1 files changed, 70 insertions, 0 deletions
diff --git a/compiler/rustc_symbol_mangling/src/test.rs b/compiler/rustc_symbol_mangling/src/test.rs
new file mode 100644
index 00000000000..24850a8a0d2
--- /dev/null
+++ b/compiler/rustc_symbol_mangling/src/test.rs
@@ -0,0 +1,70 @@
+//! Walks the crate looking for items/impl-items/trait-items that have
+//! either a `rustc_symbol_name` or `rustc_def_path` attribute and
+//! generates an error giving, respectively, the symbol name or
+//! def-path. This is used for unit testing the code that generates
+//! paths etc in all kinds of annoying scenarios.
+
+use rustc_hir as hir;
+use rustc_middle::ty::{Instance, TyCtxt};
+use rustc_span::symbol::{sym, Symbol};
+
+const SYMBOL_NAME: Symbol = sym::rustc_symbol_name;
+const DEF_PATH: Symbol = sym::rustc_def_path;
+
+pub fn report_symbol_names(tcx: TyCtxt<'_>) {
+    // if the `rustc_attrs` feature is not enabled, then the
+    // attributes we are interested in cannot be present anyway, so
+    // skip the walk.
+    if !tcx.features().rustc_attrs {
+        return;
+    }
+
+    tcx.dep_graph.with_ignore(|| {
+        let mut visitor = SymbolNamesTest { tcx };
+        tcx.hir().krate().visit_all_item_likes(&mut visitor);
+    })
+}
+
+struct SymbolNamesTest<'tcx> {
+    tcx: TyCtxt<'tcx>,
+}
+
+impl SymbolNamesTest<'tcx> {
+    fn process_attrs(&mut self, hir_id: hir::HirId) {
+        let tcx = self.tcx;
+        let def_id = tcx.hir().local_def_id(hir_id);
+        for attr in tcx.get_attrs(def_id.to_def_id()).iter() {
+            if tcx.sess.check_name(attr, SYMBOL_NAME) {
+                // for now, can only use on monomorphic names
+                let instance = Instance::mono(tcx, def_id.to_def_id());
+                let mangled = tcx.symbol_name(instance);
+                tcx.sess.span_err(attr.span, &format!("symbol-name({})", mangled));
+                if let Ok(demangling) = rustc_demangle::try_demangle(mangled.name) {
+                    tcx.sess.span_err(attr.span, &format!("demangling({})", demangling));
+                    tcx.sess.span_err(attr.span, &format!("demangling-alt({:#})", demangling));
+                }
+            } else if tcx.sess.check_name(attr, DEF_PATH) {
+                let path = tcx.def_path_str(def_id.to_def_id());
+                tcx.sess.span_err(attr.span, &format!("def-path({})", path));
+            }
+
+            // (*) The formatting of `tag({})` is chosen so that tests can elect
+            // to test the entirety of the string, if they choose, or else just
+            // some subset.
+        }
+    }
+}
+
+impl hir::itemlikevisit::ItemLikeVisitor<'tcx> for SymbolNamesTest<'tcx> {
+    fn visit_item(&mut self, item: &'tcx hir::Item<'tcx>) {
+        self.process_attrs(item.hir_id);
+    }
+
+    fn visit_trait_item(&mut self, trait_item: &'tcx hir::TraitItem<'tcx>) {
+        self.process_attrs(trait_item.hir_id);
+    }
+
+    fn visit_impl_item(&mut self, impl_item: &'tcx hir::ImplItem<'tcx>) {
+        self.process_attrs(impl_item.hir_id);
+    }
+}