XER: fixed untagged optional union decoding error (issue #585)

Signed-off-by: Botond Baranyi <botond.baranyi@ericsson.com>

compiler2/union.c

@@ -2012,7 +2012,7 @@ void defUnionClass(struct_def const *sdef, output_struct *output)
       }
       if (!sdef->isOptional) {
         src = mputstr(src,
-          "    else {\n"
+          "    else if (!(p_flavor & XER_OPTIONAL)) {\n"
           "      ec_1.set_msg(\" \");\n"
           "      TTCN_EncDec_ErrorContext::error(TTCN_EncDec::ET_INVAL_MSG, "
           "\"'%s' does not match any alternative\", elem_name);\n"

regression_test/XML/Makefile

@@ -30,7 +30,8 @@ endif
 XDIRS := $(wildcard $(SHADOWED)) xsdConverter \
 HM60295 HN15589 HQ30408 HR49727 HU13380 $(RT2_ONLY) \
 XmlWorkflow tpdValidTest AbstractBlock UseNilLong AttributeFormDefault \
-RecordOmit XSDBaseType LegacyUntaggedUnion Printing Bug570707
+RecordOmit XSDBaseType LegacyUntaggedUnion Printing Bug570707 \
+Issue545 Issue585
 
 # List of fake targets:
 .PHONY: all dep clean run $(XDIRS) $(addsuffix /, $(XDIRS)) profile