Fortify generic param default checks
This commit is contained in:
León Orell Valerian Liehr
parent
ec7c026125
commit
02ea38cfff
30 changed files with 298 additions and 286 deletions
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@ -223,60 +223,27 @@ pub(super) fn generics_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::Generics {
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"synthetic HIR should have its `generics_of` explicitly fed"
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),
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_ => span_bug!(tcx.def_span(def_id), "unhandled node {node:?}"),
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_ => span_bug!(tcx.def_span(def_id), "generics_of: unexpected node kind {node:?}"),
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};
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enum Defaults {
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Allowed,
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// See #36887
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FutureCompatDisallowed,
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Deny,
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}
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// Add in the self type parameter.
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let opt_self = if let Node::Item(item) = node
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&& let ItemKind::Trait(..) | ItemKind::TraitAlias(..) = item.kind
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{
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// Something of a hack: We reuse the node ID of the trait for the self type parameter.
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Some(ty::GenericParamDef {
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index: 0,
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name: kw::SelfUpper,
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def_id: def_id.to_def_id(),
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pure_wrt_drop: false,
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kind: ty::GenericParamDefKind::Type { has_default: false, synthetic: false },
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})
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} else {
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None
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};
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let param_default_policy = param_default_policy(node);
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let hir_generics = node.generics().unwrap_or(hir::Generics::empty());
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let (opt_self, allow_defaults) = match node {
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Node::Item(item) => {
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match item.kind {
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ItemKind::Trait(..) | ItemKind::TraitAlias(..) => {
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// Add in the self type parameter.
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//
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// Something of a hack: use the node id for the trait, also as
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// the node id for the Self type parameter.
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let opt_self = Some(ty::GenericParamDef {
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index: 0,
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name: kw::SelfUpper,
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def_id: def_id.to_def_id(),
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pure_wrt_drop: false,
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kind: ty::GenericParamDefKind::Type {
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has_default: false,
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synthetic: false,
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},
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});
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(opt_self, Defaults::Allowed)
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}
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ItemKind::TyAlias(..)
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| ItemKind::Enum(..)
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| ItemKind::Struct(..)
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| ItemKind::Union(..) => (None, Defaults::Allowed),
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ItemKind::Const(..) => (None, Defaults::Deny),
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_ => (None, Defaults::FutureCompatDisallowed),
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}
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}
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Node::OpaqueTy(..) => (None, Defaults::Allowed),
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// GATs
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Node::TraitItem(item) if matches!(item.kind, TraitItemKind::Type(..)) => {
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(None, Defaults::Deny)
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}
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Node::ImplItem(item) if matches!(item.kind, ImplItemKind::Type(..)) => {
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(None, Defaults::Deny)
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}
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_ => (None, Defaults::FutureCompatDisallowed),
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};
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let has_self = opt_self.is_some();
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let mut parent_has_self = false;
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let mut own_start = has_self as u32;
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@ -312,60 +279,53 @@ pub(super) fn generics_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::Generics {
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prev + type_start
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};
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const TYPE_DEFAULT_NOT_ALLOWED: &'static str = "defaults for type parameters are only allowed in \
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`struct`, `enum`, `type`, or `trait` definitions";
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own_params.extend(hir_generics.params.iter().filter_map(|param| match param.kind {
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GenericParamKind::Lifetime { .. } => None,
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GenericParamKind::Type { default, synthetic, .. } => {
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if default.is_some() {
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match allow_defaults {
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Defaults::Allowed => {}
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Defaults::FutureCompatDisallowed => {
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tcx.node_span_lint(
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lint::builtin::INVALID_TYPE_PARAM_DEFAULT,
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param.hir_id,
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param.span,
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|lint| {
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lint.primary_message(TYPE_DEFAULT_NOT_ALLOWED);
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},
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);
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}
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Defaults::Deny => {
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tcx.dcx().span_err(param.span, TYPE_DEFAULT_NOT_ALLOWED);
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own_params.extend(hir_generics.params.iter().filter_map(|param| {
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const MESSAGE: &str = "defaults for generic parameters are not allowed here";
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let kind = match param.kind {
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GenericParamKind::Lifetime { .. } => return None,
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GenericParamKind::Type { default, synthetic } => {
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if default.is_some() {
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match param_default_policy.expect("no policy for generic param default") {
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ParamDefaultPolicy::Allowed => {}
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ParamDefaultPolicy::FutureCompatForbidden => {
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tcx.node_span_lint(
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lint::builtin::INVALID_TYPE_PARAM_DEFAULT,
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param.hir_id,
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param.span,
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|lint| {
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lint.primary_message(MESSAGE);
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},
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);
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}
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ParamDefaultPolicy::Forbidden => {
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tcx.dcx().span_err(param.span, MESSAGE);
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}
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}
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}
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ty::GenericParamDefKind::Type { has_default: default.is_some(), synthetic }
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}
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GenericParamKind::Const { ty: _, default, synthetic } => {
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if default.is_some() {
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match param_default_policy.expect("no policy for generic param default") {
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ParamDefaultPolicy::Allowed => {}
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ParamDefaultPolicy::FutureCompatForbidden
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| ParamDefaultPolicy::Forbidden => {
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tcx.dcx().span_err(param.span, MESSAGE);
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}
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}
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}
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let kind = ty::GenericParamDefKind::Type { has_default: default.is_some(), synthetic };
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Some(ty::GenericParamDef {
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index: next_index(),
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name: param.name.ident().name,
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def_id: param.def_id.to_def_id(),
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pure_wrt_drop: param.pure_wrt_drop,
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kind,
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})
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}
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GenericParamKind::Const { ty: _, default, synthetic } => {
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if !matches!(allow_defaults, Defaults::Allowed) && default.is_some() {
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tcx.dcx().span_err(
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param.span,
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"defaults for const parameters are only allowed in \
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`struct`, `enum`, `type`, or `trait` definitions",
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);
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ty::GenericParamDefKind::Const { has_default: default.is_some(), synthetic }
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}
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let index = next_index();
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Some(ty::GenericParamDef {
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index,
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name: param.name.ident().name,
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def_id: param.def_id.to_def_id(),
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pure_wrt_drop: param.pure_wrt_drop,
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kind: ty::GenericParamDefKind::Const { has_default: default.is_some(), synthetic },
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})
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}
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};
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Some(ty::GenericParamDef {
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index: next_index(),
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name: param.name.ident().name,
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def_id: param.def_id.to_def_id(),
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pure_wrt_drop: param.pure_wrt_drop,
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kind,
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})
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}));
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// provide junk type parameter defs - the only place that
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@ -438,6 +398,48 @@ pub(super) fn generics_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::Generics {
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}
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}
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#[derive(Clone, Copy)]
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enum ParamDefaultPolicy {
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Allowed,
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/// Tracked in <https://github.com/rust-lang/rust/issues/36887>.
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FutureCompatForbidden,
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Forbidden,
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}
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fn param_default_policy(node: Node<'_>) -> Option<ParamDefaultPolicy> {
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use rustc_hir::*;
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Some(match node {
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Node::Item(item) => match item.kind {
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ItemKind::Trait(..)
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| ItemKind::TraitAlias(..)
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| ItemKind::TyAlias(..)
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| ItemKind::Enum(..)
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| ItemKind::Struct(..)
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| ItemKind::Union(..) => ParamDefaultPolicy::Allowed,
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ItemKind::Fn { .. } | ItemKind::Impl(_) => ParamDefaultPolicy::FutureCompatForbidden,
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// Re. GCI, we're not bound by backward compatibility.
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ItemKind::Const(..) => ParamDefaultPolicy::Forbidden,
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_ => return None,
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},
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Node::TraitItem(item) => match item.kind {
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// Re. GATs and GACs (generic_const_items), we're not bound by backward compatibility.
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TraitItemKind::Const(..) | TraitItemKind::Type(..) => ParamDefaultPolicy::Forbidden,
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TraitItemKind::Fn(..) => ParamDefaultPolicy::FutureCompatForbidden,
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},
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Node::ImplItem(item) => match item.kind {
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// Re. GATs and GACs (generic_const_items), we're not bound by backward compatibility.
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ImplItemKind::Const(..) | ImplItemKind::Type(..) => ParamDefaultPolicy::Forbidden,
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ImplItemKind::Fn(..) => ParamDefaultPolicy::FutureCompatForbidden,
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},
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// Generic params are (semantically) invalid on foreign items. Still, for maximum forward
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// compatibility, let's hard-reject defaults on them.
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Node::ForeignItem(_) => ParamDefaultPolicy::Forbidden,
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Node::OpaqueTy(..) => ParamDefaultPolicy::Allowed,
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_ => return None,
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})
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}
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fn has_late_bound_regions<'tcx>(tcx: TyCtxt<'tcx>, node: Node<'tcx>) -> Option<Span> {
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struct LateBoundRegionsDetector<'tcx> {
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tcx: TyCtxt<'tcx>,
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