compiles under ubuntu 18.04

cmake/CMakeLists.txt

@@ -549,8 +549,9 @@ if(NOT MSVC)
             message(FATAL_ERROR "OCCT7 requires a compiler with C++11 support")
         endif()
     else()
-        add_definitions(-std=c++03)
+        add_definitions(-std=c++0x)
     endif()
+
 endif()
 
 set(IFCOPENSHELL_LIBRARIES IfcParse IfcGeom)

src/ifcparse/IfcCharacterDecoder.cpp

@@ -70,6 +70,10 @@
 using namespace IfcParse;
 using namespace IfcWrite;
 
+#ifdef HAVE_ICU
+#include <unicode/unistr.h>
+#endif
+
 void IfcCharacterDecoder::addChar(std::stringstream& s,const UChar32& ch) {
 #ifdef HAVE_ICU
 	if ( destination ) {
@@ -386,4 +390,4 @@ IfcCharacterEncoder::operator std::string() {
 #ifdef HAVE_ICU
 UErrorCode IfcCharacterEncoder::status = U_ZERO_ERROR;
 UConverter* IfcCharacterEncoder::converter = 0;
-#endif
+#endif