Hi!

Please could you add WinMerge to the merge tool selection as it has supported 3-way merge since early 2018? Thank you! 

Current situation (Tested on Sourcetree 3.4.3 Windows 64-bit):

WinMerge is not available in the "Options > Diff > External Diff / Merge > Merge Tool" dropdown box.

Desired outcome:

WinMerge is available in the "Options > Diff > External Diff / Merge > Merge Tool" dropdown box and merging using it works.

Background / related issues:

Related bug:

The bug SRCTREEWIN-4572 ("Can't select WinMerge as merge tool") from 2016 was closed because WinMerge didn't yet support a 3-way merge. But as of 2018-01-28 WinMerge has supported 3-way merge (See WinMerge 2.15.2 changelog from 2018-01-28: "Add support for 3-way compare/merge"). I tried today (2021-03-08) using WinMerge 3-way merge with the custom merge option using the information from this Sourcetree Community question and it worked okay.

Currently working custom merge options for WinMerge:

The options I used in Sourcetree 3.4.3 for Windows 64-bit with WinMerge 2.16.10.0 x64 and which worked for merging:

• Options > Diff > External Diff / Merge:
  • Merge Tool: Custom
  • Merge Command: C:\Program Files\WinMerge\WinMergeU.exe
    • Arguments:

      -wl -wr -dl Remote -dm Base -dr Local \"$REMOTE\" \"$BASE\" \"$LOCAL\" -o \"$MERGED\"