hey @aardappel could I get a quick LGTM? :D

the change to the CMakeLists.txt is a duplicate of #8580 -- Happy to let that one go in and remove from this one.

Indeed I merged #8580 first, since its nice to recognize their change.

Looks like this changes generated code which will need to be added to the PR.

I am mildly confused how a one liner in the cpp changes generated code.. I have rebased on the tip of master with my single commit.

error:
  cannot generate code directly from .proto files

Traceback (most recent call last):
  File "D:\a\flatbuffers\flatbuffers\scripts\generate_code.py", line 194, in <module>

looks like some of the validation logic is no longer true/valid anymore..? I can probably try to spend some time hunting this down but will take me a bit as it will delve into parts of the code I'm not yet familiar with.

alright, I just removed the --proto validation check from ValidateOptions, and got the following when I manually generate the code:

python3 scripts/generate_code.py  --flatc ./build/flatc 
Fields in struct ProtoMessage have gap between ids
Fields in struct OtherMessage have gap between ids
When you use --proto, that you should check for conformity yourself, using the existing --conform
warning:
  /<...>/flatbuffers/tests/rust_namer_test.fbs:26: 8: warning: field names should be lowercase snake_case, got: Message

Yes, I guess these problems were apparently not checked for.
I wouldn't delete the error though.. maybe turning it into a warning for now is better, given that what it checks for is still valid.

changed error to warn and simplified the nesting a bit

Ok, looks good now, thanks!