Per #2948, Adding MET_CXX_STANDARD

configure.ac

@@ -15,6 +15,20 @@ AC_OPENMP()
 CPPFLAGS="${CPPFLAGS} ${OPENMP_CFLAGS}"
 LDFLAGS="${LDFLAGS} ${OPENMP_CFLAGS}"
 
+#
+# Look for a specified C++ Standard
+#
+
+# Configure the variable. The help text will appear if the user uses "configure --help".
+
+AC_ARG_VAR([MET_CXX_STANDARD], [Enable support for the specified version of the C++ standard. Default value is 17. Other values may be 11 or 14.])
+
+# Set a default value
+
+if (test -n "$MET_CXX_STANDARD"); then
+  MET_CXX_STANDARD=17
+fi
+
 #
 # Look for the Proj library.
 #
@@ -1160,7 +1174,7 @@ AM_CONDITIONAL([ENABLE_DEVELOPMENT], [test -n "$MET_DEVELOPMENT"])
 CPPFLAGS=$CPPFLAGS' -DMET_BASE="\"$(pkgdatadir)\""'
 
 # Add -std=c++11 to CXXFLAGS                                                                                                                                                 
-CXXFLAGS=$CXXFLAGS' -std=c++11'
+CXXFLAGS=$CXXFLAGS' -std=c++$MET_CXX_STANDARD'
 
 # Define other variables for the makefiles