1 //! Validity checking for weak lang items
3 use rustc_data_structures::fx::FxHashSet;
4 use rustc_errors::struct_span_err;
6 use rustc_hir::intravisit::{self, NestedVisitorMap, Visitor};
7 use rustc_hir::lang_items;
8 use rustc_hir::weak_lang_items::WEAK_ITEMS_REFS;
9 use rustc_middle::middle::lang_items::whitelisted;
10 use rustc_middle::ty::TyCtxt;
11 use rustc_session::config;
12 use rustc_span::symbol::Symbol;
15 struct Context<'a, 'tcx> {
17 items: &'a mut lang_items::LanguageItems,
20 /// Checks the crate for usage of weak lang items, returning a vector of all the
21 /// language items required by this crate, but not defined yet.
22 pub fn check_crate<'tcx>(tcx: TyCtxt<'tcx>, items: &mut lang_items::LanguageItems) {
23 // These are never called by user code, they're generated by the compiler.
24 // They will never implicitly be added to the `missing` array unless we do
26 if items.eh_personality().is_none() {
27 items.missing.push(lang_items::EhPersonalityLangItem);
31 let mut cx = Context { tcx, items };
32 tcx.hir().krate().visit_all_item_likes(&mut cx.as_deep_visitor());
37 fn verify<'tcx>(tcx: TyCtxt<'tcx>, items: &lang_items::LanguageItems) {
38 // We only need to check for the presence of weak lang items if we're
39 // emitting something that's not an rlib.
40 let needs_check = tcx.sess.crate_types.borrow().iter().any(|kind| match *kind {
41 config::CrateType::Dylib
42 | config::CrateType::ProcMacro
43 | config::CrateType::Cdylib
44 | config::CrateType::Executable
45 | config::CrateType::Staticlib => true,
46 config::CrateType::Rlib => false,
52 let mut missing = FxHashSet::default();
53 for &cnum in tcx.crates().iter() {
54 for &item in tcx.missing_lang_items(cnum).iter() {
59 for (name, &item) in WEAK_ITEMS_REFS.iter() {
60 if missing.contains(&item) && !whitelisted(tcx, item) && items.require(item).is_err() {
61 if item == lang_items::PanicImplLangItem {
62 tcx.sess.err("`#[panic_handler]` function required, but not found");
63 } else if item == lang_items::OomLangItem {
64 tcx.sess.err("`#[alloc_error_handler]` function required, but not found");
66 tcx.sess.err(&format!("language item required, but not found: `{}`", name));
72 impl<'a, 'tcx> Context<'a, 'tcx> {
73 fn register(&mut self, name: Symbol, span: Span) {
74 if let Some(&item) = WEAK_ITEMS_REFS.get(&name) {
75 if self.items.require(item).is_err() {
76 self.items.missing.push(item);
79 struct_span_err!(self.tcx.sess, span, E0264, "unknown external lang item: `{}`", name)
85 impl<'a, 'tcx, 'v> Visitor<'v> for Context<'a, 'tcx> {
86 type Map = intravisit::ErasedMap<'v>;
88 fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
89 NestedVisitorMap::None
92 fn visit_foreign_item(&mut self, i: &hir::ForeignItem<'_>) {
93 if let Some((lang_item, _)) = hir::lang_items::extract(&i.attrs) {
94 self.register(lang_item, i.span);
96 intravisit::walk_foreign_item(self, i)