Added a test for static_variant visitor call depth

tests/stacktrace_test.cpp

@@ -1,9 +1,15 @@
 #include <boost/test/unit_test.hpp>
 
+#include <boost/algorithm/string.hpp>
+
 #include <signal.h>
+
 #include <fc/stacktrace.hpp>
+#include <fc/static_variant.hpp>
 #include <fc/thread/thread.hpp>
 
+#include <iostream>
+
 BOOST_AUTO_TEST_SUITE(fc_stacktrace)
 
 BOOST_AUTO_TEST_CASE(stacktrace_test)
@@ -40,6 +46,38 @@ BOOST_AUTO_TEST_CASE(threaded_stacktrace_test)
 #endif
 }
 
+#if BOOST_VERSION / 100000 >= 1 && ((BOOST_VERSION / 100) % 1000) >= 65
+class _svdt_visitor
+{
+public:
+   typedef std::string result_type;
+   std::string operator()( int64_t i )const
+   {
+      std::stringstream ss;
+      fc::print_stacktrace(ss);
+      return ss.str();
+   }
+   template<typename T>
+   std::string operator()( T i )const { return "Unexpected!"; }
+};
+
+BOOST_AUTO_TEST_CASE(static_variant_depth_test)
+{
+   int64_t i = 1;
+   fc::static_variant<uint8_t,uint16_t,uint32_t,uint64_t,int8_t,int16_t,int32_t,int64_t> test(i);
+
+   std::string stacktrace = test.visit( _svdt_visitor() );
+   //std::cerr << stacktrace << "\n";
+   std::vector<std::string> lines;
+   boost::split( lines, stacktrace, boost::is_any_of("\n") );
+   int count = 0;
+   for( const auto& line : lines )
+      if( line.find("_svdt_visitor") != std::string::npos ) count++;
+   BOOST_CHECK_LT( 3, count ); // test.visit(), static_variant::visit, function object, visitor
+   BOOST_CHECK_GT( 8, count ); // some is implementation-dependent
+}
+#endif
+
 /* this test causes a segfault on purpose to test the event handler
 BOOST_AUTO_TEST_CASE(cause_segfault)
 {