1 files changed, 74 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 000000000..7249ce04c
--- /dev/null
+++ b/compiler/rustc_symbol_mangling/src/test.rs
@@ -0,0 +1,74 @@
+//! 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::def_id::LocalDefId;
+use rustc_middle::ty::print::with_no_trimmed_paths;
+use rustc_middle::ty::{subst::InternalSubsts, 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 symbol_names = SymbolNamesTest { tcx };
+        let crate_items = tcx.hir_crate_items(());
+
+        for id in crate_items.items() {
+            symbol_names.process_attrs(id.def_id);
+        }
+
+        for id in crate_items.trait_items() {
+            symbol_names.process_attrs(id.def_id);
+        }
+
+        for id in crate_items.impl_items() {
+            symbol_names.process_attrs(id.def_id);
+        }
+
+        for id in crate_items.foreign_items() {
+            symbol_names.process_attrs(id.def_id);
+        }
+    })
+}
+
+struct SymbolNamesTest<'tcx> {
+    tcx: TyCtxt<'tcx>,
+}
+
+impl SymbolNamesTest<'_> {
+    fn process_attrs(&mut self, def_id: LocalDefId) {
+        let tcx = self.tcx;
+        // 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.
+        for attr in tcx.get_attrs(def_id.to_def_id(), SYMBOL_NAME) {
+            let def_id = def_id.to_def_id();
+            let instance = Instance::new(
+                def_id,
+                tcx.erase_regions(InternalSubsts::identity_for_item(tcx, 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));
+            }
+        }
+
+        for attr in tcx.get_attrs(def_id.to_def_id(), DEF_PATH) {
+            let path = with_no_trimmed_paths!(tcx.def_path_str(def_id.to_def_id()));
+            tcx.sess.span_err(attr.span, &format!("def-path({})", path));
+        }
+    }
+}