CROSSTAG(OTHERWISE) one 1 field union generates incorrect Java code

Copy of titan.core#560 (closed)

Summary

CROSSTAG(OTHERWISE) one 1 field union generates incorrect C++ code and therefore it should be checked whether the generated Java code is ok or not

Steps and/or TTCN-3 code to reproduce

Following TTCN3 code compiles fine, but generates incorrect C++ code:

type union PCUIF_ContainerMsgUnion {
	octetstring	other
} with { variant "" };

type record PCUIF_container {
	uint8_t		msg_type,
	uint8_t		spare,
	uint16_t	len,
	PCUIF_ContainerMsgUnion	u
} with {
	variant (len) "LENGTHTO(u)"
	variant (u) "CROSSTAG(
			other, 	OTHERWISE)"
};

Then when C++ code is compiled:

g++  -c -DLINUX -DMAKEDEPEND_RUN -DUSE_SCTP -DLKSCTP_MULTIHOMING_ENABLED -I/usr/ttcn3/include -fPIC   -o RSL_Emulation.o RSL_Emulation.cc
PCUIF_Types.cc: In member function ‘int PCUIF__Types::PCUIF__container::RAW_decode(const TTCN_Typedescriptor_t&, TTCN_Buffer&, int, raw_order_t, boolean, int, boolean, const RAW_Force_Omit*)’:
PCUIF_Types.cc:31342:3: error: ‘else’ without a previous ‘if’
31342 |   else selected_field = 0;
      |   ^~~~

So it seems the TTCN3->C++ compiler is missing checking specific cases where the union (or the CROSSTAG) has only 1 OTHERWISE option.

Rationale for TTCN3 code shown above: I wrote that TTCN3 code since I'm implementing the container layer without having yet any specific message in top of it specified, which will come later. Hence I wanted to have some octetstring on top to send random data to test only up to the container layer, while leaving the TTCN3 records prepared to add new container payload data in the future.

Titan version

6.6.1

/cc @aknappqwt