createFromUserInput(): add capability to import PROJJSON

configure.ac

@@ -131,9 +131,6 @@ AX_CHECK_COMPILE_FLAG([-Wdeprecated], [CXX_WFLAGS="$CXX_WFLAGS -Wdeprecated"],,[
 AX_CHECK_COMPILE_FLAG([-Wabstract-vbase-init], [CXX_WFLAGS="$CXX_WFLAGS -Wabstract-vbase-init"],,[$ERROR_ON_UNKNOWN_OPTIONS])
 AX_CHECK_COMPILE_FLAG([-Winconsistent-missing-destructor-override], [CXX_WFLAGS="$CXX_WFLAGS -Winconsistent-missing-destructor-override"],,[$ERROR_ON_UNKNOWN_OPTIONS])
 
-dnl Forbid use of 'or', 'and', ... alias operators
-AX_CHECK_COMPILE_FLAG([-fno-operator-names], [CXX_WFLAGS="$CXX_WFLAGS -fno-operator-names"],,[$ERROR_ON_UNKNOWN_OPTIONS])
-
 HAVE_GCC_WARNING_ZERO_AS_NULL_POINTER_CONSTANT=no
 AX_CHECK_COMPILE_FLAG([-Wzero-as-null-pointer-constant], [CXX_WFLAGS="$CXX_WFLAGS -Wzero-as-null-pointer-constant" HAVE_GCC_WARNING_ZERO_AS_NULL_POINTER_CONSTANT=yes NO_ZERO_AS_NULL_POINTER_CONSTANT_FLAG="-Wno-zero-as-null-pointer-constant"],,[$ERROR_ON_UNKNOWN_OPTIONS])
 if test "$HAVE_GCC_WARNING_ZERO_AS_NULL_POINTER_CONSTANT" = "yes"; then
@@ -344,6 +341,7 @@ dnl Generate files
 dnl ---------------------------------------------------------------------------
 
 AC_CONFIG_FILES([Makefile cmake/Makefile src/Makefile include/Makefile include/proj/Makefile include/proj/internal/Makefile
+                 include/proj/internal/nlohmann/Makefile
                  test/Makefile test/cli/Makefile test/gie/Makefile test/gigs/Makefile test/unit/Makefile
                  man/Makefile man/man1/Makefile man/man3/Makefile data/Makefile
                  jniwrap/Makefile jniwrap/org.osgeo.proj/Makefile jniwrap/org.osgeo.proj/org/Makefile jniwrap/org.osgeo.proj/org/proj4/Makefile])

include/proj/internal/Makefile.am

@@ -1,8 +1,11 @@
+SUBDIRS = nlohmann
+
 noinst_HEADERS = \
 	coordinateoperation_constants.hpp \
 	coordinateoperation_internal.hpp \
 	esri_projection_mappings.hpp \
 	coordinatesystem_internal.hpp \
 	internal.hpp \
 	io_internal.hpp \
-	lru_cache.hpp
+	lru_cache.hpp \
+	include_nlohmann_json.hpp

include/proj/internal/include_nlohmann_json.hpp

@@ -0,0 +1,10 @@
+#if defined(__GNUC__)
+#pragma GCC system_header
+#endif
+
+// to avoid any clash if PROJ users have another version of nlohmann/json.hpp
+#define nlohmann proj_nlohmann
+
+#if !defined(DOXYGEN_ENABLED)
+#include "nlohmann/json.hpp"
+#endif

include/proj/internal/nlohmann/Makefile.am

@@ -0,0 +1,2 @@
+noinst_HEADERS = \
+	json.hpp