1179 lines
51 KiB
Rust
1179 lines
51 KiB
Rust
//! Give useful errors and suggestions to users when an item can't be
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//! found or is otherwise invalid.
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use crate::check::FnCtxt;
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use crate::middle::lang_items::FnOnceTraitLangItem;
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use crate::namespace::Namespace;
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use errors::{pluralize, struct_span_err, Applicability, DiagnosticBuilder};
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use rustc::hir::intravisit;
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use rustc::hir::map as hir_map;
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use rustc::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
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use rustc::traits::Obligation;
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use rustc::ty::print::with_crate_prefix;
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use rustc::ty::{self, ToPolyTraitRef, ToPredicate, Ty, TyCtxt, TypeFoldable};
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use rustc_data_structures::fx::FxHashSet;
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use rustc_hir as hir;
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use rustc_hir::def::{DefKind, Res};
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use rustc_hir::def_id::{DefId, CRATE_DEF_INDEX, LOCAL_CRATE};
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use rustc_hir::{ExprKind, Node, QPath};
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use rustc_span::{source_map, FileName, Span};
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use syntax::ast;
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use syntax::util::lev_distance;
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use rustc_error_codes::*;
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use std::cmp::Ordering;
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use super::probe::Mode;
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use super::{CandidateSource, MethodError, NoMatchData};
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impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
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fn is_fn_ty(&self, ty: Ty<'tcx>, span: Span) -> bool {
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let tcx = self.tcx;
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match ty.kind {
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// Not all of these (e.g., unsafe fns) implement `FnOnce`,
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// so we look for these beforehand.
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ty::Closure(..) | ty::FnDef(..) | ty::FnPtr(_) => true,
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// If it's not a simple function, look for things which implement `FnOnce`.
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_ => {
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let fn_once = match tcx.lang_items().require(FnOnceTraitLangItem) {
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Ok(fn_once) => fn_once,
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Err(..) => return false,
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};
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self.autoderef(span, ty).any(|(ty, _)| {
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self.probe(|_| {
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let fn_once_substs = tcx.mk_substs_trait(
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ty,
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&[self
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.next_ty_var(TypeVariableOrigin {
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kind: TypeVariableOriginKind::MiscVariable,
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span,
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})
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.into()],
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);
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let trait_ref = ty::TraitRef::new(fn_once, fn_once_substs);
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let poly_trait_ref = trait_ref.to_poly_trait_ref();
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let obligation = Obligation::misc(
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span,
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self.body_id,
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self.param_env,
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poly_trait_ref.to_predicate(),
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);
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self.predicate_may_hold(&obligation)
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})
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})
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}
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}
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}
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pub fn report_method_error<'b>(
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&self,
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span: Span,
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rcvr_ty: Ty<'tcx>,
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item_name: ast::Ident,
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source: SelfSource<'b>,
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error: MethodError<'tcx>,
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args: Option<&'tcx [hir::Expr<'tcx>]>,
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) -> Option<DiagnosticBuilder<'_>> {
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let orig_span = span;
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let mut span = span;
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// Avoid suggestions when we don't know what's going on.
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if rcvr_ty.references_error() {
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return None;
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}
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let report_candidates = |span: Span,
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err: &mut DiagnosticBuilder<'_>,
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mut sources: Vec<CandidateSource>,
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sugg_span: Span| {
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sources.sort();
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sources.dedup();
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// Dynamic limit to avoid hiding just one candidate, which is silly.
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let limit = if sources.len() == 5 { 5 } else { 4 };
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for (idx, source) in sources.iter().take(limit).enumerate() {
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match *source {
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CandidateSource::ImplSource(impl_did) => {
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// Provide the best span we can. Use the item, if local to crate, else
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// the impl, if local to crate (item may be defaulted), else nothing.
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let item = match self
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.associated_item(impl_did, item_name, Namespace::Value)
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.or_else(|| {
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let impl_trait_ref = self.tcx.impl_trait_ref(impl_did)?;
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self.associated_item(
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impl_trait_ref.def_id,
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item_name,
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Namespace::Value,
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)
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}) {
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Some(item) => item,
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None => continue,
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};
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let note_span = self
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.tcx
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.hir()
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.span_if_local(item.def_id)
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.or_else(|| self.tcx.hir().span_if_local(impl_did));
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let impl_ty = self.impl_self_ty(span, impl_did).ty;
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let insertion = match self.tcx.impl_trait_ref(impl_did) {
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None => String::new(),
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Some(trait_ref) => format!(
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" of the trait `{}`",
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self.tcx.def_path_str(trait_ref.def_id)
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),
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};
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let (note_str, idx) = if sources.len() > 1 {
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(
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format!(
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"candidate #{} is defined in an impl{} for the type `{}`",
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idx + 1,
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insertion,
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impl_ty,
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),
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Some(idx + 1),
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)
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} else {
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(
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format!(
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"the candidate is defined in an impl{} for the type `{}`",
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insertion, impl_ty,
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),
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None,
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)
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};
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if let Some(note_span) = note_span {
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// We have a span pointing to the method. Show note with snippet.
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err.span_note(
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self.tcx.sess.source_map().def_span(note_span),
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¬e_str,
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);
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} else {
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err.note(¬e_str);
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}
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if let Some(trait_ref) = self.tcx.impl_trait_ref(impl_did) {
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let path = self.tcx.def_path_str(trait_ref.def_id);
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let ty = match item.kind {
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ty::AssocKind::Const
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| ty::AssocKind::Type
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| ty::AssocKind::OpaqueTy => rcvr_ty,
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ty::AssocKind::Method => self
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.tcx
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.fn_sig(item.def_id)
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.inputs()
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.skip_binder()
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.get(0)
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.filter(|ty| ty.is_region_ptr() && !rcvr_ty.is_region_ptr())
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.map(|ty| *ty)
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.unwrap_or(rcvr_ty),
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};
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print_disambiguation_help(
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item_name,
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args,
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err,
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path,
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ty,
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item.kind,
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sugg_span,
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idx,
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self.tcx.sess.source_map(),
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);
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}
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}
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CandidateSource::TraitSource(trait_did) => {
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let item =
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match self.associated_item(trait_did, item_name, Namespace::Value) {
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Some(item) => item,
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None => continue,
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};
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let item_span =
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self.tcx.sess.source_map().def_span(self.tcx.def_span(item.def_id));
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let idx = if sources.len() > 1 {
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let msg = &format!(
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"candidate #{} is defined in the trait `{}`",
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idx + 1,
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self.tcx.def_path_str(trait_did)
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);
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err.span_note(item_span, msg);
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Some(idx + 1)
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} else {
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let msg = &format!(
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"the candidate is defined in the trait `{}`",
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self.tcx.def_path_str(trait_did)
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);
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err.span_note(item_span, msg);
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None
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};
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let path = self.tcx.def_path_str(trait_did);
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print_disambiguation_help(
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item_name,
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args,
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err,
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path,
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rcvr_ty,
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item.kind,
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sugg_span,
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idx,
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self.tcx.sess.source_map(),
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);
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}
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}
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}
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if sources.len() > limit {
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err.note(&format!("and {} others", sources.len() - limit));
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}
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};
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let sugg_span = if let SelfSource::MethodCall(expr) = source {
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// Given `foo.bar(baz)`, `expr` is `bar`, but we want to point to the whole thing.
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self.tcx.hir().expect_expr(self.tcx.hir().get_parent_node(expr.hir_id)).span
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} else {
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span
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};
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match error {
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MethodError::NoMatch(NoMatchData {
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static_candidates: static_sources,
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unsatisfied_predicates,
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out_of_scope_traits,
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lev_candidate,
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mode,
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}) => {
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let tcx = self.tcx;
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let actual = self.resolve_vars_if_possible(&rcvr_ty);
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let ty_str = self.ty_to_string(actual);
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let is_method = mode == Mode::MethodCall;
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let item_kind = if is_method {
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"method"
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} else if actual.is_enum() {
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"variant or associated item"
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} else {
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match (item_name.as_str().chars().next(), actual.is_fresh_ty()) {
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(Some(name), false) if name.is_lowercase() => "function or associated item",
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(Some(_), false) => "associated item",
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(Some(_), true) | (None, false) => "variant or associated item",
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(None, true) => "variant",
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}
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};
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let mut err = if !actual.references_error() {
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// Suggest clamping down the type if the method that is being attempted to
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// be used exists at all, and the type is an ambiguous numeric type
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// ({integer}/{float}).
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let mut candidates = all_traits(self.tcx).into_iter().filter_map(|info| {
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self.associated_item(info.def_id, item_name, Namespace::Value)
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});
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if let (true, false, SelfSource::MethodCall(expr), Some(_)) = (
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actual.is_numeric(),
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actual.has_concrete_skeleton(),
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source,
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candidates.next(),
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) {
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let mut err = struct_span_err!(
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tcx.sess,
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span,
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E0689,
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"can't call {} `{}` on ambiguous numeric type `{}`",
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item_kind,
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item_name,
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ty_str
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);
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let concrete_type = if actual.is_integral() { "i32" } else { "f32" };
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match expr.kind {
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ExprKind::Lit(ref lit) => {
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// numeric literal
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let snippet = tcx
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.sess
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.source_map()
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.span_to_snippet(lit.span)
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.unwrap_or_else(|_| "<numeric literal>".to_owned());
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err.span_suggestion(
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lit.span,
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&format!(
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"you must specify a concrete type for \
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this numeric value, like `{}`",
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concrete_type
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),
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format!("{}_{}", snippet, concrete_type),
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Applicability::MaybeIncorrect,
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);
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}
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ExprKind::Path(ref qpath) => {
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// local binding
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if let &QPath::Resolved(_, ref path) = &qpath {
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if let hir::def::Res::Local(hir_id) = path.res {
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let span = tcx.hir().span(hir_id);
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let snippet = tcx.sess.source_map().span_to_snippet(span);
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let filename = tcx.sess.source_map().span_to_filename(span);
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let parent_node = self
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.tcx
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.hir()
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.get(self.tcx.hir().get_parent_node(hir_id));
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let msg = format!(
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"you must specify a type for this binding, like `{}`",
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concrete_type,
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);
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match (filename, parent_node, snippet) {
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(
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FileName::Real(_),
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Node::Local(hir::Local {
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source: hir::LocalSource::Normal,
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ty,
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..
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}),
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Ok(ref snippet),
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) => {
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err.span_suggestion(
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// account for `let x: _ = 42;`
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// ^^^^
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span.to(ty
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.as_ref()
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.map(|ty| ty.span)
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.unwrap_or(span)),
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&msg,
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format!("{}: {}", snippet, concrete_type),
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Applicability::MaybeIncorrect,
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);
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}
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_ => {
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err.span_label(span, msg);
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}
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}
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}
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}
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}
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_ => {}
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}
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err.emit();
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return None;
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} else {
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span = item_name.span;
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let mut err = struct_span_err!(
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tcx.sess,
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span,
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E0599,
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"no {} named `{}` found for type `{}` in the current scope",
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item_kind,
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item_name,
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ty_str
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);
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if let Some(span) =
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tcx.sess.confused_type_with_std_module.borrow().get(&span)
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{
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if let Ok(snippet) = tcx.sess.source_map().span_to_snippet(*span) {
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err.span_suggestion(
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*span,
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"you are looking for the module in `std`, \
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not the primitive type",
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format!("std::{}", snippet),
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Applicability::MachineApplicable,
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);
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}
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}
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if let ty::RawPtr(_) = &actual.kind {
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err.note(
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"try using `<*const T>::as_ref()` to get a reference to the \
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type behind the pointer: https://doc.rust-lang.org/std/\
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primitive.pointer.html#method.as_ref",
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);
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err.note(
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"using `<*const T>::as_ref()` on a pointer \
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which is unaligned or points to invalid \
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or uninitialized memory is undefined behavior",
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);
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}
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err
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}
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} else {
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tcx.sess.diagnostic().struct_dummy()
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};
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|
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if let Some(def) = actual.ty_adt_def() {
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if let Some(full_sp) = tcx.hir().span_if_local(def.did) {
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let def_sp = tcx.sess.source_map().def_span(full_sp);
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err.span_label(
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def_sp,
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format!(
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"{} `{}` not found {}",
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item_kind,
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item_name,
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if def.is_enum() && !is_method { "here" } else { "for this" }
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),
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);
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}
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}
|
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|
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// If the method name is the name of a field with a function or closure type,
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// give a helping note that it has to be called as `(x.f)(...)`.
|
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if let SelfSource::MethodCall(expr) = source {
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let field_receiver =
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self.autoderef(span, rcvr_ty).find_map(|(ty, _)| match ty.kind {
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ty::Adt(def, substs) if !def.is_enum() => {
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let variant = &def.non_enum_variant();
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self.tcx.find_field_index(item_name, variant).map(|index| {
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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.hir().get_module_parent(self.body_id);
|
|
let is_accessible = field.vis.is_accessible_from(scope, self.tcx);
|
|
|
|
if is_accessible {
|
|
if self.is_fn_ty(&field_ty, span) {
|
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let expr_span = expr.span.to(item_name.span);
|
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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)
|
|
{
|
|
// When the "method" is resolved through dereferencing, we really want the
|
|
// original type that has the associated function for accurate suggestions.
|
|
// (#61411)
|
|
let ty = self.impl_self_ty(span, *impl_did).ty;
|
|
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, static_sources, sugg_span);
|
|
} else if static_sources.len() > 1 {
|
|
report_candidates(span, &mut err, static_sources, sugg_span);
|
|
}
|
|
|
|
if !unsatisfied_predicates.is_empty() {
|
|
let mut bound_list = unsatisfied_predicates
|
|
.iter()
|
|
.map(|p| format!("`{} : {}`", p.self_ty(), p.print_only_trait_path()))
|
|
.collect::<Vec<_>>();
|
|
bound_list.sort();
|
|
bound_list.dedup(); // #35677
|
|
let bound_list = bound_list.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() {
|
|
} else {
|
|
self.suggest_traits_to_import(
|
|
&mut err,
|
|
span,
|
|
rcvr_ty,
|
|
item_name,
|
|
source,
|
|
out_of_scope_traits,
|
|
);
|
|
}
|
|
|
|
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.as_str(),
|
|
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.as_str() == "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.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(),
|
|
span,
|
|
E0034,
|
|
"multiple applicable items in scope"
|
|
);
|
|
err.span_label(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 mut err = struct_span_err!(
|
|
self.tcx.sess,
|
|
span,
|
|
E0624,
|
|
"{} `{}` is private",
|
|
kind.descr(def_id),
|
|
item_name
|
|
);
|
|
self.suggest_valid_traits(&mut err, out_of_scope_traits);
|
|
err.emit();
|
|
}
|
|
|
|
MethodError::IllegalSizedBound(candidates, needs_mut) => {
|
|
let msg = format!("the `{}` method cannot be invoked on a trait object", item_name);
|
|
let mut err = self.sess().struct_span_err(span, &msg);
|
|
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
|
|
}
|
|
|
|
/// 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_use_candidates(
|
|
&self,
|
|
err: &mut DiagnosticBuilder<'_>,
|
|
mut msg: String,
|
|
candidates: Vec<DefId>,
|
|
) {
|
|
let module_did = self.tcx.hir().get_module_parent(self.body_id);
|
|
let module_id = self.tcx.hir().as_local_hir_id(module_did).unwrap();
|
|
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| {
|
|
// Produce an additional newline to separate the new use statement
|
|
// from the directly following item.
|
|
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: ast::Ident,
|
|
source: SelfSource<'b>,
|
|
valid_out_of_scope_traits: Vec<DefId>,
|
|
) {
|
|
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);
|
|
|
|
// 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()
|
|
.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).
|
|
(type_is_local || info.def_id.is_local())
|
|
&& self
|
|
.associated_item(info.def_id, item_name, Namespace::Value)
|
|
.filter(|item| {
|
|
// We only want to suggest public or local traits (#45781).
|
|
item.vis == ty::Visibility::Public || info.def_id.is_local()
|
|
})
|
|
.is_some()
|
|
})
|
|
.collect::<Vec<_>>();
|
|
|
|
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 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.
|
|
let mut suggested = false;
|
|
if let (Some(ref param), Some(ref table)) = (param_type, self.in_progress_tables) {
|
|
let table = table.borrow();
|
|
if let Some(did) = table.local_id_root {
|
|
let generics = self.tcx.generics_of(did);
|
|
let type_param = generics.type_param(param, self.tcx);
|
|
let hir = &self.tcx.hir();
|
|
if let Some(id) = hir.as_local_hir_id(type_param.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(ref param) => {
|
|
let mut impl_trait = false;
|
|
let has_bounds = if let hir::GenericParamKind::Type {
|
|
synthetic: Some(_),
|
|
..
|
|
} = ¶m.kind
|
|
{
|
|
// We've found `fn foo(x: impl Trait)` instead of
|
|
// `fn foo<T>(x: T)`. We want to suggest the correct
|
|
// `fn foo(x: impl Trait + TraitBound)` instead of
|
|
// `fn foo<T: TraitBound>(x: T)`. (#63706)
|
|
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` only covers `T`, change it so that it covers
|
|
// `T:` when appropriate
|
|
sp.until(first_bound.span())
|
|
} else {
|
|
sp
|
|
};
|
|
// FIXME: contrast `t.def_id` against `param.bounds` to not suggest
|
|
// traits already there. That can happen when the cause is that
|
|
// we're in a const scope or associated function used as a method.
|
|
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 mut msg = message(if let Some(param) = param_type {
|
|
format!("restrict type parameter `{}` with", param)
|
|
} else {
|
|
"implement".to_string()
|
|
});
|
|
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[..]);
|
|
}
|
|
}
|
|
}
|
|
|
|
/// 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<'_>) -> 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,
|
|
|
|
// 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)]
|
|
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.
|
|
pub fn all_traits(tcx: TyCtxt<'_>) -> Vec<TraitInfo> {
|
|
tcx.all_traits(LOCAL_CRATE).iter().map(|&def_id| TraitInfo { def_id }).collect()
|
|
}
|
|
|
|
/// Computes all traits in this crate and any dependent crates.
|
|
fn compute_all_traits(tcx: TyCtxt<'_>) -> Vec<DefId> {
|
|
use hir::itemlikevisit;
|
|
|
|
let mut traits = vec![];
|
|
|
|
// Crate-local:
|
|
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struct Visitor<'a, 'tcx> {
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map: &'a hir_map::Map<'tcx>,
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traits: &'a mut Vec<DefId>,
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}
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impl<'v, 'a, 'tcx> itemlikevisit::ItemLikeVisitor<'v> for Visitor<'a, 'tcx> {
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fn visit_item(&mut self, i: &'v hir::Item<'v>) {
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match i.kind {
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hir::ItemKind::Trait(..) | hir::ItemKind::TraitAlias(..) => {
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let def_id = self.map.local_def_id(i.hir_id);
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self.traits.push(def_id);
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}
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_ => (),
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}
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}
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fn visit_trait_item(&mut self, _trait_item: &hir::TraitItem<'_>) {}
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fn visit_impl_item(&mut self, _impl_item: &hir::ImplItem<'_>) {}
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}
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tcx.hir().krate().visit_all_item_likes(&mut Visitor { map: &tcx.hir(), traits: &mut traits });
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// Cross-crate:
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let mut external_mods = FxHashSet::default();
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fn handle_external_res(
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tcx: TyCtxt<'_>,
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traits: &mut Vec<DefId>,
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external_mods: &mut FxHashSet<DefId>,
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res: Res,
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) {
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match res {
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Res::Def(DefKind::Trait, def_id) | Res::Def(DefKind::TraitAlias, def_id) => {
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traits.push(def_id);
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}
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Res::Def(DefKind::Mod, def_id) => {
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if !external_mods.insert(def_id) {
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return;
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}
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for child in tcx.item_children(def_id).iter() {
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handle_external_res(tcx, traits, external_mods, child.res)
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}
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}
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_ => {}
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}
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}
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for &cnum in tcx.crates().iter() {
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let def_id = DefId { krate: cnum, index: CRATE_DEF_INDEX };
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handle_external_res(tcx, &mut traits, &mut external_mods, Res::Def(DefKind::Mod, def_id));
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}
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|
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traits
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|
}
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pub fn provide(providers: &mut ty::query::Providers<'_>) {
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providers.all_traits = |tcx, cnum| {
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assert_eq!(cnum, LOCAL_CRATE);
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&tcx.arena.alloc(compute_all_traits(tcx))[..]
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}
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|
}
|
|
|
|
struct UsePlacementFinder<'tcx> {
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|
target_module: hir::HirId,
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|
span: Option<Span>,
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|
found_use: bool,
|
|
tcx: TyCtxt<'tcx>,
|
|
}
|
|
|
|
impl UsePlacementFinder<'tcx> {
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|
fn check(
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|
tcx: TyCtxt<'tcx>,
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|
krate: &'tcx hir::Crate<'tcx>,
|
|
target_module: hir::HirId,
|
|
) -> (Option<Span>, bool) {
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|
let mut finder = UsePlacementFinder { target_module, span: None, found_use: false, tcx };
|
|
intravisit::walk_crate(&mut finder, krate);
|
|
(finder.span, finder.found_use)
|
|
}
|
|
}
|
|
|
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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;
|
|
}
|
|
// Find a `use` statement.
|
|
for item_id in module.item_ids {
|
|
let item = self.tcx.hir().expect_item(item_id.id);
|
|
match item.kind {
|
|
hir::ItemKind::Use(..) => {
|
|
// Don't suggest placing a `use` before the prelude
|
|
// import or other generated ones.
|
|
if !item.span.from_expansion() {
|
|
self.span = Some(item.span.shrink_to_lo());
|
|
self.found_use = true;
|
|
return;
|
|
}
|
|
}
|
|
// Don't place `use` before `extern crate`...
|
|
hir::ItemKind::ExternCrate(_) => {}
|
|
// ...but do place them before the first other item.
|
|
_ => {
|
|
if self.span.map_or(true, |span| item.span < span) {
|
|
if !item.span.from_expansion() {
|
|
// Don't insert between attributes and an item.
|
|
if item.attrs.is_empty() {
|
|
self.span = Some(item.span.shrink_to_lo());
|
|
} else {
|
|
// Find the first attribute on the item.
|
|
for attr in item.attrs {
|
|
if self.span.map_or(true, |span| attr.span < span) {
|
|
self.span = Some(attr.span.shrink_to_lo());
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
fn nested_visit_map<'this>(&'this mut self) -> intravisit::NestedVisitorMap<'this, 'tcx> {
|
|
intravisit::NestedVisitorMap::None
|
|
}
|
|
}
|
|
|
|
fn print_disambiguation_help(
|
|
item_name: ast::Ident,
|
|
args: Option<&'tcx [hir::Expr<'tcx>]>,
|
|
err: &mut DiagnosticBuilder<'_>,
|
|
trait_name: String,
|
|
rcvr_ty: Ty<'_>,
|
|
kind: ty::AssocKind,
|
|
span: Span,
|
|
candidate: Option<usize>,
|
|
source_map: &source_map::SourceMap,
|
|
) {
|
|
let mut applicability = Applicability::MachineApplicable;
|
|
let sugg_args = if let (ty::AssocKind::Method, 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.suggestion_descr(),
|
|
if let Some(candidate) = candidate {
|
|
format!("candidate #{}", candidate)
|
|
} else {
|
|
"the candidate".to_string()
|
|
},
|
|
),
|
|
sugg,
|
|
applicability,
|
|
);
|
|
}
|