fix(mgb/opr): fix string append error

GitOrigin-RevId: 295a941eddead18a3691d0b789278d505bbb48a8

src/core/include/megbrain/utils/metahelper.h

@@ -122,7 +122,7 @@ class DynTypeObj {
 //! get class name from class object
 #define _MGB_TYPEINFO_CLASS_NAME(_cls) #_cls
 #else
-#define _MGB_TYPEINFO_CLASS_NAME(_cls) nullptr
+#define _MGB_TYPEINFO_CLASS_NAME(_cls) ""
 #endif
 
 //! put in the impl file of a class that needs static typeinfo()

src/plugin/test/opr_io_dump.cpp

@@ -147,7 +147,7 @@ std::vector<std::string> getlines(std::istream& inp, size_t skip_head = 0) {
 }
 
 }  // anonymous namespace
-
+#if MGB_VERBOSE_TYPEINFO_NAME
 TEST(TestOprIODump, Text) {
     auto fname_base = output_file("test_opr_iodump");
     std::array<std::string, 3> fnames;
@@ -180,8 +180,10 @@ TEST(TestOprIODump, Text) {
 
     run_test(make_plugin, check_result);
 }
+#endif
 
 TEST(TestOprIODump, StdErr) {
+    MGB_MARK_USED_VAR(EXPECTED_TEXT_OUT_REC);
     HostTensorGenerator<> gen;
     auto host_x = gen({5});
     auto host_y = gen({5});