Add git and github tips and tricks to developer notes

Author: sipa

doc/developer-notes.md

@@ -381,3 +381,51 @@ GUI
   - *Rationale*: Model classes pass through events and data from the core, they
     should not interact with the user. That's where View classes come in. The converse also
     holds: try to not directly access core data structures from Views.
+
+Git and github tips
+---------------------
+
+- For resolving merge/rebase conflicts, it can be useful to enable diff3 style using
+  `git config merge.conflictstyle diff3`. Instead of
+
+        <<<
+        yours
+        ===
+        theirs
+        >>>
+
+  you will see
+
+        <<<
+        yours
+        |||
+        original
+        ===
+        theirs
+        >>>
+
+  This may make it much clearer what caused the conflict. In this style, you can often just look
+  at what changed between *original* and *theirs*, and mechanically apply that to *yours* (or the other way around).
+
+- When reviewing patches which change indentation in C++ files, use `git diff -w` and `git show -w`. This makes
+  the diff algorithm ignore whitespace changes. This feature is also available on github.com, by adding `?w=1`
+  at the end of any URL which shows a diff.
+
+- When reviewing patches that change symbol names in many places, use `git diff --word-diff`. This will instead
+  of showing the patch as deleted/added *lines*, show deleted/added *words*.
+
+- When reviewing patches that move code around, try using
+  `git diff --patience commit~:old/file.cpp commit:new/file/name.cpp`, and ignoring everything except the
+  moved body of code which should show up as neither `+` or `-` lines. In case it was not a pure move, this may
+  even work when combined with the `-w` or `--word-diff` options described above.
+
+- When looking at other's pull requests, it may make sense to add the following section to your `.git/config`
+  file:
+
+        [remote "upstream-pull"]
+                fetch = +refs/pull/*:refs/remotes/upstream-pull/*
+                url = [email protected]:bitcoin/bitcoin.git
+
+  This will add an `upstream-pull` remote to your git repository, which can be fetched using `git fetch --all`
+  or `git fetch upstream-pull`. Afterwards, you can use `upstream-pull/NUMBER/head` in arguments to `git show`,
+  `git checkout` and anywhere a commit id would be acceptable to see the changes from pull request NUMBER.