Bump GCC requirements to 4.8. Close #1442

cmake/TestCXX11.cmake

@@ -34,6 +34,6 @@ if(NOT DEFINED cxx11check)
 			"Error in C++11 check:\n${_CXX11Check_tryout}\n")
 		message(STATUS "Checking for C++11 support - not supported")
 		message(FATAL_ERROR " Upgrade your compiler.\n"
-			" GCC 4.7+ and Clang 3.2+ are known to work.")
+			" GCC 4.8+ and Clang 3.2+ are known to work.")
 	endif()
 endif()

cmake/cxx11check/main.cpp

@@ -10,6 +10,7 @@
 // and this notice are preserved. This file is offered as-is, without any
 // warranty.
 
+#include <map>
 
 template <typename T>
 struct check {
@@ -55,4 +56,8 @@ void test();
 void test() { func<foo>(0); }
 }
 
-int main() { return 0; }
+int main() {
+    std::map<int, int> m;
+    m.emplace(2, 4);
+    return 0;
+}

configure.ac

@@ -33,7 +33,7 @@ AC_PROG_CXX
 # "Optional" because we want custom error message
 AX_CXX_COMPILE_STDCXX_11([noext], [optional])
 if test x"$HAVE_CXX11" != x1; then
-	AC_MSG_ERROR([Upgrade your compiler. GCC 4.7+ and Clang 3.2+ are known to work.])
+	AC_MSG_ERROR([Upgrade your compiler. GCC 4.8+ and Clang 3.2+ are known to work.])
 fi
 
 appendLib () {

m4/ax_cxx_compile_stdcxx_11.m4

@@ -37,6 +37,7 @@
 #serial 5
 
 m4_define([_AX_CXX_COMPILE_STDCXX_11_testbody], [[
+  #include <map>
   template <typename T>
     struct check
     {
@@ -82,6 +83,11 @@ m4_define([_AX_CXX_COMPILE_STDCXX_11_testbody], [[
             func<foo>(0);
         }
     }
+
+    void test_map() {
+        std::map<int, int> m;
+        m.emplace(2, 4);
+    }
 ]])
 
 AC_DEFUN([AX_CXX_COMPILE_STDCXX_11], [dnl