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CS61BR

Starting the Lab

  • Open the lab04/ folder in your preferred text editor.
  • Open the lab04/ folder in your preferred terminal.
  • Run git pull skeleton main to get the latest version of the skeleton code for this lab.

Experiencing a Merge Conflict

This portion of the lab may mess up your local Git repository. Make sure to commit and push all your work to Github before starting this portion of the lab; run git status and make sure it says “On branch main; Your branch is up to date with ‘origin/main’; nothing to commit, working tree clean” before continuing.

If things go horribly wrong, you can just delete your local repository, re-clone it from Github (see lab01 setup), and start this section over.

You may have heard dark rumors of a terrible monster called a “merge conflict”. It’s a hideous beast that destroys mercilessly and strikes fear into the hearts of experienced developers.

Today you’re going to create one!

  • Open up your browser and go to your repository on Github. In the lab04/ folder, open poem.txt, and click the edit button. Notice that the 3rd verse has a missplelling: it says “l337”, but that should be “great”. Fix the missplelling and commit your change on Github. (Note: if you come back to this step, you can pick a new word besides “great”. Some candidates: “green”, “leek”, “beet”, “leaf”)
  • In your text editor (working in the local lab04/ folder), open poem.txt. Strange, the missplelling is still there! However, this time, change the word “l337” to “elite”.
  • In the terminal, add and commit your change.
  • Run git push. You should get an error: “the remote has work that you do not have locally”. Oops!
  • To get the remote’s work, run git pull. You should receive the following message: 
     Auto-merging lab04/poem.txt
 CONFLICT (content): Merge conflict in lab04/poem.txt
 Automatic merge failed; fix conflicts and then commit the result.

    Oh no! It’s a merge conflict!

  • In your text editor, open poem.txt. You should see a section that looks like: 
     <<<<<<< HEAD
 I use aliases that make me feel elite,
 =======
 I use aliases that make me feel great,
 >>>>>>> 1053959eab016f9b0ba8608d83291c8b19bb330d

    This is the merge conflict! Since “elite” actually rhymes, let’s keep the line with “elite”. Delete the 4 extra lines (the 3 lines with the strange symbols, and the line with “great”).

  • Add and commit poem.txt. This is the “merge commit”.
  • Push your change to Github. Congratulations, you’ve survived a merge conflict!

Enterprise Software Development

Your company, Flik Enterprises, has released a fine software library (flik.rs) that is able to determine whether two Integers are the same or not.

You receive an email from someone named “Horrible Steve” who describes a problem they’re having with your library:

Dear Flik Enterprises,

Your library is very bad. See the attached code. It should be printing “Incorrect. Access Denied”, but is printing “Correct. Access Granted.”

(attachment: main.rs)

If you run the program with cargo run, you’ll see that it indeed prints “Correct. Access Granted”. Figure out whether the bug is in Horrible Steve’s code or in Flik Enterprise’s library, and fix the bug.