Bumped GCC version to 6.2.

6.2 is the minimum tested compiler by our CI (on envinf1).
6.5 is the default gcc 6 in Ubuntu 16.04 when using the ubuntu-toolchain-r/test PPA.

scripts/cmake/CompilerSetup.cmake

@@ -80,8 +80,8 @@ if(COMPILER_IS_GCC OR COMPILER_IS_CLANG OR COMPILER_IS_INTEL)
     endif()
 
     if(COMPILER_IS_GCC)
-        if(CMAKE_CXX_COMPILER_VERSION VERSION_LESS "4.9")
-            message(FATAL_ERROR "GCC minimum required version is 4.9! You are \
+        if(CMAKE_CXX_COMPILER_VERSION VERSION_LESS "6.2")
+            message(FATAL_ERROR "GCC minimum required version is 6.2! You are \
                 using ${CMAKE_CXX_COMPILER_VERSION}.")
         endif()
         add_compile_options(-fext-numeric-literals)

scripts/docker/Dockerfile.gcc.full

@@ -6,14 +6,14 @@ RUN apt-get update && apt-get install -y software-properties-common curl \
   && apt-get update \
   && apt-get -y install \
     ccache \
-    gcc-4.9 g++-4.9 gcc-4.9-base \
+    g++-6 \
     git git-lfs \
     python3-pip \
     sudo \
     unzip
 
-ENV CC=gcc-4.9
-ENV CXX=g++-4.9
+ENV CC=gcc-6
+ENV CXX=g++-6
 
 RUN python3 -m pip install --upgrade pip \
   && python3 -m pip install cmake conan>=1.10.0

web/content/docs/devguide/getting-started/prerequisites.pandoc

@@ -31,11 +31,11 @@ As we use lots of features of the C++11-standard we support **Visual Studio 2015
 :::
 
 ::: {.linux}
-If you have a recent linux distribution you should also have a recent gcc. Please check that you have at least **gcc 4.9**:
+If you have a recent linux distribution you should also have a recent gcc. Please check that you have at least **gcc 6.2**:
 
 ```bash
 $ gcc --version
-gcc (GCC) 4.9.1
+gcc (GCC) 6.2.0
 ```
 :::