));
}
}
if actual.is_numeric() && actual.is_fresh() || restrict_type_params {
} else {
self.suggest_traits_to_import(
&mut err,
span,
rcvr_ty,
item_name,
source,
out_of_scope_traits,
&unsatisfied_predicates,
);
}
if actual.is_enum() {
let adt_def = actual.ty_adt_def().expect("enum is not an ADT");
if let Some(suggestion) = lev_distance::find_best_match_for_name(
adt_def.variants.iter().map(|s| &s.ident.name),
item_name.name,
None,
) {
err.span_suggestion(
span,
"there is a variant with a similar name",
suggestion.to_string(),
Applicability::MaybeIncorrect,
);
}
}
let mut fallback_span = true;
let msg = "remove this method call";
if item_name.name == sym::as_str && actual.peel_refs().is_str() {
if let SelfSource::MethodCall(expr) = source {
let call_expr =
self.tcx.hir().expect_expr(self.tcx.hir().get_parent_node(expr.hir_id));
if let Some(span) = call_expr.span.trim_start(expr.span) {
err.span_suggestion(
span,
msg,
String::new(),
Applicability::MachineApplicable,
);
fallback_span = false;
}
}
if fallback_span {
err.span_label(span, msg);
}
} else if let Some(lev_candidate) = lev_candidate {
let def_kind = lev_candidate.kind.as_def_kind();
err.span_suggestion(
span,
&format!(
"there is {} {} with a similar name",
def_kind.article(),
def_kind.descr(lev_candidate.def_id),
),
lev_candidate.ident.to_string(),
Applicability::MaybeIncorrect,
);
}
return Some(err);
}
MethodError::Ambiguity(sources) => {
let mut err = struct_span_err!(
self.sess(),
item_name.span,
E0034,
"multiple applicable items in scope"
);
err.span_label(item_name.span, format!("multiple `{}` found", item_name));
report_candidates(span, &mut err, sources, sugg_span);
err.emit();
}
MethodError::PrivateMatch(kind, def_id, out_of_scope_traits) => {
let kind = kind.descr(def_id);
let mut err = struct_span_err!(
self.tcx.sess,
item_name.span,
E0624,
"{} `{}` is private",
kind,
item_name
);
err.span_label(item_name.span, &format!("private {}", kind));
self.suggest_valid_traits(&mut err, out_of_scope_traits);
err.emit();
}
MethodError::IllegalSizedBound(candidates, needs_mut, bound_span) => {
let msg = format!("the `{}` method cannot be invoked on a trait object", item_name);
let mut err = self.sess().struct_span_err(span, &msg);
err.span_label(bound_span, "this has a `Sized` requirement");
if !candidates.is_empty() {
let help = format!(
"{an}other candidate{s} {were} found in the following trait{s}, perhaps \
add a `use` for {one_of_them}:",
an = if candidates.len() == 1 { "an" } else { "" },
s = pluralize!(candidates.len()),
were = if candidates.len() == 1 { "was" } else { "were" },
one_of_them = if candidates.len() == 1 { "it" } else { "one_of_them" },
);
self.suggest_use_candidates(&mut err, help, candidates);
}
if let ty::Ref(region, t_type, mutability) = rcvr_ty.kind() {
if needs_mut {
let trait_type = self.tcx.mk_ref(
region,
ty::TypeAndMut { ty: t_type, mutbl: mutability.invert() },
);
err.note(&format!("you need `{}` instead of `{}`", trait_type, rcvr_ty));
}
}
err.emit();
}
MethodError::BadReturnType => bug!("no return type expectations but got BadReturnType"),
}
None
}
fn ty_to_value_string(&self, ty: Ty<'tcx>) -> String {
match ty.kind() {
ty::Adt(def, substs) => format!("{}", ty::Instance::new(def.did, substs)),
_ => self.ty_to_string(ty),
}
}
fn suggest_await_before_method(
&self,
err: &mut DiagnosticBuilder<'_>,
item_name: Ident,
ty: Ty<'tcx>,
call: &hir::Expr<'_>,
span: Span,
) {
let output_ty = match self.infcx.get_impl_future_output_ty(ty) {
Some(output_ty) => self.resolve_vars_if_possible(output_ty),
_ => return,
};
let method_exists = self.method_exists(item_name, output_ty, call.hir_id, true);
debug!("suggest_await_before_method: is_method_exist={}", method_exists);
if method_exists {
err.span_suggestion_verbose(
span.shrink_to_lo(),
"consider `await`ing on the `Future` and calling the method on its `Output`",
"await.".to_string(),
Applicability::MaybeIncorrect,
);
}
}
fn suggest_use_candidates(
&self,
err: &mut DiagnosticBuilder<'_>,
mut msg: String,
candidates: Vec<DefId>,
) {
let module_did = self.tcx.parent_module(self.body_id);
let module_id = self.tcx.hir().local_def_id_to_hir_id(module_did);
let krate = self.tcx.hir().krate();
let (span, found_use) = UsePlacementFinder::check(self.tcx, krate, module_id);
if let Some(span) = span {
let path_strings = candidates.iter().map(|did| {
let additional_newline = if found_use { "" } else { "\n" };
format!(
"use {};\n{}",
with_crate_prefix(|| self.tcx.def_path_str(*did)),
additional_newline
)
});
err.span_suggestions(span, &msg, path_strings, Applicability::MaybeIncorrect);
} else {
let limit = if candidates.len() == 5 { 5 } else { 4 };
for (i, trait_did) in candidates.iter().take(limit).enumerate() {
if candidates.len() > 1 {
msg.push_str(&format!(
"\ncandidate #{}: `use {};`",
i + 1,
with_crate_prefix(|| self.tcx.def_path_str(*trait_did))
));
} else {
msg.push_str(&format!(
"\n`use {};`",
with_crate_prefix(|| self.tcx.def_path_str(*trait_did))
));
}
}
if candidates.len() > limit {
msg.push_str(&format!("\nand {} others", candidates.len() - limit));
}
err.note(&msg[..]);
}
}
fn suggest_valid_traits(
&self,
err: &mut DiagnosticBuilder<'_>,
valid_out_of_scope_traits: Vec<DefId>,
) -> bool {
if !valid_out_of_scope_traits.is_empty() {
let mut candidates = valid_out_of_scope_traits;
candidates.sort();
candidates.dedup();
err.help("items from traits can only be used if the trait is in scope");
let msg = format!(
"the following {traits_are} implemented but not in scope; \
perhaps add a `use` for {one_of_them}:",
traits_are = if candidates.len() == 1 { "trait is" } else { "traits are" },
one_of_them = if candidates.len() == 1 { "it" } else { "one of them" },
);
self.suggest_use_candidates(err, msg, candidates);
true
} else {
false
}
}
fn suggest_traits_to_import<'b>(
&self,
err: &mut DiagnosticBuilder<'_>,
span: Span,
rcvr_ty: Ty<'tcx>,
item_name: Ident,
source: SelfSource<'b>,
valid_out_of_scope_traits: Vec<DefId>,
unsatisfied_predicates: &[(ty::Predicate<'tcx>, Option<ty::Predicate<'tcx>>)],
) {
if self.suggest_valid_traits(err, valid_out_of_scope_traits) {
return;
}
let type_is_local = self.type_derefs_to_local(span, rcvr_ty, source);
let mut arbitrary_rcvr = vec![];
let mut candidates = all_traits(self.tcx)
.into_iter()
.filter(|info| match self.tcx.lookup_stability(info.def_id) {
Some(attr) => attr.level.is_stable(),
None => true,
})
.filter(|info| {
unsatisfied_predicates.iter().all(|(p, _)| {
match p.skip_binders() {
ty::PredicateAtom::Trait(t, _) => t.def_id() == info.def_id,
ty::PredicateAtom::Projection(p) => {
p.projection_ty.item_def_id == info.def_id
}
_ => false,
}
}) && (type_is_local || info.def_id.is_local())
&& self
.associated_item(info.def_id, item_name, Namespace::ValueNS)
.filter(|item| {
if let ty::AssocKind::Fn = item.kind {
let id = item
.def_id
.as_local()
.map(|def_id| self.tcx.hir().local_def_id_to_hir_id(def_id));
if let Some(hir::Node::TraitItem(hir::TraitItem {
kind: hir::TraitItemKind::Fn(fn_sig, method),
..
})) = id.map(|id| self.tcx.hir().get(id))
{
let self_first_arg = match method {
hir::TraitFn::Required([ident, ..]) => {
ident.name == kw::SelfLower
}
hir::TraitFn::Provided(body_id) => {
self.tcx.hir().body(*body_id).params.first().map_or(
false,
|param| {
matches!(
param.pat.kind,
hir::PatKind::Binding(_, _, ident, _)
if ident.name == kw::SelfLower
)
},
)
}
_ => false,
};
if !fn_sig.decl.implicit_self.has_implicit_self()
&& self_first_arg
{
if let Some(ty) = fn_sig.decl.inputs.get(0) {
arbitrary_rcvr.push(ty.span);
}
return false;
}
}
}
item.vis == ty::Visibility::Public || info.def_id.is_local()
})
.is_some()
})
.collect::<Vec<_>>();
for span in &arbitrary_rcvr {
err.span_label(
*span,
"the method might not be found because of this arbitrary self type",
);
}
if !candidates.is_empty() {
candidates.sort_by(|a, b| a.cmp(b).reverse());
candidates.dedup();
let param_type = match rcvr_ty.kind() {
ty::Param(param) => Some(param),
ty::Ref(_, ty, _) => match ty.kind() {
ty::Param(param) => Some(param),
_ => None,
},
_ => None,
};
err.help(if param_type.is_some() {
"items from traits can only be used if the type parameter is bounded by the trait"
} else {
"items from traits can only be used if the trait is implemented and in scope"
});
let message = |action| {
format!(
"the following {traits_define} an item `{name}`, perhaps you need to {action} \
{one_of_them}:",
traits_define =
if candidates.len() == 1 { "trait defines" } else { "traits define" },
action = action,
one_of_them = if candidates.len() == 1 { "it" } else { "one of them" },
name = item_name,
)
};
let mut suggested = false;
if let (Some(ref param), Some(ref table)) =
(param_type, self.in_progress_typeck_results)
{
let table_owner = table.borrow().hir_owner;
let generics = self.tcx.generics_of(table_owner.to_def_id());
let type_param = generics.type_param(param, self.tcx);
let hir = &self.tcx.hir();
if let Some(def_id) = type_param.def_id.as_local() {
let id = hir.local_def_id_to_hir_id(def_id);
match hir.get(id) {
Node::GenericParam(ref param) => {
let mut impl_trait = false;
let has_bounds =
if let hir::GenericParamKind::Type { synthetic: Some(_), .. } =
¶m.kind
{
impl_trait = true;
param.bounds.get(1)
} else {
param.bounds.get(0)
};
let sp = hir.span(id);
let sp = if let Some(first_bound) = has_bounds {
sp.until(first_bound.span())
} else {
sp
};
let trait_def_ids: FxHashSet<DefId> = param
.bounds
.iter()
.filter_map(|bound| Some(bound.trait_ref()?.trait_def_id()?))
.collect();
if !candidates.iter().any(|t| trait_def_ids.contains(&t.def_id)) {
err.span_suggestions(
sp,
&message(format!(
"restrict type parameter `{}` with",
param.name.ident(),
)),
candidates.iter().map(|t| {
format!(
"{}{} {}{}",
param.name.ident(),
if impl_trait { " +" } else { ":" },
self.tcx.def_path_str(t.def_id),
if has_bounds.is_some() { " + " } else { "" },
)
}),
Applicability::MaybeIncorrect,
);
}
suggested = true;
}
Node::Item(hir::Item {
kind: hir::ItemKind::Trait(.., bounds, _),
ident,
..
}) => {
let (sp, sep, article) = if bounds.is_empty() {
(ident.span.shrink_to_hi(), ":", "a")
} else {
(bounds.last().unwrap().span().shrink_to_hi(), " +", "another")
};
err.span_suggestions(
sp,
&message(format!("add {} supertrait for", article)),
candidates.iter().map(|t| {
format!("{} {}", sep, self.tcx.def_path_str(t.def_id),)
}),
Applicability::MaybeIncorrect,
);
suggested = true;
}
_ => {}
}
}
}
if !suggested {
let action = if let Some(param) = param_type {
format!("restrict type parameter `{}` with", param)
} else {
"implement".to_string()
};
let mut use_note = true;
if let [trait_info] = &candidates[..] {
if let Some(span) = self.tcx.hir().span_if_local(trait_info.def_id) {
err.span_note(
self.tcx.sess.source_map().guess_head_span(span),
&format!(
"`{}` defines an item `{}`, perhaps you need to {} it",
self.tcx.def_path_str(trait_info.def_id),
item_name,
action
),
);
use_note = false
}
}
if use_note {
let mut msg = message(action);
for (i, trait_info) in candidates.iter().enumerate() {
msg.push_str(&format!(
"\ncandidate #{}: `{}`",
i + 1,
self.tcx.def_path_str(trait_info.def_id),
));
}
err.note(&msg[..]);
}
}
}
}
fn type_derefs_to_local(&self, span: Span, rcvr_ty: Ty<'tcx>, source: SelfSource<'_>) -> bool {
fn is_local(ty: Ty<'_>) -> bool {
match ty.kind() {
ty::Adt(def, _) => def.did.is_local(),
ty::Foreign(did) => did.is_local(),
ty::Dynamic(ref tr, ..) => {
tr.principal().map(|d| d.def_id().is_local()).unwrap_or(false)
}
ty::Param(_) => true,
_ => false,
}
}
if let SelfSource::QPath(_) = source {
return is_local(self.resolve_vars_with_obligations(rcvr_ty));
}
self.autoderef(span, rcvr_ty).any(|(ty, _)| is_local(ty))
}
}
#[derive(Copy, Clone)]
pub enum SelfSource<'a> {
QPath(&'a hir::Ty<'a>),
MethodCall(&'a hir::Expr<'a> ),
}
#[derive(Copy, Clone)]
pub struct TraitInfo {
pub def_id: DefId,
}
impl PartialEq for TraitInfo {
fn eq(&self, other: &TraitInfo) -> bool {
self.cmp(other) == Ordering::Equal
}
}
impl Eq for TraitInfo {}
impl PartialOrd for TraitInfo {
fn partial_cmp(&self, other: &TraitInfo) -> Option<Ordering> {
Some(self.cmp(other))
}
}
impl Ord for TraitInfo {
fn cmp(&self, other: &TraitInfo) -> Ordering {
let lhs = (other.def_id.krate, other.def_id);
let rhs = (self.def_id.krate, self.def_id);
lhs.cmp(&rhs)
}
}
pub fn all_traits(tcx: TyCtxt<'_>) -> Vec<TraitInfo> {
tcx.all_traits(LOCAL_CRATE).iter().map(|&def_id| TraitInfo { def_id }).collect()
}
fn compute_all_traits(tcx: TyCtxt<'_>) -> Vec<DefId> {
use hir::itemlikevisit;
let mut traits = vec![];
struct Visitor<'a, 'tcx> {
map: &'a hir_map::Map<'tcx>,
traits: &'a mut Vec<DefId>,
}
impl<'v, 'a, 'tcx> itemlikevisit::ItemLikeVisitor<'v> for Visitor<'a, 'tcx> {
fn visit_item(&mut self, i: &'v hir::Item<'v>) {
match i.kind {
hir::ItemKind::Trait(..) | hir::ItemKind::TraitAlias(..) => {
let def_id = self.map.local_def_id(i.hir_id);
self.traits.push(def_id.to_def_id());
}
_ => (),
}
}
fn visit_trait_item(&mut self, _trait_item: &hir::TraitItem<'_>) {}
fn visit_impl_item(&mut self, _impl_item: &hir::ImplItem<'_>) {}
}
tcx.hir().krate().visit_all_item_likes(&mut Visitor { map: &tcx.hir(), traits: &mut traits });
let mut external_mods = FxHashSet::default();
fn handle_external_res(
tcx: TyCtxt<'_>,
traits: &mut Vec<DefId>,
external_mods: &mut FxHashSet<DefId>,
res: Res,
) {
match res {
Res::Def(DefKind::Trait | DefKind::TraitAlias, def_id) => {
traits.push(def_id);
}
Res::Def(DefKind::Mod, def_id) => {
if !external_mods.insert(def_id) {
return;
}
for child in tcx.item_children(def_id).iter() {
handle_external_res(tcx, traits, external_mods, child.res)
}
}
_ => {}
}
}
for &cnum in tcx.crates().iter() {
let def_id = DefId { krate: cnum, index: CRATE_DEF_INDEX };
handle_external_res(tcx, &mut traits, &mut external_mods, Res::Def(DefKind::Mod, def_id));
}
traits
}
pub fn provide(providers: &mut ty::query::Providers) {
providers.all_traits = |tcx, cnum| {
assert_eq!(cnum, LOCAL_CRATE);
&tcx.arena.alloc(compute_all_traits(tcx))[..]
}
}
struct UsePlacementFinder<'tcx> {
target_module: hir::HirId,
span: Option<Span>,
found_use: bool,
tcx: TyCtxt<'tcx>,
}
impl UsePlacementFinder<'tcx> {
fn check(
tcx: TyCtxt<'tcx>,
krate: &'tcx hir::Crate<'tcx>,
target_module: hir::HirId,
) -> (Option<Span>, bool) {
let mut finder = UsePlacementFinder { target_module, span: None, found_use: false, tcx };
intravisit::walk_crate(&mut finder, krate);
(finder.span, finder.found_use)
}
}
impl intravisit::Visitor<'tcx> for UsePlacementFinder<'tcx> {
fn visit_mod(&mut self, module: &'tcx hir::Mod<'tcx>, _: Span, hir_id: hir::HirId) {
if self.span.is_some() {
return;
}
if hir_id != self.target_module {
intravisit::walk_mod(self, module, hir_id);
return;
}
for item_id in module.item_ids {
let item = self.tcx.hir().expect_item(item_id.id);
match item.kind {
hir::ItemKind::Use(..) => {
if !item.span.from_expansion() {
self.span = Some(item.span.shrink_to_lo());
self.found_use = true;
return;
}
}
hir::ItemKind::ExternCrate(_) => {}
_ => {
if self.span.map_or(true, |span| item.span < span) {
if !item.span.from_expansion() {
if item.attrs.is_empty() {
self.span = Some(item.span.shrink_to_lo());
} else {
for attr in item.attrs {
if self.span.map_or(true, |span| attr.span < span) {
self.span = Some(attr.span.shrink_to_lo());
}
}
}
}
}
}
}
}
}
type Map = intravisit::ErasedMap<'tcx>;
fn nested_visit_map(&mut self) -> intravisit::NestedVisitorMap<Self::Map> {
intravisit::NestedVisitorMap::None
}
}
fn print_disambiguation_help(
item_name: Ident,
args: Option<&'tcx [hir::Expr<'tcx>]>,
err: &mut DiagnosticBuilder<'_>,
trait_name: String,
rcvr_ty: Ty<'_>,
kind: ty::AssocKind,
def_id: DefId,
span: Span,
candidate: Option<usize>,
source_map: &source_map::SourceMap,
) {
let mut applicability = Applicability::MachineApplicable;
let sugg_args = if let (ty::AssocKind::Fn, Some(args)) = (kind, args) {
format!(
"({}{})",
if rcvr_ty.is_region_ptr() {
if rcvr_ty.is_mutable_ptr() { "&mut " } else { "&" }
} else {
""
},
args.iter()
.map(|arg| source_map.span_to_snippet(arg.span).unwrap_or_else(|_| {
applicability = Applicability::HasPlaceholders;
"_".to_owned()
}))
.collect::<Vec<_>>()
.join(", "),
)
} else {
String::new()
};
let sugg = format!("{}::{}{}", trait_name, item_name, sugg_args);
err.span_suggestion(
span,
&format!(
"disambiguate the {} for {}",
kind.as_def_kind().descr(def_id),
if let Some(candidate) = candidate {
format!("candidate #{}", candidate)
} else {
"the candidate".to_string()
},
),
sugg,
applicability,
);
}