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_data_structures::fx::FxHashSet;
17 use rustc_target::spec::PanicStrategy;
19 use syntax::symbol::Symbol;
21 use hir::def_id::DefId;
22 use hir::intravisit::{Visitor, NestedVisitorMap};
27 macro_rules! weak_lang_items {
28 ($($name:ident, $item:ident, $sym:ident;)*) => (
30 struct Context<'a, 'tcx: 'a> {
31 tcx: TyCtxt<'a, 'tcx, 'tcx>,
32 items: &'a mut lang_items::LanguageItems,
35 /// Checks the crate for usage of weak lang items, returning a vector of all the
36 /// language items required by this crate, but not defined yet.
37 pub fn check_crate<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
38 items: &mut lang_items::LanguageItems) {
39 // These are never called by user code, they're generated by the compiler.
40 // They will never implicitly be added to the `missing` array unless we do
42 if items.eh_personality().is_none() {
43 items.missing.push(lang_items::EhPersonalityLangItem);
45 if tcx.sess.target.target.options.custom_unwind_resume &
46 items.eh_unwind_resume().is_none() {
47 items.missing.push(lang_items::EhUnwindResumeLangItem);
51 let mut cx = Context { tcx, items };
52 tcx.hir.krate().visit_all_item_likes(&mut cx.as_deep_visitor());
57 pub fn link_name(attrs: &[ast::Attribute]) -> Option<Symbol> {
58 lang_items::extract(attrs).and_then(|(name, _)| {
59 $(if name == stringify!($name) {
60 Some(Symbol::intern(stringify!($sym)))
67 /// Returns whether the specified `lang_item` doesn't actually need to be
68 /// present for this compilation.
70 /// Not all lang items are always required for each compilation, particularly in
71 /// the case of panic=abort. In these situations some lang items are injected by
72 /// crates and don't actually need to be defined in libstd.
73 pub fn whitelisted(tcx: TyCtxt, lang_item: lang_items::LangItem) -> bool {
74 // If we're not compiling with unwinding, we won't actually need these
75 // symbols. Other panic runtimes ensure that the relevant symbols are
76 // available to link things together, but they're never exercised.
77 if tcx.sess.panic_strategy() != PanicStrategy::Unwind {
78 return lang_item == lang_items::EhPersonalityLangItem ||
79 lang_item == lang_items::EhUnwindResumeLangItem
85 fn verify<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
86 items: &lang_items::LanguageItems) {
87 // We only need to check for the presence of weak lang items if we're
88 // emitting something that's not an rlib.
89 let needs_check = tcx.sess.crate_types.borrow().iter().any(|kind| {
91 config::CrateType::Dylib |
92 config::CrateType::ProcMacro |
93 config::CrateType::Cdylib |
94 config::CrateType::Executable |
95 config::CrateType::Staticlib => true,
96 config::CrateType::Rlib => false,
103 let mut missing = FxHashSet::default();
104 for &cnum in tcx.crates().iter() {
105 for &item in tcx.missing_lang_items(cnum).iter() {
106 missing.insert(item);
111 if missing.contains(&lang_items::$item) &&
112 !whitelisted(tcx, lang_items::$item) &&
113 items.$name().is_none() {
114 if lang_items::$item == lang_items::PanicImplLangItem {
115 tcx.sess.err(&format!("`#[panic_handler]` function required, \
117 } else if lang_items::$item == lang_items::OomLangItem {
118 tcx.sess.err(&format!("`#[alloc_error_handler]` function required, \
121 tcx.sess.err(&format!("language item required, but not found: `{}`",
128 impl<'a, 'tcx> Context<'a, 'tcx> {
129 fn register(&mut self, name: &str, span: Span) {
130 $(if name == stringify!($name) {
131 if self.items.$name().is_none() {
132 self.items.missing.push(lang_items::$item);
135 span_err!(self.tcx.sess, span, E0264,
136 "unknown external lang item: `{}`",
142 impl<'a, 'tcx, 'v> Visitor<'v> for Context<'a, 'tcx> {
143 fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'v> {
144 NestedVisitorMap::None
147 fn visit_foreign_item(&mut self, i: &hir::ForeignItem) {
148 if let Some((lang_item, _)) = lang_items::extract(&i.attrs) {
149 self.register(&lang_item.as_str(), i.span);
151 intravisit::walk_foreign_item(self, i)
155 impl<'a, 'tcx, 'gcx> TyCtxt<'a, 'tcx, 'gcx> {
156 pub fn is_weak_lang_item(&self, item_def_id: DefId) -> bool {
157 let lang_items = self.lang_items();
158 let did = Some(item_def_id);
160 $(lang_items.$name() == did)||+
167 panic_impl, PanicImplLangItem, rust_begin_unwind;
168 eh_personality, EhPersonalityLangItem, rust_eh_personality;
169 eh_unwind_resume, EhUnwindResumeLangItem, rust_eh_unwind_resume;
170 oom, OomLangItem, rust_oom;