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Explain that in paths generics can't be set on both the enum and the variant #134981

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Merged
merged 2 commits into from
Feb 12, 2025
Merged

Explain that in paths generics can't be set on both the enum and the variant #134981

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1b98d0e
Explain that in paths generics can't be set on both the enum and the …
estebank Dec 31, 2024
23daa8c
Remove some the spans pointing at the enum in the path and its generi…
estebank Feb 11, 2025
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7 changes: 4 additions & 3 deletions compiler/rustc_hir_analysis/src/collect.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -614,9 +614,10 @@ impl<'tcx> HirTyLowerer<'tcx> for ItemCtxt<'tcx> {
if !infer_replacements.is_empty() {
diag.multipart_suggestion(
format!(
"try replacing `_` with the type{} in the corresponding trait method signature",
rustc_errors::pluralize!(infer_replacements.len()),
),
"try replacing `_` with the type{} in the corresponding trait method \
signature",
rustc_errors::pluralize!(infer_replacements.len()),
),
infer_replacements,
Applicability::MachineApplicable,
);
Expand Down
55 changes: 38 additions & 17 deletions compiler/rustc_hir_analysis/src/hir_ty_lowering/errors.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -6,7 +6,7 @@ use rustc_errors::{
Applicability, Diag, ErrorGuaranteed, MultiSpan, listify, pluralize, struct_span_code_err,
};
use rustc_hir as hir;
use rustc_hir::def::{DefKind, Res};
use rustc_hir::def::{CtorOf, DefKind, Res};
use rustc_hir::def_id::DefId;
use rustc_middle::bug;
use rustc_middle::ty::fast_reject::{TreatParams, simplify_type};
Expand Down Expand Up @@ -1027,7 +1027,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
&self,
segments: impl Iterator<Item = &'a hir::PathSegment<'a>> + Clone,
args_visitors: impl Iterator<Item = &'a hir::GenericArg<'a>> + Clone,
err_extend: GenericsArgsErrExtend<'_>,
err_extend: GenericsArgsErrExtend<'a>,
) -> ErrorGuaranteed {
#[derive(PartialEq, Eq, Hash)]
enum ProhibitGenericsArg {
Expand All @@ -1047,23 +1047,24 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
};
});

let segments: Vec<_> = segments.collect();
let types_and_spans: Vec<_> = segments
.clone()
.iter()
.flat_map(|segment| {
if segment.args().args.is_empty() {
None
} else {
Some((
match segment.res {
hir::def::Res::PrimTy(ty) => {
Res::PrimTy(ty) => {
format!("{} `{}`", segment.res.descr(), ty.name())
}
hir::def::Res::Def(_, def_id)
Res::Def(_, def_id)
if let Some(name) = self.tcx().opt_item_name(def_id) =>
{
format!("{} `{name}`", segment.res.descr())
}
hir::def::Res::Err => "this type".to_string(),
Res::Err => "this type".to_string(),
_ => segment.res.descr().to_string(),
},
segment.ident.span,
Expand All @@ -1074,11 +1075,8 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
let this_type = listify(&types_and_spans, |(t, _)| t.to_string())
.expect("expected one segment to deny");

let arg_spans: Vec<Span> = segments
.clone()
.flat_map(|segment| segment.args().args)
.map(|arg| arg.span())
.collect();
let arg_spans: Vec<Span> =
segments.iter().flat_map(|segment| segment.args().args).map(|arg| arg.span()).collect();

let mut kinds = Vec::with_capacity(4);
prohibit_args.iter().for_each(|arg| match arg {
Expand All @@ -1103,7 +1101,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
for (what, span) in types_and_spans {
err.span_label(span, format!("not allowed on {what}"));
}
generics_args_err_extend(self.tcx(), segments, &mut err, err_extend);
generics_args_err_extend(self.tcx(), segments.into_iter(), &mut err, err_extend);
err.emit()
}

Expand Down Expand Up @@ -1400,15 +1398,15 @@ pub enum GenericsArgsErrExtend<'tcx> {
},
SelfTyParam(Span),
Param(DefId),
DefVariant,
DefVariant(&'tcx [hir::PathSegment<'tcx>]),
None,
}

fn generics_args_err_extend<'a>(
tcx: TyCtxt<'_>,
segments: impl Iterator<Item = &'a hir::PathSegment<'a>> + Clone,
err: &mut Diag<'_>,
err_extend: GenericsArgsErrExtend<'_>,
err_extend: GenericsArgsErrExtend<'a>,
) {
match err_extend {
GenericsArgsErrExtend::EnumVariant { qself, assoc_segment, adt_def } => {
Expand Down Expand Up @@ -1496,6 +1494,32 @@ fn generics_args_err_extend<'a>(
];
err.multipart_suggestion_verbose(msg, suggestion, Applicability::MaybeIncorrect);
}
GenericsArgsErrExtend::DefVariant(segments) => {
let args: Vec<Span> = segments
.iter()
.filter_map(|segment| match segment.res {
Res::Def(
DefKind::Ctor(CtorOf::Variant, _) | DefKind::Variant | DefKind::Enum,
_,
) => segment.args().span_ext().map(|s| s.with_lo(segment.ident.span.hi())),
_ => None,
})
.collect();
if args.len() > 1
&& let Some(span) = args.into_iter().last()
{
err.note(
"generic arguments are not allowed on both an enum and its variant's path \
segments simultaneously; they are only valid in one place or the other",
);
err.span_suggestion_verbose(
span,
"remove the generics arguments from one of the path segments",
String::new(),
Applicability::MaybeIncorrect,
);
}
}
GenericsArgsErrExtend::PrimTy(prim_ty) => {
let name = prim_ty.name_str();
for segment in segments {
Expand All @@ -1512,9 +1536,6 @@ fn generics_args_err_extend<'a>(
GenericsArgsErrExtend::OpaqueTy => {
err.note("`impl Trait` types can't have type parameters");
}
GenericsArgsErrExtend::DefVariant => {
err.note("enum variants can't have type parameters");
}
GenericsArgsErrExtend::Param(def_id) => {
let span = tcx.def_ident_span(def_id).unwrap();
let kind = tcx.def_descr(def_id);
Expand Down
4 changes: 2 additions & 2 deletions compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1694,7 +1694,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
pub fn prohibit_generic_args<'a>(
&self,
segments: impl Iterator<Item = &'a hir::PathSegment<'a>> + Clone,
err_extend: GenericsArgsErrExtend<'_>,
err_extend: GenericsArgsErrExtend<'a>,
) -> Result<(), ErrorGuaranteed> {
let args_visitors = segments.clone().flat_map(|segment| segment.args().args);
let mut result = Ok(());
Expand Down Expand Up @@ -1911,7 +1911,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
path.segments.iter().enumerate().filter_map(|(index, seg)| {
if !indices.contains(&index) { Some(seg) } else { None }
}),
GenericsArgsErrExtend::DefVariant,
GenericsArgsErrExtend::DefVariant(&path.segments),
);

let GenericPathSegment(def_id, index) = generic_segments.last().unwrap();
Expand Down
7 changes: 6 additions & 1 deletion compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1043,12 +1043,17 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {

let mut user_self_ty = None;
let mut is_alias_variant_ctor = false;
let mut err_extend = GenericsArgsErrExtend::None;
match res {
Res::Def(DefKind::Ctor(CtorOf::Variant, _), _) if let Some(self_ty) = self_ty => {
let adt_def = self_ty.normalized.ty_adt_def().unwrap();
user_self_ty =
Some(UserSelfTy { impl_def_id: adt_def.did(), self_ty: self_ty.raw });
is_alias_variant_ctor = true;
err_extend = GenericsArgsErrExtend::DefVariant(segments);
}
Res::Def(DefKind::Ctor(CtorOf::Variant, _), _) => {
err_extend = GenericsArgsErrExtend::DefVariant(segments);
}
Res::Def(DefKind::AssocFn | DefKind::AssocConst, def_id) => {
let assoc_item = tcx.associated_item(def_id);
Expand Down Expand Up @@ -1095,7 +1100,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
segments.iter().enumerate().filter_map(|(index, seg)| {
if !indices.contains(&index) || is_alias_variant_ctor { Some(seg) } else { None }
}),
GenericsArgsErrExtend::None,
err_extend,
);

if let Res::Local(hid) = res {
Expand Down
21 changes: 20 additions & 1 deletion tests/ui/type-alias-enum-variants/enum-variant-generic-args.stderr
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Expand Up @@ -285,6 +285,13 @@ LL | Enum::<()>::TSVariant::<()>(());
| --------- ^^ type argument not allowed
| |
| not allowed on tuple variant `TSVariant`
|
= note: generic arguments are not allowed on both an enum and its variant's path segments simultaneously; they are only valid in one place or the other
help: remove the generics arguments from one of the path segments
|
LL - Enum::<()>::TSVariant::<()>(());
LL + Enum::<()>::TSVariant(());
|

error[E0109]: type arguments are not allowed on this type
--> $DIR/enum-variant-generic-args.rs:57:24
Expand Down Expand Up @@ -354,7 +361,12 @@ LL | Enum::<()>::SVariant::<()> { v: () };
| |
| not allowed on variant `SVariant`
|
= note: enum variants can't have type parameters
= note: generic arguments are not allowed on both an enum and its variant's path segments simultaneously; they are only valid in one place or the other
help: remove the generics arguments from one of the path segments
|
LL - Enum::<()>::SVariant::<()> { v: () };
LL + Enum::<()>::SVariant { v: () };
|

error[E0109]: type arguments are not allowed on this type
--> $DIR/enum-variant-generic-args.rs:75:23
Expand Down Expand Up @@ -451,6 +463,13 @@ LL | Enum::<()>::UVariant::<()>;
| -------- ^^ type argument not allowed
| |
| not allowed on unit variant `UVariant`
|
= note: generic arguments are not allowed on both an enum and its variant's path segments simultaneously; they are only valid in one place or the other
help: remove the generics arguments from one of the path segments
|
LL - Enum::<()>::UVariant::<()>;
LL + Enum::<()>::UVariant;
|

error[E0109]: type arguments are not allowed on this type
--> $DIR/enum-variant-generic-args.rs:93:23
Expand Down
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