[PATCH 0/4] Sparse index integration with 'git show'

This continues our sequence of integrating builtins with the sparse index.

'git show' is relatively simple to get working in a way that doesn't fail when it would previously succeed, but there are some sutbleties when the user passes a directory path. If that path happens to be a sparse directory entry, we suddenly start succeeding and printing the tree information!

Since this behavior can change depending on the sparse checkout definition and the state of index entries within that directory, this new behavior would be more likely to confuse users than help them.

Here is an outline of this series:

 * Patch 1: Add more tests around 'git show :' in t1092.

 * Patch 2: Make 'git show' stop expanding the index by default. Make note
   of this behavior change in the tests.

 * Patches 3-4: Make the subtle changes to object-name.c that help us reject
   sparse directories (patch 3) and print the correct error message (patch
   4).

Patches 2-4 could realistically be squashed into a single commit, but I thought it might be instructive to show these individual steps, especially as an example for our GSoC project.

This series is based on the current 'master'. I know that Victoria intends to submit her 'git stash' integration soon, and this provides a way to test if our split of test changes in t1092 are easy to merge without conflict. If that is successful, then I will likely submit my integration with the 'sparse-checkout' builtin after this series is complete.

Thanks, -Stolee

Derrick Stolee (4):
  t1092: add compatibility tests for 'git show'
  show: integrate with the sparse index
  object-name: reject trees found in the index
  object-name: diagnose trees in index properly

 builtin/log.c                            |  5 ++++
 object-name.c                            | 25 +++++++++++++++---
 t/t1092-sparse-checkout-compatibility.sh | 33 ++++++++++++++++++++++++
 3 files changed, 60 insertions(+), 3 deletions(-)

base-commit: 07330a41d66a2c9589b585a3a24ecdcf19994f19
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-1207%2Fderrickstolee%2Fsparse-index%2Fgit-show-v1
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-1207/derrickstolee/sparse-index/git-show-v1
Pull-Request: https://github.com/gitgitgadget/git/pull/1207