The diff commands 'git-diff-index', 'git-diff-files', and 'git-diff-tree'
can be told to manipulate differences they find in
-unconventional ways before showing `diff` output. The manipulation
+unconventional ways before showing 'diff' output. The manipulation
is collectively called "diffcore transformation". This short note
describes what they are and how to use them to produce 'diff' output
that is easier to understand than the conventional kind.
- 'git-diff-tree' compares contents of two "tree" objects;
-In all of these cases, the commands themselves compare
-corresponding paths in the two sets of files. The result of
-comparison is passed from these commands to what is internally
-called "diffcore", in a format similar to what is output when
-the -p option is not used. E.g.
+In all of these cases, the commands themselves first optionally limit
+the two sets of files by any pathspecs given on their command-lines,
+and compare corresponding paths in the two resulting sets of files.
+
+The pathspecs are used to limit the world diff operates in. They remove
+the filepairs outside the specified sets of pathnames. E.g. If the
+input set of filepairs included:
+
+------------------------------------------------
+:100644 100644 bcd1234... 0123456... M junkfile
+------------------------------------------------
+
+but the command invocation was `git diff-files myfile`, then the
+junkfile entry would be removed from the list because only "myfile"
+is under consideration.
+
+The result of comparison is passed from these commands to what is
+internally called "diffcore", in a format similar to what is output
+when the -p option is not used. E.g.
------------------------------------------------
in-place edit :100644 100644 bcd1234... 0123456... M file0
The diffcore mechanism is fed a list of such comparison results
(each of which is called "filepair", although at this point each
of them talks about a single file), and transforms such a list
-into another list. There are currently 6 such transformations:
+into another list. There are currently 5 such transformations:
-- diffcore-pathspec
- diffcore-break
- diffcore-rename
- diffcore-merge-broken
- diffcore-order
These are applied in sequence. The set of filepairs 'git-diff-{asterisk}'
-commands find are used as the input to diffcore-pathspec, and
-the output from diffcore-pathspec is used as the input to the
+commands find are used as the input to diffcore-break, and
+the output from diffcore-break is used as the input to the
next transformation. The final result is then passed to the
output routine and generates either diff-raw format (see Output
format sections of the manual for 'git-diff-{asterisk}' commands) or
diff-patch format.
-diffcore-pathspec: For Ignoring Files Outside Our Consideration
----------------------------------------------------------------
-
-The first transformation in the chain is diffcore-pathspec, and
-is controlled by giving the pathname parameters to the
-'git-diff-{asterisk}' commands on the command line. The pathspec is used
-to limit the world diff operates in. It removes the filepairs
-outside the specified set of pathnames. E.g. If the input set
-of filepairs included:
-
-------------------------------------------------
-:100644 100644 bcd1234... 0123456... M junkfile
-------------------------------------------------
-
-but the command invocation was `git diff-files myfile`, then the
-junkfile entry would be removed from the list because only "myfile"
-is under consideration.
-
-Implementation note. For performance reasons, 'git-diff-tree'
-uses the pathname parameters on the command line to cull set of
-filepairs it feeds the diffcore mechanism itself, and does not
-use diffcore-pathspec, but the end result is the same.
-
-
diffcore-break: For Splitting Up "Complete Rewrites"
----------------------------------------------------