range-diff doc: add a section about output stability

The range-diff command is already advertised as porcelain, but let's make it really clear that the output is completely subject to change, particularly when it comes to diff options such as --stat. Right now that option doesn't work, but fixing that is the subject of a later change. Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>

Ævar Arnfjörð Bjarmason committed Nov 9, 2018 at 10:18 UTC df569c3f31f4aab5f9fd003029090a321bacd2bd
1 file changed +17
Documentation/git-range-diff.txt
+17
@@ -78,6 +78,23 @@ between patches", i.e. to compare the author, commit message and diff of
78 corresponding old/new commits. There is currently no means to tweak the
79 diff options passed to `git log` when generating those patches.
80
81 +OUTPUT STABILITY
82 +----------------
83 +
84 +The output of the `range-diff` command is subject to change. It is
85 +intended to be human-readable porcelain output, not something that can
86 +be used across versions of Git to get a textually stable `range-diff`
87 +(as opposed to something like the `--stable` option to
88 +linkgit:git-patch-id[1]). There's also no equivalent of
89 +linkgit:git-apply[1] for `range-diff`, the output is not intended to
90 +be machine-readable.
91 +
92 +This is particularly true when passing in diff options. Currently some
93 +options like `--stat` can, as an emergent effect, produce output
94 +that's quite useless in the context of `range-diff`. Future versions
95 +of `range-diff` may learn to interpret such options in a manner
96 +specific to `range-diff` (e.g. for `--stat` producing human-readable
97 +output which summarizes how the diffstat changed).
98
99 CONFIGURATION
100 -------------