THRIFT-4797: Golang: Fix import collisions

[johnboiles]

See THRIFT-4797 for details. In short, Golang compilation fails when a Thrift file includes two files that have the same final namespace component (e.g. namespace go packagea.common and namespace go packageb.common)

Somewhat based on fbthrift's implementation though their implementation simply always adds an alias with a unique numerical prefix.

• Did you create an Apache Jira ticket? (not required for trivial changes)
• Does your pull request title follow the pattern "THRIFT-NNNN: describe my issue"? (not required for trivial changes)
• Did you squash your changes to a single commit?
• Did you do your best to avoid breaking changes? If one was needed, did you label the Jira ticket with "Breaking-Change"

[johnboiles]

Just found another case to handle here. I should also detect collisions with the golang packages that get imported like bytes context reflect

[dcelasun]

For stdlib collisions like context etc, it would be great if the import list was a vector instead of a hardcoded string so we could reuse it everywhere.

[johnboiles]

@dcelasun I made it use a vector for system imports can you take a look? I’ll squash it together if/when it looks good to you!

[dcelasun]

Looks good!

[johnboiles]

@dcelasun squashed and ready to merge!

[johnboiles]

Actually hold on merging for a bit. I may have found another edge case

[johnboiles]

Yep, confirmed. If the package has a service, and that package’s last namespace component conflicts with a previously imported package, it won’t get aliased. Hopefully I can get a chance to fix tomorrow

[johnboiles]

@dcelasun one more commit to review to fix the issue with the remote package import collisions! Hopefully this is it

[dcelasun]

LGTM. Tried testing a few different scenarios locally, everything works fine. Thanks for the PR!