bug with option --json-printer and vector of enums

[jobol]

The command

flatcc --json-printer bug.fbs

crashes when processing the schema bug.fbs below

enum id : int {
    none = 0
}

table get_in {
    ids: [id];
}

The message it prints is:

flatcc: ...flatcc/src/compiler/codegen_c.h:102: scalar_type_prefix: Assertion `0' failed.
Aborted (core dumped)

[mikkelfj]

Is that on master from today, or ealier. I just pushed a change affecting enums in semantics.h

[mikkelfj]

https://github.com/dvidelabs/flatcc/commit/149f6d3f92ebdf0aeeba4a873113e2936d8a25df

[mikkelfj]

Happens both before and after that commit.

[mikkelfj]

Please check https://github.com/dvidelabs/flatcc/tree/issue182

[mikkelfj]

It appears that no one ever attempted to print vectors of enums to JSON? Certainly the symbol table was accessed incorrectly in this case, triggering an internal error.

[jobol]

the fix works also here. thank you maybe adding the case in monster_test.fbs is valuable

[mikkelfj]

Are you up for that?

[mikkelfj]

If so, please note that the main monster table attempts to keep in sync with flatc monster test, at least from time to time. Therefore other tests are added to other tables in schema.

[jobol]

no sorry adding just 3 lines seems suddenly very confuse.

In an experiment, added a thing like

table testjsonprinter1 {
   colors: [Color];
}

in monster_test.fbs and it worked, that crashed!

[mikkelfj]

I'm getting an error

monster_test.fbs:367:13: error: 'Color': unknown vector type reference used with table field: monster_test.fbs:367:4: 'colors'
output failed

If I add the testjsonprinter1 last in the monster_test file. This is probably a namespace issue. You get a crash? If I add the enum and the table in a separate file, it seems to run OK.

[mikkelfj]

If I add the following last in monster_test, it also appears to be working:

366 namespace MyGame.Example;
367
368 table testjsonprinter1 {
369    colors: [Color];
370 }

[mikkelfj]

However, running the tests with the above change results in a compile error:

test/json_test/generated/monster_test_json_printer.h:670:76: error: too many arguments to function call, expected 6, have 7
    flatcc_json_printer_int8_enum_vector_field(ctx, td, 0, "colors", 6, 0, MyGame_Example_Color_print_json_enum);

[jobol]

I have not compiled the generated code.... (postponed) trying that now....

[mikkelfj]

Just pushed a fix for the extra argument, looks like a copy paste bug.

[jobol]

I tested on my side and it works

[mikkelfj]

So how about tests?

[jobol]

I have a schema and I can parse pipe print json items. flatcc with your fixes works very well

[mikkelfj]

Does the printed output also work? If so, maybe we should just merge the fix without tests.

Ideally the json printer test should be updated, but that is a lot of work, and I have changed all the JSON tests on an unpublished branch.

[mikkelfj]

Rereading your comment, you mean that you can pipe printed output to the parser? If so, we are good.

[jobol]

I did the opposite, I used the parser to create a memory object that I printed then. A tiny main using generated headers. I just checked the buggy case. I am not about to push anything because I have nothing.

[mikkelfj]

Can you check that the printed output can be parsed, or at least is valid JSON?

[jobol]

Using schema

enum id : ushort {
    none = 0,
    led1 = 101,
    led2 = 102,
    led3 = 103,
    button1 = 401,
    button2 = 402,
    button3 = 403
}
table get_in {
    ids: [id];
}

I got:

$ ./a.out '{"ids":[101,"led1",0]}'
{"ids":["led1","led1","none"]}
$ ./a.out '{"ids":[20,400,401]}'
{"ids":[20,400,"button1"]}

What seems correct IMHO

[mikkelfj]

Yes that looks fine, I'll merge and close. Thanks for reporting and testing.

[mikkelfj]

Merge to master