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rust/compiler/rustc_resolve/src/late/diagnostics.rs

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use crate::diagnostics::{ImportSuggestion, LabelSuggestion, TypoSuggestion};
use crate::late::lifetimes::{ElisionFailureInfo, LifetimeContext};
use crate::late::{AliasPossibility, LateResolutionVisitor, RibKind};
use crate::path_names_to_string;
use crate::{CrateLint, Module, ModuleKind, ModuleOrUniformRoot};
use crate::{PathResult, PathSource, Segment};
use rustc_ast::visit::FnKind;
use rustc_ast::{self as ast, Expr, ExprKind, Item, ItemKind, NodeId, Path, Ty, TyKind};
use rustc_ast_pretty::pprust::path_segment_to_string;
use rustc_data_structures::fx::FxHashSet;
use rustc_errors::{pluralize, struct_span_err, Applicability, DiagnosticBuilder};
use rustc_hir as hir;
use rustc_hir::def::Namespace::{self, *};
use rustc_hir::def::{self, CtorKind, CtorOf, DefKind};
use rustc_hir::def_id::{DefId, CRATE_DEF_INDEX, LOCAL_CRATE};
use rustc_hir::PrimTy;
use rustc_session::parse::feature_err;
use rustc_span::edition::Edition;
use rustc_span::hygiene::MacroKind;
use rustc_span::lev_distance::find_best_match_for_name;
use rustc_span::symbol::{kw, sym, Ident, Symbol};
use rustc_span::{BytePos, MultiSpan, Span, DUMMY_SP};
use tracing::debug;
type Res = def::Res<ast::NodeId>;
/// A field or associated item from self type suggested in case of resolution failure.
enum AssocSuggestion {
Field,
MethodWithSelf,
AssocFn,
AssocType,
AssocConst,
}
impl AssocSuggestion {
fn action(&self) -> &'static str {
match self {
AssocSuggestion::Field => "use the available field",
AssocSuggestion::MethodWithSelf => "call the method with the fully-qualified path",
AssocSuggestion::AssocFn => "call the associated function",
AssocSuggestion::AssocConst => "use the associated `const`",
AssocSuggestion::AssocType => "use the associated type",
}
}
}
crate enum MissingLifetimeSpot<'tcx> {
Generics(&'tcx hir::Generics<'tcx>),
HigherRanked { span: Span, span_type: ForLifetimeSpanType },
Static,
}
crate enum ForLifetimeSpanType {
BoundEmpty,
BoundTail,
TypeEmpty,
TypeTail,
}
impl ForLifetimeSpanType {
crate fn descr(&self) -> &'static str {
match self {
Self::BoundEmpty | Self::BoundTail => "bound",
Self::TypeEmpty | Self::TypeTail => "type",
}
}
crate fn suggestion(&self, sugg: &str) -> String {
match self {
Self::BoundEmpty | Self::TypeEmpty => format!("for<{}> ", sugg),
Self::BoundTail | Self::TypeTail => format!(", {}", sugg),
}
}
}
impl<'tcx> Into<MissingLifetimeSpot<'tcx>> for &'tcx hir::Generics<'tcx> {
fn into(self) -> MissingLifetimeSpot<'tcx> {
MissingLifetimeSpot::Generics(self)
}
}
fn is_self_type(path: &[Segment], namespace: Namespace) -> bool {
namespace == TypeNS && path.len() == 1 && path[0].ident.name == kw::SelfUpper
}
fn is_self_value(path: &[Segment], namespace: Namespace) -> bool {
namespace == ValueNS && path.len() == 1 && path[0].ident.name == kw::SelfLower
}
/// Gets the stringified path for an enum from an `ImportSuggestion` for an enum variant.
fn import_candidate_to_enum_paths(suggestion: &ImportSuggestion) -> (String, String) {
let variant_path = &suggestion.path;
let variant_path_string = path_names_to_string(variant_path);
let path_len = suggestion.path.segments.len();
let enum_path = ast::Path {
span: suggestion.path.span,
segments: suggestion.path.segments[0..path_len - 1].to_vec(),
tokens: None,
};
let enum_path_string = path_names_to_string(&enum_path);
(variant_path_string, enum_path_string)
}
impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> {
fn def_span(&self, def_id: DefId) -> Option<Span> {
match def_id.krate {
LOCAL_CRATE => self.r.opt_span(def_id),
_ => Some(
self.r
.session
.source_map()
.guess_head_span(self.r.cstore().get_span_untracked(def_id, self.r.session)),
),
}
}
/// Handles error reporting for `smart_resolve_path_fragment` function.
/// Creates base error and amends it with one short label and possibly some longer helps/notes.
pub(crate) fn smart_resolve_report_errors(
&mut self,
path: &[Segment],
span: Span,
source: PathSource<'_>,
res: Option<Res>,
) -> (DiagnosticBuilder<'a>, Vec<ImportSuggestion>) {
let ident_span = path.last().map_or(span, |ident| ident.ident.span);
let ns = source.namespace();
let is_expected = &|res| source.is_expected(res);
let is_enum_variant = &|res| matches!(res, Res::Def(DefKind::Variant, _));
// Make the base error.
let mut expected = source.descr_expected();
let path_str = Segment::names_to_string(path);
let item_str = path.last().unwrap().ident;
let (base_msg, fallback_label, base_span, could_be_expr) = if let Some(res) = res {
(
format!("expected {}, found {} `{}`", expected, res.descr(), path_str),
format!("not a {}", expected),
span,
match res {
Res::Def(DefKind::Fn, _) => {
// Verify whether this is a fn call or an Fn used as a type.
self.r
.session
.source_map()
.span_to_snippet(span)
.map(|snippet| snippet.ends_with(')'))
.unwrap_or(false)
}
Res::Def(
DefKind::Ctor(..) | DefKind::AssocFn | DefKind::Const | DefKind::AssocConst,
_,
)
| Res::SelfCtor(_)
| Res::PrimTy(_)
| Res::Local(_) => true,
_ => false,
},
)
} else {
let item_span = path.last().unwrap().ident.span;
let (mod_prefix, mod_str) = if path.len() == 1 {
(String::new(), "this scope".to_string())
} else if path.len() == 2 && path[0].ident.name == kw::PathRoot {
if self.r.session.edition() > Edition::Edition2015 {
// In edition 2018 onwards, the `::foo` syntax may only pull from the extern prelude
// which overrides all other expectations of item type
expected = "crate";
(String::new(), "the list of imported crates".to_string())
} else {
(String::new(), "the crate root".to_string())
}
} else if path.len() == 2 && path[0].ident.name == kw::Crate {
(String::new(), "the crate root".to_string())
} else {
let mod_path = &path[..path.len() - 1];
let mod_prefix =
match self.resolve_path(mod_path, Some(TypeNS), false, span, CrateLint::No) {
PathResult::Module(ModuleOrUniformRoot::Module(module)) => module.res(),
_ => None,
}
.map_or(String::new(), |res| format!("{} ", res.descr()));
(mod_prefix, format!("`{}`", Segment::names_to_string(mod_path)))
};
(
format!("cannot find {} `{}` in {}{}", expected, item_str, mod_prefix, mod_str),
if path_str == "async" && expected.starts_with("struct") {
"`async` blocks are only allowed in Rust 2018 or later".to_string()
} else {
format!("not found in {}", mod_str)
},
item_span,
false,
)
};
let code = source.error_code(res.is_some());
let mut err = self.r.session.struct_span_err_with_code(base_span, &base_msg, code);
match (source, self.diagnostic_metadata.in_if_condition) {
(PathSource::Expr(_), Some(Expr { span, kind: ExprKind::Assign(..), .. })) => {
err.span_suggestion_verbose(
span.shrink_to_lo(),
"you might have meant to use pattern matching",
"let ".to_string(),
Applicability::MaybeIncorrect,
);
self.r.session.if_let_suggestions.borrow_mut().insert(*span);
}
_ => {}
}
let is_assoc_fn = self.self_type_is_available(span);
// Emit help message for fake-self from other languages (e.g., `this` in Javascript).
if ["this", "my"].contains(&&*item_str.as_str()) && is_assoc_fn {
err.span_suggestion_short(
span,
"you might have meant to use `self` here instead",
"self".to_string(),
Applicability::MaybeIncorrect,
);
if !self.self_value_is_available(path[0].ident.span, span) {
if let Some((FnKind::Fn(_, _, sig, ..), fn_span)) =
&self.diagnostic_metadata.current_function
{
let (span, sugg) = if let Some(param) = sig.decl.inputs.get(0) {
(param.span.shrink_to_lo(), "&self, ")
} else {
(
self.r
.session
.source_map()
.span_through_char(*fn_span, '(')
.shrink_to_hi(),
"&self",
)
};
err.span_suggestion_verbose(
span,
"if you meant to use `self`, you are also missing a `self` receiver \
argument",
sugg.to_string(),
Applicability::MaybeIncorrect,
);
}
}
}
// Emit special messages for unresolved `Self` and `self`.
if is_self_type(path, ns) {
err.code(rustc_errors::error_code!(E0411));
err.span_label(
span,
"`Self` is only available in impls, traits, and type definitions".to_string(),
);
return (err, Vec::new());
}
if is_self_value(path, ns) {
debug!("smart_resolve_path_fragment: E0424, source={:?}", source);
err.code(rustc_errors::error_code!(E0424));
err.span_label(span, match source {
PathSource::Pat => "`self` value is a keyword and may not be bound to variables or shadowed"
.to_string(),
_ => "`self` value is a keyword only available in methods with a `self` parameter"
.to_string(),
});
if let Some((fn_kind, span)) = &self.diagnostic_metadata.current_function {
// The current function has a `self' parameter, but we were unable to resolve
// a reference to `self`. This can only happen if the `self` identifier we
// are resolving came from a different hygiene context.
if fn_kind.decl().inputs.get(0).map_or(false, |p| p.is_self()) {
err.span_label(*span, "this function has a `self` parameter, but a macro invocation can only access identifiers it receives from parameters");
} else {
let doesnt = if is_assoc_fn {
let (span, sugg) = fn_kind
.decl()
.inputs
.get(0)
.map(|p| (p.span.shrink_to_lo(), "&self, "))
.unwrap_or_else(|| {
(
self.r
.session
.source_map()
.span_through_char(*span, '(')
.shrink_to_hi(),
"&self",
)
});
err.span_suggestion_verbose(
span,
"add a `self` receiver parameter to make the associated `fn` a method",
sugg.to_string(),
Applicability::MaybeIncorrect,
);
"doesn't"
} else {
"can't"
};
if let Some(ident) = fn_kind.ident() {
err.span_label(
ident.span,
&format!("this function {} have a `self` parameter", doesnt),
);
}
}
}
return (err, Vec::new());
}
// Try to lookup name in more relaxed fashion for better error reporting.
let ident = path.last().unwrap().ident;
let candidates = self
.r
.lookup_import_candidates(ident, ns, &self.parent_scope, is_expected)
.drain(..)
.filter(|ImportSuggestion { did, .. }| {
match (did, res.and_then(|res| res.opt_def_id())) {
(Some(suggestion_did), Some(actual_did)) => *suggestion_did != actual_did,
_ => true,
}
})
.collect::<Vec<_>>();
let crate_def_id = DefId::local(CRATE_DEF_INDEX);
if candidates.is_empty() && is_expected(Res::Def(DefKind::Enum, crate_def_id)) {
let mut enum_candidates: Vec<_> = self
.r
.lookup_import_candidates(ident, ns, &self.parent_scope, is_enum_variant)
.into_iter()
.map(|suggestion| import_candidate_to_enum_paths(&suggestion))
.filter(|(_, enum_ty_path)| !enum_ty_path.starts_with("std::prelude::"))
.collect();
if !enum_candidates.is_empty() {
if let (PathSource::Type, Some(span)) =
(source, self.diagnostic_metadata.current_type_ascription.last())
{
if self
.r
.session
.parse_sess
.type_ascription_path_suggestions
.borrow()
.contains(span)
{
// Already reported this issue on the lhs of the type ascription.
err.delay_as_bug();
return (err, candidates);
}
}
enum_candidates.sort();
// Contextualize for E0412 "cannot find type", but don't belabor the point
// (that it's a variant) for E0573 "expected type, found variant".
let preamble = if res.is_none() {
let others = match enum_candidates.len() {
1 => String::new(),
2 => " and 1 other".to_owned(),
n => format!(" and {} others", n),
};
format!("there is an enum variant `{}`{}; ", enum_candidates[0].0, others)
} else {
String::new()
};
let msg = format!("{}try using the variant's enum", preamble);
err.span_suggestions(
span,
&msg,
enum_candidates.into_iter().map(|(_variant_path, enum_ty_path)| enum_ty_path),
Applicability::MachineApplicable,
);
}
}
if path.len() == 1 && self.self_type_is_available(span) {
if let Some(candidate) = self.lookup_assoc_candidate(ident, ns, is_expected) {
let self_is_available = self.self_value_is_available(path[0].ident.span, span);
match candidate {
AssocSuggestion::Field => {
if self_is_available {
err.span_suggestion(
span,
"you might have meant to use the available field",
format!("self.{}", path_str),
Applicability::MachineApplicable,
);
} else {
err.span_label(span, "a field by this name exists in `Self`");
}
}
AssocSuggestion::MethodWithSelf if self_is_available => {
err.span_suggestion(
span,
"you might have meant to call the method",
format!("self.{}", path_str),
Applicability::MachineApplicable,
);
}
AssocSuggestion::MethodWithSelf
| AssocSuggestion::AssocFn
| AssocSuggestion::AssocConst
| AssocSuggestion::AssocType => {
err.span_suggestion(
span,
&format!("you might have meant to {}", candidate.action()),
format!("Self::{}", path_str),
Applicability::MachineApplicable,
);
}
}
return (err, candidates);
}
// If the first argument in call is `self` suggest calling a method.
if let Some((call_span, args_span)) = self.call_has_self_arg(source) {
let mut args_snippet = String::new();
if let Some(args_span) = args_span {
if let Ok(snippet) = self.r.session.source_map().span_to_snippet(args_span) {
args_snippet = snippet;
}
}
err.span_suggestion(
call_span,
&format!("try calling `{}` as a method", ident),
format!("self.{}({})", path_str, args_snippet),
Applicability::MachineApplicable,
);
return (err, candidates);
}
}
// Try Levenshtein algorithm.
let typo_sugg = self.lookup_typo_candidate(path, ns, is_expected, span);
// Try context-dependent help if relaxed lookup didn't work.
if let Some(res) = res {
if self.smart_resolve_context_dependent_help(
&mut err,
span,
source,
res,
&path_str,
&fallback_label,
) {
// We do this to avoid losing a secondary span when we override the main error span.
self.r.add_typo_suggestion(&mut err, typo_sugg, ident_span);
return (err, candidates);
}
}
if !self.type_ascription_suggestion(&mut err, base_span) {
let mut fallback = false;
if let (
PathSource::Trait(AliasPossibility::Maybe),
Some(Res::Def(DefKind::Struct | DefKind::Enum | DefKind::Union, _)),
) = (source, res)
{
if let Some(bounds @ [_, .., _]) = self.diagnostic_metadata.current_trait_object {
fallback = true;
let spans: Vec<Span> = bounds
.iter()
.map(|bound| bound.span())
.filter(|&sp| sp != base_span)
.collect();
let start_span = bounds.iter().map(|bound| bound.span()).next().unwrap();
// `end_span` is the end of the poly trait ref (Foo + 'baz + Bar><)
let end_span = bounds.iter().map(|bound| bound.span()).last().unwrap();
// `last_bound_span` is the last bound of the poly trait ref (Foo + >'baz< + Bar)
let last_bound_span = spans.last().cloned().unwrap();
let mut multi_span: MultiSpan = spans.clone().into();
for sp in spans {
let msg = if sp == last_bound_span {
format!(
"...because of {} bound{}",
if bounds.len() <= 2 { "this" } else { "these" },
if bounds.len() <= 2 { "" } else { "s" },
)
} else {
String::new()
};
multi_span.push_span_label(sp, msg);
}
multi_span.push_span_label(
base_span,
"expected this type to be a trait...".to_string(),
);
err.span_help(
multi_span,
"`+` is used to constrain a \"trait object\" type with lifetimes or \
auto-traits; structs and enums can't be bound in that way",
);
if bounds.iter().all(|bound| match bound {
ast::GenericBound::Outlives(_) => true,
ast::GenericBound::Trait(tr, _) => tr.span == base_span,
}) {
let mut sugg = vec![];
if base_span != start_span {
sugg.push((start_span.until(base_span), String::new()));
}
if base_span != end_span {
sugg.push((base_span.shrink_to_hi().to(end_span), String::new()));
}
err.multipart_suggestion(
"if you meant to use a type and not a trait here, remove the bounds",
sugg,
Applicability::MaybeIncorrect,
);
}
}
}
fallback |= self.restrict_assoc_type_in_where_clause(span, &mut err);
if !self.r.add_typo_suggestion(&mut err, typo_sugg, ident_span) {
fallback = true;
match self.diagnostic_metadata.current_let_binding {
Some((pat_sp, Some(ty_sp), None))
if ty_sp.contains(base_span) && could_be_expr =>
{
err.span_suggestion_short(
pat_sp.between(ty_sp),
"use `=` if you meant to assign",
" = ".to_string(),
Applicability::MaybeIncorrect,
);
}
_ => {}
}
}
if fallback {
// Fallback label.
err.span_label(base_span, fallback_label);
}
}
if let Some(err_code) = &err.code {
if err_code == &rustc_errors::error_code!(E0425) {
for label_rib in &self.label_ribs {
for (label_ident, node_id) in &label_rib.bindings {
if format!("'{}", ident) == label_ident.to_string() {
err.span_label(label_ident.span, "a label with a similar name exists");
if let PathSource::Expr(Some(Expr {
kind: ExprKind::Break(None, Some(_)),
..
})) = source
{
err.span_suggestion(
span,
"use the similarly named label",
label_ident.name.to_string(),
Applicability::MaybeIncorrect,
);
// Do not lint against unused label when we suggest them.
self.diagnostic_metadata.unused_labels.remove(node_id);
}
}
}
}
} else if err_code == &rustc_errors::error_code!(E0412) {
if let Some(correct) = Self::likely_rust_type(path) {
err.span_suggestion(
span,
"perhaps you intended to use this type",
correct.to_string(),
Applicability::MaybeIncorrect,
);
}
}
}
(err, candidates)
}
/// Given `where <T as Bar>::Baz: String`, suggest `where T: Bar<Baz = String>`.
fn restrict_assoc_type_in_where_clause(
&mut self,
span: Span,
err: &mut DiagnosticBuilder<'_>,
) -> bool {
// Detect that we are actually in a `where` predicate.
let (bounded_ty, bounds, where_span) =
if let Some(ast::WherePredicate::BoundPredicate(ast::WhereBoundPredicate {
bounded_ty,
bound_generic_params,
bounds,
span,
})) = self.diagnostic_metadata.current_where_predicate
{
if !bound_generic_params.is_empty() {
return false;
}
(bounded_ty, bounds, span)
} else {
return false;
};
// Confirm that the target is an associated type.
let (ty, position, path) = if let ast::TyKind::Path(
Some(ast::QSelf { ty, position, .. }),
path,
) = &bounded_ty.kind
{
// use this to verify that ident is a type param.
let partial_res = if let Ok(Some(partial_res)) = self.resolve_qpath_anywhere(
bounded_ty.id,
None,
&Segment::from_path(path),
Namespace::TypeNS,
span,
true,
CrateLint::No,
) {
partial_res
} else {
return false;
};
if !(matches!(
partial_res.base_res(),
hir::def::Res::Def(hir::def::DefKind::AssocTy, _)
) && partial_res.unresolved_segments() == 0)
{
return false;
}
(ty, position, path)
} else {
return false;
};
if let ast::TyKind::Path(None, type_param_path) = &ty.peel_refs().kind {
// Confirm that the `SelfTy` is a type parameter.
let partial_res = if let Ok(Some(partial_res)) = self.resolve_qpath_anywhere(
bounded_ty.id,
None,
&Segment::from_path(type_param_path),
Namespace::TypeNS,
span,
true,
CrateLint::No,
) {
partial_res
} else {
return false;
};
if !(matches!(
partial_res.base_res(),
hir::def::Res::Def(hir::def::DefKind::TyParam, _)
) && partial_res.unresolved_segments() == 0)
{
return false;
}
if let (
[ast::PathSegment { ident: constrain_ident, args: None, .. }],
[ast::GenericBound::Trait(poly_trait_ref, ast::TraitBoundModifier::None)],
) = (&type_param_path.segments[..], &bounds[..])
{
if let [ast::PathSegment { ident, args: None, .. }] =
&poly_trait_ref.trait_ref.path.segments[..]
{
if ident.span == span {
err.span_suggestion_verbose(
*where_span,
&format!("constrain the associated type to `{}`", ident),
format!(
"{}: {}<{} = {}>",
self.r
.session
.source_map()
.span_to_snippet(ty.span) // Account for `<&'a T as Foo>::Bar`.
.unwrap_or_else(|_| constrain_ident.to_string()),
path.segments[..*position]
.iter()
.map(|segment| path_segment_to_string(segment))
.collect::<Vec<_>>()
.join("::"),
path.segments[*position..]
.iter()
.map(|segment| path_segment_to_string(segment))
.collect::<Vec<_>>()
.join("::"),
ident,
),
Applicability::MaybeIncorrect,
);
}
return true;
}
}
}
false
}
/// Check if the source is call expression and the first argument is `self`. If true,
/// return the span of whole call and the span for all arguments expect the first one (`self`).
fn call_has_self_arg(&self, source: PathSource<'_>) -> Option<(Span, Option<Span>)> {
let mut has_self_arg = None;
if let PathSource::Expr(Some(parent)) = source {
match &parent.kind {
ExprKind::Call(_, args) if !args.is_empty() => {
let mut expr_kind = &args[0].kind;
loop {
match expr_kind {
ExprKind::Path(_, arg_name) if arg_name.segments.len() == 1 => {
if arg_name.segments[0].ident.name == kw::SelfLower {
let call_span = parent.span;
let tail_args_span = if args.len() > 1 {
Some(Span::new(
args[1].span.lo(),
args.last().unwrap().span.hi(),
call_span.ctxt(),
))
} else {
None
};
has_self_arg = Some((call_span, tail_args_span));
}
break;
}
ExprKind::AddrOf(_, _, expr) => expr_kind = &expr.kind,
_ => break,
}
}
}
_ => (),
}
};
has_self_arg
}
fn followed_by_brace(&self, span: Span) -> (bool, Option<Span>) {
// HACK(estebank): find a better way to figure out that this was a
// parser issue where a struct literal is being used on an expression
// where a brace being opened means a block is being started. Look
// ahead for the next text to see if `span` is followed by a `{`.
let sm = self.r.session.source_map();
let mut sp = span;
loop {
sp = sm.next_point(sp);
match sm.span_to_snippet(sp) {
Ok(ref snippet) => {
if snippet.chars().any(|c| !c.is_whitespace()) {
break;
}
}
_ => break,
}
}
let followed_by_brace = matches!(sm.span_to_snippet(sp), Ok(ref snippet) if snippet == "{");
// In case this could be a struct literal that needs to be surrounded
// by parentheses, find the appropriate span.
let mut i = 0;
let mut closing_brace = None;
loop {
sp = sm.next_point(sp);
match sm.span_to_snippet(sp) {
Ok(ref snippet) => {
if snippet == "}" {
closing_brace = Some(span.to(sp));
break;
}
}
_ => break,
}
i += 1;
// The bigger the span, the more likely we're incorrect --
// bound it to 100 chars long.
if i > 100 {
break;
}
}
(followed_by_brace, closing_brace)
}
/// Provides context-dependent help for errors reported by the `smart_resolve_path_fragment`
/// function.
/// Returns `true` if able to provide context-dependent help.
fn smart_resolve_context_dependent_help(
&mut self,
err: &mut DiagnosticBuilder<'a>,
span: Span,
source: PathSource<'_>,
res: Res,
path_str: &str,
fallback_label: &str,
) -> bool {
let ns = source.namespace();
let is_expected = &|res| source.is_expected(res);
let path_sep = |err: &mut DiagnosticBuilder<'_>, expr: &Expr| match expr.kind {
ExprKind::Field(_, ident) => {
err.span_suggestion(
expr.span,
"use the path separator to refer to an item",
format!("{}::{}", path_str, ident),
Applicability::MaybeIncorrect,
);
true
}
ExprKind::MethodCall(ref segment, ..) => {
let span = expr.span.with_hi(segment.ident.span.hi());
err.span_suggestion(
span,
"use the path separator to refer to an item",
format!("{}::{}", path_str, segment.ident),
Applicability::MaybeIncorrect,
);
true
}
_ => false,
};
let mut bad_struct_syntax_suggestion = |def_id: DefId| {
let (followed_by_brace, closing_brace) = self.followed_by_brace(span);
match source {
PathSource::Expr(Some(
parent @ Expr { kind: ExprKind::Field(..) | ExprKind::MethodCall(..), .. },
)) if path_sep(err, &parent) => {}
PathSource::Expr(
None
| Some(Expr {
kind:
ExprKind::Path(..)
| ExprKind::Binary(..)
| ExprKind::Unary(..)
| ExprKind::If(..)
| ExprKind::While(..)
| ExprKind::ForLoop(..)
| ExprKind::Match(..),
..
}),
) if followed_by_brace => {
if let Some(sp) = closing_brace {
err.span_label(span, fallback_label);
err.multipart_suggestion(
"surround the struct literal with parentheses",
vec![
(sp.shrink_to_lo(), "(".to_string()),
(sp.shrink_to_hi(), ")".to_string()),
],
Applicability::MaybeIncorrect,
);
} else {
err.span_label(
span, // Note the parentheses surrounding the suggestion below
format!(
"you might want to surround a struct literal with parentheses: \
`({} {{ /* fields */ }})`?",
path_str
),
);
}
}
PathSource::Expr(_) | PathSource::TupleStruct(..) | PathSource::Pat => {
let span = match &source {
PathSource::Expr(Some(Expr {
span, kind: ExprKind::Call(_, _), ..
}))
| PathSource::TupleStruct(span, _) => {
// We want the main underline to cover the suggested code as well for
// cleaner output.
err.set_span(*span);
*span
}
_ => span,
};
if let Some(span) = self.def_span(def_id) {
err.span_label(span, &format!("`{}` defined here", path_str));
}
let (tail, descr, applicability) = match source {
PathSource::Pat | PathSource::TupleStruct(..) => {
("", "pattern", Applicability::MachineApplicable)
}
_ => (": val", "literal", Applicability::HasPlaceholders),
};
let (fields, applicability) = match self.r.field_names.get(&def_id) {
Some(fields) => (
fields
.iter()
.map(|f| format!("{}{}", f.node, tail))
.collect::<Vec<String>>()
.join(", "),
applicability,
),
None => ("/* fields */".to_string(), Applicability::HasPlaceholders),
};
let pad = match self.r.field_names.get(&def_id) {
Some(fields) if fields.is_empty() => "",
_ => " ",
};
err.span_suggestion(
span,
&format!("use struct {} syntax instead", descr),
format!("{path_str} {{{pad}{fields}{pad}}}"),
applicability,
);
}
_ => {
err.span_label(span, fallback_label);
}
}
};
match (res, source) {
(Res::Def(DefKind::Macro(MacroKind::Bang), _), _) => {
err.span_label(span, fallback_label);
err.span_suggestion_verbose(
span.shrink_to_hi(),
"use `!` to invoke the macro",
"!".to_string(),
Applicability::MaybeIncorrect,
);
if path_str == "try" && span.rust_2015() {
err.note("if you want the `try` keyword, you need Rust 2018 or later");
}
}
(Res::Def(DefKind::TyAlias, def_id), PathSource::Trait(_)) => {
err.span_label(span, "type aliases cannot be used as traits");
if self.r.session.is_nightly_build() {
let msg = "you might have meant to use `#![feature(trait_alias)]` instead of a \
`type` alias";
if let Some(span) = self.def_span(def_id) {
err.span_help(span, msg);
} else {
err.help(msg);
}
}
}
(Res::Def(DefKind::Mod, _), PathSource::Expr(Some(parent))) => {
if !path_sep(err, &parent) {
return false;
}
}
(
Res::Def(DefKind::Enum, def_id),
PathSource::TupleStruct(..) | PathSource::Expr(..),
) => {
if self
.diagnostic_metadata
.current_type_ascription
.last()
.map(|sp| {
self.r
.session
.parse_sess
.type_ascription_path_suggestions
.borrow()
.contains(&sp)
})
.unwrap_or(false)
{
err.delay_as_bug();
// We already suggested changing `:` into `::` during parsing.
return false;
}
self.suggest_using_enum_variant(err, source, def_id, span);
}
(Res::Def(DefKind::Struct, def_id), _) if ns == ValueNS => {
let (ctor_def, ctor_vis, fields) =
if let Some(struct_ctor) = self.r.struct_constructors.get(&def_id).cloned() {
struct_ctor
} else {
bad_struct_syntax_suggestion(def_id);
return true;
};
let is_accessible = self.r.is_accessible_from(ctor_vis, self.parent_scope.module);
if !is_expected(ctor_def) || is_accessible {
return true;
}
let field_spans = match source {
// e.g. `if let Enum::TupleVariant(field1, field2) = _`
PathSource::TupleStruct(_, pattern_spans) => {
err.set_primary_message(
"cannot match against a tuple struct which contains private fields",
);
// Use spans of the tuple struct pattern.
Some(Vec::from(pattern_spans))
}
// e.g. `let _ = Enum::TupleVariant(field1, field2);`
_ if source.is_call() => {
err.set_primary_message(
"cannot initialize a tuple struct which contains private fields",
);
// Use spans of the tuple struct definition.
self.r
.field_names
.get(&def_id)
.map(|fields| fields.iter().map(|f| f.span).collect::<Vec<_>>())
}
_ => None,
};
if let Some(spans) =
field_spans.filter(|spans| spans.len() > 0 && fields.len() == spans.len())
{
let non_visible_spans: Vec<Span> = fields
.iter()
.zip(spans.iter())
.filter(|(vis, _)| {
!self.r.is_accessible_from(**vis, self.parent_scope.module)
})
.map(|(_, span)| *span)
.collect();
if non_visible_spans.len() > 0 {
let mut m: rustc_span::MultiSpan = non_visible_spans.clone().into();
non_visible_spans
.into_iter()
.for_each(|s| m.push_span_label(s, "private field".to_string()));
err.span_note(m, "constructor is not visible here due to private fields");
}
return true;
}
err.span_label(
span,
"constructor is not visible here due to private fields".to_string(),
);
}
(
Res::Def(
DefKind::Union | DefKind::Variant | DefKind::Ctor(_, CtorKind::Fictive),
def_id,
),
_,
) if ns == ValueNS => {
bad_struct_syntax_suggestion(def_id);
}
(Res::Def(DefKind::Ctor(_, CtorKind::Fn), def_id), _) if ns == ValueNS => {
if let Some(span) = self.def_span(def_id) {
err.span_label(span, &format!("`{}` defined here", path_str));
}
let fields =
self.r.field_names.get(&def_id).map_or("/* fields */".to_string(), |fields| {
vec!["_"; fields.len()].join(", ")
});
err.span_suggestion(
span,
"use the tuple variant pattern syntax instead",
format!("{}({})", path_str, fields),
Applicability::HasPlaceholders,
);
}
(Res::SelfTy(..), _) if ns == ValueNS => {
err.span_label(span, fallback_label);
err.note("can't use `Self` as a constructor, you must use the implemented struct");
}
(Res::Def(DefKind::TyAlias | DefKind::AssocTy, _), _) if ns == ValueNS => {
err.note("can't use a type alias as a constructor");
}
_ => return false,
}
true
}
fn lookup_assoc_candidate<FilterFn>(
&mut self,
ident: Ident,
ns: Namespace,
filter_fn: FilterFn,
) -> Option<AssocSuggestion>
where
FilterFn: Fn(Res) -> bool,
{
fn extract_node_id(t: &Ty) -> Option<NodeId> {
match t.kind {
TyKind::Path(None, _) => Some(t.id),
TyKind::Rptr(_, ref mut_ty) => extract_node_id(&mut_ty.ty),
// This doesn't handle the remaining `Ty` variants as they are not
// that commonly the self_type, it might be interesting to provide
// support for those in future.
_ => None,
}
}
// Fields are generally expected in the same contexts as locals.
if filter_fn(Res::Local(ast::DUMMY_NODE_ID)) {
if let Some(node_id) =
self.diagnostic_metadata.current_self_type.as_ref().and_then(extract_node_id)
{
// Look for a field with the same name in the current self_type.
if let Some(resolution) = self.r.partial_res_map.get(&node_id) {
match resolution.base_res() {
Res::Def(DefKind::Struct | DefKind::Union, did)
if resolution.unresolved_segments() == 0 =>
{
if let Some(field_names) = self.r.field_names.get(&did) {
if field_names
.iter()
.any(|&field_name| ident.name == field_name.node)
{
return Some(AssocSuggestion::Field);
}
}
}
_ => {}
}
}
}
}
if let Some(items) = self.diagnostic_metadata.current_trait_assoc_items {
for assoc_item in items {
if assoc_item.ident == ident {
return Some(match &assoc_item.kind {
ast::AssocItemKind::Const(..) => AssocSuggestion::AssocConst,
ast::AssocItemKind::Fn(box ast::FnKind(_, sig, ..))
if sig.decl.has_self() =>
{
AssocSuggestion::MethodWithSelf
}
ast::AssocItemKind::Fn(..) => AssocSuggestion::AssocFn,
ast::AssocItemKind::TyAlias(..) => AssocSuggestion::AssocType,
ast::AssocItemKind::MacCall(_) => continue,
});
}
}
}
// Look for associated items in the current trait.
if let Some((module, _)) = self.current_trait_ref {
if let Ok(binding) = self.r.resolve_ident_in_module(
ModuleOrUniformRoot::Module(module),
ident,
ns,
&self.parent_scope,
false,
module.span,
) {
let res = binding.res();
if filter_fn(res) {
if self.r.has_self.contains(&res.def_id()) {
return Some(AssocSuggestion::MethodWithSelf);
} else {
match res {
Res::Def(DefKind::AssocFn, _) => return Some(AssocSuggestion::AssocFn),
Res::Def(DefKind::AssocConst, _) => {
return Some(AssocSuggestion::AssocConst);
}
Res::Def(DefKind::AssocTy, _) => {
return Some(AssocSuggestion::AssocType);
}
_ => {}
}
}
}
}
}
None
}
fn lookup_typo_candidate(
&mut self,
path: &[Segment],
ns: Namespace,
filter_fn: &impl Fn(Res) -> bool,
span: Span,
) -> Option<TypoSuggestion> {
let mut names = Vec::new();
if path.len() == 1 {
// Search in lexical scope.
// Walk backwards up the ribs in scope and collect candidates.
for rib in self.ribs[ns].iter().rev() {
// Locals and type parameters
for (ident, &res) in &rib.bindings {
if filter_fn(res) {
names.push(TypoSuggestion::from_res(ident.name, res));
}
}
// Items in scope
if let RibKind::ModuleRibKind(module) = rib.kind {
// Items from this module
self.r.add_module_candidates(module, &mut names, &filter_fn);
if let ModuleKind::Block(..) = module.kind {
// We can see through blocks
} else {
// Items from the prelude
if !module.no_implicit_prelude {
let extern_prelude = self.r.extern_prelude.clone();
names.extend(extern_prelude.iter().flat_map(|(ident, _)| {
self.r.crate_loader.maybe_process_path_extern(ident.name).and_then(
|crate_id| {
let crate_mod = Res::Def(
DefKind::Mod,
DefId { krate: crate_id, index: CRATE_DEF_INDEX },
);
if filter_fn(crate_mod) {
Some(TypoSuggestion::from_res(ident.name, crate_mod))
} else {
None
}
},
)
}));
if let Some(prelude) = self.r.prelude {
self.r.add_module_candidates(prelude, &mut names, &filter_fn);
}
}
break;
}
}
}
// Add primitive types to the mix
if filter_fn(Res::PrimTy(PrimTy::Bool)) {
names.extend(
PrimTy::ALL.iter().map(|prim_ty| {
TypoSuggestion::from_res(prim_ty.name(), Res::PrimTy(*prim_ty))
}),
)
}
} else {
// Search in module.
let mod_path = &path[..path.len() - 1];
if let PathResult::Module(module) =
self.resolve_path(mod_path, Some(TypeNS), false, span, CrateLint::No)
{
if let ModuleOrUniformRoot::Module(module) = module {
self.r.add_module_candidates(module, &mut names, &filter_fn);
}
}
}
let name = path[path.len() - 1].ident.name;
// Make sure error reporting is deterministic.
names.sort_by_cached_key(|suggestion| suggestion.candidate.as_str());
match find_best_match_for_name(
&names.iter().map(|suggestion| suggestion.candidate).collect::<Vec<Symbol>>(),
name,
None,
) {
Some(found) if found != name => {
names.into_iter().find(|suggestion| suggestion.candidate == found)
}
_ => None,
}
}
// Returns the name of the Rust type approximately corresponding to
// a type name in another programming language.
fn likely_rust_type(path: &[Segment]) -> Option<Symbol> {
let name = path[path.len() - 1].ident.as_str();
// Common Java types
Some(match &*name {
"byte" => sym::u8, // In Java, bytes are signed, but in practice one almost always wants unsigned bytes.
"short" => sym::i16,
"boolean" => sym::bool,
"int" => sym::i32,
"long" => sym::i64,
"float" => sym::f32,
"double" => sym::f64,
_ => return None,
})
}
/// Only used in a specific case of type ascription suggestions
fn get_colon_suggestion_span(&self, start: Span) -> Span {
let sm = self.r.session.source_map();
start.to(sm.next_point(start))
}
fn type_ascription_suggestion(&self, err: &mut DiagnosticBuilder<'_>, base_span: Span) -> bool {
let sm = self.r.session.source_map();
let base_snippet = sm.span_to_snippet(base_span);
if let Some(&sp) = self.diagnostic_metadata.current_type_ascription.last() {
if let Ok(snippet) = sm.span_to_snippet(sp) {
let len = snippet.trim_end().len() as u32;
if snippet.trim() == ":" {
let colon_sp =
sp.with_lo(sp.lo() + BytePos(len - 1)).with_hi(sp.lo() + BytePos(len));
let mut show_label = true;
if sm.is_multiline(sp) {
err.span_suggestion_short(
colon_sp,
"maybe you meant to write `;` here",
";".to_string(),
Applicability::MaybeIncorrect,
);
} else {
let after_colon_sp =
self.get_colon_suggestion_span(colon_sp.shrink_to_hi());
if snippet.len() == 1 {
// `foo:bar`
err.span_suggestion(
colon_sp,
"maybe you meant to write a path separator here",
"::".to_string(),
Applicability::MaybeIncorrect,
);
show_label = false;
if !self
.r
.session
.parse_sess
.type_ascription_path_suggestions
.borrow_mut()
.insert(colon_sp)
{
err.delay_as_bug();
}
}
if let Ok(base_snippet) = base_snippet {
let mut sp = after_colon_sp;
for _ in 0..100 {
// Try to find an assignment
sp = sm.next_point(sp);
let snippet = sm.span_to_snippet(sp.to(sm.next_point(sp)));
match snippet {
Ok(ref x) if x.as_str() == "=" => {
err.span_suggestion(
base_span,
"maybe you meant to write an assignment here",
format!("let {}", base_snippet),
Applicability::MaybeIncorrect,
);
show_label = false;
break;
}
Ok(ref x) if x.as_str() == "\n" => break,
Err(_) => break,
Ok(_) => {}
}
}
}
}
if show_label {
err.span_label(
base_span,
"expecting a type here because of type ascription",
);
}
return show_label;
}
}
}
false
}
fn find_module(&mut self, def_id: DefId) -> Option<(Module<'a>, ImportSuggestion)> {
let mut result = None;
let mut seen_modules = FxHashSet::default();
let mut worklist = vec![(self.r.graph_root, Vec::new())];
while let Some((in_module, path_segments)) = worklist.pop() {
// abort if the module is already found
if result.is_some() {
break;
}
in_module.for_each_child(self.r, |_, ident, _, name_binding| {
// abort if the module is already found or if name_binding is private external
if result.is_some() || !name_binding.vis.is_visible_locally() {
return;
}
if let Some(module) = name_binding.module() {
// form the path
let mut path_segments = path_segments.clone();
path_segments.push(ast::PathSegment::from_ident(ident));
let module_def_id = module.def_id().unwrap();
if module_def_id == def_id {
let path =
Path { span: name_binding.span, segments: path_segments, tokens: None };
result = Some((
module,
ImportSuggestion {
did: Some(def_id),
descr: "module",
path,
accessible: true,
},
));
} else {
// add the module to the lookup
if seen_modules.insert(module_def_id) {
worklist.push((module, path_segments));
}
}
}
});
}
result
}
fn collect_enum_ctors(&mut self, def_id: DefId) -> Option<Vec<(Path, DefId, CtorKind)>> {
self.find_module(def_id).map(|(enum_module, enum_import_suggestion)| {
let mut variants = Vec::new();
enum_module.for_each_child(self.r, |_, ident, _, name_binding| {
if let Res::Def(DefKind::Ctor(CtorOf::Variant, kind), def_id) = name_binding.res() {
let mut segms = enum_import_suggestion.path.segments.clone();
segms.push(ast::PathSegment::from_ident(ident));
let path = Path { span: name_binding.span, segments: segms, tokens: None };
variants.push((path, def_id, kind));
}
});
variants
})
}
/// Adds a suggestion for using an enum's variant when an enum is used instead.
fn suggest_using_enum_variant(
&mut self,
err: &mut DiagnosticBuilder<'a>,
source: PathSource<'_>,
def_id: DefId,
span: Span,
) {
let variants = match self.collect_enum_ctors(def_id) {
Some(variants) => variants,
None => {
err.note("you might have meant to use one of the enum's variants");
return;
}
};
let suggest_only_tuple_variants =
matches!(source, PathSource::TupleStruct(..)) || source.is_call();
if suggest_only_tuple_variants {
// Suggest only tuple variants regardless of whether they have fields and do not
// suggest path with added parenthesis.
let mut suggestable_variants = variants
.iter()
.filter(|(.., kind)| *kind == CtorKind::Fn)
.map(|(variant, ..)| path_names_to_string(variant))
.collect::<Vec<_>>();
let non_suggestable_variant_count = variants.len() - suggestable_variants.len();
let source_msg = if source.is_call() {
"to construct"
} else if matches!(source, PathSource::TupleStruct(..)) {
"to match against"
} else {
unreachable!()
};
if !suggestable_variants.is_empty() {
let msg = if non_suggestable_variant_count == 0 && suggestable_variants.len() == 1 {
format!("try {} the enum's variant", source_msg)
} else {
format!("try {} one of the enum's variants", source_msg)
};
err.span_suggestions(
span,
&msg,
suggestable_variants.drain(..),
Applicability::MaybeIncorrect,
);
}
// If the enum has no tuple variants..
if non_suggestable_variant_count == variants.len() {
err.help(&format!("the enum has no tuple variants {}", source_msg));
}
// If there are also non-tuple variants..
if non_suggestable_variant_count == 1 {
err.help(&format!(
"you might have meant {} the enum's non-tuple variant",
source_msg
));
} else if non_suggestable_variant_count >= 1 {
err.help(&format!(
"you might have meant {} one of the enum's non-tuple variants",
source_msg
));
}
} else {
let needs_placeholder = |def_id: DefId, kind: CtorKind| {
let has_no_fields = self.r.field_names.get(&def_id).map_or(false, |f| f.is_empty());
match kind {
CtorKind::Const => false,
CtorKind::Fn | CtorKind::Fictive if has_no_fields => false,
_ => true,
}
};
let mut suggestable_variants = variants
.iter()
.filter(|(_, def_id, kind)| !needs_placeholder(*def_id, *kind))
.map(|(variant, _, kind)| (path_names_to_string(variant), kind))
.map(|(variant, kind)| match kind {
CtorKind::Const => variant,
CtorKind::Fn => format!("({}())", variant),
CtorKind::Fictive => format!("({} {{}})", variant),
})
.collect::<Vec<_>>();
if !suggestable_variants.is_empty() {
let msg = if suggestable_variants.len() == 1 {
"you might have meant to use the following enum variant"
} else {
"you might have meant to use one of the following enum variants"
};
err.span_suggestions(
span,
msg,
suggestable_variants.drain(..),
Applicability::MaybeIncorrect,
);
}
let mut suggestable_variants_with_placeholders = variants
.iter()
.filter(|(_, def_id, kind)| needs_placeholder(*def_id, *kind))
.map(|(variant, _, kind)| (path_names_to_string(variant), kind))
.filter_map(|(variant, kind)| match kind {
CtorKind::Fn => Some(format!("({}(/* fields */))", variant)),
CtorKind::Fictive => Some(format!("({} {{ /* fields */ }})", variant)),
_ => None,
})
.collect::<Vec<_>>();
if !suggestable_variants_with_placeholders.is_empty() {
let msg = match (
suggestable_variants.is_empty(),
suggestable_variants_with_placeholders.len(),
) {
(true, 1) => "the following enum variant is available",
(true, _) => "the following enum variants are available",
(false, 1) => "alternatively, the following enum variant is available",
(false, _) => "alternatively, the following enum variants are also available",
};
err.span_suggestions(
span,
msg,
suggestable_variants_with_placeholders.drain(..),
Applicability::HasPlaceholders,
);
}
};
if def_id.is_local() {
if let Some(span) = self.def_span(def_id) {
err.span_note(span, "the enum is defined here");
}
}
}
crate fn report_missing_type_error(
&self,
path: &[Segment],
) -> Option<(Span, &'static str, String, Applicability)> {
let (ident, span) = match path {
[segment] if !segment.has_generic_args => {
(segment.ident.to_string(), segment.ident.span)
}
_ => return None,
};
let mut iter = ident.chars().map(|c| c.is_uppercase());
let single_uppercase_char =
matches!(iter.next(), Some(true)) && matches!(iter.next(), None);
if !self.diagnostic_metadata.currently_processing_generics && !single_uppercase_char {
return None;
}
match (self.diagnostic_metadata.current_item, single_uppercase_char) {
(Some(Item { kind: ItemKind::Fn(..), ident, .. }), _) if ident.name == sym::main => {
// Ignore `fn main()` as we don't want to suggest `fn main<T>()`
}
(
Some(Item {
kind:
kind @ ItemKind::Fn(..)
| kind @ ItemKind::Enum(..)
| kind @ ItemKind::Struct(..)
| kind @ ItemKind::Union(..),
..
}),
true,
)
| (Some(Item { kind, .. }), false) => {
// Likely missing type parameter.
if let Some(generics) = kind.generics() {
if span.overlaps(generics.span) {
// Avoid the following:
// error[E0405]: cannot find trait `A` in this scope
// --> $DIR/typo-suggestion-named-underscore.rs:CC:LL
// |
// L | fn foo<T: A>(x: T) {} // Shouldn't suggest underscore
// | ^- help: you might be missing a type parameter: `, A`
// | |
// | not found in this scope
return None;
}
let msg = "you might be missing a type parameter";
let (span, sugg) = if let [.., param] = &generics.params[..] {
let span = if let [.., bound] = &param.bounds[..] {
bound.span()
} else {
param.ident.span
};
(span, format!(", {}", ident))
} else {
(generics.span, format!("<{}>", ident))
};
// Do not suggest if this is coming from macro expansion.
if !span.from_expansion() {
return Some((
span.shrink_to_hi(),
msg,
sugg,
Applicability::MaybeIncorrect,
));
}
}
}
_ => {}
}
None
}
/// Given the target `label`, search the `rib_index`th label rib for similarly named labels,
/// optionally returning the closest match and whether it is reachable.
crate fn suggestion_for_label_in_rib(
&self,
rib_index: usize,
label: Ident,
) -> Option<LabelSuggestion> {
// Are ribs from this `rib_index` within scope?
let within_scope = self.is_label_valid_from_rib(rib_index);
let rib = &self.label_ribs[rib_index];
let names = rib
.bindings
.iter()
.filter(|(id, _)| id.span.ctxt() == label.span.ctxt())
.map(|(id, _)| id.name)
.collect::<Vec<Symbol>>();
find_best_match_for_name(&names, label.name, None).map(|symbol| {
// Upon finding a similar name, get the ident that it was from - the span
// contained within helps make a useful diagnostic. In addition, determine
// whether this candidate is within scope.
let (ident, _) = rib.bindings.iter().find(|(ident, _)| ident.name == symbol).unwrap();
(*ident, within_scope)
})
}
}
impl<'tcx> LifetimeContext<'_, 'tcx> {
crate fn report_missing_lifetime_specifiers(
&self,
span: Span,
count: usize,
) -> DiagnosticBuilder<'tcx> {
struct_span_err!(
self.tcx.sess,
span,
E0106,
"missing lifetime specifier{}",
pluralize!(count)
)
}
crate fn emit_undeclared_lifetime_error(&self, lifetime_ref: &hir::Lifetime) {
let mut err = struct_span_err!(
self.tcx.sess,
lifetime_ref.span,
E0261,
"use of undeclared lifetime name `{}`",
lifetime_ref
);
err.span_label(lifetime_ref.span, "undeclared lifetime");
let mut suggests_in_band = false;
let mut suggest_note = true;
for missing in &self.missing_named_lifetime_spots {
match missing {
MissingLifetimeSpot::Generics(generics) => {
let (span, sugg) = if let Some(param) = generics.params.iter().find(|p| {
!matches!(
p.kind,
hir::GenericParamKind::Type {
synthetic: Some(hir::SyntheticTyParamKind::ImplTrait),
..
} | hir::GenericParamKind::Lifetime {
kind: hir::LifetimeParamKind::Elided,
}
)
}) {
(param.span.shrink_to_lo(), format!("{}, ", lifetime_ref))
} else {
suggests_in_band = true;
(generics.span, format!("<{}>", lifetime_ref))
};
if !span.from_expansion() {
err.span_suggestion(
span,
&format!("consider introducing lifetime `{}` here", lifetime_ref),
sugg,
Applicability::MaybeIncorrect,
);
} else if suggest_note {
suggest_note = false; // Avoid displaying the same help multiple times.
err.span_label(
span,
&format!(
"lifetime `{}` is missing in item created through this procedural \
macro",
lifetime_ref,
),
);
}
}
MissingLifetimeSpot::HigherRanked { span, span_type } => {
err.span_suggestion(
*span,
&format!(
"consider making the {} lifetime-generic with a new `{}` lifetime",
span_type.descr(),
lifetime_ref
),
span_type.suggestion(&lifetime_ref.to_string()),
Applicability::MaybeIncorrect,
);
err.note(
"for more information on higher-ranked polymorphism, visit \
https://doc.rust-lang.org/nomicon/hrtb.html",
);
}
_ => {}
}
}
if self.tcx.sess.is_nightly_build()
&& !self.tcx.features().in_band_lifetimes
&& suggests_in_band
{
err.help(
"if you want to experiment with in-band lifetime bindings, \
add `#![feature(in_band_lifetimes)]` to the crate attributes",
);
}
err.emit();
}
// FIXME(const_generics): This patches over a ICE caused by non-'static lifetimes in const
// generics. We are disallowing this until we can decide on how we want to handle non-'static
// lifetimes in const generics. See issue #74052 for discussion.
crate fn emit_non_static_lt_in_const_generic_error(&self, lifetime_ref: &hir::Lifetime) {
let mut err = struct_span_err!(
self.tcx.sess,
lifetime_ref.span,
E0771,
"use of non-static lifetime `{}` in const generic",
lifetime_ref
);
err.note(
"for more information, see issue #74052 \
<https://github.com/rust-lang/rust/issues/74052>",
);
err.emit();
}
crate fn is_trait_ref_fn_scope(&mut self, trait_ref: &'tcx hir::PolyTraitRef<'tcx>) -> bool {
if let def::Res::Def(_, did) = trait_ref.trait_ref.path.res {
if [
self.tcx.lang_items().fn_once_trait(),
self.tcx.lang_items().fn_trait(),
self.tcx.lang_items().fn_mut_trait(),
]
.contains(&Some(did))
{
let (span, span_type) = match &trait_ref.bound_generic_params {
[] => (trait_ref.span.shrink_to_lo(), ForLifetimeSpanType::BoundEmpty),
[.., bound] => (bound.span.shrink_to_hi(), ForLifetimeSpanType::BoundTail),
};
self.missing_named_lifetime_spots
.push(MissingLifetimeSpot::HigherRanked { span, span_type });
return true;
}
};
false
}
crate fn add_missing_lifetime_specifiers_label(
&self,
err: &mut DiagnosticBuilder<'_>,
span: Span,
count: usize,
lifetime_names: &FxHashSet<Symbol>,
lifetime_spans: Vec<Span>,
params: &[ElisionFailureInfo],
) {
let snippet = self.tcx.sess.source_map().span_to_snippet(span).ok();
err.span_label(
span,
&format!(
"expected {} lifetime parameter{}",
if count == 1 { "named".to_string() } else { count.to_string() },
pluralize!(count)
),
);
let suggest_existing = |err: &mut DiagnosticBuilder<'_>,
name: &str,
formatter: &dyn Fn(&str) -> String| {
if let Some(MissingLifetimeSpot::HigherRanked { span: for_span, span_type }) =
self.missing_named_lifetime_spots.iter().rev().next()
{
// When we have `struct S<'a>(&'a dyn Fn(&X) -> &X);` we want to not only suggest
// using `'a`, but also introduce the concept of HRLTs by suggesting
// `struct S<'a>(&'a dyn for<'b> Fn(&X) -> &'b X);`. (#72404)
let mut introduce_suggestion = vec![];
let a_to_z_repeat_n = |n| {
(b'a'..=b'z').map(move |c| {
let mut s = '\''.to_string();
s.extend(std::iter::repeat(char::from(c)).take(n));
s
})
};
// If all single char lifetime names are present, we wrap around and double the chars.
let lt_name = (1..)
.flat_map(a_to_z_repeat_n)
.find(|lt| !lifetime_names.contains(&Symbol::intern(&lt)))
.unwrap();
let msg = format!(
"consider making the {} lifetime-generic with a new `{}` lifetime",
span_type.descr(),
lt_name,
);
err.note(
"for more information on higher-ranked polymorphism, visit \
https://doc.rust-lang.org/nomicon/hrtb.html",
);
let for_sugg = span_type.suggestion(&lt_name);
for param in params {
if let Ok(snippet) = self.tcx.sess.source_map().span_to_snippet(param.span) {
if snippet.starts_with('&') && !snippet.starts_with("&'") {
introduce_suggestion
.push((param.span, format!("&{} {}", lt_name, &snippet[1..])));
} else if let Some(stripped) = snippet.strip_prefix("&'_ ") {
introduce_suggestion
.push((param.span, format!("&{} {}", lt_name, stripped)));
}
}
}
introduce_suggestion.push((*for_span, for_sugg));
introduce_suggestion.push((span, formatter(&lt_name)));
err.multipart_suggestion(&msg, introduce_suggestion, Applicability::MaybeIncorrect);
}
err.span_suggestion_verbose(
span,
&format!("consider using the `{}` lifetime", lifetime_names.iter().next().unwrap()),
formatter(name),
Applicability::MaybeIncorrect,
);
};
let suggest_new = |err: &mut DiagnosticBuilder<'_>, sugg: &str| {
for missing in self.missing_named_lifetime_spots.iter().rev() {
let mut introduce_suggestion = vec![];
let msg;
let should_break;
introduce_suggestion.push(match missing {
MissingLifetimeSpot::Generics(generics) => {
if generics.span == DUMMY_SP {
// Account for malformed generics in the HIR. This shouldn't happen,
// but if we make a mistake elsewhere, mainly by keeping something in
// `missing_named_lifetime_spots` that we shouldn't, like associated
// `const`s or making a mistake in the AST lowering we would provide
// non-sensical suggestions. Guard against that by skipping these.
// (#74264)
continue;
}
msg = "consider introducing a named lifetime parameter".to_string();
should_break = true;
if let Some(param) = generics.params.iter().find(|p| {
!matches!(
p.kind,
hir::GenericParamKind::Type {
synthetic: Some(hir::SyntheticTyParamKind::ImplTrait),
..
}
)
}) {
(param.span.shrink_to_lo(), "'a, ".to_string())
} else {
(generics.span, "<'a>".to_string())
}
}
MissingLifetimeSpot::HigherRanked { span, span_type } => {
msg = format!(
"consider making the {} lifetime-generic with a new `'a` lifetime",
span_type.descr(),
);
should_break = false;
err.note(
"for more information on higher-ranked polymorphism, visit \
https://doc.rust-lang.org/nomicon/hrtb.html",
);
(*span, span_type.suggestion("'a"))
}
MissingLifetimeSpot::Static => {
let (span, sugg) = match snippet.as_deref() {
Some("&") => (span.shrink_to_hi(), "'static ".to_owned()),
Some("'_") => (span, "'static".to_owned()),
Some(snippet) if !snippet.ends_with('>') => {
if snippet == "" {
(
span,
std::iter::repeat("'static")
.take(count)
.collect::<Vec<_>>()
.join(", "),
)
} else {
(
span.shrink_to_hi(),
format!(
"<{}>",
std::iter::repeat("'static")
.take(count)
.collect::<Vec<_>>()
.join(", ")
),
)
}
}
_ => continue,
};
err.span_suggestion_verbose(
span,
"consider using the `'static` lifetime",
sugg.to_string(),
Applicability::MaybeIncorrect,
);
continue;
}
});
for param in params {
if let Ok(snippet) = self.tcx.sess.source_map().span_to_snippet(param.span) {
if snippet.starts_with('&') && !snippet.starts_with("&'") {
introduce_suggestion
.push((param.span, format!("&'a {}", &snippet[1..])));
} else if let Some(stripped) = snippet.strip_prefix("&'_ ") {
introduce_suggestion.push((param.span, format!("&'a {}", &stripped)));
}
}
}
introduce_suggestion.push((span, sugg.to_string()));
err.multipart_suggestion(&msg, introduce_suggestion, Applicability::MaybeIncorrect);
if should_break {
break;
}
}
};
let lifetime_names: Vec<_> = lifetime_names.iter().collect();
match (&lifetime_names[..], snippet.as_deref()) {
([name], Some("&")) => {
suggest_existing(err, &name.as_str()[..], &|name| format!("&{} ", name));
}
([name], Some("'_")) => {
suggest_existing(err, &name.as_str()[..], &|n| n.to_string());
}
([name], Some("")) => {
suggest_existing(err, &name.as_str()[..], &|n| format!("{}, ", n).repeat(count));
}
([name], Some(snippet)) if !snippet.ends_with('>') => {
let f = |name: &str| {
format!(
"{}<{}>",
snippet,
std::iter::repeat(name.to_string())
.take(count)
.collect::<Vec<_>>()
.join(", ")
)
};
suggest_existing(err, &name.as_str()[..], &f);
}
([], Some("&")) if count == 1 => {
suggest_new(err, "&'a ");
}
([], Some("'_")) if count == 1 => {
suggest_new(err, "'a");
}
([], Some(snippet)) if !snippet.ends_with('>') => {
if snippet == "" {
// This happens when we have `type Bar<'a> = Foo<T>` where we point at the space
// before `T`. We will suggest `type Bar<'a> = Foo<'a, T>`.
suggest_new(
err,
&std::iter::repeat("'a, ").take(count).collect::<Vec<_>>().join(""),
);
} else {
suggest_new(
err,
&format!(
"{}<{}>",
snippet,
std::iter::repeat("'a").take(count).collect::<Vec<_>>().join(", ")
),
);
}
}
(lts, ..) if lts.len() > 1 => {
err.span_note(lifetime_spans, "these named lifetimes are available to use");
if Some("") == snippet.as_deref() {
// This happens when we have `Foo<T>` where we point at the space before `T`,
// but this can be confusing so we give a suggestion with placeholders.
err.span_suggestion_verbose(
span,
"consider using one of the available lifetimes here",
"'lifetime, ".repeat(count),
Applicability::HasPlaceholders,
);
}
}
_ => {}
}
}
/// Non-static lifetimes are prohibited in anonymous constants under `min_const_generics`.
/// This function will emit an error if `const_generics` is not enabled, the body identified by
/// `body_id` is an anonymous constant and `lifetime_ref` is non-static.
crate fn maybe_emit_forbidden_non_static_lifetime_error(
&self,
body_id: hir::BodyId,
lifetime_ref: &'tcx hir::Lifetime,
) {
let is_anon_const = matches!(
self.tcx.def_kind(self.tcx.hir().body_owner_def_id(body_id)),
hir::def::DefKind::AnonConst
);
let is_allowed_lifetime = matches!(
lifetime_ref.name,
hir::LifetimeName::Implicit | hir::LifetimeName::Static | hir::LifetimeName::Underscore
);
if !self.tcx.lazy_normalization() && is_anon_const && !is_allowed_lifetime {
feature_err(
&self.tcx.sess.parse_sess,
sym::const_generics,
lifetime_ref.span,
"a non-static lifetime is not allowed in a `const`",
)
.emit();
}
}
}
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