Require GCC 4.9

GCC 4.9 has improved support for C++11; in particular regex support.

.travis.yml

@@ -44,8 +44,9 @@ addons:
     packages:
      - cmake-data
      - cmake
-     # 4.8.1 is the first version of GCC with full C++11 support.
-     - g++-4.8
+     # 4.9 is the first version of GCC with good enough C++11 support; in
+     # particular regex support.
+     - g++-4.9
      # Required to build the OmniSharp server.
      - mono-devel
      - ninja-build

ci/travis/travis_install.linux.sh

@@ -1,13 +1,13 @@
 # Linux-specific installation
 
 # We can't use sudo, so we have to approximate the behaviour of the following:
-# $ sudo update-alternatives --install /usr/bin/g++ g++ /usr/bin/g++-6 90
+# $ sudo update-alternatives --install /usr/bin/g++ g++ /usr/bin/g++-4.9 90
 
 mkdir ${HOME}/bin
 
-ln -s /usr/bin/g++-4.8 ${HOME}/bin/c++
-ln -s /usr/bin/gcc-4.8 ${HOME}/bin/cc
-ln -s /usr/bin/gcov-4.8 ${HOME}/bin/gcov
+ln -s /usr/bin/g++-4.9 ${HOME}/bin/c++
+ln -s /usr/bin/gcc-4.9 ${HOME}/bin/cc
+ln -s /usr/bin/gcov-4.9 ${HOME}/bin/gcov
 
 export PATH=${HOME}/bin:${PATH}
 

cpp/CMakeLists.txt

@@ -115,17 +115,17 @@ endif()
 # Determining the presence of C++11 support in the compiler
 set( CPP11_AVAILABLE false )
 if ( CMAKE_COMPILER_IS_GNUCXX )
-  if ( NOT  CMAKE_CXX_COMPILER_VERSION VERSION_LESS 4.6  )
+  if ( NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS 4.9 )
     set( CPP11_AVAILABLE true )
   endif()
 elseif( COMPILER_IS_CLANG )
-  if ( NOT  CMAKE_CXX_COMPILER_VERSION VERSION_LESS 3.3  )
+  if ( NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS 3.3 )
     set( CPP11_AVAILABLE true )
     set( CMAKE_XCODE_ATTRIBUTE_CLANG_CXX_LANGUAGE_STANDARD "c++11" )
     set( CMAKE_XCODE_ATTRIBUTE_CLANG_CXX_LIBRARY "libc++" )
   endif()
 elseif( MSVC )
-  if ( NOT  MSVC_VERSION LESS 1800  )
+  if ( NOT MSVC_VERSION LESS 1800 )
     set( CPP11_AVAILABLE true )
   endif()
 endif()
@@ -185,7 +185,7 @@ if ( CPP11_AVAILABLE )
     add_definitions( -std=c++11 )
   endif()
 else()
-  message( FATAL_ERROR "Your C++ compiler does NOT support C++11." )
+  message( FATAL_ERROR "Your C++ compiler does NOT fully support C++11." )
 endif()
 
 # Note: build.py always explicitly sets this option, so the default used here