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android / toolchain / rustc / 89a0a0cd9cbd0a0138a09bd877bbc73859a8c330 / . / compiler / rustc_hir_typeck / src / method / suggest.rs
blob: 6c21ed902d007112c7b256412fafeb6f86ae8f85 [file] [log] [blame]
//! Give useful errors and suggestions to users when an item can't be
//! found or is otherwise invalid.
use crate::errors;
use crate::FnCtxt;
use rustc_ast::ast::Mutability;
use rustc_data_structures::fx::{FxHashMap, FxHashSet};
use rustc_errors::{
pluralize, struct_span_err, Applicability, Diagnostic, DiagnosticBuilder, ErrorGuaranteed,
MultiSpan,
};
use rustc_hir as hir;
use rustc_hir::def::DefKind;
use rustc_hir::def_id::DefId;
use rustc_hir::lang_items::LangItem;
use rustc_hir::{ExprKind, Node, QPath};
use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
use rustc_middle::traits::util::supertraits;
use rustc_middle::ty::fast_reject::{simplify_type, TreatParams};
use rustc_middle::ty::print::with_crate_prefix;
use rustc_middle::ty::{self, DefIdTree, ToPredicate, Ty, TyCtxt, TypeVisitable};
use rustc_middle::ty::{IsSuggestable, ToPolyTraitRef};
use rustc_span::symbol::{kw, sym, Ident};
use rustc_span::Symbol;
use rustc_span::{lev_distance, source_map, ExpnKind, FileName, MacroKind, Span};
use rustc_trait_selection::traits::error_reporting::on_unimplemented::TypeErrCtxtExt as _;
use rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt as _;
use rustc_trait_selection::traits::{
FulfillmentError, Obligation, ObligationCause, ObligationCauseCode, OnUnimplementedNote,
};
use std::cmp::Ordering;
use std::iter;
use super::probe::{AutorefOrPtrAdjustment, IsSuggestion, Mode, ProbeScope};
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() {
// Not all of these (e.g., unsafe fns) implement `FnOnce`,
// so we look for these beforehand.
ty::Closure(..) | ty::FnDef(..) | ty::FnPtr(_) => true,
// If it's not a simple function, look for things which implement `FnOnce`.
_ => {
let Some(fn_once) = tcx.lang_items().fn_once_trait() else {
return false;
};
// This conditional prevents us from asking to call errors and unresolved types.
// It might seem that we can use `predicate_must_hold_modulo_regions`,
// but since a Dummy binder is used to fill in the FnOnce trait's arguments,
// type resolution always gives a "maybe" here.
if self.autoderef(span, ty).any(|(ty, _)| {
info!("check deref {:?} error", ty);
matches!(ty.kind(), ty::Error(_) | ty::Infer(_))
}) {
return false;
}
self.autoderef(span, ty).any(|(ty, _)| {
info!("check deref {:?} impl FnOnce", 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 = ty::Binder::dummy(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)
})
})
}
}
}
fn is_slice_ty(&self, ty: Ty<'tcx>, span: Span) -> bool {
self.autoderef(span, ty).any(|(ty, _)| matches!(ty.kind(), ty::Slice(..) | ty::Array(..)))
}
pub fn report_method_error(
&self,
mut span: Span,
rcvr_ty: Ty<'tcx>,
item_name: Ident,
source: SelfSource<'tcx>,
error: MethodError<'tcx>,
args: Option<(&'tcx hir::Expr<'tcx>, &'tcx [hir::Expr<'tcx>])>,
) -> Option<DiagnosticBuilder<'_, ErrorGuaranteed>> {
// Avoid suggestions when we don't know what's going on.
if rcvr_ty.references_error() {
return None;
}
let report_candidates = |span: Span,
err: &mut Diagnostic,
sources: &mut Vec<CandidateSource>,
sugg_span: Span| {
sources.sort();
sources.dedup();
// Dynamic limit to avoid hiding just one candidate, which is silly.
let limit = if sources.len() == 5 { 5 } else { 4 };
for (idx, source) in sources.iter().take(limit).enumerate() {
match *source {
CandidateSource::Impl(impl_did) => {
// Provide the best span we can. Use the item, if local to crate, else
// the impl, if local to crate (item may be defaulted), else nothing.
let Some(item) = self.associated_value(impl_did, item_name).or_else(|| {
let impl_trait_ref = self.tcx.impl_trait_ref(impl_did)?;
self.associated_value(impl_trait_ref.def_id, item_name)
}) else {
continue;
};
let note_span = if item.def_id.is_local() {
Some(self.tcx.def_span(item.def_id))
} else if impl_did.is_local() {
Some(self.tcx.def_span(impl_did))
} else {
None
};
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 {
// We have a span pointing to the method. Show note with snippet.
err.span_note(note_span, &note_str);
} else {
err.note(&note_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(),
item.fn_has_self_parameter,
);
}
}
CandidateSource::Trait(trait_did) => {
let Some(item) = self.associated_value(trait_did, item_name) else { continue };
let item_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(),
item.fn_has_self_parameter,
);
}
}
}
if sources.len() > limit {
err.note(&format!("and {} others", sources.len() - limit));
}
};
let sugg_span = if let SelfSource::MethodCall(expr) = source {
// Given `foo.bar(baz)`, `expr` is `bar`, but we want to point to the whole thing.
self.tcx.hir().expect_expr(self.tcx.hir().get_parent_node(expr.hir_id)).span
} else {
span
};
match error {
MethodError::NoMatch(NoMatchData {
static_candidates: mut 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",
}
};
if self.suggest_wrapping_range_with_parens(
tcx, actual, source, span, item_name, &ty_str,
) || self.suggest_constraining_numerical_ty(
tcx, actual, source, span, item_kind, item_name, &ty_str,
) {
return None;
}
span = item_name.span;
// Don't show generic arguments when the method can't be found in any implementation (#81576).
let mut ty_str_reported = ty_str.clone();
if let ty::Adt(_, generics) = actual.kind() {
if generics.len() > 0 {
let mut autoderef = self.autoderef(span, actual);
let candidate_found = autoderef.any(|(ty, _)| {
if let ty::Adt(adt_deref, _) = ty.kind() {
self.tcx
.inherent_impls(adt_deref.did())
.iter()
.filter_map(|def_id| self.associated_value(*def_id, item_name))
.count()
>= 1
} else {
false
}
});
let has_deref = autoderef.step_count() > 0;
if !candidate_found && !has_deref && unsatisfied_predicates.is_empty() {
if let Some((path_string, _)) = ty_str.split_once('<') {
ty_str_reported = path_string.to_string();
}
}
}
}
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(self.tcx),
ty_str_reported,
);
if actual.references_error() {
err.downgrade_to_delayed_bug();
}
if let Mode::MethodCall = mode && let SelfSource::MethodCall(cal) = source {
self.suggest_await_before_method(
&mut err, item_name, actual, cal, span,
);
}
if let Some(span) = tcx.resolutions(()).confused_type_with_std_module.get(&span) {
err.span_suggestion(
span.shrink_to_lo(),
"you are looking for the module in `std`, not the primitive type",
"std::",
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",
);
}
let ty_span = match actual.kind() {
ty::Param(param_type) => {
let generics = self.tcx.generics_of(self.body_id.owner.to_def_id());
let type_param = generics.type_param(param_type, self.tcx);
Some(self.tcx.def_span(type_param.def_id))
}
ty::Adt(def, _) if def.did().is_local() => Some(tcx.def_span(def.did())),
_ => None,
};
if let Some(span) = ty_span {
err.span_label(
span,
format!(
"{item_kind} `{item_name}` not found for this {}",
actual.prefix_string(self.tcx)
),
);
}
if let SelfSource::MethodCall(rcvr_expr) = source {
self.suggest_fn_call(&mut err, rcvr_expr, rcvr_ty, |output_ty| {
let call_expr = self
.tcx
.hir()
.expect_expr(self.tcx.hir().get_parent_node(rcvr_expr.hir_id));
let probe = self.lookup_probe(
span,
item_name,
output_ty,
call_expr,
ProbeScope::AllTraits,
);
probe.is_ok()
});
}
let mut custom_span_label = false;
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");
custom_span_label = true;
}
if static_sources.len() == 1 {
let ty_str =
if let Some(CandidateSource::Impl(impl_did)) = static_sources.get(0) {
// When the "method" is resolved through dereferencing, we really want the
// original type that has the associated function for accurate suggestions.
// (#61411)
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 => {
// Use `actual` as it will have more `substs` filled in.
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, &mut static_sources, sugg_span);
} else if static_sources.len() > 1 {
report_candidates(span, &mut err, &mut static_sources, sugg_span);
}
let mut bound_spans = vec![];
let mut restrict_type_params = false;
let mut unsatisfied_bounds = false;
if item_name.name == sym::count && self.is_slice_ty(actual, span) {
let msg = "consider using `len` instead";
if let SelfSource::MethodCall(_expr) = source {
err.span_suggestion_short(
span,
msg,
"len",
Applicability::MachineApplicable,
);
} else {
err.span_label(span, msg);
}
if let Some(iterator_trait) = self.tcx.get_diagnostic_item(sym::Iterator) {
let iterator_trait = self.tcx.def_path_str(iterator_trait);
err.note(&format!("`count` is defined on `{iterator_trait}`, which `{actual}` does not implement"));
}
} else if !unsatisfied_predicates.is_empty() {
let mut type_params = FxHashMap::default();
// Pick out the list of unimplemented traits on the receiver.
// This is used for custom error messages with the `#[rustc_on_unimplemented]` attribute.
let mut unimplemented_traits = FxHashMap::default();
let mut unimplemented_traits_only = true;
for (predicate, _parent_pred, cause) in &unsatisfied_predicates {
if let (ty::PredicateKind::Trait(p), Some(cause)) =
(predicate.kind().skip_binder(), cause.as_ref())
{
if p.trait_ref.self_ty() != rcvr_ty {
// This is necessary, not just to keep the errors clean, but also
// because our derived obligations can wind up with a trait ref that
// requires a different param_env to be correctly compared.
continue;
}
unimplemented_traits.entry(p.trait_ref.def_id).or_insert((
predicate.kind().rebind(p.trait_ref),
Obligation {
cause: cause.clone(),
param_env: self.param_env,
predicate: *predicate,
recursion_depth: 0,
},
));
}
}
// Make sure that, if any traits other than the found ones were involved,
// we don't don't report an unimplemented trait.
// We don't want to say that `iter::Cloned` is not an iterator, just
// because of some non-Clone item being iterated over.
for (predicate, _parent_pred, _cause) in &unsatisfied_predicates {
match predicate.kind().skip_binder() {
ty::PredicateKind::Trait(p)
if unimplemented_traits.contains_key(&p.trait_ref.def_id) => {}
_ => {
unimplemented_traits_only = false;
break;
}
}
}
let mut collect_type_param_suggestions =
|self_ty: Ty<'tcx>, parent_pred: ty::Predicate<'tcx>, obligation: &str| {
// We don't care about regions here, so it's fine to skip the binder here.
if let (ty::Param(_), ty::PredicateKind::Trait(p)) =
(self_ty.kind(), parent_pred.kind().skip_binder())
{
let node = match p.trait_ref.self_ty().kind() {
ty::Param(_) => {
// Account for `fn` items like in `issue-35677.rs` to
// suggest restricting its type params.
let did = self.tcx.hir().body_owner_def_id(hir::BodyId {
hir_id: self.body_id,
});
Some(
self.tcx
.hir()
.get(self.tcx.hir().local_def_id_to_hir_id(did)),
)
}
ty::Adt(def, _) => def.did().as_local().map(|def_id| {
self.tcx
.hir()
.get(self.tcx.hir().local_def_id_to_hir_id(def_id))
}),
_ => None,
};
if let Some(hir::Node::Item(hir::Item { kind, .. })) = node {
if let Some(g) = kind.generics() {
let key = (
g.tail_span_for_predicate_suggestion(),
g.add_where_or_trailing_comma(),
);
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() {
// Point at the type that couldn't satisfy the bound.
ty::Adt(def, _) => {
bound_spans.push((self.tcx.def_span(def.did()), msg))
}
// Point at the trait object that couldn't satisfy the bound.
ty::Dynamic(preds, _, _) => {
for pred in preds.iter() {
match pred.skip_binder() {
ty::ExistentialPredicate::Trait(tr) => bound_spans
.push((self.tcx.def_span(tr.def_id), msg.clone())),
ty::ExistentialPredicate::Projection(_)
| ty::ExistentialPredicate::AutoTrait(_) => {}
}
}
}
// Point at the closure that couldn't satisfy the bound.
ty::Closure(def_id, _) => bound_spans.push((
tcx.def_span(*def_id),
format!("doesn't satisfy `{}`", quiet),
)),
_ => {}
}
};
let mut format_pred = |pred: ty::Predicate<'tcx>| {
let bound_predicate = pred.kind();
match bound_predicate.skip_binder() {
ty::PredicateKind::Projection(pred) => {
let pred = bound_predicate.rebind(pred);
// `<Foo as Iterator>::Item = String`.
let projection_ty = pred.skip_binder().projection_ty;
let substs_with_infer_self = tcx.mk_substs(
iter::once(tcx.mk_ty_var(ty::TyVid::from_u32(0)).into())
.chain(projection_ty.substs.iter().skip(1)),
);
let quiet_projection_ty = ty::ProjectionTy {
substs: substs_with_infer_self,
item_def_id: projection_ty.item_def_id,
};
let term = pred.skip_binder().term;
let obligation = format!("{} = {}", projection_ty, term);
let quiet = format!("{} = {}", quiet_projection_ty, term);
bound_span_label(projection_ty.self_ty(), &obligation, &quiet);
Some((obligation, projection_ty.self_ty()))
}
ty::PredicateKind::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,
}
};
// Find all the requirements that come from a local `impl` block.
let mut skip_list: FxHashSet<_> = Default::default();
let mut spanned_predicates: FxHashMap<MultiSpan, _> = Default::default();
for (data, p, parent_p, impl_def_id, cause) in unsatisfied_predicates
.iter()
.filter_map(|(p, parent, c)| c.as_ref().map(|c| (p, parent, c)))
.filter_map(|(p, parent, c)| match c.code() {
ObligationCauseCode::ImplDerivedObligation(ref data) => {
Some((&data.derived, p, parent, data.impl_def_id, data))
}
_ => None,
})
{
let parent_trait_ref = data.parent_trait_pred;
let path = parent_trait_ref.print_modifiers_and_trait_path();
let tr_self_ty = parent_trait_ref.skip_binder().self_ty();
let unsatisfied_msg = "unsatisfied trait bound introduced here";
let derive_msg =
"unsatisfied trait bound introduced in this `derive` macro";
match self.tcx.hir().get_if_local(impl_def_id) {
// Unmet obligation comes from a `derive` macro, point at it once to
// avoid multiple span labels pointing at the same place.
Some(Node::Item(hir::Item {
kind: hir::ItemKind::Trait(..),
ident,
..
})) if matches!(
ident.span.ctxt().outer_expn_data().kind,
ExpnKind::Macro(MacroKind::Derive, _)
) =>
{
let span = ident.span.ctxt().outer_expn_data().call_site;
let mut spans: MultiSpan = span.into();
spans.push_span_label(span, derive_msg);
let entry = spanned_predicates.entry(spans);
entry.or_insert_with(|| (path, tr_self_ty, Vec::new())).2.push(p);
}
Some(Node::Item(hir::Item {
kind: hir::ItemKind::Impl(hir::Impl { of_trait, self_ty, .. }),
..
})) if matches!(
self_ty.span.ctxt().outer_expn_data().kind,
ExpnKind::Macro(MacroKind::Derive, _)
) || matches!(
of_trait.as_ref().map(|t| t
.path
.span
.ctxt()
.outer_expn_data()
.kind),
Some(ExpnKind::Macro(MacroKind::Derive, _))
) =>
{
let span = self_ty.span.ctxt().outer_expn_data().call_site;
let mut spans: MultiSpan = span.into();
spans.push_span_label(span, derive_msg);
let entry = spanned_predicates.entry(spans);
entry.or_insert_with(|| (path, tr_self_ty, Vec::new())).2.push(p);
}
// Unmet obligation coming from a `trait`.
Some(Node::Item(hir::Item {
kind: hir::ItemKind::Trait(..),
ident,
span: item_span,
..
})) if !matches!(
ident.span.ctxt().outer_expn_data().kind,
ExpnKind::Macro(MacroKind::Derive, _)
) =>
{
if let Some(pred) = parent_p {
// Done to add the "doesn't satisfy" `span_label`.
let _ = format_pred(*pred);
}
skip_list.insert(p);
let mut spans = if cause.span != *item_span {
let mut spans: MultiSpan = cause.span.into();
spans.push_span_label(cause.span, unsatisfied_msg);
spans
} else {
ident.span.into()
};
spans.push_span_label(ident.span, "in this trait");
let entry = spanned_predicates.entry(spans);
entry.or_insert_with(|| (path, tr_self_ty, Vec::new())).2.push(p);
}
// Unmet obligation coming from an `impl`.
Some(Node::Item(hir::Item {
kind:
hir::ItemKind::Impl(hir::Impl {
of_trait, self_ty, generics, ..
}),
span: item_span,
..
})) if !matches!(
self_ty.span.ctxt().outer_expn_data().kind,
ExpnKind::Macro(MacroKind::Derive, _)
) && !matches!(
of_trait.as_ref().map(|t| t
.path
.span
.ctxt()
.outer_expn_data()
.kind),
Some(ExpnKind::Macro(MacroKind::Derive, _))
) =>
{
let sized_pred =
unsatisfied_predicates.iter().any(|(pred, _, _)| {
match pred.kind().skip_binder() {
ty::PredicateKind::Trait(pred) => {
Some(pred.def_id())
== self.tcx.lang_items().sized_trait()
&& pred.polarity == ty::ImplPolarity::Positive
}
_ => false,
}
});
for param in generics.params {
if param.span == cause.span && sized_pred {
let (sp, sugg) = match param.colon_span {
Some(sp) => (sp.shrink_to_hi(), " ?Sized +"),
None => (param.span.shrink_to_hi(), ": ?Sized"),
};
err.span_suggestion_verbose(
sp,
"consider relaxing the type parameter's implicit \
`Sized` bound",
sugg,
Applicability::MachineApplicable,
);
}
}
if let Some(pred) = parent_p {
// Done to add the "doesn't satisfy" `span_label`.
let _ = format_pred(*pred);
}
skip_list.insert(p);
let mut spans = if cause.span != *item_span {
let mut spans: MultiSpan = cause.span.into();
spans.push_span_label(cause.span, unsatisfied_msg);
spans
} else {
let mut spans = Vec::with_capacity(2);
if let Some(trait_ref) = of_trait {
spans.push(trait_ref.path.span);
}
spans.push(self_ty.span);
spans.into()
};
if let Some(trait_ref) = of_trait {
spans.push_span_label(trait_ref.path.span, "");
}
spans.push_span_label(self_ty.span, "");
let entry = spanned_predicates.entry(spans);
entry.or_insert_with(|| (path, tr_self_ty, Vec::new())).2.push(p);
}
_ => {}
}
}
let mut spanned_predicates: Vec<_> = spanned_predicates.into_iter().collect();
spanned_predicates.sort_by_key(|(span, (_, _, _))| span.primary_span());
for (span, (_path, _self_ty, preds)) in spanned_predicates {
let mut preds: Vec<_> = preds
.into_iter()
.filter_map(|pred| format_pred(*pred))
.map(|(p, _)| format!("`{}`", p))
.collect();
preds.sort();
preds.dedup();
let msg = if let [pred] = &preds[..] {
format!("trait bound {} was not satisfied", pred)
} else {
format!(
"the following trait bounds were not satisfied:\n{}",
preds.join("\n"),
)
};
err.span_note(span, &msg);
unsatisfied_bounds = true;
}
// The requirements that didn't have an `impl` span to show.
let mut bound_list = unsatisfied_predicates
.iter()
.filter_map(|(pred, parent_pred, _cause)| {
format_pred(*pred).map(|(p, self_ty)| {
collect_type_param_suggestions(self_ty, *pred, &p);
(
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
)
}
},
},
*pred,
)
})
})
.filter(|(_, pred)| !skip_list.contains(&pred))
.map(|(t, _)| t)
.enumerate()
.collect::<Vec<(usize, String)>>();
for ((span, add_where_or_comma), obligations) in type_params.into_iter() {
restrict_type_params = true;
// #74886: Sort here so that the output is always the same.
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!("{} {}", add_where_or_comma, obligations.join(", ")),
Applicability::MaybeIncorrect,
);
}
bound_list.sort_by(|(_, a), (_, b)| a.cmp(b)); // Sort alphabetically.
bound_list.dedup_by(|(_, a), (_, b)| a == b); // #35677
bound_list.sort_by_key(|(pos, _)| *pos); // Keep the original predicate order.
if !bound_list.is_empty() || !skip_list.is_empty() {
let bound_list = bound_list
.into_iter()
.map(|(_, path)| path)
.collect::<Vec<_>>()
.join("\n");
let actual_prefix = actual.prefix_string(self.tcx);
info!("unimplemented_traits.len() == {}", unimplemented_traits.len());
let (primary_message, label) =
if unimplemented_traits.len() == 1 && unimplemented_traits_only {
unimplemented_traits
.into_iter()
.next()
.map(|(_, (trait_ref, obligation))| {
if trait_ref.self_ty().references_error()
|| actual.references_error()
{
// Avoid crashing.
return (None, None);
}
let OnUnimplementedNote { message, label, .. } = self
.err_ctxt()
.on_unimplemented_note(trait_ref, &obligation);
(message, label)
})
.unwrap_or((None, None))
} else {
(None, None)
};
let primary_message = primary_message.unwrap_or_else(|| format!(
"the {item_kind} `{item_name}` exists for {actual_prefix} `{ty_str}`, but its trait bounds were not satisfied"
));
err.set_primary_message(&primary_message);
if let Some(label) = label {
custom_span_label = true;
err.span_label(span, label);
}
if !bound_list.is_empty() {
err.note(&format!(
"the following trait bounds were not satisfied:\n{bound_list}"
));
}
self.suggest_derive(&mut err, &unsatisfied_predicates);
unsatisfied_bounds = true;
}
}
let label_span_not_found = |err: &mut Diagnostic| {
if unsatisfied_predicates.is_empty() {
err.span_label(span, format!("{item_kind} not found in `{ty_str}`"));
let is_string_or_ref_str = match actual.kind() {
ty::Ref(_, ty, _) => {
ty.is_str()
|| matches!(
ty.kind(),
ty::Adt(adt, _) if self.tcx.is_diagnostic_item(sym::String, adt.did())
)
}
ty::Adt(adt, _) => self.tcx.is_diagnostic_item(sym::String, adt.did()),
_ => false,
};
if is_string_or_ref_str && item_name.name == sym::iter {
err.span_suggestion_verbose(
item_name.span,
"because of the in-memory representation of `&str`, to obtain \
an `Iterator` over each of its codepoint use method `chars`",
"chars",
Applicability::MachineApplicable,
);
}
if let ty::Adt(adt, _) = rcvr_ty.kind() {
let mut inherent_impls_candidate = self
.tcx
.inherent_impls(adt.did())
.iter()
.copied()
.filter(|def_id| {
if let Some(assoc) = self.associated_value(*def_id, item_name) {
// Check for both mode is the same so we avoid suggesting
// incorrect associated item.
match (mode, assoc.fn_has_self_parameter, source) {
(Mode::MethodCall, true, SelfSource::MethodCall(_)) => {
// We check that the suggest type is actually
// different from the received one
// So we avoid suggestion method with Box<Self>
// for instance
self.tcx.at(span).type_of(*def_id) != actual
&& self.tcx.at(span).type_of(*def_id) != rcvr_ty
}
(Mode::Path, false, _) => true,
_ => false,
}
} else {
false
}
})
.collect::<Vec<_>>();
if !inherent_impls_candidate.is_empty() {
inherent_impls_candidate.sort();
inherent_impls_candidate.dedup();
// number of type to shows at most.
let limit = if inherent_impls_candidate.len() == 5 { 5 } else { 4 };
let type_candidates = inherent_impls_candidate
.iter()
.take(limit)
.map(|impl_item| {
format!("- `{}`", self.tcx.at(span).type_of(*impl_item))
})
.collect::<Vec<_>>()
.join("\n");
let additional_types = if inherent_impls_candidate.len() > limit {
format!(
"\nand {} more types",
inherent_impls_candidate.len() - limit
)
} else {
"".to_string()
};
err.note(&format!(
"the {item_kind} was found for\n{}{}",
type_candidates, additional_types
));
}
}
} else {
err.span_label(span, format!("{item_kind} cannot be called on `{ty_str}` due to unsatisfied trait bounds"));
}
};
// If the method name is the name of a field with a function or closure type,
// give a helping note that it has to be called as `(x.f)(...)`.
if let SelfSource::MethodCall(expr) = source {
if !self.suggest_field_call(span, rcvr_ty, expr, item_name, &mut err)
&& lev_candidate.is_none()
&& !custom_span_label
{
label_span_not_found(&mut err);
}
} else if !custom_span_label {
label_span_not_found(&mut err);
}
// Don't suggest (for example) `expr.field.method()` if `expr.method()`
// doesn't exist due to unsatisfied predicates.
if unsatisfied_predicates.is_empty() {
self.check_for_field_method(&mut err, source, span, actual, item_name);
}
self.check_for_inner_self(&mut err, source, span, actual, item_name);
bound_spans.sort();
bound_spans.dedup();
for (span, msg) in bound_spans.into_iter() {
err.span_label(span, &msg);
}
if actual.is_numeric() && actual.is_fresh() || restrict_type_params {
} else {
self.suggest_traits_to_import(
&mut err,
span,
rcvr_ty,
item_name,
args.map(|(_, args)| args.len() + 1),
source,
out_of_scope_traits,
&unsatisfied_predicates,
&static_sources,
unsatisfied_bounds,
);
}
// Don't emit a suggestion if we found an actual method
// that had unsatisfied trait bounds
if unsatisfied_predicates.is_empty() && 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.name).collect::<Vec<_>>(),
item_name.name,
None,
) {
err.span_suggestion(
span,
"there is a variant with a similar name",
suggestion,
Applicability::MaybeIncorrect,
);
}
}
if item_name.name == sym::as_str && actual.peel_refs().is_str() {
let msg = "remove this method call";
let mut fallback_span = true;
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, "", Applicability::MachineApplicable);
fallback_span = false;
}
}
if fallback_span {
err.span_label(span, msg);
}
} else if let Some(lev_candidate) = lev_candidate {
// Don't emit a suggestion if we found an actual method
// that had unsatisfied trait bounds
if unsatisfied_predicates.is_empty() {
let def_kind = lev_candidate.kind.as_def_kind();
// Methods are defined within the context of a struct and their first parameter is always self,
// which represents the instance of the struct the method is being called on
// Associated functions don’t take self as a parameter and
// they are not methods because they don’t have an instance of the struct to work with.
if def_kind == DefKind::AssocFn && lev_candidate.fn_has_self_parameter {
err.span_suggestion(
span,
&format!("there is a method with a similar name",),
lev_candidate.name,
Applicability::MaybeIncorrect,
);
} else {
err.span_suggestion(
span,
&format!(
"there is {} {} with a similar name",
def_kind.article(),
def_kind.descr(lev_candidate.def_id),
),
lev_candidate.name,
Applicability::MaybeIncorrect,
);
}
}
}
self.check_for_deref_method(&mut err, source, rcvr_ty, item_name);
return Some(err);
}
MethodError::Ambiguity(mut 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, &mut 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));
let sp = self
.tcx
.hir()
.span_if_local(def_id)
.unwrap_or_else(|| self.tcx.def_span(def_id));
err.span_label(sp, &format!("private {} defined here", 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 = pluralize!("was", candidates.len()),
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 suggest_field_call(
&self,
span: Span,
rcvr_ty: Ty<'tcx>,
expr: &hir::Expr<'_>,
item_name: Ident,
err: &mut Diagnostic,
) -> bool {
let tcx = self.tcx;
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();
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 = tcx.parent_module(self.body_id);
let is_accessible = field.vis.is_accessible_from(scope, 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 = tcx.hir().expect_expr(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",
"",
Applicability::MaybeIncorrect,
);
}
}
}
let field_kind = if is_accessible { "field" } else { "private field" };
err.span_label(item_name.span, format!("{}, not a method", field_kind));
return true;
}
false
}
/// Suggest possible range with adding parentheses, for example:
/// when encountering `0..1.map(|i| i + 1)` suggest `(0..1).map(|i| i + 1)`.
fn suggest_wrapping_range_with_parens(
&self,
tcx: TyCtxt<'tcx>,
actual: Ty<'tcx>,
source: SelfSource<'tcx>,
span: Span,
item_name: Ident,
ty_str: &str,
) -> bool {
if let SelfSource::MethodCall(expr) = source {
for (_, parent) in tcx.hir().parent_iter(expr.hir_id).take(5) {
if let Node::Expr(parent_expr) = parent {
let lang_item = match parent_expr.kind {
ExprKind::Struct(ref qpath, _, _) => match **qpath {
QPath::LangItem(LangItem::Range, ..) => Some(LangItem::Range),
QPath::LangItem(LangItem::RangeTo, ..) => Some(LangItem::RangeTo),
QPath::LangItem(LangItem::RangeToInclusive, ..) => {
Some(LangItem::RangeToInclusive)
}
_ => None,
},
ExprKind::Call(ref func, _) => match func.kind {
// `..=` desugars into `::std::ops::RangeInclusive::new(...)`.
ExprKind::Path(QPath::LangItem(LangItem::RangeInclusiveNew, ..)) => {
Some(LangItem::RangeInclusiveStruct)
}
_ => None,
},
_ => None,
};
if lang_item.is_none() {
continue;
}
let span_included = match parent_expr.kind {
hir::ExprKind::Struct(_, eps, _) => {
eps.len() > 0 && eps.last().map_or(false, |ep| ep.span.contains(span))
}
// `..=` desugars into `::std::ops::RangeInclusive::new(...)`.
hir::ExprKind::Call(ref func, ..) => func.span.contains(span),
_ => false,
};
if !span_included {
continue;
}
let range_def_id = self.tcx.require_lang_item(lang_item.unwrap(), None);
let range_ty =
self.tcx.bound_type_of(range_def_id).subst(self.tcx, &[actual.into()]);
let pick = self.probe_for_name(
span,
Mode::MethodCall,
item_name,
IsSuggestion(true),
range_ty,
expr.hir_id,
ProbeScope::AllTraits,
);
if pick.is_ok() {
let range_span = parent_expr.span.with_hi(expr.span.hi());
tcx.sess.emit_err(errors::MissingParentheseInRange {
span,
ty_str: ty_str.to_string(),
method_name: item_name.as_str().to_string(),
add_missing_parentheses: Some(errors::AddMissingParenthesesInRange {
func_name: item_name.name.as_str().to_string(),
left: range_span.shrink_to_lo(),
right: range_span.shrink_to_hi(),
}),
});
return true;
}
}
}
}
false
}
fn suggest_constraining_numerical_ty(
&self,
tcx: TyCtxt<'tcx>,
actual: Ty<'tcx>,
source: SelfSource<'_>,
span: Span,
item_kind: &str,
item_name: Ident,
ty_str: &str,
) -> bool {
let found_candidate = all_traits(self.tcx)
.into_iter()
.any(|info| self.associated_value(info.def_id, item_name).is_some());
let found_assoc = |ty: Ty<'tcx>| {
simplify_type(tcx, ty, TreatParams::AsInfer)
.and_then(|simp| {
tcx.incoherent_impls(simp)
.iter()
.find_map(|&id| self.associated_value(id, item_name))
})
.is_some()
};
let found_candidate = found_candidate
|| found_assoc(tcx.types.i8)
|| found_assoc(tcx.types.i16)
|| found_assoc(tcx.types.i32)
|| found_assoc(tcx.types.i64)
|| found_assoc(tcx.types.i128)
|| found_assoc(tcx.types.u8)
|| found_assoc(tcx.types.u16)
|| found_assoc(tcx.types.u32)
|| found_assoc(tcx.types.u64)
|| found_assoc(tcx.types.u128)
|| found_assoc(tcx.types.f32)
|| found_assoc(tcx.types.f32);
if found_candidate
&& actual.is_numeric()
&& !actual.has_concrete_skeleton()
&& let SelfSource::MethodCall(expr) = source
{
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) => {
// numeric literal
let snippet = tcx
.sess
.source_map()
.span_to_snippet(lit.span)
.unwrap_or_else(|_| "<numeric literal>".to_owned());
// If this is a floating point literal that ends with '.',
// get rid of it to stop this from becoming a member access.
let snippet = snippet.strip_suffix('.').unwrap_or(&snippet);
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(QPath::Resolved(_, path)) => {
// local binding
if let hir::def::Res::Local(hir_id) = path.res {
let span = tcx.hir().span(hir_id);
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) {
(
FileName::Real(_),
Node::Local(hir::Local {
source: hir::LocalSource::Normal,
ty,
..
}),
) => {
let type_span = ty.map(|ty| ty.span.with_lo(span.hi())).unwrap_or(span.shrink_to_hi());
err.span_suggestion(
// account for `let x: _ = 42;`
// ^^^
type_span,
&msg,
format!(": {concrete_type}"),
Applicability::MaybeIncorrect,
);
}
_ => {
err.span_label(span, msg);
}
}
}
}
_ => {}
}
err.emit();
return true;
}
false
}
fn check_for_field_method(
&self,
err: &mut Diagnostic,
source: SelfSource<'tcx>,
span: Span,
actual: Ty<'tcx>,
item_name: Ident,
) {
if let SelfSource::MethodCall(expr) = source
&& let mod_id = self.tcx.parent_module(expr.hir_id).to_def_id()
&& let Some((fields, substs)) =
self.get_field_candidates_considering_privacy(span, actual, mod_id)
{
let call_expr = self.tcx.hir().expect_expr(self.tcx.hir().get_parent_node(expr.hir_id));
let lang_items = self.tcx.lang_items();
let never_mention_traits = [
lang_items.clone_trait(),
lang_items.deref_trait(),
lang_items.deref_mut_trait(),
self.tcx.get_diagnostic_item(sym::AsRef),
self.tcx.get_diagnostic_item(sym::AsMut),
self.tcx.get_diagnostic_item(sym::Borrow),
self.tcx.get_diagnostic_item(sym::BorrowMut),
];
let candidate_fields: Vec<_> = fields
.filter_map(|candidate_field| {
self.check_for_nested_field_satisfying(
span,
&|_, field_ty| {
self.lookup_probe(
span,
item_name,
field_ty,
call_expr,
ProbeScope::TraitsInScope,
)
.map_or(false, |pick| {
!never_mention_traits
.iter()
.flatten()
.any(|def_id| self.tcx.parent(pick.item.def_id) == *def_id)
})
},
candidate_field,
substs,
vec![],
mod_id,
)
})
.map(|field_path| {
field_path
.iter()
.map(|id| id.name.to_ident_string())
.collect::<Vec<String>>()
.join(".")
})
.collect();
let len = candidate_fields.len();
if len > 0 {
err.span_suggestions(
item_name.span.shrink_to_lo(),
format!(
"{} of the expressions' fields {} a method of the same name",
if len > 1 { "some" } else { "one" },
if len > 1 { "have" } else { "has" },
),
candidate_fields.iter().map(|path| format!("{path}.")),
Applicability::MaybeIncorrect,
);
}
}
}
fn check_for_inner_self(
&self,
err: &mut Diagnostic,
source: SelfSource<'tcx>,
span: Span,
actual: Ty<'tcx>,
item_name: Ident,
) {
let tcx = self.tcx;
let SelfSource::MethodCall(expr) = source else { return; };
let call_expr = tcx.hir().expect_expr(tcx.hir().get_parent_node(expr.hir_id));
let ty::Adt(kind, substs) = actual.kind() else { return; };
match kind.adt_kind() {
ty::AdtKind::Enum => {
let matching_variants: Vec<_> = kind
.variants()
.iter()
.flat_map(|variant| {
let [field] = &variant.fields[..] else { return None; };
let field_ty = field.ty(tcx, substs);
// Skip `_`, since that'll just lead to ambiguity.
if self.resolve_vars_if_possible(field_ty).is_ty_var() {
return None;
}
self.lookup_probe(
span,
item_name,
field_ty,
call_expr,
ProbeScope::TraitsInScope,
)
.ok()
.map(|pick| (variant, field, pick))
})
.collect();
let ret_ty_matches = |diagnostic_item| {
if let Some(ret_ty) = self
.ret_coercion
.as_ref()
.map(|c| self.resolve_vars_if_possible(c.borrow().expected_ty()))
&& let ty::Adt(kind, _) = ret_ty.kind()
&& tcx.get_diagnostic_item(diagnostic_item) == Some(kind.did())
{
true
} else {
false
}
};
match &matching_variants[..] {
[(_, field, pick)] => {
let self_ty = field.ty(tcx, substs);
err.span_note(
tcx.def_span(pick.item.def_id),
&format!("the method `{item_name}` exists on the type `{self_ty}`"),
);
let (article, kind, variant, question) =
if tcx.is_diagnostic_item(sym::Result, kind.did()) {
("a", "Result", "Err", ret_ty_matches(sym::Result))
} else if tcx.is_diagnostic_item(sym::Option, kind.did()) {
("an", "Option", "None", ret_ty_matches(sym::Option))
} else {
return;
};
if question {
err.span_suggestion_verbose(
expr.span.shrink_to_hi(),
format!(
"use the `?` operator to extract the `{self_ty}` value, propagating \
{article} `{kind}::{variant}` value to the caller"
),
"?",
Applicability::MachineApplicable,
);
} else {
err.span_suggestion_verbose(
expr.span.shrink_to_hi(),
format!(
"consider using `{kind}::expect` to unwrap the `{self_ty}` value, \
panicking if the value is {article} `{kind}::{variant}`"
),
".expect(\"REASON\")",
Applicability::HasPlaceholders,
);
}
}
// FIXME(compiler-errors): Support suggestions for other matching enum variants
_ => {}
}
}
// Target wrapper types - types that wrap or pretend to wrap another type,
// perhaps this inner type is meant to be called?
ty::AdtKind::Struct | ty::AdtKind::Union => {
let [first] = ***substs else { return; };
let ty::GenericArgKind::Type(ty) = first.unpack() else { return; };
let Ok(pick) = self.lookup_probe(
span,
item_name,
ty,
call_expr,
ProbeScope::TraitsInScope,
) else { return; };
let name = self.ty_to_value_string(actual);
let inner_id = kind.did();
let mutable = if let Some(AutorefOrPtrAdjustment::Autoref { mutbl, .. }) =
pick.autoref_or_ptr_adjustment
{
Some(mutbl)
} else {
None
};
if tcx.is_diagnostic_item(sym::LocalKey, inner_id) {
err.help("use `with` or `try_with` to access thread local storage");
} else if Some(kind.did()) == tcx.lang_items().maybe_uninit() {
err.help(format!(
"if this `{name}` has been initialized, \
use one of the `assume_init` methods to access the inner value"
));
} else if tcx.is_diagnostic_item(sym::RefCell, inner_id) {
let (suggestion, borrow_kind, panic_if) = match mutable {
Some(Mutability::Not) => (".borrow()", "borrow", "a mutable borrow exists"),
Some(Mutability::Mut) => {
(".borrow_mut()", "mutably borrow", "any borrows exist")
}
None => return,
};
err.span_suggestion_verbose(
expr.span.shrink_to_hi(),
format!(
"use `{suggestion}` to {borrow_kind} the `{ty}`, \
panicking if {panic_if}"
),
suggestion,
Applicability::MaybeIncorrect,
);
} else if tcx.is_diagnostic_item(sym::Mutex, inner_id) {
err.span_suggestion_verbose(
expr.span.shrink_to_hi(),
format!(
"use `.lock().unwrap()` to borrow the `{ty}`, \
blocking the current thread until it can be acquired"
),
".lock().unwrap()",
Applicability::MaybeIncorrect,
);
} else if tcx.is_diagnostic_item(sym::RwLock, inner_id) {
let (suggestion, borrow_kind) = match mutable {
Some(Mutability::Not) => (".read().unwrap()", "borrow"),
Some(Mutability::Mut) => (".write().unwrap()", "mutably borrow"),
None => return,
};
err.span_suggestion_verbose(
expr.span.shrink_to_hi(),
format!(
"use `{suggestion}` to {borrow_kind} the `{ty}`, \
blocking the current thread until it can be acquired"
),
suggestion,
Applicability::MaybeIncorrect,
);
} else {
return;
};
err.span_note(
tcx.def_span(pick.item.def_id),
&format!("the method `{item_name}` exists on the type `{ty}`"),
);
}
}
}
pub(crate) fn note_unmet_impls_on_type(
&self,
err: &mut Diagnostic,
errors: Vec<FulfillmentError<'tcx>>,
) {
let all_local_types_needing_impls =
errors.iter().all(|e| match e.obligation.predicate.kind().skip_binder() {
ty::PredicateKind::Trait(pred) => match pred.self_ty().kind() {
ty::Adt(def, _) => def.did().is_local(),
_ => false,
},
_ => false,
});
let mut preds: Vec<_> = errors
.iter()
.filter_map(|e| match e.obligation.predicate.kind().skip_binder() {
ty::PredicateKind::Trait(pred) => Some(pred),
_ => None,
})
.collect();
preds.sort_by_key(|pred| (pred.def_id(), pred.self_ty()));
let def_ids = preds
.iter()
.filter_map(|pred| match pred.self_ty().kind() {
ty::Adt(def, _) => Some(def.did()),
_ => None,
})
.collect::<FxHashSet<_>>();
let mut spans: MultiSpan = def_ids
.iter()
.filter_map(|def_id| {
let span = self.tcx.def_span(*def_id);
if span.is_dummy() { None } else { Some(span) }
})
.collect::<Vec<_>>()
.into();
for pred in &preds {
match pred.self_ty().kind() {
ty::Adt(def, _) if def.did().is_local() => {
spans.push_span_label(
self.tcx.def_span(def.did()),
format!("must implement `{}`", pred.trait_ref.print_only_trait_path()),
);
}
_ => {}
}
}
if all_local_types_needing_impls && spans.primary_span().is_some() {
let msg = if preds.len() == 1 {
format!(
"an implementation of `{}` might be missing for `{}`",
preds[0].trait_ref.print_only_trait_path(),
preds[0].self_ty()
)
} else {
format!(
"the following type{} would have to `impl` {} required trait{} for this \
operation to be valid",
pluralize!(def_ids.len()),
if def_ids.len() == 1 { "its" } else { "their" },
pluralize!(preds.len()),
)
};
err.span_note(spans, &msg);
}
let preds: Vec<_> = errors
.iter()
.map(|e| (e.obligation.predicate, None, Some(e.obligation.cause.clone())))
.collect();
self.suggest_derive(err, &preds);
}
fn suggest_derive(
&self,
err: &mut Diagnostic,
unsatisfied_predicates: &[(
ty::Predicate<'tcx>,
Option<ty::Predicate<'tcx>>,
Option<ObligationCause<'tcx>>,
)],
) {
let mut derives = Vec::<(String, Span, Symbol)>::new();
let mut traits = Vec::<Span>::new();
for (pred, _, _) in unsatisfied_predicates {
let ty::PredicateKind::Trait(trait_pred) = pred.kind().skip_binder() else { continue };
let adt = match trait_pred.self_ty().ty_adt_def() {
Some(adt) if adt.did().is_local() => adt,
_ => continue,
};
if let Some(diagnostic_name) = self.tcx.get_diagnostic_name(trait_pred.def_id()) {
let can_derive = match diagnostic_name {
sym::Default => !adt.is_enum(),
sym::Eq
| sym::PartialEq
| sym::Ord
| sym::PartialOrd
| sym::Clone
| sym::Copy
| sym::Hash
| sym::Debug => true,
_ => false,
};
if can_derive {
let self_name = trait_pred.self_ty().to_string();
let self_span = self.tcx.def_span(adt.did());
if let Some(poly_trait_ref) = pred.to_opt_poly_trait_pred() {
for super_trait in supertraits(self.tcx, poly_trait_ref.to_poly_trait_ref())
{
if let Some(parent_diagnostic_name) =
self.tcx.get_diagnostic_name(super_trait.def_id())
{
derives.push((
self_name.clone(),
self_span,
parent_diagnostic_name,
));
}
}
}
derives.push((self_name, self_span, diagnostic_name));
} else {
traits.push(self.tcx.def_span(trait_pred.def_id()));
}
} else {
traits.push(self.tcx.def_span(trait_pred.def_id()));
}
}
traits.sort();
traits.dedup();
derives.sort();
derives.dedup();
let mut derives_grouped = Vec::<(String, Span, String)>::new();
for (self_name, self_span, trait_name) in derives.into_iter() {
if let Some((last_self_name, _, ref mut last_trait_names)) = derives_grouped.last_mut()
{
if last_self_name == &self_name {
last_trait_names.push_str(format!(", {}", trait_name).as_str());
continue;
}
}
derives_grouped.push((self_name, self_span, trait_name.to_string()));
}
let len = traits.len();
if len > 0 {
let span: MultiSpan = traits.into();
err.span_note(
span,
&format!("the following trait{} must be implemented", pluralize!(len),),
);
}
for (self_name, self_span, traits) in &derives_grouped {
err.span_suggestion_verbose(
self_span.shrink_to_lo(),
&format!("consider annotating `{}` with `#[derive({})]`", self_name, traits),
format!("#[derive({})]\n", traits),
Applicability::MaybeIncorrect,
);
}
}
fn check_for_deref_method(
&self,
err: &mut Diagnostic,
self_source: SelfSource<'tcx>,
rcvr_ty: Ty<'tcx>,
item_name: Ident,
) {
let SelfSource::QPath(ty) = self_source else { return; };
for (deref_ty, _) in self.autoderef(rustc_span::DUMMY_SP, rcvr_ty).skip(1) {
if let Ok(pick) = self.probe_for_name(
ty.span,
Mode::Path,
item_name,
IsSuggestion(true),
deref_ty,
ty.hir_id,
ProbeScope::TraitsInScope,
) {
if deref_ty.is_suggestable(self.tcx, true)
// If this method receives `&self`, then the provided
// argument _should_ coerce, so it's valid to suggest
// just changing the path.
&& pick.item.fn_has_self_parameter
&& let Some(self_ty) =
self.tcx.fn_sig(pick.item.def_id).inputs().skip_binder().get(0)
&& self_ty.is_ref()
{
let suggested_path = match deref_ty.kind() {
ty::Bool
| ty::Char
| ty::Int(_)
| ty::Uint(_)
| ty::Float(_)
| ty::Adt(_, _)
| ty::Str
| ty::Projection(_)
| ty::Param(_) => format!("{deref_ty}"),
_ => format!("<{deref_ty}>"),
};
err.span_suggestion_verbose(
ty.span,
format!("the function `{item_name}` is implemented on `{deref_ty}`"),
suggested_path,
Applicability::MaybeIncorrect,
);
} else {
err.span_note(
ty.span,
format!("the function `{item_name}` is implemented on `{deref_ty}`"),
);
}
return;
}
}
}
/// Print out the type for use in value namespace.
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 Diagnostic,
item_name: Ident,
ty: Ty<'tcx>,
call: &hir::Expr<'_>,
span: Span,
) {
let output_ty = match self.get_impl_future_output_ty(ty) {
Some(output_ty) => self.resolve_vars_if_possible(output_ty).skip_binder(),
_ => 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.",
Applicability::MaybeIncorrect,
);
}
}
fn suggest_use_candidates(&self, err: &mut Diagnostic, msg: String, candidates: Vec<DefId>) {
let parent_map = self.tcx.visible_parent_map(());
// Separate out candidates that must be imported with a glob, because they are named `_`
// and cannot be referred with their identifier.
let (candidates, globs): (Vec<_>, Vec<_>) = candidates.into_iter().partition(|trait_did| {
if let Some(parent_did) = parent_map.get(trait_did) {
// If the item is re-exported as `_`, we should suggest a glob-import instead.
if *parent_did != self.tcx.parent(*trait_did)
&& self
.tcx
.module_children(*parent_did)
.iter()
.filter(|child| child.res.opt_def_id() == Some(*trait_did))
.all(|child| child.ident.name == kw::Underscore)
{
return false;
}
}
true
});
let module_did = self.tcx.parent_module(self.body_id);
let (module, _, _) = self.tcx.hir().get_module(module_did);
let span = module.spans.inject_use_span;
let path_strings = candidates.iter().map(|trait_did| {
format!("use {};\n", with_crate_prefix!(self.tcx.def_path_str(*trait_did)),)
});
let glob_path_strings = globs.iter().map(|trait_did| {
let parent_did = parent_map.get(trait_did).unwrap();
format!(
"use {}::*; // trait {}\n",
with_crate_prefix!(self.tcx.def_path_str(*parent_did)),
self.tcx.item_name(*trait_did),
)
});
err.span_suggestions(
span,
&msg,
path_strings.chain(glob_path_strings),
Applicability::MaybeIncorrect,
);
}
fn suggest_valid_traits(
&self,
err: &mut Diagnostic,
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();
// `TryFrom` and `FromIterator` have no methods
let edition_fix = candidates
.iter()
.find(|did| self.tcx.is_diagnostic_item(sym::TryInto, **did))
.copied();
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);
if let Some(did) = edition_fix {
err.note(&format!(
"'{}' is included in the prelude starting in Edition 2021",
with_crate_prefix!(self.tcx.def_path_str(did))
));
}
true
} else {
false
}
}
fn suggest_traits_to_import(
&self,
err: &mut Diagnostic,
span: Span,
rcvr_ty: Ty<'tcx>,
item_name: Ident,
inputs_len: Option<usize>,
source: SelfSource<'tcx>,
valid_out_of_scope_traits: Vec<DefId>,
unsatisfied_predicates: &[(
ty::Predicate<'tcx>,
Option<ty::Predicate<'tcx>>,
Option<ObligationCause<'tcx>>,
)],
static_candidates: &[CandidateSource],
unsatisfied_bounds: bool,
) {
let mut alt_rcvr_sugg = false;
if let (SelfSource::MethodCall(rcvr), false) = (source, unsatisfied_bounds) {
debug!(?span, ?item_name, ?rcvr_ty, ?rcvr);
let skippable = [
self.tcx.lang_items().clone_trait(),
self.tcx.lang_items().deref_trait(),
self.tcx.lang_items().deref_mut_trait(),
self.tcx.lang_items().drop_trait(),
self.tcx.get_diagnostic_item(sym::AsRef),
];
// Try alternative arbitrary self types that could fulfill this call.
// FIXME: probe for all types that *could* be arbitrary self-types, not
// just this list.
for (rcvr_ty, post) in &[
(rcvr_ty, ""),
(self.tcx.mk_mut_ref(self.tcx.lifetimes.re_erased, rcvr_ty), "&mut "),
(self.tcx.mk_imm_ref(self.tcx.lifetimes.re_erased, rcvr_ty), "&"),
] {
match self.lookup_probe(span, item_name, *rcvr_ty, rcvr, ProbeScope::AllTraits) {
Ok(pick) => {
// If the method is defined for the receiver we have, it likely wasn't `use`d.
// We point at the method, but we just skip the rest of the check for arbitrary
// self types and rely on the suggestion to `use` the trait from
// `suggest_valid_traits`.
let did = Some(pick.item.container_id(self.tcx));
let skip = skippable.contains(&did);
if pick.autoderefs == 0 && !skip {
err.span_label(
pick.item.ident(self.tcx).span,
&format!("the method is available for `{}` here", rcvr_ty),
);
}
break;
}
Err(MethodError::Ambiguity(_)) => {
// If the method is defined (but ambiguous) for the receiver we have, it is also
// likely we haven't `use`d it. It may be possible that if we `Box`/`Pin`/etc.
// the receiver, then it might disambiguate this method, but I think these
// suggestions are generally misleading (see #94218).
break;
}
_ => {}
}
for (rcvr_ty, pre) in &[
(self.tcx.mk_lang_item(*rcvr_ty, LangItem::OwnedBox), "Box::new"),
(self.tcx.mk_lang_item(*rcvr_ty, LangItem::Pin), "Pin::new"),
(self.tcx.mk_diagnostic_item(*rcvr_ty, sym::Arc), "Arc::new"),
(self.tcx.mk_diagnostic_item(*rcvr_ty, sym::Rc), "Rc::new"),
] {
if let Some(new_rcvr_t) = *rcvr_ty
&& let Ok(pick) = self.lookup_probe(
span,
item_name,
new_rcvr_t,
rcvr,
ProbeScope::AllTraits,
)
{
debug!("try_alt_rcvr: pick candidate {:?}", pick);
let did = Some(pick.item.container_id(self.tcx));
// We don't want to suggest a container type when the missing
// method is `.clone()` or `.deref()` otherwise we'd suggest
// `Arc::new(foo).clone()`, which is far from what the user wants.
// Explicitly ignore the `Pin::as_ref()` method as `Pin` does not
// implement the `AsRef` trait.
let skip = skippable.contains(&did)
|| (("Pin::new" == *pre) && (sym::as_ref == item_name.name))
|| inputs_len.map_or(false, |inputs_len| pick.item.kind == ty::AssocKind::Fn && self.tcx.fn_sig(pick.item.def_id).skip_binder().inputs().len() != inputs_len);
// Make sure the method is defined for the *actual* receiver: we don't
// want to treat `Box<Self>` as a receiver if it only works because of
// an autoderef to `&self`
if pick.autoderefs == 0 && !skip {
err.span_label(
pick.item.ident(self.tcx).span,
&format!("the method is available for `{}` here", new_rcvr_t),
);
err.multipart_suggestion(
"consider wrapping the receiver expression with the \
appropriate type",
vec![
(rcvr.span.shrink_to_lo(), format!("{}({}", pre, post)),
(rcvr.span.shrink_to_hi(), ")".to_string()),
],
Applicability::MaybeIncorrect,
);
// We don't care about the other suggestions.
alt_rcvr_sugg = true;
}
}
}
}
}
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![];
// There are no traits implemented, so lets suggest some traits to
// implement, by finding ones that have the item name, and are
// legal to implement.
let mut candidates = all_traits(self.tcx)
.into_iter()
// Don't issue suggestions for unstable traits since they're
// unlikely to be implementable anyway
.filter(|info| match self.tcx.lookup_stability(info.def_id) {
Some(attr) => attr.level.is_stable(),
None => true,
})
.filter(|info| {
// Static candidates are already implemented, and known not to work
// Do not suggest them again
static_candidates.iter().all(|sc| match *sc {
CandidateSource::Trait(def_id) => def_id != info.def_id,
CandidateSource::Impl(def_id) => {
self.tcx.trait_id_of_impl(def_id) != Some(info.def_id)
}
})
})
.filter(|info| {
// We approximate the coherence rules to only suggest
// traits that are legal to implement by requiring that
// either the type or trait is local. Multi-dispatch means
// this isn't perfect (that is, there are cases when
// implementing a trait would be legal but is rejected
// here).
unsatisfied_predicates.iter().all(|(p, _, _)| {
match p.kind().skip_binder() {
// Hide traits if they are present in predicates as they can be fixed without
// having to implement them.
ty::PredicateKind::Trait(t) => t.def_id() == info.def_id,
ty::PredicateKind::Projection(p) => {
p.projection_ty.item_def_id == info.def_id
}
_ => false,
}
}) && (type_is_local || info.def_id.is_local())
&& self
.associated_value(info.def_id, item_name)
.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;
}
}
}
// We only want to suggest public or local traits (#45781).
item.visibility(self.tcx).is_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 alt_rcvr_sugg {
return;
}
if !candidates.is_empty() {
// Sort from most relevant to least relevant.
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 candidates_len = candidates.len();
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,
)
};
// Obtain the span for `param` and use it for a structured suggestion.
if let Some(param) = param_type {
let generics = self.tcx.generics_of(self.body_id.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);
// Get the `hir::Param` to verify whether it already has any bounds.
// We do this to avoid suggesting code that ends up as `T: FooBar`,
// instead we suggest `T: Foo + Bar` in that case.
match hir.get(id) {
Node::GenericParam(param) => {
enum Introducer {
Plus,
Colon,
Nothing,
}
let ast_generics = hir.get_generics(id.owner.def_id).unwrap();
let (sp, mut introducer) = if let Some(span) =
ast_generics.bounds_span_for_suggestions(def_id)
{
(span, Introducer::Plus)
} else if let Some(colon_span) = param.colon_span {
(colon_span.shrink_to_hi(), Introducer::Nothing)
} else {
(param.span.shrink_to_hi(), Introducer::Colon)
};
if matches!(
param.kind,
hir::GenericParamKind::Type { synthetic: true, .. },
) {
introducer = Introducer::Plus
}
let trait_def_ids: FxHashSet<DefId> = ast_generics
.bounds_for_param(def_id)
.flat_map(|bp| bp.bounds.iter())
.filter_map(|bound| 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!(
"{} {}",
match introducer {
Introducer::Plus => " +",
Introducer::Colon => ":",
Introducer::Nothing => "",
},
self.tcx.def_path_str(t.def_id),
)
}),
Applicability::MaybeIncorrect,
);
}
return;
}
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,
);
return;
}
_ => {}
}
}
}
let (potential_candidates, explicitly_negative) = if param_type.is_some() {
// FIXME: Even though negative bounds are not implemented, we could maybe handle
// cases where a positive bound implies a negative impl.
(candidates, Vec::new())
} else if let Some(simp_rcvr_ty) =
simplify_type(self.tcx, rcvr_ty, TreatParams::AsPlaceholder)
{
let mut potential_candidates = Vec::new();
let mut explicitly_negative = Vec::new();
for candidate in candidates {
// Check if there's a negative impl of `candidate` for `rcvr_ty`
if self
.tcx
.all_impls(candidate.def_id)
.filter(|imp_did| {
self.tcx.impl_polarity(*imp_did) == ty::ImplPolarity::Negative
})
.any(|imp_did| {
let imp = self.tcx.impl_trait_ref(imp_did).unwrap();
let imp_simp =
simplify_type(self.tcx, imp.self_ty(), TreatParams::AsPlaceholder);
imp_simp.map_or(false, |s| s == simp_rcvr_ty)
})
{
explicitly_negative.push(candidate);
} else {
potential_candidates.push(candidate);
}
}
(potential_candidates, explicitly_negative)
} else {
// We don't know enough about `recv_ty` to make proper suggestions.
(candidates, Vec::new())
};
let action = if let Some(param) = param_type {
format!("restrict type parameter `{}` with", param)
} else {
// FIXME: it might only need to be imported into scope, not implemented.
"implement".to_string()
};
match &potential_candidates[..] {
[] => {}
[trait_info] if trait_info.def_id.is_local() => {
err.span_note(
self.tcx.def_span(trait_info.def_id),
&format!(
"`{}` defines an item `{}`, perhaps you need to {} it",
self.tcx.def_path_str(trait_info.def_id),
item_name,
action
),
);
}
trait_infos => {
let mut msg = message(action);
for (i, trait_info) in trait_infos.iter().enumerate() {
msg.push_str(&format!(
"\ncandidate #{}: `{}`",
i + 1,
self.tcx.def_path_str(trait_info.def_id),
));
}
err.note(&msg);
}
}
match &explicitly_negative[..] {
[] => {}
[trait_info] => {
let msg = format!(
"the trait `{}` defines an item `{}`, but is explicitly unimplemented",
self.tcx.def_path_str(trait_info.def_id),
item_name
);
err.note(&msg);
}
trait_infos => {
let mut msg = format!(
"the following traits define an item `{}`, but are explicitly unimplemented:",
item_name
);
for trait_info in trait_infos {
msg.push_str(&format!("\n{}", self.tcx.def_path_str(trait_info.def_id)));
}
err.note(&msg);
}
}
}
}
/// issue #102320, for `unwrap_or` with closure as argument, suggest `unwrap_or_else`
/// FIXME: currently not working for suggesting `map_or_else`, see #102408
pub(crate) fn suggest_else_fn_with_closure(
&self,
err: &mut Diagnostic,
expr: &hir::Expr<'_>,
found: Ty<'tcx>,
expected: Ty<'tcx>,
) -> bool {
let Some((_def_id_or_name, output, _inputs)) = self.extract_callable_info(expr, found)
else { return false; };
if !self.can_coerce(output, expected) {
return false;
}
let parent = self.tcx.hir().get_parent_node(expr.hir_id);
if let Some(Node::Expr(call_expr)) = self.tcx.hir().find(parent) &&
let hir::ExprKind::MethodCall(
hir::PathSegment { ident: method_name, .. },
self_expr,
args,
..,
) = call_expr.kind &&
let Some(self_ty) = self.typeck_results.borrow().expr_ty_opt(self_expr) {
let new_name = Ident {
name: Symbol::intern(&format!("{}_else", method_name.as_str())),
span: method_name.span,
};
let probe = self.lookup_probe(
expr.span,
new_name,
self_ty,
self_expr,
ProbeScope::TraitsInScope,
);
// check the method arguments number
if let Ok(pick) = probe &&
let fn_sig = self.tcx.fn_sig(pick.item.def_id) &&
let fn_args = fn_sig.skip_binder().inputs() &&
fn_args.len() == args.len() + 1 {
err.span_suggestion_verbose(
method_name.span.shrink_to_hi(),
&format!("try calling `{}` instead", new_name.name.as_str()),
"_else",
Applicability::MaybeIncorrect,
);
return true;
}
}
false
}
/// Checks whether there is a local type somewhere in the chain of
/// autoderefs of `rcvr_ty`.
fn type_derefs_to_local(
&self,
span: Span,
rcvr_ty: Ty<'tcx>,
source: SelfSource<'tcx>,
) -> 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(tr, ..) => tr.principal().map_or(false, |d| d.def_id().is_local()),
ty::Param(_) => true,
// Everything else (primitive types, etc.) is effectively
// non-local (there are "edge" cases, e.g., `(LocalType,)`, but
// the noise from these sort of types is usually just really
// annoying, rather than any sort of help).
_ => false,
}
}
// This occurs for UFCS desugaring of `T::method`, where there is no
// receiver expression for the method call, and thus no autoderef.
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, Debug)]
pub enum SelfSource<'a> {
QPath(&'a hir::Ty<'a>),
MethodCall(&'a hir::Expr<'a> /* rcvr */),
}
#[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 {
// Local crates are more important than remote ones (local:
// `cnum == 0`), and otherwise we throw in the defid for totality.
let lhs = (other.def_id.krate, other.def_id);
let rhs = (self.def_id.krate, self.def_id);
lhs.cmp(&rhs)
}
}
/// Retrieves all traits in this crate and any dependent crates,
/// and wraps them into `TraitInfo` for custom sorting.
pub fn all_traits(tcx: TyCtxt<'_>) -> Vec<TraitInfo> {
tcx.all_traits().map(|def_id| TraitInfo { def_id }).collect()
}
fn print_disambiguation_help<'tcx>(
item_name: Ident,
args: Option<(&'tcx hir::Expr<'tcx>, &'tcx [hir::Expr<'tcx>])>,
err: &mut Diagnostic,
trait_name: String,
rcvr_ty: Ty<'_>,
kind: ty::AssocKind,
def_id: DefId,
span: Span,
candidate: Option<usize>,
source_map: &source_map::SourceMap,
fn_has_self_parameter: bool,
) {
let mut applicability = Applicability::MachineApplicable;
let (span, sugg) = if let (ty::AssocKind::Fn, Some((receiver, args))) = (kind, args) {
let args = format!(
"({}{})",
if rcvr_ty.is_region_ptr() {
if rcvr_ty.is_mutable_ptr() { "&mut " } else { "&" }
} else {
""
},
std::iter::once(receiver)
.chain(args.iter())
.map(|arg| source_map.span_to_snippet(arg.span).unwrap_or_else(|_| {
applicability = Applicability::HasPlaceholders;
"_".to_owned()
}))
.collect::<Vec<_>>()
.join(", "),
);
let trait_name = if !fn_has_self_parameter {
format!("<{} as {}>", rcvr_ty, trait_name)
} else {
trait_name
};
(span, format!("{}::{}{}", trait_name, item_name, args))
} else {
(span.with_hi(item_name.span.lo()), format!("<{} as {}>::", rcvr_ty, trait_name))
};
err.span_suggestion_verbose(
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,
);
}