[rustc.git] / src / librustc / middle / lang_items.rs

// Copyright 2012 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

// Detecting language items.
//
// Language items are items that represent concepts intrinsic to the language
// itself. Examples are:
//
// * Traits that specify "kinds"; e.g. "Sync", "Send".
//
// * Traits that represent operators; e.g. "Add", "Sub", "Index".
//
// * Functions called by the compiler itself.

pub use self::LangItem::*;

use hir::def_id::DefId;
use hir::check_attr::Target;
use ty::{self, TyCtxt};
use middle::weak_lang_items;
use util::nodemap::FxHashMap;

use syntax::ast;
use syntax::symbol::Symbol;
use syntax_pos::Span;
use hir::itemlikevisit::ItemLikeVisitor;
use hir;

// The actual lang items defined come at the end of this file in one handy table.
// So you probably just want to nip down to the end.
macro_rules! language_item_table {
    (
        $( $variant:ident, $name:expr, $method:ident, $target:path; )*
    ) => {

enum_from_u32! {
    #[derive(Debug, Copy, Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
    pub enum LangItem {
        $($variant,)*
    }
}

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

pub struct LanguageItems {
    pub items: Vec<Option<DefId>>,
    pub missing: Vec<LangItem>,
}

impl LanguageItems {
    pub fn new() -> LanguageItems {
        fn foo(_: LangItem) -> Option<DefId> { None }

        LanguageItems {
            items: vec![$(foo($variant)),*],
            missing: Vec::new(),
        }
    }

    pub fn items(&self) -> &[Option<DefId>] {
        &*self.items
    }

    pub fn require(&self, it: LangItem) -> Result<DefId, String> {
        self.items[it as usize].ok_or_else(|| format!("requires `{}` lang_item", it.name()))
    }

    pub fn fn_trait_kind(&self, id: DefId) -> Option<ty::ClosureKind> {
        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),
            _ => None
        }
    }

    $(
        #[allow(dead_code)]
        pub fn $method(&self) -> Option<DefId> {
            self.items[$variant as usize]
        }
    )*
}

struct LanguageItemCollector<'a, 'tcx: 'a> {
    items: LanguageItems,
    tcx: TyCtxt<'a, 'tcx, 'tcx>,
    item_refs: FxHashMap<&'static str, (usize, Target)>,
}

impl<'a, 'v, 'tcx> ItemLikeVisitor<'v> for LanguageItemCollector<'a, 'tcx> {
    fn visit_item(&mut self, item: &hir::Item) {
        if let Some((value, span)) = extract(&item.attrs) {
            let actual_target = Target::from_item(item);
            match self.item_refs.get(&*value.as_str()).cloned() {
                // Known lang item with attribute on correct target.
                Some((item_index, expected_target)) if actual_target == expected_target => {
                    let def_id = self.tcx.hir.local_def_id(item.id);
                    self.collect_item(item_index, def_id);
                },
                // Known lang item with attribute on incorrect target.
                Some((_, expected_target)) => {
                    let mut err = struct_span_err!(
                        self.tcx.sess, span, E0718,
                        "`{}` language item must be applied to a {}",
                        value, expected_target,
                    );
                    err.span_label(
                        span,
                        format!(
                            "attribute should be applied to a {}, not a {}",
                            expected_target, actual_target,
                        ),
                    );
                    err.emit();
                },
                // Unknown lang item.
                _ => {
                    let mut err = struct_span_err!(
                        self.tcx.sess, span, E0522,
                        "definition of an unknown language item: `{}`",
                        value
                    );
                    err.span_label(
                        span,
                        format!("definition of unknown language item `{}`", value)
                    );
                    err.emit();
                },
            }
        }
    }

    fn visit_trait_item(&mut self, _trait_item: &hir::TraitItem) {
        // at present, lang items are always items, not trait items
    }

    fn visit_impl_item(&mut self, _impl_item: &hir::ImplItem) {
        // at present, lang items are always items, not impl items
    }
}

impl<'a, 'tcx> LanguageItemCollector<'a, 'tcx> {
    fn new(tcx: TyCtxt<'a, 'tcx, 'tcx>) -> LanguageItemCollector<'a, 'tcx> {
        let mut item_refs = FxHashMap::default();

        $( item_refs.insert($name, ($variant as usize, $target)); )*

        LanguageItemCollector {
            tcx,
            items: LanguageItems::new(),
            item_refs,
        }
    }

    fn collect_item(&mut self, item_index: usize, item_def_id: DefId) {
        // Check for duplicates.
        if let Some(original_def_id) = self.items.items[item_index] {
            if original_def_id != item_def_id {
                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,
                        span,
                        E0152,
                        "duplicate lang item found: `{}`.",
                        name),
                    None => self.tcx.sess.struct_err(&format!(
                            "duplicate lang item in crate `{}`: `{}`.",
                            self.tcx.crate_name(item_def_id.krate),
                            name)),
                };
                if let Some(span) = self.tcx.hir.span_if_local(original_def_id) {
                    span_note!(&mut err, span, "first defined here.");
                } else {
                    err.note(&format!("first defined in crate `{}`.",
                                      self.tcx.crate_name(original_def_id.krate)));
                }
                err.emit();
            }
        }

        // Matched.
        self.items.items[item_index] = Some(item_def_id);
    }
}

pub fn extract(attrs: &[ast::Attribute]) -> Option<(Symbol, Span)> {
    for attribute in attrs {
        if attribute.check_name("lang") {
            if let Some(value) = attribute.value_str() {
                return Some((value, attribute.span));
            }
        } else if attribute.check_name("panic_implementation") ||
            attribute.check_name("panic_handler")
        {
            return Some((Symbol::intern("panic_impl"), attribute.span))
        } else if attribute.check_name("alloc_error_handler") {
            return Some((Symbol::intern("oom"), attribute.span))
        }
    }

    None
}

pub fn collect<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>) -> LanguageItems {
    let mut collector = LanguageItemCollector::new(tcx);
    for &cnum in tcx.crates().iter() {
        for &(def_id, item_index) in tcx.defined_lang_items(cnum).iter() {
            collector.collect_item(item_index, def_id);
        }
    }
    tcx.hir.krate().visit_all_item_likes(&mut collector);
    let LanguageItemCollector { mut items, .. } = collector;
    weak_lang_items::check_crate(tcx, &mut items);
    items
}

// End of the macro
    }
}

language_item_table! {
//  Variant name,                Name,                 Method name,             Target;
    CharImplItem,                "char",               char_impl,               Target::Impl;
    StrImplItem,                 "str",                str_impl,                Target::Impl;
    SliceImplItem,               "slice",              slice_impl,              Target::Impl;
    SliceU8ImplItem,             "slice_u8",           slice_u8_impl,           Target::Impl;
    StrAllocImplItem,            "str_alloc",          str_alloc_impl,          Target::Impl;
    SliceAllocImplItem,          "slice_alloc",        slice_alloc_impl,        Target::Impl;
    SliceU8AllocImplItem,        "slice_u8_alloc",     slice_u8_alloc_impl,     Target::Impl;
    ConstPtrImplItem,            "const_ptr",          const_ptr_impl,          Target::Impl;
    MutPtrImplItem,              "mut_ptr",            mut_ptr_impl,            Target::Impl;
    I8ImplItem,                  "i8",                 i8_impl,                 Target::Impl;
    I16ImplItem,                 "i16",                i16_impl,                Target::Impl;
    I32ImplItem,                 "i32",                i32_impl,                Target::Impl;
    I64ImplItem,                 "i64",                i64_impl,                Target::Impl;
    I128ImplItem,                "i128",               i128_impl,               Target::Impl;
    IsizeImplItem,               "isize",              isize_impl,              Target::Impl;
    U8ImplItem,                  "u8",                 u8_impl,                 Target::Impl;
    U16ImplItem,                 "u16",                u16_impl,                Target::Impl;
    U32ImplItem,                 "u32",                u32_impl,                Target::Impl;
    U64ImplItem,                 "u64",                u64_impl,                Target::Impl;
    U128ImplItem,                "u128",               u128_impl,               Target::Impl;
    UsizeImplItem,               "usize",              usize_impl,              Target::Impl;
    F32ImplItem,                 "f32",                f32_impl,                Target::Impl;
    F64ImplItem,                 "f64",                f64_impl,                Target::Impl;
    F32RuntimeImplItem,          "f32_runtime",        f32_runtime_impl,        Target::Impl;
    F64RuntimeImplItem,          "f64_runtime",        f64_runtime_impl,        Target::Impl;

    SizedTraitLangItem,          "sized",              sized_trait,             Target::Trait;
    UnsizeTraitLangItem,         "unsize",             unsize_trait,            Target::Trait;
    CopyTraitLangItem,           "copy",               copy_trait,              Target::Trait;
    CloneTraitLangItem,          "clone",              clone_trait,             Target::Trait;
    SyncTraitLangItem,           "sync",               sync_trait,              Target::Trait;
    FreezeTraitLangItem,         "freeze",             freeze_trait,            Target::Trait;

    DropTraitLangItem,           "drop",               drop_trait,              Target::Trait;

    CoerceUnsizedTraitLangItem,  "coerce_unsized",     coerce_unsized_trait,    Target::Trait;

    AddTraitLangItem,            "add",                add_trait,               Target::Trait;
    SubTraitLangItem,            "sub",                sub_trait,               Target::Trait;
    MulTraitLangItem,            "mul",                mul_trait,               Target::Trait;
    DivTraitLangItem,            "div",                div_trait,               Target::Trait;
    RemTraitLangItem,            "rem",                rem_trait,               Target::Trait;
    NegTraitLangItem,            "neg",                neg_trait,               Target::Trait;
    NotTraitLangItem,            "not",                not_trait,               Target::Trait;
    BitXorTraitLangItem,         "bitxor",             bitxor_trait,            Target::Trait;
    BitAndTraitLangItem,         "bitand",             bitand_trait,            Target::Trait;
    BitOrTraitLangItem,          "bitor",              bitor_trait,             Target::Trait;
    ShlTraitLangItem,            "shl",                shl_trait,               Target::Trait;
    ShrTraitLangItem,            "shr",                shr_trait,               Target::Trait;
    AddAssignTraitLangItem,      "add_assign",         add_assign_trait,        Target::Trait;
    SubAssignTraitLangItem,      "sub_assign",         sub_assign_trait,        Target::Trait;
    MulAssignTraitLangItem,      "mul_assign",         mul_assign_trait,        Target::Trait;
    DivAssignTraitLangItem,      "div_assign",         div_assign_trait,        Target::Trait;
    RemAssignTraitLangItem,      "rem_assign",         rem_assign_trait,        Target::Trait;
    BitXorAssignTraitLangItem,   "bitxor_assign",      bitxor_assign_trait,     Target::Trait;
    BitAndAssignTraitLangItem,   "bitand_assign",      bitand_assign_trait,     Target::Trait;
    BitOrAssignTraitLangItem,    "bitor_assign",       bitor_assign_trait,      Target::Trait;
    ShlAssignTraitLangItem,      "shl_assign",         shl_assign_trait,        Target::Trait;
    ShrAssignTraitLangItem,      "shr_assign",         shr_assign_trait,        Target::Trait;
    IndexTraitLangItem,          "index",              index_trait,             Target::Trait;
    IndexMutTraitLangItem,       "index_mut",          index_mut_trait,         Target::Trait;

    UnsafeCellTypeLangItem,      "unsafe_cell",        unsafe_cell_type,        Target::Struct;

    DerefTraitLangItem,          "deref",              deref_trait,             Target::Trait;
    DerefMutTraitLangItem,       "deref_mut",          deref_mut_trait,         Target::Trait;

    FnTraitLangItem,             "fn",                 fn_trait,                Target::Trait;
    FnMutTraitLangItem,          "fn_mut",             fn_mut_trait,            Target::Trait;
    FnOnceTraitLangItem,         "fn_once",            fn_once_trait,           Target::Trait;

    GeneratorStateLangItem,      "generator_state",    gen_state,               Target::Enum;
    GeneratorTraitLangItem,      "generator",          gen_trait,               Target::Trait;

    EqTraitLangItem,             "eq",                 eq_trait,                Target::Trait;
    PartialOrdTraitLangItem,     "partial_ord",        partial_ord_trait,       Target::Trait;
    OrdTraitLangItem,            "ord",                ord_trait,               Target::Trait;

    // A number of panic-related lang items. The `panic` item corresponds to
    // divide-by-zero and various panic cases with `match`. The
    // `panic_bounds_check` item is for indexing arrays.
    //
    // The `begin_unwind` lang item has a predefined symbol name and is sort of
    // a "weak lang item" in the sense that a crate is not required to have it
    // defined to use it, but a final product is required to define it
    // somewhere. Additionally, there are restrictions on crates that use a weak
    // lang item, but do not have it defined.
    PanicFnLangItem,             "panic",              panic_fn,                Target::Fn;
    PanicBoundsCheckFnLangItem,  "panic_bounds_check", panic_bounds_check_fn,   Target::Fn;
    PanicInfoLangItem,           "panic_info",         panic_info,              Target::Struct;
    PanicImplLangItem,           "panic_impl",         panic_impl,              Target::Fn;
    // Libstd panic entry point. Necessary for const eval to be able to catch it
    BeginPanicFnLangItem,        "begin_panic",        begin_panic_fn,          Target::Fn;

    ExchangeMallocFnLangItem,    "exchange_malloc",    exchange_malloc_fn,      Target::Fn;
    BoxFreeFnLangItem,           "box_free",           box_free_fn,             Target::Fn;
    DropInPlaceFnLangItem,       "drop_in_place",      drop_in_place_fn,        Target::Fn;
    OomLangItem,                 "oom",                oom,                     Target::Fn;
    AllocLayoutLangItem,         "alloc_layout",       alloc_layout,            Target::Struct;

    StartFnLangItem,             "start",              start_fn,                Target::Fn;

    EhPersonalityLangItem,       "eh_personality",     eh_personality,          Target::Fn;
    EhUnwindResumeLangItem,      "eh_unwind_resume",   eh_unwind_resume,        Target::Fn;
    MSVCTryFilterLangItem,       "msvc_try_filter",    msvc_try_filter,         Target::Static;

    OwnedBoxLangItem,            "owned_box",          owned_box,               Target::Struct;

    PhantomDataItem,             "phantom_data",       phantom_data,            Target::Struct;

    ManuallyDropItem,            "manually_drop",      manually_drop,           Target::Struct;

    DebugTraitLangItem,          "debug_trait",        debug_trait,             Target::Trait;

    // A lang item for each of the 128-bit operators we can optionally lower.
    I128AddFnLangItem,           "i128_add",           i128_add_fn,             Target::Fn;
    U128AddFnLangItem,           "u128_add",           u128_add_fn,             Target::Fn;
    I128SubFnLangItem,           "i128_sub",           i128_sub_fn,             Target::Fn;
    U128SubFnLangItem,           "u128_sub",           u128_sub_fn,             Target::Fn;
    I128MulFnLangItem,           "i128_mul",           i128_mul_fn,             Target::Fn;
    U128MulFnLangItem,           "u128_mul",           u128_mul_fn,             Target::Fn;
    I128DivFnLangItem,           "i128_div",           i128_div_fn,             Target::Fn;
    U128DivFnLangItem,           "u128_div",           u128_div_fn,             Target::Fn;
    I128RemFnLangItem,           "i128_rem",           i128_rem_fn,             Target::Fn;
    U128RemFnLangItem,           "u128_rem",           u128_rem_fn,             Target::Fn;
    I128ShlFnLangItem,           "i128_shl",           i128_shl_fn,             Target::Fn;
    U128ShlFnLangItem,           "u128_shl",           u128_shl_fn,             Target::Fn;
    I128ShrFnLangItem,           "i128_shr",           i128_shr_fn,             Target::Fn;
    U128ShrFnLangItem,           "u128_shr",           u128_shr_fn,             Target::Fn;
    // And overflow versions for the operators that are checkable.
    // While MIR calls these Checked*, they return (T,bool), not Option<T>.
    I128AddoFnLangItem,          "i128_addo",          i128_addo_fn,            Target::Fn;
    U128AddoFnLangItem,          "u128_addo",          u128_addo_fn,            Target::Fn;
    I128SuboFnLangItem,          "i128_subo",          i128_subo_fn,            Target::Fn;
    U128SuboFnLangItem,          "u128_subo",          u128_subo_fn,            Target::Fn;
    I128MuloFnLangItem,          "i128_mulo",          i128_mulo_fn,            Target::Fn;
    U128MuloFnLangItem,          "u128_mulo",          u128_mulo_fn,            Target::Fn;
    I128ShloFnLangItem,          "i128_shlo",          i128_shlo_fn,            Target::Fn;
    U128ShloFnLangItem,          "u128_shlo",          u128_shlo_fn,            Target::Fn;
    I128ShroFnLangItem,          "i128_shro",          i128_shro_fn,            Target::Fn;
    U128ShroFnLangItem,          "u128_shro",          u128_shro_fn,            Target::Fn;

    // Align offset for stride != 1, must not panic.
    AlignOffsetLangItem,         "align_offset",       align_offset_fn,         Target::Fn;

    TerminationTraitLangItem,    "termination",        termination,             Target::Trait;

    Arc,                         "arc",                arc,                     Target::Struct;
    Rc,                          "rc",                 rc,                      Target::Struct;
}

impl<'a, 'tcx, 'gcx> TyCtxt<'a, 'tcx, 'gcx> {
    pub fn require_lang_item(&self, lang_item: LangItem) -> DefId {
        self.lang_items().require(lang_item).unwrap_or_else(|msg| {
            self.sess.fatal(&msg)
        })
    }
}
Commit	Line	Data
223e47cc LB	1	// Copyright 2012 The Rust Project Developers. See the COPYRIGHT
	2	// file at the top-level directory of this distribution and at
	3	// http://rust-lang.org/COPYRIGHT.
	4	//
	5	// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
	6	// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
	7	// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
	8	// option. This file may not be copied, modified, or distributed
	9	// except according to those terms.
	10
223e47cc LB	11	// Detecting language items.
	12	//
	13	// Language items are items that represent concepts intrinsic to the language
	14	// itself. Examples are:
	15	//
1a4d82fc	16	// * Traits that specify "kinds"; e.g. "Sync", "Send".
223e47cc	17	//
970d7e83	18	// * Traits that represent operators; e.g. "Add", "Sub", "Index".
223e47cc LB	19	//
	20	// * Functions called by the compiler itself.
	21
1a4d82fc	22	pub use self::LangItem::*;
223e47cc	23
54a0048b	24	use hir::def_id::DefId;
0bf4aa26	25	use hir::check_attr::Target;
ea8adc8c	26	use ty::{self, TyCtxt};
1a4d82fc	27	use middle::weak_lang_items;
476ff2be	28	use util::nodemap::FxHashMap;
223e47cc	29
b039eaaf	30	use syntax::ast;
476ff2be	31	use syntax::symbol::Symbol;
2c00a5a8	32	use syntax_pos::Span;
476ff2be	33	use hir::itemlikevisit::ItemLikeVisitor;
54a0048b	34	use hir;
1a4d82fc	35
1a4d82fc JJ	36	// The actual lang items defined come at the end of this file in one handy table.
1a4d82fc JJ	37	// So you probably just want to nip down to the end.
3157f602	38	macro_rules! language_item_table {
1a4d82fc	39	(
0bf4aa26	40	$( $variant:ident, $name:expr, $method:ident, $target:path; )*
1a4d82fc JJ	41	) => {
1a4d82fc JJ	42
9346a6ac	43	enum_from_u32! {
ff7c6d11	44	#[derive(Debug, Copy, Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
9346a6ac AL	45	pub enum LangItem {
	46	$($variant,)*
	47	}
223e47cc LB	48	}
223e47cc LB	49
ea8adc8c XL	50	impl LangItem {
	51	fn name(self) -> &'static str {
	52	match self {
	53	$( $variant => $name, )*
	54	}
	55	}
	56	}
	57
223e47cc	58	pub struct LanguageItems {
e9174d1e	59	pub items: Vec<Option<DefId>>,
1a4d82fc	60	pub missing: Vec<LangItem>,
223e47cc LB	61	}
223e47cc LB	62
970d7e83	63	impl LanguageItems {
223e47cc	64	pub fn new() -> LanguageItems {
e9174d1e	65	fn foo(_: LangItem) -> Option<DefId> { None }
1a4d82fc	66
223e47cc	67	LanguageItems {
c30ab7b3	68	items: vec![$(foo($variant)),*],
1a4d82fc	69	missing: Vec::new(),
223e47cc LB	70	}
	71	}
	72
7453a54e SL	73	pub fn items(&self) -> &[Option<DefId>] {
7453a54e SL	74	&*self.items
223e47cc LB	75	}
223e47cc LB	76
e9174d1e	77	pub fn require(&self, it: LangItem) -> Result<DefId, String> {
ea8adc8c	78	self.items[it as usize].ok_or_else(\|\| format!("requires `{}` lang_item", it.name()))
c1a9b12d SL	79	}
c1a9b12d SL	80
e9174d1e	81	pub fn fn_trait_kind(&self, id: DefId) -> Option<ty::ClosureKind> {
ea8adc8c XL	82	match Some(id) {
	83	x if x == self.fn_trait() => Some(ty::ClosureKind::Fn),
	84	x if x == self.fn_mut_trait() => Some(ty::ClosureKind::FnMut),
	85	x if x == self.fn_once_trait() => Some(ty::ClosureKind::FnOnce),
	86	_ => None
1a4d82fc	87	}
223e47cc	88	}
1a4d82fc JJ	89
	90	$(
	91	#[allow(dead_code)]
e9174d1e	92	pub fn $method(&self) -> Option<DefId> {
c34b1796	93	self.items[$variant as usize]
1a4d82fc JJ	94	}
1a4d82fc JJ	95	)*
223e47cc LB	96	}
223e47cc LB	97
b039eaaf	98	struct LanguageItemCollector<'a, 'tcx: 'a> {
970d7e83	99	items: LanguageItems,
ea8adc8c	100	tcx: TyCtxt<'a, 'tcx, 'tcx>,
0bf4aa26	101	item_refs: FxHashMap<&'static str, (usize, Target)>,
223e47cc LB	102	}
223e47cc LB	103
476ff2be	104	impl<'a, 'v, 'tcx> ItemLikeVisitor<'v> for LanguageItemCollector<'a, 'tcx> {
e9174d1e	105	fn visit_item(&mut self, item: &hir::Item) {
2c00a5a8	106	if let Some((value, span)) = extract(&item.attrs) {
0bf4aa26 XL	107	let actual_target = Target::from_item(item);
	108	match self.item_refs.get(&*value.as_str()).cloned() {
	109	// Known lang item with attribute on correct target.
	110	Some((item_index, expected_target)) if actual_target == expected_target => {
	111	let def_id = self.tcx.hir.local_def_id(item.id);
	112	self.collect_item(item_index, def_id);
	113	},
	114	// Known lang item with attribute on incorrect target.
	115	Some((_, expected_target)) => {
	116	let mut err = struct_span_err!(
	117	self.tcx.sess, span, E0718,
	118	"`{}` language item must be applied to a {}",
	119	value, expected_target,
	120	);
	121	err.span_label(
	122	span,
	123	format!(
	124	"attribute should be applied to a {}, not a {}",
	125	expected_target, actual_target,
	126	),
	127	);
	128	err.emit();
	129	},
	130	// Unknown lang item.
	131	_ => {
	132	let mut err = struct_span_err!(
	133	self.tcx.sess, span, E0522,
	134	"definition of an unknown language item: `{}`",
	135	value
	136	);
	137	err.span_label(
	138	span,
	139	format!("definition of unknown language item `{}`", value)
	140	);
	141	err.emit();
	142	},
1a4d82fc	143	}
1a4d82fc	144	}
1a4d82fc	145	}
476ff2be	146
32a655c1 SL	147	fn visit_trait_item(&mut self, _trait_item: &hir::TraitItem) {
	148	// at present, lang items are always items, not trait items
	149	}
	150
476ff2be SL	151	fn visit_impl_item(&mut self, _impl_item: &hir::ImplItem) {
	152	// at present, lang items are always items, not impl items
	153	}
1a4d82fc JJ	154	}
1a4d82fc JJ	155
b039eaaf	156	impl<'a, 'tcx> LanguageItemCollector<'a, 'tcx> {
ea8adc8c	157	fn new(tcx: TyCtxt<'a, 'tcx, 'tcx>) -> LanguageItemCollector<'a, 'tcx> {
0bf4aa26	158	let mut item_refs = FxHashMap::default();
1a4d82fc	159
0bf4aa26	160	$( item_refs.insert($name, ($variant as usize, $target)); )*
970d7e83 LB	161
970d7e83 LB	162	LanguageItemCollector {
ea8adc8c	163	tcx,
970d7e83	164	items: LanguageItems::new(),
041b39d2	165	item_refs,
970d7e83 LB	166	}
	167	}
	168
ea8adc8c	169	fn collect_item(&mut self, item_index: usize, item_def_id: DefId) {
223e47cc	170	// Check for duplicates.
0bf4aa26 XL	171	if let Some(original_def_id) = self.items.items[item_index] {
0bf4aa26 XL	172	if original_def_id != item_def_id {
ea8adc8c XL	173	let name = LangItem::from_u32(item_index as u32).unwrap().name();
ea8adc8c XL	174	let mut err = match self.tcx.hir.span_if_local(item_def_id) {
a7813a04	175	Some(span) => struct_span_err!(
ea8adc8c	176	self.tcx.sess,
a7813a04 XL	177	span,
	178	E0152,
	179	"duplicate lang item found: `{}`.",
	180	name),
ea8adc8c	181	None => self.tcx.sess.struct_err(&format!(
a7813a04	182	"duplicate lang item in crate `{}`: `{}`.",
ea8adc8c	183	self.tcx.crate_name(item_def_id.krate),
a7813a04 XL	184	name)),
a7813a04 XL	185	};
ea8adc8c	186	if let Some(span) = self.tcx.hir.span_if_local(original_def_id) {
0bf4aa26	187	span_note!(&mut err, span, "first defined here.");
54a0048b SL	188	} else {
54a0048b SL	189	err.note(&format!("first defined in crate `{}`.",
ea8adc8c	190	self.tcx.crate_name(original_def_id.krate)));
54a0048b SL	191	}
54a0048b SL	192	err.emit();
223e47cc	193	}
223e47cc LB	194	}
	195
	196	// Matched.
	197	self.items.items[item_index] = Some(item_def_id);
	198	}
1a4d82fc	199	}
223e47cc	200
2c00a5a8	201	pub fn extract(attrs: &[ast::Attribute]) -> Option<(Symbol, Span)> {
85aaf69f	202	for attribute in attrs {
cc61c64b XL	203	if attribute.check_name("lang") {
cc61c64b XL	204	if let Some(value) = attribute.value_str() {
2c00a5a8	205	return Some((value, attribute.span));
cc61c64b	206	}
b7449926 XL	207	} else if attribute.check_name("panic_implementation") \|\|
	208	attribute.check_name("panic_handler")
	209	{
94b46f34	210	return Some((Symbol::intern("panic_impl"), attribute.span))
8faf50e0 XL	211	} else if attribute.check_name("alloc_error_handler") {
8faf50e0 XL	212	return Some((Symbol::intern("oom"), attribute.span))
223e47cc LB	213	}
	214	}
	215
0bf4aa26	216	None
223e47cc LB	217	}
223e47cc LB	218
ea8adc8c XL	219	pub fn collect<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>) -> LanguageItems {
	220	let mut collector = LanguageItemCollector::new(tcx);
	221	for &cnum in tcx.crates().iter() {
	222	for &(def_id, item_index) in tcx.defined_lang_items(cnum).iter() {
	223	collector.collect_item(item_index, def_id);
	224	}
	225	}
	226	tcx.hir.krate().visit_all_item_likes(&mut collector);
1a4d82fc	227	let LanguageItemCollector { mut items, .. } = collector;
ea8adc8c	228	weak_lang_items::check_crate(tcx, &mut items);
970d7e83	229	items
223e47cc	230	}
1a4d82fc JJ	231
	232	// End of the macro
	233	}
	234	}
	235
3157f602	236	language_item_table! {
0bf4aa26 XL	237	// Variant name, Name, Method name, Target;
	238	CharImplItem, "char", char_impl, Target::Impl;
	239	StrImplItem, "str", str_impl, Target::Impl;
	240	SliceImplItem, "slice", slice_impl, Target::Impl;
	241	SliceU8ImplItem, "slice_u8", slice_u8_impl, Target::Impl;
	242	StrAllocImplItem, "str_alloc", str_alloc_impl, Target::Impl;
	243	SliceAllocImplItem, "slice_alloc", slice_alloc_impl, Target::Impl;
	244	SliceU8AllocImplItem, "slice_u8_alloc", slice_u8_alloc_impl, Target::Impl;
	245	ConstPtrImplItem, "const_ptr", const_ptr_impl, Target::Impl;
	246	MutPtrImplItem, "mut_ptr", mut_ptr_impl, Target::Impl;
	247	I8ImplItem, "i8", i8_impl, Target::Impl;
	248	I16ImplItem, "i16", i16_impl, Target::Impl;
	249	I32ImplItem, "i32", i32_impl, Target::Impl;
	250	I64ImplItem, "i64", i64_impl, Target::Impl;
	251	I128ImplItem, "i128", i128_impl, Target::Impl;
	252	IsizeImplItem, "isize", isize_impl, Target::Impl;
	253	U8ImplItem, "u8", u8_impl, Target::Impl;
	254	U16ImplItem, "u16", u16_impl, Target::Impl;
	255	U32ImplItem, "u32", u32_impl, Target::Impl;
	256	U64ImplItem, "u64", u64_impl, Target::Impl;
	257	U128ImplItem, "u128", u128_impl, Target::Impl;
	258	UsizeImplItem, "usize", usize_impl, Target::Impl;
	259	F32ImplItem, "f32", f32_impl, Target::Impl;
	260	F64ImplItem, "f64", f64_impl, Target::Impl;
	261	F32RuntimeImplItem, "f32_runtime", f32_runtime_impl, Target::Impl;
	262	F64RuntimeImplItem, "f64_runtime", f64_runtime_impl, Target::Impl;
	263
	264	SizedTraitLangItem, "sized", sized_trait, Target::Trait;
	265	UnsizeTraitLangItem, "unsize", unsize_trait, Target::Trait;
	266	CopyTraitLangItem, "copy", copy_trait, Target::Trait;
	267	CloneTraitLangItem, "clone", clone_trait, Target::Trait;
	268	SyncTraitLangItem, "sync", sync_trait, Target::Trait;
	269	FreezeTraitLangItem, "freeze", freeze_trait, Target::Trait;
	270
	271	DropTraitLangItem, "drop", drop_trait, Target::Trait;
	272
	273	CoerceUnsizedTraitLangItem, "coerce_unsized", coerce_unsized_trait, Target::Trait;
	274
	275	AddTraitLangItem, "add", add_trait, Target::Trait;
	276	SubTraitLangItem, "sub", sub_trait, Target::Trait;
	277	MulTraitLangItem, "mul", mul_trait, Target::Trait;
	278	DivTraitLangItem, "div", div_trait, Target::Trait;
	279	RemTraitLangItem, "rem", rem_trait, Target::Trait;
	280	NegTraitLangItem, "neg", neg_trait, Target::Trait;
	281	NotTraitLangItem, "not", not_trait, Target::Trait;
	282	BitXorTraitLangItem, "bitxor", bitxor_trait, Target::Trait;
	283	BitAndTraitLangItem, "bitand", bitand_trait, Target::Trait;
	284	BitOrTraitLangItem, "bitor", bitor_trait, Target::Trait;
	285	ShlTraitLangItem, "shl", shl_trait, Target::Trait;
	286	ShrTraitLangItem, "shr", shr_trait, Target::Trait;
	287	AddAssignTraitLangItem, "add_assign", add_assign_trait, Target::Trait;
	288	SubAssignTraitLangItem, "sub_assign", sub_assign_trait, Target::Trait;
	289	MulAssignTraitLangItem, "mul_assign", mul_assign_trait, Target::Trait;
	290	DivAssignTraitLangItem, "div_assign", div_assign_trait, Target::Trait;
	291	RemAssignTraitLangItem, "rem_assign", rem_assign_trait, Target::Trait;
	292	BitXorAssignTraitLangItem, "bitxor_assign", bitxor_assign_trait, Target::Trait;
	293	BitAndAssignTraitLangItem, "bitand_assign", bitand_assign_trait, Target::Trait;
	294	BitOrAssignTraitLangItem, "bitor_assign", bitor_assign_trait, Target::Trait;
	295	ShlAssignTraitLangItem, "shl_assign", shl_assign_trait, Target::Trait;
	296	ShrAssignTraitLangItem, "shr_assign", shr_assign_trait, Target::Trait;
	297	IndexTraitLangItem, "index", index_trait, Target::Trait;
	298	IndexMutTraitLangItem, "index_mut", index_mut_trait, Target::Trait;
	299
	300	UnsafeCellTypeLangItem, "unsafe_cell", unsafe_cell_type, Target::Struct;
301
302	DerefTraitLangItem, "deref", deref_trait, Target::Trait;
303	DerefMutTraitLangItem, "deref_mut", deref_mut_trait, Target::Trait;
304
305	FnTraitLangItem, "fn", fn_trait, Target::Trait;
306	FnMutTraitLangItem, "fn_mut", fn_mut_trait, Target::Trait;
307	FnOnceTraitLangItem, "fn_once", fn_once_trait, Target::Trait;
308
309	GeneratorStateLangItem, "generator_state", gen_state, Target::Enum;
310	GeneratorTraitLangItem, "generator", gen_trait, Target::Trait;
311
312	EqTraitLangItem, "eq", eq_trait, Target::Trait;
313	PartialOrdTraitLangItem, "partial_ord", partial_ord_trait, Target::Trait;
314	OrdTraitLangItem, "ord", ord_trait, Target::Trait;
1a4d82fc	315
1a4d82fc JJ	316	// A number of panic-related lang items. The `panic` item corresponds to
	317	// divide-by-zero and various panic cases with `match`. The
	318	// `panic_bounds_check` item is for indexing arrays.
	319	//
	320	// The `begin_unwind` lang item has a predefined symbol name and is sort of
	321	// a "weak lang item" in the sense that a crate is not required to have it
	322	// defined to use it, but a final product is required to define it
	323	// somewhere. Additionally, there are restrictions on crates that use a weak
	324	// lang item, but do not have it defined.
0bf4aa26 XL	325	PanicFnLangItem, "panic", panic_fn, Target::Fn;
	326	PanicBoundsCheckFnLangItem, "panic_bounds_check", panic_bounds_check_fn, Target::Fn;
	327	PanicInfoLangItem, "panic_info", panic_info, Target::Struct;
	328	PanicImplLangItem, "panic_impl", panic_impl, Target::Fn;
b7449926	329	// Libstd panic entry point. Necessary for const eval to be able to catch it
0bf4aa26	330	BeginPanicFnLangItem, "begin_panic", begin_panic_fn, Target::Fn;
1a4d82fc	331
0bf4aa26 XL	332	ExchangeMallocFnLangItem, "exchange_malloc", exchange_malloc_fn, Target::Fn;
	333	BoxFreeFnLangItem, "box_free", box_free_fn, Target::Fn;
	334	DropInPlaceFnLangItem, "drop_in_place", drop_in_place_fn, Target::Fn;
	335	OomLangItem, "oom", oom, Target::Fn;
	336	AllocLayoutLangItem, "alloc_layout", alloc_layout, Target::Struct;
1a4d82fc	337
0bf4aa26	338	StartFnLangItem, "start", start_fn, Target::Fn;
1a4d82fc	339
0bf4aa26 XL	340	EhPersonalityLangItem, "eh_personality", eh_personality, Target::Fn;
	341	EhUnwindResumeLangItem, "eh_unwind_resume", eh_unwind_resume, Target::Fn;
	342	MSVCTryFilterLangItem, "msvc_try_filter", msvc_try_filter, Target::Static;
1a4d82fc	343
0bf4aa26	344	OwnedBoxLangItem, "owned_box", owned_box, Target::Struct;
1a4d82fc	345
0bf4aa26	346	PhantomDataItem, "phantom_data", phantom_data, Target::Struct;
85aaf69f	347
0bf4aa26	348	ManuallyDropItem, "manually_drop", manually_drop, Target::Struct;
8faf50e0	349
0bf4aa26	350	DebugTraitLangItem, "debug_trait", debug_trait, Target::Trait;
ff7c6d11 XL	351
ff7c6d11 XL	352	// A lang item for each of the 128-bit operators we can optionally lower.
0bf4aa26 XL	353	I128AddFnLangItem, "i128_add", i128_add_fn, Target::Fn;
	354	U128AddFnLangItem, "u128_add", u128_add_fn, Target::Fn;
	355	I128SubFnLangItem, "i128_sub", i128_sub_fn, Target::Fn;
	356	U128SubFnLangItem, "u128_sub", u128_sub_fn, Target::Fn;
	357	I128MulFnLangItem, "i128_mul", i128_mul_fn, Target::Fn;
	358	U128MulFnLangItem, "u128_mul", u128_mul_fn, Target::Fn;
	359	I128DivFnLangItem, "i128_div", i128_div_fn, Target::Fn;
	360	U128DivFnLangItem, "u128_div", u128_div_fn, Target::Fn;
	361	I128RemFnLangItem, "i128_rem", i128_rem_fn, Target::Fn;
	362	U128RemFnLangItem, "u128_rem", u128_rem_fn, Target::Fn;
	363	I128ShlFnLangItem, "i128_shl", i128_shl_fn, Target::Fn;
	364	U128ShlFnLangItem, "u128_shl", u128_shl_fn, Target::Fn;
	365	I128ShrFnLangItem, "i128_shr", i128_shr_fn, Target::Fn;
	366	U128ShrFnLangItem, "u128_shr", u128_shr_fn, Target::Fn;
ff7c6d11 XL	367	// And overflow versions for the operators that are checkable.
ff7c6d11 XL	368	// While MIR calls these Checked*, they return (T,bool), not Option<T>.
0bf4aa26 XL	369	I128AddoFnLangItem, "i128_addo", i128_addo_fn, Target::Fn;
	370	U128AddoFnLangItem, "u128_addo", u128_addo_fn, Target::Fn;
	371	I128SuboFnLangItem, "i128_subo", i128_subo_fn, Target::Fn;
	372	U128SuboFnLangItem, "u128_subo", u128_subo_fn, Target::Fn;
	373	I128MuloFnLangItem, "i128_mulo", i128_mulo_fn, Target::Fn;
	374	U128MuloFnLangItem, "u128_mulo", u128_mulo_fn, Target::Fn;
	375	I128ShloFnLangItem, "i128_shlo", i128_shlo_fn, Target::Fn;
	376	U128ShloFnLangItem, "u128_shlo", u128_shlo_fn, Target::Fn;
	377	I128ShroFnLangItem, "i128_shro", i128_shro_fn, Target::Fn;
	378	U128ShroFnLangItem, "u128_shro", u128_shro_fn, Target::Fn;
ff7c6d11	379
94b46f34	380	// Align offset for stride != 1, must not panic.
0bf4aa26 XL	381	AlignOffsetLangItem, "align_offset", align_offset_fn, Target::Fn;
	382
	383	TerminationTraitLangItem, "termination", termination, Target::Trait;
94b46f34	384
0bf4aa26 XL	385	Arc, "arc", arc, Target::Struct;
0bf4aa26 XL	386	Rc, "rc", rc, Target::Struct;
1a4d82fc	387	}
476ff2be	388
ea8adc8c	389	impl<'a, 'tcx, 'gcx> TyCtxt<'a, 'tcx, 'gcx> {
476ff2be	390	pub fn require_lang_item(&self, lang_item: LangItem) -> DefId {
ea8adc8c	391	self.lang_items().require(lang_item).unwrap_or_else(\|msg\| {
476ff2be SL	392	self.sess.fatal(&msg)
	393	})
	394	}
	395	}