Subject: Re: [GSoC PATCH v2] backfill: auto-detect sparse-checkout from config

From: Junio C Hamano <[email-masked]>
Date: Mon, 06 Apr 2026 09:27:41 -0700

Derrick Stolee <[email-masked]> writes:

> On 4/4/26 7:15 AM, Trieu Huynh wrote:
>> From: Trieu Huynh <[email-masked]>
>> 
>> Commit 85127bcdea ("backfill: assume --sparse when sparse-checkout is
>> enabled") intended for 'git backfill' to consult the repository
>> configuration when the user does not pass '--sparse' or
>> '--no-sparse' on the command line. It added the sentinel check:
>> 
>>      if (ctx->sparse < 0)
>>          ctx->sparse = cfg->apply_sparse_checkout;
>> 
>> However, the ctx->sparse field is initialized to 0 instead of -1,
>> so this guard never triggers. Consequently, the repository config
>> (core.sparseCheckout) is never checked, and the command always
>> performs a full backfill even when sparse-checkout is enabled.
>
> Thanks for adding this context. This patch LGTM.

Yup, thanks, both of you.  The original patch without this
explanation may not be so obvious but after taking a look at what
that commit did, it is very clear what went wrong.