title: error: ‘chrono’ in namespace ‘std’ does not name a type
body: <p>Any idea what does this message mean? I am using gcc 4.9 to compile <a href="https://github.com/facebook/squangle" rel="nofollow">squangle</a>.</p>
  
  <pre><code>In file included from /home/ubuntu/Devel/hhvm/third-party/squangle/squangle/mysql_client/Row.cpp:10:0:
  /home/ubuntu/Devel/hhvm/third-party/squangle/src/squangle/mysql_client/Row.h:171:6: error: ‘chrono’ in namespace ‘std’ does not name a type
   std::chrono::system_clock::time_point parseDateTime(StringPiece datetime,
        ^
  /home/ubuntu/Devel/hhvm/third-party/squangle/src/squangle/mysql_client/Row.h:174:6: error: ‘chrono’ in namespace ‘std’ does not name a type
   std::chrono::microseconds parseTimeOnly(StringPiece mysql_time,
        ^
  /home/ubuntu/Devel/hhvm/third-party/squangle/src/squangle/mysql_client/Row.h:354:6: error: ‘chrono’ in namespace ‘std’ does not name a type
   std::chrono::system_clock::time_point RowBlock::getField(
        ^
  /home/ubuntu/Devel/hhvm/third-party/squangle/src/squangle/mysql_client/Row.h:358:6: error: ‘chrono’ in namespace ‘std’ does not name a type
   std::chrono::microseconds RowBlock::getField(size_t row,
        ^
  /home/ubuntu/Devel/hhvm/third-party/squangle/squangle/mysql_client/Row.cpp: In member function ‘T facebook::common::mysql_client::RowBlock::getField(size_t, size_t) const [with T = std::chrono::time_point&lt;std::chrono::_V2::system_clock, std::chrono::duration&lt;long int, std::ratio&lt;1l, 1000000000l&gt; &gt; &gt;; size_t = long unsigned int]’:
  </code></pre>
  
  <p>Here is part of the code:</p>
  
  <pre><code>std::chrono::system_clock::time_point parseDateTime(StringPiece datetime,
                                                      enum_field_types date_type);
  
  std::chrono::microseconds parseTimeOnly(StringPiece mysql_time,
                                          enum_field_types field_type);
  </code></pre>
  
  <p>CXX_FLAGS </p>
  
  <pre><code>CXX_FLAGS =  -Wall -std=gnu++11 -ffunction-sections -fno-gcse -fno-omit-frame-pointer -Woverloaded-virtual -Wno-deprecated -Wno-strict-aliasing -Wno-write-strings -Wno-invalid-offsetof -fno-operator-names -Wno-error=array-bounds -Wno-error=switch -Werror=format-security -Wno-unused-result -Wno-sign-compare -Wno-attributes -Wno-maybe-uninitialized -Wno-unused-local-typedefs -fno-canonical-system-headers -Wno-deprecated-declarations -Wno-unused-function  -ftrack-macro-expansion=0 -fno-builtin-memcmp -fno-delete-null-pointer-checks  -Wno-unused-variable -O3 -DNDEBUG -fno-gcse  --param max-inline-insns-auto=100 --param early-inlining-insns=200 --param max-early-inliner-iterations=50 -I/usr/include/powerpc64le-linux-gnu -I/home/ubuntu/Devel/hhvm/third-party/re2/src -I/home/ubuntu/Devel/hhvm/third-party/squangle/src -I/home/ubuntu/Devel/hhvm/third-party/webscalesqlclient/src/include -I/usr/include/libxml2 -I/usr/include/double-conversion -I/usr/include/security -I/home/ubuntu/Devel/hhvm/hphp -I/home/ubuntu/Devel/hhvm/third-party/libzip -I/home/ubuntu/Devel/hhvm/third-party/pcre -I/home/ubuntu/Devel/hhvm/third-party/fastlz -I/home/ubuntu/Devel/hhvm/third-party/timelib -I/home/ubuntu/Devel/hhvm/third-party/libafdt/src -I/home/ubuntu/Devel/hhvm/third-party/libmbfl -I/home/ubuntu/Devel/hhvm/third-party/libmbfl/mbfl -I/home/ubuntu/Devel/hhvm/third-party/libmbfl/filter -I/home/ubuntu/Devel/hhvm/third-party/mcrouter -I/home/ubuntu/Devel/hhvm/third-party/folly -I/home/ubuntu/Devel/hhvm/third-party/thrift -I/home/ubuntu/Devel/hhvm/third-party -I/home/ubuntu/Devel/hhvm -I/home/ubuntu/Devel/hhvm/third-party/squangle
  </code></pre>
  
  <p>Compiler line:</p>
  
  <pre><code>g++
  -DENABLE_FASTCGI=1
  -DENABLE_ZEND_COMPAT=1
  -DFOLLY_HAVE_CLOCK_GETTIME=1
  -DFOLLY_HAVE_FEATURES_H=1
  -DFOLLY_HAVE_PTHREAD_ATFORK=1
  -DFOLLY_HAVE_PTHREAD_SPINLOCK_T=1
  -DFOLLY_HAVE_WEAK_SYMBOLS=1
  -DFOLLY_NO_CONFIG=1
  -DHAVE_BOOST1_49
  -DHAVE_CURL_MULTI_WAIT
  -DHAVE_ELF_GETSHDRSTRNDX
  -DHAVE_FEATURES_H=1
  -DHAVE_LIBDL
  -DHHVM
  -DHHVM_DYNAMIC_EXTENSION_DIR="/usr/local/lib/hhvm/extensions"
  -DHPHP_OSS=1
  -DLIBDWARF_USE_INIT_C
  -DNDEBUG
  -DNO_LIB_GFLAGS
  -DNO_TCMALLOC=1
  -DPACKAGE=hhvm
  -DPACKAGE_VERSION=Release
  -DPHP_MYSQL_UNIX_SOCK_ADDR="/var/run/mysqld/mysqld.sock"
  -DRELEASE=1
  -DTHRIFT_MUTEX_EMULATE_PTHREAD_TIMEDLOCK
  -DUSE_EDITLINE
  -DUSE_JEMALLOC=1
  -D_GNU_SOURCE
  -D_PTHREADS=1
  -D_REENTRANT=1
  -D__STDC_FORMAT_MACROS
  -Wall
  -std=gnu++11
  -ffunction-sections
  -fno-gcse
  -fno-omit-frame-pointer
  -Woverloaded-virtual
  -Wno-deprecated
  -Wno-strict-aliasing
  -Wno-write-strings
  -Wno-invalid-offsetof
  -fno-operator-names
  -Wno-error=array-bounds
  -Wno-error=switch
  -Werror=format-security
  -Wno-unused-result
  -Wno-sign-compare
  -Wno-attributes
  -Wno-maybe-uninitialized
  -Wno-unused-local-typedefs
  -fno-canonical-system-headers
  -Wno-deprecated-declarations
  -Wno-unused-function
  -ftrack-macro-expansion=0
  -fno-builtin-memcmp
  -fno-delete-null-pointer-checks
  -Wno-unused-variable
  -O3
  -DNDEBUG
  -fno-gcse
  --param
  max-inline-insns-auto=100
  --param
  early-inlining-insns=200
  --param
  max-early-inliner-iterations=50
  -I/usr/include/powerpc64le-linux-gnu
  -I/home/ubuntu/Devel/hhvm/third-party/re2/src
  -I/home/ubuntu/Devel/hhvm/third-party/squangle/src
  -I/home/ubuntu/Devel/hhvm/third-party/webscalesqlclient/src/include
  -I/usr/include/libxml2
  -I/usr/include/double-conversion
  -I/usr/include/security
  -I/home/ubuntu/Devel/hhvm/hphp
  -I/home/ubuntu/Devel/hhvm/third-party/libzip
  -I/home/ubuntu/Devel/hhvm/third-party/pcre
  -I/home/ubuntu/Devel/hhvm/third-party/fastlz
  -I/home/ubuntu/Devel/hhvm/third-party/timelib
  -I/home/ubuntu/Devel/hhvm/third-party/libafdt/src
  -I/home/ubuntu/Devel/hhvm/third-party/libmbfl
  -I/home/ubuntu/Devel/hhvm/third-party/libmbfl/mbfl
  -I/home/ubuntu/Devel/hhvm/third-party/libmbfl/filter
  -I/home/ubuntu/Devel/hhvm/third-party/mcrouter
  -I/home/ubuntu/Devel/hhvm/third-party/folly
  -I/home/ubuntu/Devel/hhvm/third-party/thrift
  -I/home/ubuntu/Devel/hhvm/third-party
  -I/home/ubuntu/Devel/hhvm
  -I/home/ubuntu/Devel/hhvm/third-party/squangle
  -o
  CMakeFiles/squangle.dir/squangle/mysql_client/Row.cpp.o
  -c
  /home/ubuntu/Devel/hhvm/third-party/squangle/squangle/mysql_client/Row.cpp
  </code></pre>