Cleaned up generated code for closed Enums

[nicked]

For closed enums there no special UNRECOGNIZED case, so a plain Swift Int enum with explicit values can be used directly.

This results in the generated init?(rawValue:) and var rawValue functions not being needed, since the compiler will create them automatically.

[thomasvl]

Huh, never really thought out this; since the open enums needed it we didn't consider if the closed could avoid the extra generation.

@tbkka any thoughts?

[tbkka]

Looks like a nice simplification.

[thomasvl]

Looks like the PR needs the Reference directory updated also for the plugin tests.

[nicked]

Hi, any idea why protobuf itself would fail to build?

[thomasvl]

Hi, any idea why protobuf itself would fail to build?

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90415
https://gcc.gnu.org/git/gitweb.cgi?p=gcc.git;h=14597b680a24b6f7375e4470dea935da9c369feb

Appears to be a compiler bug. I've let the protobuf team upstream know, hopefully they can tweak their sources to avoid this since it will be an issue for their customers on older (but supported) versions.

[nicked]

Think I've got the workflow figured out now, thanks for your help!

[thomasvl]

Looks like an upstream fix is coming: protocolbuffers/protobuf#20234

[thomasvl]

And with a respin everything is happy.

Thanks for noticing this, merging.