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Rollup merge of #117110 - estebank:deref-field-suggestion, r=b-naber
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Suggest field typo through derefs

Take into account implicit dereferences when suggesting fields.

```
error[E0609]: no field `longname` on type `Arc<S>`
  --> $DIR/suggest-field-through-deref.rs:10:15
   |
LL |     let _ = x.longname;
   |               ^^^^^^^^ help: a field with a similar name exists: `long_name`
```

CC #78374 (comment)
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@TaKO8Ki
TaKO8Ki authored Nov 18, 2023
2 parents baf3059 + 289ce57 commit 9e84f6d
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Showing 55 changed files with 491 additions and 241 deletions.
215 changes: 112 additions & 103 deletions compiler/rustc_hir_typeck/src/expr.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -2191,7 +2191,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
if let Some(field_name) =
find_best_match_for_name(&available_field_names, field.ident.name, None)
{
err.span_suggestion(
err.span_label(field.ident.span, "unknown field");
err.span_suggestion_verbose(
field.ident.span,
"a field with a similar name exists",
field_name,
Expand Down Expand Up @@ -2420,35 +2421,32 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
ty: Ty<'tcx>,
) {
let Some(output_ty) = self.get_impl_future_output_ty(ty) else {
err.span_label(field_ident.span, "unknown field");
return;
};
let mut add_label = true;
if let ty::Adt(def, _) = output_ty.kind() {
// no field access on enum type
if !def.is_enum() {
if def
.non_enum_variant()
.fields
.iter()
.any(|field| field.ident(self.tcx) == field_ident)
{
add_label = false;
err.span_label(
field_ident.span,
"field not available in `impl Future`, but it is available in its `Output`",
);
err.span_suggestion_verbose(
base.span.shrink_to_hi(),
"consider `await`ing on the `Future` and access the field of its `Output`",
".await",
Applicability::MaybeIncorrect,
);
}
}
let ty::Adt(def, _) = output_ty.kind() else {
err.span_label(field_ident.span, "unknown field");
return;
};
// no field access on enum type
if def.is_enum() {
err.span_label(field_ident.span, "unknown field");
return;
}
if add_label {
err.span_label(field_ident.span, format!("field not found in `{ty}`"));
if !def.non_enum_variant().fields.iter().any(|field| field.ident(self.tcx) == field_ident) {
err.span_label(field_ident.span, "unknown field");
return;
}
err.span_label(
field_ident.span,
"field not available in `impl Future`, but it is available in its `Output`",
);
err.span_suggestion_verbose(
base.span.shrink_to_hi(),
"consider `await`ing on the `Future` and access the field of its `Output`",
".await",
Applicability::MaybeIncorrect,
);
}

fn ban_nonexisting_field(
Expand All @@ -2471,16 +2469,16 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
ty::RawPtr(..) => {
self.suggest_first_deref_field(&mut err, expr, base, ident);
}
ty::Adt(def, _) if !def.is_enum() => {
self.suggest_fields_on_recordish(&mut err, expr, def, ident);
}
ty::Param(param_ty) => {
err.span_label(ident.span, "unknown field");
self.point_at_param_definition(&mut err, param_ty);
}
ty::Alias(ty::Opaque, _) => {
self.suggest_await_on_field_access(&mut err, ident, base, base_ty.peel_refs());
}
_ => {}
_ => {
err.span_label(ident.span, "unknown field");
}
}

self.suggest_fn_call(&mut err, base, base_ty, |output_ty| {
Expand Down Expand Up @@ -2633,34 +2631,6 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
err.span_label(param_span, format!("type parameter '{param_name}' declared here"));
}

fn suggest_fields_on_recordish(
&self,
err: &mut Diagnostic,
expr: &hir::Expr<'_>,
def: ty::AdtDef<'tcx>,
field: Ident,
) {
let available_field_names = self.available_field_names(def.non_enum_variant(), expr, &[]);
if let Some(suggested_field_name) =
find_best_match_for_name(&available_field_names, field.name, None)
{
err.span_suggestion(
field.span,
"a field with a similar name exists",
suggested_field_name,
Applicability::MaybeIncorrect,
);
} else {
err.span_label(field.span, "unknown field");
if !available_field_names.is_empty() {
err.note(format!(
"available fields are: {}",
self.name_series_display(available_field_names),
));
}
}
}

fn maybe_suggest_array_indexing(
&self,
err: &mut Diagnostic,
Expand All @@ -2669,6 +2639,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
field: Ident,
len: ty::Const<'tcx>,
) {
err.span_label(field.span, "unknown field");
if let (Some(len), Ok(user_index)) =
(len.try_eval_target_usize(self.tcx, self.param_env), field.as_str().parse::<u64>())
&& let Ok(base) = self.tcx.sess.source_map().span_to_snippet(base.span)
Expand All @@ -2691,6 +2662,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
base: &hir::Expr<'_>,
field: Ident,
) {
err.span_label(field.span, "unknown field");
if let Ok(base) = self.tcx.sess.source_map().span_to_snippet(base.span) {
let msg = format!("`{base}` is a raw pointer; try dereferencing it");
let suggestion = format!("(*{base}).{field}");
Expand All @@ -2709,18 +2681,30 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {

let mut err = type_error_struct!(
self.tcx().sess,
field.span,
span,
expr_t,
E0609,
"no field `{field}` on type `{expr_t}`",
);

// try to add a suggestion in case the field is a nested field of a field of the Adt
let mod_id = self.tcx.parent_module(id).to_def_id();
if let Some((fields, args)) =
self.get_field_candidates_considering_privacy(span, expr_t, mod_id)
let (ty, unwrap) = if let ty::Adt(def, args) = expr_t.kind()
&& (self.tcx.is_diagnostic_item(sym::Result, def.did())
|| self.tcx.is_diagnostic_item(sym::Option, def.did()))
&& let Some(arg) = args.get(0)
&& let Some(ty) = arg.as_type()
{
let candidate_fields: Vec<_> = fields
(ty, "unwrap().")
} else {
(expr_t, "")
};
for (found_fields, args) in
self.get_field_candidates_considering_privacy(span, ty, mod_id, id)
{
let field_names = found_fields.iter().map(|field| field.name).collect::<Vec<_>>();
let candidate_fields: Vec<_> = found_fields
.into_iter()
.filter_map(|candidate_field| {
self.check_for_nested_field_satisfying(
span,
Expand All @@ -2729,15 +2713,15 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
args,
vec![],
mod_id,
id,
)
})
.map(|mut field_path| {
field_path.pop();
field_path
.iter()
.map(|id| id.name.to_ident_string())
.collect::<Vec<String>>()
.join(".")
.map(|id| format!("{}.", id.name.to_ident_string()))
.collect::<String>()
})
.collect::<Vec<_>>();

Expand All @@ -2750,9 +2734,24 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
if len > 1 { "some" } else { "one" },
if len > 1 { "have" } else { "has" },
),
candidate_fields.iter().map(|path| format!("{path}.")),
candidate_fields.iter().map(|path| format!("{unwrap}{path}")),
Applicability::MaybeIncorrect,
);
} else {
if let Some(field_name) = find_best_match_for_name(&field_names, field.name, None) {
err.span_suggestion_verbose(
field.span,
"a field with a similar name exists",
format!("{unwrap}{}", field_name),
Applicability::MaybeIncorrect,
);
} else if !field_names.is_empty() {
let is = if field_names.len() == 1 { " is" } else { "s are" };
err.note(format!(
"available field{is}: {}",
self.name_series_display(field_names),
));
}
}
}
err
Expand Down Expand Up @@ -2781,33 +2780,39 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
span: Span,
base_ty: Ty<'tcx>,
mod_id: DefId,
) -> Option<(impl Iterator<Item = &'tcx ty::FieldDef> + 'tcx, GenericArgsRef<'tcx>)> {
hir_id: hir::HirId,
) -> Vec<(Vec<&'tcx ty::FieldDef>, GenericArgsRef<'tcx>)> {
debug!("get_field_candidates(span: {:?}, base_t: {:?}", span, base_ty);

for (base_t, _) in self.autoderef(span, base_ty) {
match base_t.kind() {
ty::Adt(base_def, args) if !base_def.is_enum() => {
let tcx = self.tcx;
let fields = &base_def.non_enum_variant().fields;
// Some struct, e.g. some that impl `Deref`, have all private fields
// because you're expected to deref them to access the _real_ fields.
// This, for example, will help us suggest accessing a field through a `Box<T>`.
if fields.iter().all(|field| !field.vis.is_accessible_from(mod_id, tcx)) {
continue;
self.autoderef(span, base_ty)
.filter_map(move |(base_t, _)| {
match base_t.kind() {
ty::Adt(base_def, args) if !base_def.is_enum() => {
let tcx = self.tcx;
let fields = &base_def.non_enum_variant().fields;
// Some struct, e.g. some that impl `Deref`, have all private fields
// because you're expected to deref them to access the _real_ fields.
// This, for example, will help us suggest accessing a field through a `Box<T>`.
if fields.iter().all(|field| !field.vis.is_accessible_from(mod_id, tcx)) {
return None;
}
return Some((
fields
.iter()
.filter(move |field| {
field.vis.is_accessible_from(mod_id, tcx)
&& self.is_field_suggestable(field, hir_id, span)
})
// For compile-time reasons put a limit on number of fields we search
.take(100)
.collect::<Vec<_>>(),
*args,
));
}
return Some((
fields
.iter()
.filter(move |field| field.vis.is_accessible_from(mod_id, tcx))
// For compile-time reasons put a limit on number of fields we search
.take(100),
args,
));
_ => None,
}
_ => {}
}
}
None
})
.collect()
}

/// This method is called after we have encountered a missing field error to recursively
Expand All @@ -2820,6 +2825,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
subst: GenericArgsRef<'tcx>,
mut field_path: Vec<Ident>,
mod_id: DefId,
hir_id: HirId,
) -> Option<Vec<Ident>> {
debug!(
"check_for_nested_field_satisfying(span: {:?}, candidate_field: {:?}, field_path: {:?}",
Expand All @@ -2835,20 +2841,23 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
let field_ty = candidate_field.ty(self.tcx, subst);
if matches(candidate_field, field_ty) {
return Some(field_path);
} else if let Some((nested_fields, subst)) =
self.get_field_candidates_considering_privacy(span, field_ty, mod_id)
{
// recursively search fields of `candidate_field` if it's a ty::Adt
for field in nested_fields {
if let Some(field_path) = self.check_for_nested_field_satisfying(
span,
matches,
field,
subst,
field_path.clone(),
mod_id,
) {
return Some(field_path);
} else {
for (nested_fields, subst) in
self.get_field_candidates_considering_privacy(span, field_ty, mod_id, hir_id)
{
// recursively search fields of `candidate_field` if it's a ty::Adt
for field in nested_fields {
if let Some(field_path) = self.check_for_nested_field_satisfying(
span,
matches,
field,
subst,
field_path.clone(),
mod_id,
hir_id,
) {
return Some(field_path);
}
}
}
}
Expand Down
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