1 //! Validity checking for weak lang items
3 use rustc_ast::Attribute;
4 use rustc_data_structures::fx::FxHashSet;
5 use rustc_errors::struct_span_err;
7 use rustc_hir::intravisit::{self, NestedVisitorMap, Visitor};
8 use rustc_hir::lang_items::{self, LangItem};
9 use rustc_hir::weak_lang_items::WEAK_ITEMS_REFS;
10 use rustc_middle::middle::lang_items::required;
11 use rustc_middle::ty::TyCtxt;
12 use rustc_session::config::CrateType;
13 use rustc_span::symbol::Symbol;
16 struct Context<'a, 'tcx> {
18 items: &'a mut lang_items::LanguageItems,
21 /// Checks the crate for usage of weak lang items, returning a vector of all the
22 /// language items required by this crate, but not defined yet.
23 pub fn check_crate<'tcx>(tcx: TyCtxt<'tcx>, items: &mut lang_items::LanguageItems) {
24 // These are never called by user code, they're generated by the compiler.
25 // They will never implicitly be added to the `missing` array unless we do
27 if items.eh_personality().is_none() {
28 items.missing.push(LangItem::EhPersonality);
30 if tcx.sess.target.is_like_emscripten && items.eh_catch_typeinfo().is_none() {
31 items.missing.push(LangItem::EhCatchTypeinfo);
35 let mut cx = Context { tcx, items };
36 tcx.hir().krate().visit_all_item_likes(&mut cx.as_deep_visitor());
41 fn verify<'tcx>(tcx: TyCtxt<'tcx>, items: &lang_items::LanguageItems) {
42 // We only need to check for the presence of weak lang items if we're
43 // emitting something that's not an rlib.
44 let needs_check = tcx.sess.crate_types().iter().any(|kind| match *kind {
46 | CrateType::ProcMacro
48 | CrateType::Executable
49 | CrateType::Staticlib => true,
50 CrateType::Rlib => false,
56 let mut missing = FxHashSet::default();
57 for &cnum in tcx.crates(()).iter() {
58 for &item in tcx.missing_lang_items(cnum).iter() {
63 for (name, item) in WEAK_ITEMS_REFS.clone().into_sorted_vector().into_iter() {
64 if missing.contains(&item) && required(tcx, item) && items.require(item).is_err() {
65 if item == LangItem::PanicImpl {
66 tcx.sess.err("`#[panic_handler]` function required, but not found");
67 } else if item == LangItem::Oom {
68 if !tcx.features().default_alloc_error_handler {
69 tcx.sess.err("`#[alloc_error_handler]` function required, but not found.");
70 tcx.sess.note_without_error("Use `#![feature(default_alloc_error_handler)]` for a default error handler.");
73 tcx.sess.err(&format!("language item required, but not found: `{}`", name));
79 impl<'a, 'tcx> Context<'a, 'tcx> {
80 fn register(&mut self, name: Symbol, span: Span) {
81 if let Some(&item) = WEAK_ITEMS_REFS.get(&name) {
82 if self.items.require(item).is_err() {
83 self.items.missing.push(item);
86 struct_span_err!(self.tcx.sess, span, E0264, "unknown external lang item: `{}`", name)
92 impl<'a, 'tcx, 'v> Visitor<'v> for Context<'a, 'tcx> {
93 type Map = intravisit::ErasedMap<'v>;
95 fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
96 NestedVisitorMap::None
99 fn visit_foreign_item(&mut self, i: &hir::ForeignItem<'_>) {
100 let check_name = |attr: &Attribute, sym| attr.has_name(sym);
101 let attrs = self.tcx.hir().attrs(i.hir_id());
102 if let Some((lang_item, _)) = lang_items::extract(check_name, attrs) {
103 self.register(lang_item, i.span);
105 intravisit::walk_foreign_item(self, i)