ftbfs with gcc 6

[Michael Hudson-Doyle]

The immediate problem is -Werror=nonnull-compare:

g++ -o build/opt/mongo/db/fts/fts_spec.o -c -g -O2 -fstack-protector-strong -Wformat -Werror=format-security -Wnon-virtual-dtor -Woverloaded-virtual -Wno-maybe-uninitialized -std=c++11 -fno-omit-frame-pointer -fPIC -fno-strict-aliasing -ggdb -pthread -Wall -Wsign-compare -Wno-unknown-pragmas -Winvalid-pch -Werror -O2 -Wno-unused-local-typedefs -Wno-unused-function -Wno-deprecated-declarations -Wno-unused-const-variable -Wno-unused-but-set-variable -Wno-unused-variable -Wno-maybe-uninitialized -Wno-missing-braces -fno-builtin-memcmp -DNDEBUG -DBOOST_THREAD_VERSION=4 -DBOOST_THREAD_DONT_PROVIDE_VARIADIC_THREAD -DBOOST_SYSTEM_NO_DEPRECATED -Isrc/third_party/libstemmer_c/include -Isrc/third_party/s2 -Ibuild/opt -Isrc src/mongo/db/fts/fts_spec.cpp
In file included from src/mongo/platform/compiler.h:132:0,
                 from src/mongo/util/invariant.h:30,
                 from src/mongo/base/string_data.h:39,
                 from build/opt/mongo/base/error_codes.h:31,
                 from src/mongo/base/status.h:34,
                 from src/mongo/client/dbclient.cpp:36:
src/mongo/client/dbclientcursor.h: In member function 'void mongo::DBClientCursor::_assertIfNull() const':
src/mongo/util/assert_util.h:233:28: error: nonnull argument 'this' compared to NULL [-Werror=nonnull-compare]
         if (MONGO_unlikely(!(expr))) { \
                            ^~~~~~~
src/mongo/platform/compiler_gcc.h:66:80: note: in definition of macro 'MONGO_unlikely'
 #define MONGO_unlikely(x) static_cast<bool>(__builtin_expect(static_cast<bool>(x), 0))
                                                                                ^
src/mongo/util/assert_util.h:319:17: note: in expansion of macro 'MONGO_uassert'
 #define uassert MONGO_uassert
                 ^~~~~~~~~~~~~
src/mongo/client/dbclientcursor.h:295:9: note: in expansion of macro 'uassert'
         uassert(13348, "connection died", this);
         ^~~~~~~

[Michael Hudson-Doyle (mwhudson)]

That appears to be the only new warning, so I guess we should add -Wno-error=nonnull-compare to disable-warnings.patch (this is https://jira.mongodb.org/browse/SERVER-25385).

The next failure is this:

In file included from src/mongo/base/parse_number_test.cpp:38:0:
src/mongo/base/parse_number_test.cpp:297:49: error: exponent has no digits
     ASSERT_PARSES(double, "0xabcab.defdefP-10", 0xabcab.defdefP-10);
                                                 ^
src/mongo/unittest/unittest.h:105:93: note: in definition of macro '_ASSERT_COMPARISON'
             ::mongo::unittest::ComparisonAssertion_##COMPARISON(__FILE__, __LINE__, #a, #b, a, b)) \
                                                                                             ^
src/mongo/unittest/unittest.h:84:29: note: in expansion of macro 'ASSERT_EQ'
 #define ASSERT_EQUALS(a, b) ASSERT_EQ(a, b)
                             ^~~~~~~~~
src/mongo/base/parse_number_test.cpp:44:9: note: in expansion of macro 'ASSERT_EQUALS'
         ASSERT_EQUALS(static_cast<TYPE>(EXPECTED_VALUE), v); \
         ^~~~~~~~~~~~~
src/mongo/base/parse_number_test.cpp:297:5: note: in expansion of macro 'ASSERT_PARSES'
     ASSERT_PARSES(double, "0xabcab.defdefP-10", 0xabcab.defdefP-10);
     ^~~~~~~~~~~~~

which I think could be fixed by backporting the SConstruct part of

https://github.com/mongodb/mongo/commit/a0c60da29313848e6b4207a8d301d2facdf3fd7c

and adding --cxx-std=14 to COMMON_OPTIONS.

[Michael Hudson-Doyle (mwhudson)]

I was wrong about that last bit.

[Michael Hudson-Doyle (mwhudson)]

Ah those constants are only a C++17 feature, so I'm going to try building with -std=c++17. But probably a better fix is just to comment that single line out of the test file.

[Launchpad Janitor (janitor)]

This bug was fixed in the package juju-mongodb3.2 - 3.2.8-0ubuntu3

---------------
juju-mongodb3.2 (3.2.8-0ubuntu3) yakkety; urgency=medium

  * Fix ftbfs: (LP: #1610767):
    - Add d/patches/gcc6-ftbfs.patch to fix 2 warnings and 1 error.
    - Add d/patches/SERVER-16221-SERVER-23712-Aggregation-unit-tests-sho.patch,
      backported from master.

 -- Michael Hudson-Doyle <email address hidden> Mon, 08 Aug 2016 13:41:08 +1200