Add auto-formatting of json file

Given the just added json-file formatter, we can generate a diff
formatting properly all json files, i.e., all target, rules, and
expression files, by applying that formatter to every target file
and combining the patches. A target description doing precisely
this can easily be obtained as computed root. In this way, we also
make good use of caching. To avoid doing recomputing the target
description unnecessarily, we factor through the tree structure of
the repository tree; the latter, we obtain from the to-git view of
the top-level directory, whereas for computing the diff we use the
actual (not necessarily committed) files.

1 files changed, 6 insertions, 0 deletions

diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 6badaf33..bb49ae60 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -28,6 +28,12 @@ is honored. As a consequence, (transitively) depending on the
 first time requires a significant amount of time to build the tools
 from first principles. This is also true when calling `bin/format-code.sh`.
 
+Target, rules, and expression files should be formatted using
+`bin/json-format.py`. The corresponding target is `["@", "format-json", "", ""]`
+which provides a diff to be applied in order to obtain well-formatted
+target, rules, and expression files; the script `bin/format-json.sh`
+computes and applies that diff.
+
 Changes should be organized as a patch series, i.e., as a sequence of
 small changes that are easy to review, but nevertheless self-contained
 in the sense that after each such change, the code builds and the