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Suggest similarly named assoc items in trait impls

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Previously, the compiler didn't suggest similarly named associated items
unlike we do in many situations. This patch adds such diagnostics for
associated functions, types and constants.
This commit is contained in:
Hirochika Matsumoto 2021-09-26 00:53:37 +09:00
parent 60fe8b3a65
commit cef736f8a0
8 changed files with 216 additions and 18 deletions
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30
compiler/rustc_resolve/src/diagnostics.rs
View file

@ -198,7 +198,7 @@ impl<'a> Resolver<'a> {
err.span_label(first_use_span, format!("first use of `{}`", name));
err
}
ResolutionError::MethodNotMemberOfTrait(method, trait_) => {
ResolutionError::MethodNotMemberOfTrait(method, trait_, candidate) => {
let mut err = struct_span_err!(
self.session,
span,
@ -208,9 +208,17 @@ impl<'a> Resolver<'a> {
trait_
);
err.span_label(span, format!("not a member of trait `{}`", trait_));
if let Some(candidate) = candidate {
err.span_suggestion(
method.span,
"there is an associated function with a similar name",
candidate.to_ident_string(),
Applicability::MaybeIncorrect,
);
}
err
}
ResolutionError::TypeNotMemberOfTrait(type_, trait_) => {
ResolutionError::TypeNotMemberOfTrait(type_, trait_, candidate) => {
let mut err = struct_span_err!(
self.session,
span,
@ -220,9 +228,17 @@ impl<'a> Resolver<'a> {
trait_
);
err.span_label(span, format!("not a member of trait `{}`", trait_));
if let Some(candidate) = candidate {
err.span_suggestion(
type_.span,
"there is an associated type with a similar name",
candidate.to_ident_string(),
Applicability::MaybeIncorrect,
);
}
err
}
ResolutionError::ConstNotMemberOfTrait(const_, trait_) => {
ResolutionError::ConstNotMemberOfTrait(const_, trait_, candidate) => {
let mut err = struct_span_err!(
self.session,
span,
@ -232,6 +248,14 @@ impl<'a> Resolver<'a> {
trait_
);
err.span_label(span, format!("not a member of trait `{}`", trait_));
if let Some(candidate) = candidate {
err.span_suggestion(
const_.span,
"there is an associated constant with a similar name",
candidate.to_ident_string(),
Applicability::MaybeIncorrect,
);
}
err
}
ResolutionError::VariableNotBoundInPattern(binding_error) => {

28
compiler/rustc_resolve/src/late.rs
View file

@ -1309,14 +1309,15 @@ impl<'a: 'ast, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
use crate::ResolutionError::*;
match &item.kind {
AssocItemKind::Const(_default, _ty, _expr) => {
debug!("resolve_implementation AssocItemKind::Const",);
debug!("resolve_implementation AssocItemKind::Const");
// If this is a trait impl, ensure the const
// exists in trait
this.check_trait_item(
item.ident,
&item.kind,
ValueNS,
item.span,
|n, s| ConstNotMemberOfTrait(n, s),
|i, s, c| ConstNotMemberOfTrait(i, s, c),
);
// We allow arbitrary const expressions inside of associated consts,
@ -1338,6 +1339,7 @@ impl<'a: 'ast, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
);
}
AssocItemKind::Fn(box FnKind(.., generics, _)) => {
debug!("resolve_implementation AssocItemKind::Fn");
// We also need a new scope for the impl item type parameters.
this.with_generic_param_rib(
generics,
@ -1347,9 +1349,10 @@ impl<'a: 'ast, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
// exists in trait
this.check_trait_item(
item.ident,
&item.kind,
ValueNS,
item.span,
|n, s| MethodNotMemberOfTrait(n, s),
|i, s, c| MethodNotMemberOfTrait(i, s, c),
);
visit::walk_assoc_item(
@ -1366,6 +1369,7 @@ impl<'a: 'ast, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
_,
_,
)) => {
debug!("resolve_implementation AssocItemKind::TyAlias");
// We also need a new scope for the impl item type parameters.
this.with_generic_param_rib(
generics,
@ -1375,9 +1379,10 @@ impl<'a: 'ast, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
// exists in trait
this.check_trait_item(
item.ident,
&item.kind,
TypeNS,
item.span,
|n, s| TypeNotMemberOfTrait(n, s),
|i, s, c| TypeNotMemberOfTrait(i, s, c),
);
visit::walk_assoc_item(
@ -1401,9 +1406,15 @@ impl<'a: 'ast, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
});
}
fn check_trait_item<F>(&mut self, ident: Ident, ns: Namespace, span: Span, err: F)
where
F: FnOnce(Symbol, &str) -> ResolutionError<'_>,
fn check_trait_item<F>(
&mut self,
ident: Ident,
kind: &AssocItemKind,
ns: Namespace,
span: Span,
err: F,
) where
F: FnOnce(Ident, &str, Option<Symbol>) -> ResolutionError<'_>,
{
// If there is a TraitRef in scope for an impl, then the method must be in the
// trait.
@ -1420,8 +1431,9 @@ impl<'a: 'ast, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
)
.is_err()
{
let candidate = self.find_similarly_named_assoc_item(ident.name, kind);
let path = &self.current_trait_ref.as_ref().unwrap().1.path;
self.report_error(span, err(ident.name, &path_names_to_string(path)));
self.report_error(span, err(ident, &path_names_to_string(path), candidate));
}
}
}

38
compiler/rustc_resolve/src/late/diagnostics.rs
View file

@ -7,8 +7,8 @@ use crate::{PathResult, PathSource, Segment};
use rustc_ast::visit::FnKind;
use rustc_ast::{
self as ast, Expr, ExprKind, GenericParam, GenericParamKind, Item, ItemKind, NodeId, Path, Ty,
TyKind,
self as ast, AssocItemKind, Expr, ExprKind, GenericParam, GenericParamKind, Item, ItemKind,
NodeId, Path, Ty, TyKind,
};
use rustc_ast_pretty::pprust::path_segment_to_string;
use rustc_data_structures::fx::FxHashSet;
@ -1144,6 +1144,40 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> {
true
}
/// Given the target `ident` and `kind`, search for the similarly named associated item
/// in `self.current_trait_ref`.
crate fn find_similarly_named_assoc_item(
&mut self,
ident: Symbol,
kind: &AssocItemKind,
) -> Option<Symbol> {
let module = if let Some((module, _)) = self.current_trait_ref {
module
} else {
return None;
};
if ident == kw::Underscore {
// We do nothing for `_`.
return None;
}
let resolutions = self.r.resolutions(module);
let targets = resolutions
.borrow()
.iter()
.filter_map(|(key, res)| res.borrow().binding.map(|binding| (key, binding.res())))
.filter(|(_, res)| match (kind, res) {
(AssocItemKind::Const(..), Res::Def(DefKind::AssocConst, _)) => true,
(AssocItemKind::Fn(_), Res::Def(DefKind::AssocFn, _)) => true,
(AssocItemKind::TyAlias(..), Res::Def(DefKind::AssocTy, _)) => true,
_ => false,
})
.map(|(key, _)| key.ident.name)
.collect::<Vec<_>>();
find_best_match_for_name(&targets, ident, None)
}
fn lookup_assoc_candidate<FilterFn>(
&mut self,
ident: Ident,

6
compiler/rustc_resolve/src/lib.rs
View file

@ -202,11 +202,11 @@ enum ResolutionError<'a> {
/// parameter list.
NameAlreadyUsedInParameterList(Symbol, Span),
/// Error E0407: method is not a member of trait.
MethodNotMemberOfTrait(Symbol, &'a str),
MethodNotMemberOfTrait(Ident, &'a str, Option<Symbol>),
/// Error E0437: type is not a member of trait.
TypeNotMemberOfTrait(Symbol, &'a str),
TypeNotMemberOfTrait(Ident, &'a str, Option<Symbol>),
/// Error E0438: const is not a member of trait.
ConstNotMemberOfTrait(Symbol, &'a str),
ConstNotMemberOfTrait(Ident, &'a str, Option<Symbol>),
/// Error E0408: variable `{}` is not bound in all patterns.
VariableNotBoundInPattern(&'a BindingError),
/// Error E0409: variable `{}` is bound in inconsistent ways within the same match arm.