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Remove deprecated lang items #44526

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Merged
merged 5 commits into from
Sep 14, 2017
Merged

Remove deprecated lang items #44526

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4738231
Remove deprecated lang items
leoyvens Sep 12, 2017
74107f9
Remove require_owned_box
leoyvens Sep 13, 2017
ab30b6a
Refactor how to get a lang item's name
leoyvens Sep 13, 2017
c2fb70b
Refactor fn_trait_kind
leoyvens Sep 13, 2017
9218e44
Fix initial review
leoyvens Sep 13, 2017
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55 changes: 15 additions & 40 deletions src/librustc/middle/lang_items.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -46,6 +46,14 @@ enum_from_u32! {
}
}

impl LangItem {
fn name(self) -> &'static str {
match self {
$( $variant => $name, )*
}
}
}

pub struct LanguageItems {
pub items: Vec<Option<DefId>>,
pub missing: Vec<LangItem>,
Expand All @@ -65,42 +73,17 @@ impl LanguageItems {
&*self.items
}

pub fn item_name(index: usize) -> &'static str {
let item: Option<LangItem> = LangItem::from_u32(index as u32);
match item {
$( Some($variant) => $name, )*
None => "???"
}
}

pub fn require(&self, it: LangItem) -> Result<DefId, String> {
match self.items[it as usize] {
Some(id) => Ok(id),
None => {
Err(format!("requires `{}` lang_item",
LanguageItems::item_name(it as usize)))
}
}
}

pub fn require_owned_box(&self) -> Result<DefId, String> {
self.require(OwnedBoxLangItem)
self.items[it as usize].ok_or(format!("requires `{}` lang_item", it.name()))
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@Mark-Simulacrum Mark-Simulacrum Sep 13, 2017

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Please make this an ok_or_else since otherwise we allocate a String each name, and also go through a lookup table to get the name of the lang item, both of which are somewhat expensive operations to do for lang item lookup.

}

pub fn fn_trait_kind(&self, id: DefId) -> Option<ty::ClosureKind> {
let def_id_kinds = [
(self.fn_trait(), ty::ClosureKind::Fn),
(self.fn_mut_trait(), ty::ClosureKind::FnMut),
(self.fn_once_trait(), ty::ClosureKind::FnOnce),
];

for &(opt_def_id, kind) in &def_id_kinds {
if Some(id) == opt_def_id {
return Some(kind);
}
match Some(id) {
x if x == self.fn_trait() => Some(ty::ClosureKind::Fn),
x if x == self.fn_mut_trait() => Some(ty::ClosureKind::FnMut),
x if x == self.fn_once_trait() => Some(ty::ClosureKind::FnOnce),
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@Mark-Simulacrum Mark-Simulacrum Sep 13, 2017

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nit: Extra space after the =>.

_ => None
}

None
}

$(
Expand Down Expand Up @@ -162,7 +145,7 @@ impl<'a, 'tcx> LanguageItemCollector<'a, 'tcx> {
// Check for duplicates.
match self.items.items[item_index] {
Some(original_def_id) if original_def_id != item_def_id => {
let name = LanguageItems::item_name(item_index);
let name = LangItem::from_u32(item_index as u32).unwrap().name();
let mut err = match self.tcx.hir.span_if_local(item_def_id) {
Some(span) => struct_span_err!(
self.tcx.sess,
Expand Down Expand Up @@ -327,14 +310,6 @@ language_item_table! {

PhantomDataItem, "phantom_data", phantom_data;

// Deprecated:
CovariantTypeItem, "covariant_type", covariant_type;
ContravariantTypeItem, "contravariant_type", contravariant_type;
InvariantTypeItem, "invariant_type", invariant_type;
CovariantLifetimeItem, "covariant_lifetime", covariant_lifetime;
ContravariantLifetimeItem, "contravariant_lifetime", contravariant_lifetime;
InvariantLifetimeItem, "invariant_lifetime", invariant_lifetime;

NonZeroItem, "non_zero", non_zero;

DebugTraitLangItem, "debug_trait", debug_trait;
Expand Down
9 changes: 0 additions & 9 deletions src/librustc_typeck/variance/terms.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -98,15 +98,6 @@ fn lang_items(tcx: TyCtxt) -> Vec<(ast::NodeId, Vec<ty::Variance>)> {
let all = vec![
(lang_items.phantom_data(), vec![ty::Covariant]),
(lang_items.unsafe_cell_type(), vec![ty::Invariant]),

// Deprecated:
(lang_items.covariant_type(), vec![ty::Covariant]),
(lang_items.contravariant_type(), vec![ty::Contravariant]),
(lang_items.invariant_type(), vec![ty::Invariant]),
(lang_items.covariant_lifetime(), vec![ty::Covariant]),
(lang_items.contravariant_lifetime(), vec![ty::Contravariant]),
(lang_items.invariant_lifetime(), vec![ty::Invariant]),

];

all.into_iter() // iterating over (Option<DefId>, Variance)
Expand Down