How to set up a code review using Gitlab?

Question

How does one set up a code review using Gitlab? I see it listed as a feature on the Gitlab website, but I can\'t seem to find instructions on how to set one up (For that matter

Answer 1

Note: since GitLab 6.4, side-by-side diff view is available: see "pull request 5308".

(July 2013)There is no possibility yet to comment on each line though, only at the file level.
Daniel Sokolowski mentions in the comments that Per line comments are now supported (09/2014):

Your team members can comment on the merge request in general or on specific lines with line comments.

That still can help for code review activity.

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6 years later, for GitLab 13.1 (June 2020):

Merge Request Reviews moved to Core

Originally introduced in GitLab 11.4 as a GitLab Premium feature, Merge Request Reviews allow merge request reviewers to:

• submit multiple comments at once,
• cutting down on notification noise for the merge request author, and
• allowing for a more cohesive and streamlined review process.

Since its introduction, we’ve re-evaluated its place in our buyer-based pricing model and as part of 13.1 we’re excited to announce this feature has now moved to GitLab Core.

See Documentation and Issue