1 // Copyright 2014 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.
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.
11 //! Validity checking for weak lang items
14 use middle::lang_items;
16 use rustc_target::spec::PanicStrategy;
18 use syntax::symbol::Symbol;
20 use hir::def_id::DefId;
21 use hir::intravisit::{Visitor, NestedVisitorMap};
26 use std::collections::HashSet;
28 macro_rules! weak_lang_items {
29 ($($name:ident, $item:ident, $sym:ident;)*) => (
31 struct Context<'a, 'tcx: 'a> {
32 tcx: TyCtxt<'a, 'tcx, 'tcx>,
33 items: &'a mut lang_items::LanguageItems,
36 /// Checks the crate for usage of weak lang items, returning a vector of all the
37 /// language items required by this crate, but not defined yet.
38 pub fn check_crate<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
39 items: &mut lang_items::LanguageItems) {
40 // These are never called by user code, they're generated by the compiler.
41 // They will never implicitly be added to the `missing` array unless we do
43 if items.eh_personality().is_none() {
44 items.missing.push(lang_items::EhPersonalityLangItem);
46 if tcx.sess.target.target.options.custom_unwind_resume &
47 items.eh_unwind_resume().is_none() {
48 items.missing.push(lang_items::EhUnwindResumeLangItem);
52 let mut cx = Context { tcx, items };
53 tcx.hir.krate().visit_all_item_likes(&mut cx.as_deep_visitor());
58 pub fn link_name(attrs: &[ast::Attribute]) -> Option<Symbol> {
59 lang_items::extract(attrs).and_then(|(name, _)| {
60 $(if name == stringify!($name) {
61 Some(Symbol::intern(stringify!($sym)))
68 /// Returns whether the specified `lang_item` doesn't actually need to be
69 /// present for this compilation.
71 /// Not all lang items are always required for each compilation, particularly in
72 /// the case of panic=abort. In these situations some lang items are injected by
73 /// crates and don't actually need to be defined in libstd.
74 pub fn whitelisted(tcx: TyCtxt, lang_item: lang_items::LangItem) -> bool {
75 // If we're not compiling with unwinding, we won't actually need these
76 // symbols. Other panic runtimes ensure that the relevant symbols are
77 // available to link things together, but they're never exercised.
78 if tcx.sess.panic_strategy() != PanicStrategy::Unwind {
79 return lang_item == lang_items::EhPersonalityLangItem ||
80 lang_item == lang_items::EhUnwindResumeLangItem
86 fn verify<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
87 items: &lang_items::LanguageItems) {
88 // We only need to check for the presence of weak lang items if we're
89 // emitting something that's not an rlib.
90 let needs_check = tcx.sess.crate_types.borrow().iter().any(|kind| {
92 config::CrateTypeDylib |
93 config::CrateTypeProcMacro |
94 config::CrateTypeCdylib |
95 config::CrateTypeExecutable |
96 config::CrateTypeStaticlib => true,
97 config::CrateTypeRlib => false,
104 let mut missing = HashSet::new();
105 for &cnum in tcx.crates().iter() {
106 for &item in tcx.missing_lang_items(cnum).iter() {
107 missing.insert(item);
112 if missing.contains(&lang_items::$item) &&
113 !whitelisted(tcx, lang_items::$item) &&
114 items.$name().is_none() {
115 if lang_items::$item == lang_items::PanicImplLangItem {
116 tcx.sess.err(&format!("`#[panic_implementation]` function required, \
118 } else if lang_items::$item == lang_items::OomLangItem {
119 tcx.sess.err(&format!("`#[alloc_error_handler]` function required, \
122 tcx.sess.err(&format!("language item required, but not found: `{}`",
129 impl<'a, 'tcx> Context<'a, 'tcx> {
130 fn register(&mut self, name: &str, span: Span) {
131 $(if name == stringify!($name) {
132 if self.items.$name().is_none() {
133 self.items.missing.push(lang_items::$item);
136 span_err!(self.tcx.sess, span, E0264,
137 "unknown external lang item: `{}`",
143 impl<'a, 'tcx, 'v> Visitor<'v> for Context<'a, 'tcx> {
144 fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'v> {
145 NestedVisitorMap::None
148 fn visit_foreign_item(&mut self, i: &hir::ForeignItem) {
149 if let Some((lang_item, _)) = lang_items::extract(&i.attrs) {
150 self.register(&lang_item.as_str(), i.span);
152 intravisit::walk_foreign_item(self, i)
156 impl<'a, 'tcx, 'gcx> TyCtxt<'a, 'tcx, 'gcx> {
157 pub fn is_weak_lang_item(&self, item_def_id: DefId) -> bool {
158 let lang_items = self.lang_items();
159 let did = Some(item_def_id);
161 $(lang_items.$name() == did)||+
168 panic_impl, PanicImplLangItem, rust_begin_unwind;
169 eh_personality, EhPersonalityLangItem, rust_eh_personality;
170 eh_unwind_resume, EhUnwindResumeLangItem, rust_eh_unwind_resume;
171 oom, OomLangItem, rust_oom;