Fix infinite loop when there is circular typedef

Summary: Otherwise thrift compiler will never finish running since functions like `get_true_type()` takes literally forever to return.

Reviewed By: createdbysk

Differential Revision: D67924820

fbshipit-source-id: c3aadb12cb2fbcd22a4ff61ea690073726c77653

Author: Mizuchi

third-party/thrift/src/thrift/compiler/sema/sema.cc

@@ -610,7 +610,33 @@ bool sema::resolve_all_types(sema_context& diags, t_program_bundle& bundle) {
     assert(!td.resolve());
     success = false;
   }
-  return success;
+  return success && check_circular_typedef(diags, bundle);
+}
+
+bool sema::check_circular_typedef(
+    sema_context& diags, t_program_bundle& bundle) {
+  std::unordered_set<const t_type*> checked;
+  for (auto& td : bundle.root_program()->scope()->placeholder_typedefs()) {
+    if (checked.count(td.get_type())) {
+      continue;
+    }
+    std::unordered_set<const t_type*> visited;
+    std::vector<const t_type*> chain;
+    if (nullptr != t_typedef::find_type_if(td.get_type(), [&](const t_type* t) {
+          // Find the first typedef which insertion failed
+          checked.insert(t);
+          chain.push_back(t);
+          return visited.insert(t).second == false;
+        })) {
+      std::string msg;
+      for (const auto& i : chain) {
+        msg += i->name() + (&i != &chain.back() ? " --> " : "");
+      }
+      diags.error(td, "Circular typedef: {}", msg);
+      return false;
+    }
+  }
+  return true;
 }
 
 sema::result sema::run(sema_context& ctx, t_program_bundle& bundle) {

third-party/thrift/src/thrift/compiler/sema/sema.h

@@ -32,6 +32,12 @@ struct sema {
   // successful and reporting any errors via diags.
   bool resolve_all_types(sema_context& diags, t_program_bundle& bundle);
 
+  // Check whether we have circular typedef, returning true if successful and
+  // reporting any errors via diags. Example of circular typedef:
+  //    typedef Foo Bar
+  //    typedef Bar Foo
+  bool check_circular_typedef(sema_context& diags, t_program_bundle& bundle);
+
  public:
   explicit sema(bool use_legacy_type_ref_resolution)
       : use_legacy_type_ref_resolution_(use_legacy_type_ref_resolution) {}

third-party/thrift/src/thrift/compiler/test/compiler_test.cc

@@ -2350,3 +2350,10 @@ TEST(CompilerTest, not_bundled_annotation) {
       {},
       options);
 }
+
+TEST(CompilerTest, circular_typedef) {
+  check_compile(R"(
+    typedef Foo Bar # expected-error: Circular typedef: Foo --> Bar --> Foo
+    typedef Bar Foo
+  )");
+}