Fix compile for libstdc++ with _GLIBCXX_DEBUG

9 jobs for prop-partial-specialisation in 3 minutes and 53 seconds (queued for 1 second)
Status Name Job ID Coverage
  Test
passed clang-c++11 #68948
Linux

00:03:50

passed cppcheck #68950
Linux

00:00:34

passed doc #68955
Linux

00:00:18

passed gcc-c++11 #68947
Linux

00:03:53

passed macos-c++11 #68949
Apple

00:01:38

passed VS2015-32-bit #68954
VS2015

00:01:16

passed VS2015-64-bit #68953
VS2015

00:01:18

passed VS2017-32-bit #68952
VS2017

00:01:16

passed VS2017-64-bit #68951
VS2015

00:01:18