[PATCH 0/2] restore: better integrate with sparse index

["Derrick Stolee via GitGitGadget" <gitgitgadget@gmail.com>]

There's still a long tail of situations where Git expands a sparse index
in-memory in order to operate on blob path entries instead of intelligently
handling trees. I was recently alerted to one such case with git restore
--staged -- ..

The basic idea here is that the pathspec . signals that all paths matter,
but what we want to do across those pathspecs will ignore the expanded blob
paths with the SKIP_WORKTREE bit, so we should avoid expanding the tree when
we can.

This series has two patches: first a test to demonstrate the baseline
behavior of git restore across different sparsity cases as well as
demonstrate that the index is currently expanded. The second patch includes
the fix and maintains the same end-to-end behavior with the only change
being the performance improvement from not expanding the sparse index.

Thanks, -Stolee

Derrick Stolee (2):
  t1092: test 'git restore' with sparse index
  restore: avoid sparse index expansion

 builtin/checkout.c                       | 57 +++++++++++++++++++++---
 t/t1092-sparse-checkout-compatibility.sh | 50 +++++++++++++++++++++
 2 files changed, 101 insertions(+), 6 deletions(-)


base-commit: aec3f587505a472db67e9462d0702e7d463a449d
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-2121%2Fderrickstolee%2Frestore-sparse-index-v1
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-2121/derrickstolee/restore-sparse-index-v1
Pull-Request: https://github.com/gitgitgadget/git/pull/2121
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