Fix missing detached leading comments

[trunghai95]

There's a bug causing the LeadingDetachedComments not copied properly to the source info.

[jhump]

Doh! Thanks for finding and fixing this. I clearly don't have good enough test coverage in here.

Is this an easy issue to reproduce? If so, it would be great to add a test that reproduces the bug, and then confirm that this change fixes it.

[trunghai95]

Doh! Thanks for finding and fixing this. I clearly don't have good enough test coverage in here.

Is this an easy issue to reproduce? If so, it would be great to add a test that reproduces the bug, and then confirm that this change fixes it.

Yes, it is easy to reproduce. It happens every time I trigger Build() from a builder.

I think I can modify TestBuildersFromDescriptors_PreserveComments under builder_test.go to cover this case. Do you have a generator for internal/testprotos/desc_test1.proto? Or should I just manually modify one or some of the elements there?

[jhump]

Or should I just manually modify one or some of the elements there?

You can manually modify it, but it might impact other test cases across the repo that use that file. I think it may be better to define a small, minimal file that reproduces the issue and then inline it into the test case. You can compile the source into descriptors using the protoparse package. See the test TestParseAndPrintWithUnrecognizedOptions in the protoprint package as an example.

[trunghai95]

Added a test for it. This is the test result before and after the fix.

[jhump]

I think this is a much bigger example than necessary. Maybe just one enum and value and one message and field?

[jhump]

Thanks for the contribution!