On Wed, Dec 09, 2020 at 12:52:26PM +0100, Patrick Steinhardt wrote:

Co-authored-by: Jeff King [off-list ref]
Signed-off-by: Patrick Steinhardt <redacted>

In case we want it, this is also:

  Signed-off-by: Jeff King [off-list ref]

+--config-env=<name>=<envvar>::
+	Pass a configuration parameter to the command. The <envvar>
+	given will be replaced with the contents of the environment
+	variable of that name. In contrast to `-c`, an envvar must
+	always be given and exist in the environment. Passing an
+	environment variable with empty value will set <name> to the
+	empty string which `git config --type=bool` will convert to
+	`false`.

I agree with Ævar that we probably should keep an empty variable as the
empty string. I think some options use an empty string to clear a list
(e.g., push.pushOption), and I'm not sure how they'd react to a bool
instead. It would be nice to also have a way to do the implicit-bool
thing, but I don't think it's strictly necessary (it's always correct to
put the string "true" into the variable instead).

I think we should also document that <envvar> can't contain an "=" sign.
Of course using strrchr() here doesn't help much with just this patch,
because we flatten the string before stuffing it into
$GIT_CONFIG_PARAMETERS, so the reading side would mis-parse it.

But here's a fix for that. I built it on top of your whole series, since
you touched some of the related functions, but it could easily be
rebased onto just this part.

  [1/3]: quote: make sq_dequote_step() a public function
  [2/3]: config: parse more robust format in GIT_CONFIG_PARAMETERS
  [3/3]: config: store "git -c" variables using more robust format

 config.c          | 118 +++++++++++++++++++++++++++++++++++++---------
 quote.c           |  15 ++++--
 quote.h           |  18 ++++++-
 t/t1300-config.sh |  60 +++++++++++++++++++++++
 4 files changed, 183 insertions(+), 28 deletions(-)

-Peff