From 4548bd1a650ea302bfa04fe4fa28be97c261a106 Mon Sep 17 00:00:00 2001
From: Tomasz Grabiec <tgrabiec@cloudius-systems.com>
Date: Fri, 5 Jun 2015 13:50:14 +0200
Subject: [PATCH] cql_test_env: Work-around infinite recursion in boost::any

cql_query_test segfaults in debug mode due to infinite recursion (see
trace below). The problem started to appear after Avi's always-defer
change.

It looks like the following boost::any() constructor template is
instantiated when boost::any is copied into a lambda:

        // Perfect forwarding of ValueType
        template<typename ValueType>
        any(ValueType&& value, typename boost::disable_if<boost::is_same<any&, ValueType> >::type* = 0)
          : content(new holder< typename remove_reference<ValueType>::type >(static_cast<ValueType&&>(value)))
        {
        }

It checks for any& to disable itself on forwarding, but it doesn't
check for const any&. There are (non-template) constructors which take
const any&, but I guess some C++ rule favors the template
version. This results in infinite recursion of constructor invocations
between any() and holder().

Workaround is to make the lambda mutable, so that the argument type is
any& and template doesn't kick in.

Trace:

CU 0x4debed5, DIE 0x4f176e6>, this=0x602000044550) at /usr/include/boost/any.hpp:175
ql_query_test, CU 0x4debed5, DIE 0x4f6c509>, this=0x602000044518) at /usr/include/boost/any.hpp:72
CU 0x4debed5, DIE 0x4f176e6>, this=0x602000044510) at /usr/include/boost/any.hpp:175
ql_query_test, CU 0x4debed5, DIE 0x4f6c509>, this=0x6020000444e8) at /usr/include/boost/any.hpp:72
CU 0x4debed5, DIE 0x4f176e6>, this=0x6020000444e0) at /usr/include/boost/any.hpp:175
oost::any const>, void>::type*) (this=0x7ffff2ffa6f0, value=<unknown type in /home/tgrabiec/src/urchin2/build
/release/tests/urchin/cql_query_test, CU 0x4debed5, DIE 0x4f6c509>) at /usr/include/boost/any.hpp:72
5u> const&, std::vector<boost::any, std::allocator<boost::any> >, std::vector<boost::any, std::allocator<boos
t::any> >, basic_sstring<char, unsigned int, 15u> const&, boost::any)::{lambda(database&)#1}::operator()(data
base&) const::{lambda(std::unique_ptr<mutation_partition const, std::default_delete<mutation_partition> >)#1}
::unique_ptr(std::unique_ptr<mutation_partition const, std::default_delete<mutation_partition> >&&) (this=0x7
ffff2ffa6c0) at tests/urchin/cql_test_env.cc:126
---
 tests/urchin/cql_test_env.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tests/urchin/cql_test_env.cc b/tests/urchin/cql_test_env.cc
index ca754820ed..10de724ef9 100644
--- a/tests/urchin/cql_test_env.cc
+++ b/tests/urchin/cql_test_env.cc
@@ -120,7 +120,7 @@ public:
                                       ks_name = std::move(ks_name),
                                       column_name = std::move(column_name),
                                       expected = std::move(expected),
-                                      table_name = std::move(table_name)] (database& db) {
+                                      table_name = std::move(table_name)] (database& db) mutable {
           auto& cf = db.find_column_family(ks_name, table_name);
           auto schema = cf.schema();
           return cf.find_partition_slow(pkey).then([schema, ck, column_name, expected] (column_family::const_mutation_partition_ptr p) {