jsonfortran: add UTF8 feature check

Author: scivision

cmake/compilers.cmake

@@ -1,3 +1,12 @@
+include(CheckSourceCompiles)
+# Compiler capability test
+check_source_compiles(Fortran
+"program test
+character(kind=selected_char_kind('ISO_10646')) :: c
+end program"
+HAS_Fortran_UTF8
+)
+
 # compiler flags for gfortran
 if(CMAKE_Fortran_COMPILER_ID STREQUAL "GNU")
 

cmake/json.cmake

@@ -23,7 +23,10 @@ ${_src}/json_module.F90
 )
 
 add_library(jsonfortran ${JF_LIB_SRCS})
-target_compile_definitions(jsonfortran PRIVATE ${JSON_REAL_KIND} ${JSON_INT_KIND})
+target_compile_definitions(jsonfortran PRIVATE
+${JSON_REAL_KIND} ${JSON_INT_KIND}
+$<$<BOOL:${HAS_Fortran_UTF8}>:USE_UCS4>
+)
 target_include_directories(jsonfortran PUBLIC
 $<BUILD_INTERFACE:${CMAKE_BINARY_DIR}/include>
 $<INSTALL_INTERFACE:include>