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ZalatharZalathar
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Various style improvements to rustc_lint::levels
- Replace some nested if-let with let-chains - Tweak a match pattern to allow shorthand struct syntax - Fuse an `is_empty` check with getting the last element - Merge some common code that emits `MalformedAttribute` and continues - Format `"{tool}::{name}"` in a way that's consistent with other match arms - Replace if-let-else-panic with let-else - Use early-exit to flatten a method body
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-128
lines changed

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+121
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‎compiler/rustc_lint/src/levels.rs

+121-128
Original file line numberDiff line numberDiff line change
@@ -103,11 +103,12 @@ impl LintLevelSets {
103103
mut idx: LintStackIndex,
104104
aux: Option<&FxIndexMap<LintId, LevelAndSource>>,
105105
) -> (Option<Level>, LintLevelSource) {
106-
if let Some(specs) = aux {
107-
if let Some(&(level, src)) = specs.get(&id) {
108-
return (Some(level), src);
109-
}
106+
if let Some(specs) = aux
107+
&& let Some(&(level, src)) = specs.get(&id)
108+
{
109+
return (Some(level), src);
110110
}
111+
111112
loop {
112113
let LintSet { ref specs, parent } = self.list[idx];
113114
if let Some(&(level, src)) = specs.get(&id) {
@@ -177,7 +178,7 @@ fn shallow_lint_levels_on(tcx: TyCtxt<'_>, owner: hir::OwnerId) -> ShallowLintLe
177178
// There is only something to do if there are attributes at all.
178179
[] => {}
179180
// Most of the time, there is only one attribute. Avoid fetching HIR in that case.
180-
[(local_id, _)] => levels.add_id(HirId { owner, local_id: *local_id }),
181+
&[(local_id, _)] => levels.add_id(HirId { owner, local_id }),
181182
// Otherwise, we need to visit the attributes in source code order, so we fetch HIR and do
182183
// a standard visit.
183184
// FIXME(#102522) Just iterate on attrs once that iteration order matches HIR's.
@@ -643,63 +644,61 @@ impl<'s, P: LintLevelsProvider> LintLevelsBuilder<'s, P> {
643644
//
644645
// This means that this only errors if we're truly lowering the lint
645646
// level from forbid.
646-
if self.lint_added_lints && level != Level::Forbid {
647-
if let Level::Forbid = old_level {
648-
// Backwards compatibility check:
649-
//
650-
// We used to not consider `forbid(lint_group)`
651-
// as preventing `allow(lint)` for some lint `lint` in
652-
// `lint_group`. For now, issue a future-compatibility
653-
// warning for this case.
654-
let id_name = id.lint.name_lower();
655-
let fcw_warning = match old_src {
656-
LintLevelSource::Default => false,
657-
LintLevelSource::Node { name, .. } => self.store.is_lint_group(name),
658-
LintLevelSource::CommandLine(symbol, _) => self.store.is_lint_group(symbol),
659-
};
660-
debug!(
661-
"fcw_warning={:?}, specs.get(&id) = {:?}, old_src={:?}, id_name={:?}",
662-
fcw_warning,
663-
self.current_specs(),
664-
old_src,
665-
id_name
666-
);
667-
let sub = match old_src {
668-
LintLevelSource::Default => {
669-
OverruledAttributeSub::DefaultSource { id: id.to_string() }
670-
}
671-
LintLevelSource::Node { span, reason, .. } => {
672-
OverruledAttributeSub::NodeSource { span, reason }
673-
}
674-
LintLevelSource::CommandLine(_, _) => OverruledAttributeSub::CommandLineSource,
675-
};
676-
if !fcw_warning {
677-
self.sess.dcx().emit_err(OverruledAttribute {
678-
span: src.span(),
647+
if self.lint_added_lints && level != Level::Forbid && old_level == Level::Forbid {
648+
// Backwards compatibility check:
649+
//
650+
// We used to not consider `forbid(lint_group)`
651+
// as preventing `allow(lint)` for some lint `lint` in
652+
// `lint_group`. For now, issue a future-compatibility
653+
// warning for this case.
654+
let id_name = id.lint.name_lower();
655+
let fcw_warning = match old_src {
656+
LintLevelSource::Default => false,
657+
LintLevelSource::Node { name, .. } => self.store.is_lint_group(name),
658+
LintLevelSource::CommandLine(symbol, _) => self.store.is_lint_group(symbol),
659+
};
660+
debug!(
661+
"fcw_warning={:?}, specs.get(&id) = {:?}, old_src={:?}, id_name={:?}",
662+
fcw_warning,
663+
self.current_specs(),
664+
old_src,
665+
id_name
666+
);
667+
let sub = match old_src {
668+
LintLevelSource::Default => {
669+
OverruledAttributeSub::DefaultSource { id: id.to_string() }
670+
}
671+
LintLevelSource::Node { span, reason, .. } => {
672+
OverruledAttributeSub::NodeSource { span, reason }
673+
}
674+
LintLevelSource::CommandLine(_, _) => OverruledAttributeSub::CommandLineSource,
675+
};
676+
if !fcw_warning {
677+
self.sess.dcx().emit_err(OverruledAttribute {
678+
span: src.span(),
679+
overruled: src.span(),
680+
lint_level: level.as_str(),
681+
lint_source: src.name(),
682+
sub,
683+
});
684+
} else {
685+
self.emit_span_lint(
686+
FORBIDDEN_LINT_GROUPS,
687+
src.span().into(),
688+
OverruledAttributeLint {
679689
overruled: src.span(),
680690
lint_level: level.as_str(),
681691
lint_source: src.name(),
682692
sub,
683-
});
684-
} else {
685-
self.emit_span_lint(
686-
FORBIDDEN_LINT_GROUPS,
687-
src.span().into(),
688-
OverruledAttributeLint {
689-
overruled: src.span(),
690-
lint_level: level.as_str(),
691-
lint_source: src.name(),
692-
sub,
693-
},
694-
);
695-
}
693+
},
694+
);
695+
}
696696

697-
// Retain the forbid lint level, unless we are
698-
// issuing a FCW. In the FCW case, we want to
699-
// respect the new setting.
700-
if !fcw_warning {
701-
return;
702-
}
697+
// Retain the forbid lint level, unless we are
698+
// issuing a FCW. In the FCW case, we want to
699+
// respect the new setting.
700+
if !fcw_warning {
701+
return;
703702
}
704703
}
705704

@@ -770,15 +769,15 @@ impl<'s, P: LintLevelsProvider> LintLevelsBuilder<'s, P> {
770769

771770
let Some(mut metas) = attr.meta_item_list() else { continue };
772771

773-
if metas.is_empty() {
772+
// Check whether `metas` is empty, and get its last element.
773+
let Some(tail_li) = metas.last() else {
774774
// This emits the unused_attributes lint for `#[level()]`
775775
continue;
776-
}
776+
};
777777

778778
// Before processing the lint names, look for a reason (RFC 2383)
779779
// at the end.
780780
let mut reason = None;
781-
let tail_li = &metas[metas.len() - 1];
782781
if let Some(item) = tail_li.meta_item() {
783782
match item.kind {
784783
ast::MetaItemKind::Word => {} // actual lint names handled later
@@ -834,21 +833,16 @@ impl<'s, P: LintLevelsProvider> LintLevelsBuilder<'s, P> {
834833
let meta_item = match li {
835834
ast::NestedMetaItem::MetaItem(meta_item) if meta_item.is_word() => meta_item,
836835
_ => {
837-
if let Some(item) = li.meta_item() {
838-
if let ast::MetaItemKind::NameValue(_) = item.kind {
839-
if item.path == sym::reason {
840-
sess.dcx().emit_err(MalformedAttribute {
841-
span: sp,
842-
sub: MalformedAttributeSub::ReasonMustComeLast(sp),
843-
});
844-
continue;
845-
}
846-
}
847-
}
848-
sess.dcx().emit_err(MalformedAttribute {
849-
span: sp,
850-
sub: MalformedAttributeSub::BadAttributeArgument(sp),
851-
});
836+
let sub = if let Some(item) = li.meta_item()
837+
&& let ast::MetaItemKind::NameValue(_) = item.kind
838+
&& item.path == sym::reason
839+
{
840+
MalformedAttributeSub::ReasonMustComeLast(sp)
841+
} else {
842+
MalformedAttributeSub::BadAttributeArgument(sp)
843+
};
844+
845+
sess.dcx().emit_err(MalformedAttribute { span: sp, sub });
852846
continue;
853847
}
854848
};
@@ -987,11 +981,7 @@ impl<'s, P: LintLevelsProvider> LintLevelsBuilder<'s, P> {
987981
}
988982

989983
CheckLintNameResult::NoLint(suggestion) => {
990-
let name = if let Some(tool_ident) = tool_ident {
991-
format!("{}::{}", tool_ident.name, name)
992-
} else {
993-
name.to_string()
994-
};
984+
let name = tool_ident.map(|tool| format!("{tool}::{name}")).unwrap_or(name);
995985
let suggestion = suggestion.map(|(replace, from_rustc)| {
996986
UnknownLintSuggestion::WithSpan { suggestion: sp, replace, from_rustc }
997987
});
@@ -1005,27 +995,24 @@ impl<'s, P: LintLevelsProvider> LintLevelsBuilder<'s, P> {
1005995
if let CheckLintNameResult::Renamed(new_name) = lint_result {
1006996
// Ignore any errors or warnings that happen because the new name is inaccurate
1007997
// NOTE: `new_name` already includes the tool name, so we don't have to add it again.
1008-
if let CheckLintNameResult::Ok(ids) =
998+
let CheckLintNameResult::Ok(ids) =
1009999
self.store.check_lint_name(&new_name, None, self.registered_tools)
1010-
{
1011-
let src = LintLevelSource::Node {
1012-
name: Symbol::intern(&new_name),
1013-
span: sp,
1014-
reason,
1015-
};
1016-
for &id in ids {
1017-
if self.check_gated_lint(id, attr.span, false) {
1018-
self.insert_spec(id, (level, src));
1019-
}
1020-
}
1021-
if let Level::Expect(expect_id) = level {
1022-
self.provider.push_expectation(
1023-
expect_id,
1024-
LintExpectation::new(reason, sp, false, tool_name),
1025-
);
1026-
}
1027-
} else {
1000+
else {
10281001
panic!("renamed lint does not exist: {new_name}");
1002+
};
1003+
1004+
let src =
1005+
LintLevelSource::Node { name: Symbol::intern(&new_name), span: sp, reason };
1006+
for &id in ids {
1007+
if self.check_gated_lint(id, attr.span, false) {
1008+
self.insert_spec(id, (level, src));
1009+
}
1010+
}
1011+
if let Level::Expect(expect_id) = level {
1012+
self.provider.push_expectation(
1013+
expect_id,
1014+
LintExpectation::new(reason, sp, false, tool_name),
1015+
);
10291016
}
10301017
}
10311018
}
@@ -1058,38 +1045,44 @@ impl<'s, P: LintLevelsProvider> LintLevelsBuilder<'s, P> {
10581045
/// Returns `true` if the lint's feature is enabled.
10591046
#[track_caller]
10601047
fn check_gated_lint(&self, lint_id: LintId, span: Span, lint_from_cli: bool) -> bool {
1061-
if let Some(feature) = lint_id.lint.feature_gate {
1062-
if !self.features.active(feature) {
1063-
if self.lint_added_lints {
1064-
let lint = builtin::UNKNOWN_LINTS;
1065-
let (level, src) = self.lint_level(builtin::UNKNOWN_LINTS);
1066-
// FIXME: make this translatable
1067-
#[allow(rustc::diagnostic_outside_of_impl)]
1068-
#[allow(rustc::untranslatable_diagnostic)]
1069-
lint_level(
1070-
self.sess,
1048+
let feature = if let Some(feature) = lint_id.lint.feature_gate
1049+
&& !self.features.active(feature)
1050+
{
1051+
// Lint is behind a feature that is not enabled; eventually return false.
1052+
feature
1053+
} else {
1054+
// Lint is ungated or its feature is enabled; exit early.
1055+
return true;
1056+
};
1057+
1058+
if self.lint_added_lints {
1059+
let lint = builtin::UNKNOWN_LINTS;
1060+
let (level, src) = self.lint_level(builtin::UNKNOWN_LINTS);
1061+
// FIXME: make this translatable
1062+
#[allow(rustc::diagnostic_outside_of_impl)]
1063+
#[allow(rustc::untranslatable_diagnostic)]
1064+
lint_level(
1065+
self.sess,
1066+
lint,
1067+
level,
1068+
src,
1069+
Some(span.into()),
1070+
fluent::lint_unknown_gated_lint,
1071+
|lint| {
1072+
lint.arg("name", lint_id.lint.name_lower());
1073+
lint.note(fluent::lint_note);
1074+
rustc_session::parse::add_feature_diagnostics_for_issue(
10711075
lint,
1072-
level,
1073-
src,
1074-
Some(span.into()),
1075-
fluent::lint_unknown_gated_lint,
1076-
|lint| {
1077-
lint.arg("name", lint_id.lint.name_lower());
1078-
lint.note(fluent::lint_note);
1079-
rustc_session::parse::add_feature_diagnostics_for_issue(
1080-
lint,
1081-
&self.sess,
1082-
feature,
1083-
GateIssue::Language,
1084-
lint_from_cli,
1085-
);
1086-
},
1076+
&self.sess,
1077+
feature,
1078+
GateIssue::Language,
1079+
lint_from_cli,
10871080
);
1088-
}
1089-
return false;
1090-
}
1081+
},
1082+
);
10911083
}
1092-
true
1084+
1085+
false
10931086
}
10941087

10951088
/// Find the lint level for a lint.

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