ZCBOR code generator generates names not compatible with C++

[kborowski3]

Describe the bug
There is a problem with compiling ZBOR code generated from .cddl files when we use it in the application written in C++.
To be precise the problem occurs if we want to generate Union type. The generated code can be compiled in C but it is not working for C++ due to generated variables names conflicts.

To Reproduce
Simple example showing the problem was created and it is available on my repository -> https://github.com/kborowski3/zcbor_union_test

This is a simple application, which just includes the generated zcbor code. ZCBOR code is generated using zcbor_union_test.cddl which contains a simple union definition.

zcbor_union_test.cddl file content

Foo = int / bstr

where Foo is either an int or bstr.

The code is generated using ZCBOR code generator:

python3 ${ZCBOR_PATH}/zcbor/zcbor.py code -c zcbor_union_test.cddl --encode -t Foo --oc src/zcbor_union_test.c --oh src/zcbor_union_test.h

The problem is in the zcbor_union_test.h file. The content of the file was pasted below.

/*
 * Generated using zcbor version 0.6.99
 * https://github.com/NordicSemiconductor/zcbor
 * Generated with a --default-max-qty of 3
 */

#ifndef ZCBOR_UNION_TEST_TYPES_H__
#define ZCBOR_UNION_TEST_TYPES_H__

#include <stdint.h>
#include <stdbool.h>
#include <stddef.h>
#include <string.h>
#include "zcbor_encode.h"

/** Which value for --default-max-qty this file was created with.
 *
 *  The define is used in the other generated file to do a build-time
 *  compatibility check.
 *
 *  See `zcbor --help` for more information about --default-max-qty
 */
#define DEFAULT_MAX_QTY 3

struct Foo_ {
	union {
		int32_t _Foo_int;
		struct zcbor_string _Foo_bstr;
	};
	enum {
		_Foo_int,
		_Foo_bstr,
	} _Foo_choice;
};


#endif /* ZCBOR_UNION_TEST_TYPES_H__ */

As you can see there is a problem with the enum's and union's fields names. Both union and enum has a member _Foo_int and _Foo_bstr, which cannot be compiled in C++ code.

Steps to reproduce the behavior:

1. git clone https://github.com/kborowski3/zcbor_union_test.git
2. cd zcbor_union_test
3. west build -p always -b nucleo_wb55rg ./
4. See error

Expected behavior
The application compiles successfully.

Logs and console output

/zcbor_union_test/src/zcbor_union_test_types.h:31:17: error: '_Foo_int' conflicts with a previous declaration
   31 |                 _Foo_int,
      |                 ^~~~~~~~
/zcbor_union_test/src/zcbor_union_test_types.h:27:25: note: previous declaration 'int32_t Foo_::<unnamed union>::_Foo_int'
   27 |                 int32_t _Foo_int;
      |                         ^~~~~~~~
/zcbor_union_test/src/zcbor_union_test_types.h:32:17: error: '_Foo_bstr' conflicts with a previous declaration
   32 |                 _Foo_bstr,
      |                 ^~~~~~~~~
/zcbor_union_test/src/zcbor_union_test_types.h:28:37: note: previous declaration 'zcbor_string Foo_::<unnamed union>::_Foo_bstr'
   28 |                 struct zcbor_string _Foo_bstr;
      |       

Environment

• Zephyr SDK version 0.15.1
• ZCBOR version 0.6.99

[nordicjm]

This should really have been posted to https://github.com/NordicSemiconductor/zcbor

[kborowski3]

Actually I can see that there are some C++ improvements commits but they are not available on the zephyrproject-rtos/zcbor forked repository. Can you bump there the newest version?

[github-actions]

This issue has been marked as stale because it has been open (more than) 60 days with no activity. Remove the stale label or add a comment saying that you would like to have the label removed otherwise this issue will automatically be closed in 14 days. Note, that you can always re-open a closed issue at any time.

[github-actions]

This issue has been marked as stale because it has been open (more than) 60 days with no activity. Remove the stale label or add a comment saying that you would like to have the label removed otherwise this issue will automatically be closed in 14 days. Note, that you can always re-open a closed issue at any time.

[jgl-meta]

@oyvindronningstad this has been marked as stale 3 times. Is this an issue? If it isn't can you close this?

[oyvindronningstad]

It is an issue. It is tracked by NordicSemiconductor/zcbor#314.

[github-actions]

This issue has been marked as stale because it has been open (more than) 60 days with no activity. Remove the stale label or add a comment saying that you would like to have the label removed otherwise this issue will automatically be closed in 14 days. Note, that you can always re-open a closed issue at any time.

[r2r0]

@oyvindronningstad Any chance to upstream zcbor fix to zephyr?

[github-actions]

This issue has been marked as stale because it has been open (more than) 60 days with no activity. Remove the stale label or add a comment saying that you would like to have the label removed otherwise this issue will automatically be closed in 14 days. Note, that you can always re-open a closed issue at any time.

[r2r0]

@oyvindronningstad Ping

[github-actions]

This issue has been marked as stale because it has been open (more than) 60 days with no activity. Remove the stale label or add a comment saying that you would like to have the label removed otherwise this issue will automatically be closed in 14 days. Note, that you can always re-open a closed issue at any time.

[r2r0]

@oyvindronningstad If upstreaming is not possibel or planned then please close this issue.

[oyvindronningstad]

@r2r0 sorry for the delay. This is coming with zcbor 0.8.0 in #67418