git/Documentation/technical/api-merge.txt

merge API
=========

The merge API helps a program to reconcile two competing sets of
improvements to some files (e.g., unregistered changes from the work
tree versus changes involved in switching to a new branch), reporting
conflicts if found.  The library called through this API is
responsible for a few things.

 * determining which trees to merge (recursive ancestor consolidation);

 * lining up corresponding files in the trees to be merged (rename
   detection, subtree shifting), reporting edge cases like add/add
   and rename/rename conflicts to the user;

 * performing a three-way merge of corresponding files, taking
   path-specific merge drivers (specified in `.gitattributes`)
   into account.

Data structures
---------------

* `mmbuffer_t`, `mmfile_t`

These store data usable for use by the xdiff backend, for writing and
for reading, respectively.  See `xdiff/xdiff.h` for the definitions
and `diff.c` for examples.

* `struct ll_merge_options`

Check ll-merge.h for details.

Low-level (single file) merge
-----------------------------

Check ll-merge.h for details.