Enforce C++11 [skip appveyor]

Author: robertodr

chapter-09/recipe-01/fortran-cxx-example/CMakeLists.txt

@@ -2,6 +2,10 @@ cmake_minimum_required(VERSION 3.5 FATAL_ERROR)
 
 project(recipe-01 LANGUAGES Fortran CXX)
 
+set(CMAKE_CXX_STANDARD 11)
+set(CMAKE_CXX_EXTENSIONS OFF)
+set(CMAKE_CXX_STANDARD_REQUIRED ON)
+
 set(CMAKE_ARCHIVE_OUTPUT_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/lib)
 set(CMAKE_LIBRARY_OUTPUT_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/lib)
 set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/bin)