rustc_passes/
weak_lang_items.rs
1use rustc_ast as ast;
4use rustc_ast::visit;
5use rustc_data_structures::fx::FxHashSet;
6use rustc_hir::lang_items::{self, LangItem};
7use rustc_hir::weak_lang_items::WEAK_LANG_ITEMS;
8use rustc_middle::middle::lang_items::required;
9use rustc_middle::ty::TyCtxt;
10use rustc_session::config::CrateType;
11
12use crate::errors::{
13 MissingLangItem, MissingPanicHandler, PanicUnwindWithoutStd, UnknownExternLangItem,
14};
15
16pub(crate) fn check_crate(
19 tcx: TyCtxt<'_>,
20 items: &mut lang_items::LanguageItems,
21 krate: &ast::Crate,
22) {
23 if items.eh_personality().is_none() {
27 items.missing.push(LangItem::EhPersonality);
28 }
29 if tcx.sess.target.os == "emscripten"
30 && items.eh_catch_typeinfo().is_none()
31 && !tcx.sess.opts.unstable_opts.emscripten_wasm_eh
32 {
33 items.missing.push(LangItem::EhCatchTypeinfo);
34 }
35
36 visit::Visitor::visit_crate(&mut WeakLangItemVisitor { tcx, items }, krate);
37
38 verify(tcx, items);
39}
40
41struct WeakLangItemVisitor<'a, 'tcx> {
42 tcx: TyCtxt<'tcx>,
43 items: &'a mut lang_items::LanguageItems,
44}
45
46impl<'ast> visit::Visitor<'ast> for WeakLangItemVisitor<'_, '_> {
47 fn visit_foreign_item(&mut self, i: &'ast ast::ForeignItem) {
48 if let Some((lang_item, _)) = lang_items::extract(&i.attrs) {
49 if let Some(item) = LangItem::from_name(lang_item)
50 && item.is_weak()
51 {
52 if self.items.get(item).is_none() {
53 self.items.missing.push(item);
54 }
55 } else {
56 self.tcx.dcx().emit_err(UnknownExternLangItem { span: i.span, lang_item });
57 }
58 }
59 }
60}
61
62fn verify(tcx: TyCtxt<'_>, items: &lang_items::LanguageItems) {
63 let needs_check = tcx.crate_types().iter().any(|kind| match *kind {
66 CrateType::Dylib
67 | CrateType::ProcMacro
68 | CrateType::Cdylib
69 | CrateType::Executable
70 | CrateType::Staticlib => true,
71 CrateType::Rlib => false,
72 });
73 if !needs_check {
74 return;
75 }
76
77 let mut missing = FxHashSet::default();
78 for &cnum in tcx.crates(()).iter() {
79 for &item in tcx.missing_lang_items(cnum).iter() {
80 missing.insert(item);
81 }
82 }
83
84 for &item in WEAK_LANG_ITEMS.iter() {
85 if missing.contains(&item) && required(tcx, item) && items.get(item).is_none() {
86 if item == LangItem::PanicImpl {
87 tcx.dcx().emit_err(MissingPanicHandler);
88 } else if item == LangItem::EhPersonality {
89 tcx.dcx().emit_err(PanicUnwindWithoutStd);
90 } else {
91 tcx.dcx().emit_err(MissingLangItem { name: item.name() });
92 }
93 }
94 }
95}