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On private tuple struct, suggest Default::default when possible

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This commit is contained in:
Esteban Küber 2023-11-08 21:58:44 +00:00
parent f1ae02f4bd
commit a4f47de7ff
2 changed files with 60 additions and 1 deletions
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57
compiler/rustc_resolve/src/late/diagnostics.rs
View File

@ -1,6 +1,7 @@
use crate::diagnostics::{ImportSuggestion, LabelSuggestion, TypoSuggestion};
use crate::late::{AliasPossibility, LateResolutionVisitor, RibKind};
use crate::late::{LifetimeBinderKind, LifetimeRes, LifetimeRibKind, LifetimeUseSet};
use crate::ty::fast_reject::SimplifiedType;
use crate::{errors, path_names_to_string};
use crate::{Module, ModuleKind, ModuleOrUniformRoot};
use crate::{PathResult, PathSource, Segment};
@ -1595,7 +1596,11 @@ impl<'a: 'ast, 'ast, 'tcx> LateResolutionVisitor<'a, '_, 'ast, 'tcx> {
Some(Vec::from(pattern_spans))
}
// e.g. `let _ = Enum::TupleVariant(field1, field2);`
PathSource::Expr(Some(Expr { kind: ExprKind::Call(_, ref args), .. })) => {
PathSource::Expr(Some(Expr {
kind: ExprKind::Call(path, ref args),
span: call_span,
..
})) => {
err.set_primary_message(
"cannot initialize a tuple struct which contains private fields",
);
@ -1675,6 +1680,56 @@ impl<'a: 'ast, 'ast, 'tcx> LateResolutionVisitor<'a, '_, 'ast, 'tcx> {
);
}
}
// We'd ideally use `type_implements_trait` but don't have access to
// the trait solver here. We can't use `get_diagnostic_item` or
// `all_traits` in resolve either. So instead we abuse the import
// suggestion machinery to get `std::default::Default` and perform some
// checks to confirm that we got *only* that trait. We then see if the
// Adt we have has a direct implementation of `Default`. If so, we
// provide a structured suggestion.
let default_trait = self
.r
.lookup_import_candidates(
Ident::with_dummy_span(sym::Default),
Namespace::TypeNS,
&self.parent_scope,
&|res: Res| matches!(res, Res::Def(DefKind::Trait, _)),
)
.iter()
.filter_map(|candidate| candidate.did)
.filter(|did| {
self.r
.tcx
.get_attrs(*did, sym::rustc_diagnostic_item)
.any(|attr| attr.value_str() == Some(sym::Default))
})
.next();
if let Some(default_trait) = default_trait
&& self.r.extern_crate_map.iter().flat_map(|(_, crate_)| {
self
.r
.tcx
.implementations_of_trait((*crate_, default_trait))
})
.filter_map(|(_, simplified_self_ty)| *simplified_self_ty)
.filter_map(|simplified_self_ty| match simplified_self_ty {
SimplifiedType::Adt(did) => Some(did),
_ => None
})
.any(|did| did == def_id)
{
err.multipart_suggestion(
"consider using the `Default` trait",
vec![
(path.span.shrink_to_lo(), "<".to_string()),
(
path.span.shrink_to_hi().with_hi(call_span.hi()),
" as std::default::Default>::default()".to_string(),
),
],
Applicability::MaybeIncorrect,
);
}
}
// Use spans of the tuple struct definition.
self.r.field_def_ids(def_id).map(|field_ids| {

4
tests/ui/privacy/suggest-box-new.stderr
View File

@ -21,6 +21,10 @@ LL | wtf: Some(Box::new_zeroed_in(U {
LL | wtf: Some(Box::new_uninit_slice(U {
| ++++++++++++++++++
and 10 other candidates
help: consider using the `Default` trait
|
LL | wtf: Some(<Box as std::default::Default>::default()),
| + ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
error: aborting due to previous error