Re: [PATCH v5 3/3] builtin/grep.c: walking tree instead of expanding index with --sparse

Derrick Stolee [off-list ref] writes:

On 9/8/2022 1:59 PM, Junio C Hamano wrote:

quoted

Shaoxuan Yuan [off-list ref] writes:

quoted

+
+	/*
+	 * NEEDSWORK: when reading a submodule, the sparsity settings in the
+	 * superproject are incorrectly forgotten or misused. For example:
+	 *
+	 * 1. "command_requires_full_index"
+	 * 	When this setting is turned on for `grep`, only the superproject
+	 *	knows it. All the submodules are read with their own configs
+	 *	and get prepare_repo_settings()'d. Therefore, these submodules
+	 *	"forget" the sparse-index feature switch. As a result, the index
+	 *	of these submodules are expanded unexpectedly.

 ...

I think this comment is misplaced. It should either be contained in
the commit message or placed closer to this diff hunk:

OK, so given what you wrote below, except for such a minor
shuffling, the current series is ready to go?

Thanks.

...
Shaoxuan's comment is attempting to list the reasons why submodules
do not currently work with sparse-index, and specifically that we
can add tests that _should_ exercise this code in a meaningful way,
but because of the current limitations of the codebase, the code
isn't actually exercised in that scenario.

In order to actually create a test that demonstrates how submodules
and sparse-checkout work with this logic, we need to do some serious
refactoring of the sparse-checkout logic to care about the repository
struct, along with some other concerns specifically around the sparse
index. This doesn't seem appropriate for the GSoC timeline or even for
just this topic.