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2022-03-09Merge branch 'en/present-despite-skipped'Libravatar Junio C Hamano1-30/+46
In sparse-checkouts, files mis-marked as missing from the working tree could lead to later problems. Such files were hard to discover, and harder to correct. Automatically detecting and correcting the marking of such files has been added to avoid these problems. * en/present-despite-skipped: repo_read_index: add config to expect files outside sparse patterns Accelerate clear_skip_worktree_from_present_files() by caching Update documentation related to sparsity and the skip-worktree bit repo_read_index: clear SKIP_WORKTREE bit from files present in worktree unpack-trees: fix accidental loss of user changes t1011: add testcase demonstrating accidental loss of user modifications
2022-02-08sparse-checkout: set worktree-config correctlyLibravatar Derrick Stolee1-4/+12
`git sparse-checkout set/init` enables worktree-specific configuration[*] by setting extensions.worktreeConfig=true, but neglects to perform the additional necessary bookkeeping of relocating `core.bare=true` and `core.worktree` from $GIT_COMMON_DIR/config to $GIT_COMMON_DIR/config.worktree, as documented in git-worktree.txt. As a result of this oversight, these settings, which are nonsensical for secondary worktrees, can cause Git commands to incorrectly consider a worktree bare (in the case of `core.bare`) or operate on the wrong worktree (in the case of `core.worktree`). Fix this problem by taking advantage of the recently-added init_worktree_config() which enables `extensions.worktreeConfig` and takes care of necessary bookkeeping. While at it, for backward-compatibility reasons, also stop upgrading the repository format to "1" since doing so is (unintentionally) not required to take advantage of `extensions.worktreeConfig`, as explained by 11664196ac ("Revert "check_repository_format_gently(): refuse extensions for old repositories"", 2020-07-15). [*] The main reason to use worktree-specific config for the sparse-checkout builtin was to avoid enabling sparse-checkout patterns in one and causing a loss of files in another. If a worktree does not have a sparse-checkout patterns file, then the sparse-checkout logic will not kick in on that worktree. Reported-by: Sean Allred <allred.sean@gmail.com> Helped-by: Eric Sunshine <sunshine@sunshineco.com> Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Reviewed-by: Elijah Newren <newren@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-01-14Update documentation related to sparsity and the skip-worktree bitLibravatar Elijah Newren1-30/+46
Make several small updates, to address a few documentation issues I spotted: * sparse-checkout focused on "patterns" even though the inputs (and outputs in the case of `list`) are directories in cone-mode * The description section of the sparse-checkout documentation was a bit sparse (no pun intended), and focused more on internal mechanics rather than end user usage. This made sense in the early days when the command was even more experimental, but let's adjust a bit to try to make it more approachable to end users who may want to consider using it. Keep the scary backward compatibility warning, though; we're still hard at work trying to fix up commands to behave reasonably in sparse checkouts. * both read-tree and update-index tried to describe how to use the skip-worktree bit, but both predated the sparse-checkout command. The sparse-checkout command is a far easier mechanism to use and for users trying to reduce the size of their working tree, we should recommend users to look at it instead. * The update-index documentation pointed out that assume-unchanged and skip-worktree sounded similar but had different purposes. However, it made no attempt to explain the differences, only to point out that they were different. Explain the differences. * The update-index documentation focused much more on (internal?) implementation details than on end-user usage. Try to explain its purpose better for users of update-index, rather than fellow developers trying to work with the SKIP_WORKTREE bit. * Clarify that when core.sparseCheckout=true, we treat a file's presence in the working tree as being an override to the SKIP_WORKTREE bit (i.e. in sparse checkouts when the file is present we ignore the SKIP_WORKTREE bit). Note that this commit, like many touching documentation, is best viewed with the `--color-words` option to diff/log. Signed-off-by: Elijah Newren <newren@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-01-03Merge branch 'en/sparse-checkout-set'Libravatar Junio C Hamano1-44/+56
The "init" and "set" subcommands in "git sparse-checkout" have been unified for a better user experience and performance. * en/sparse-checkout-set: sparse-checkout: remove stray trailing space clone: avoid using deprecated `sparse-checkout init` Documentation: clarify/correct a few sparsity related statements git-sparse-checkout.txt: update to document init/set/reapply changes sparse-checkout: enable reapply to take --[no-]{cone,sparse-index} sparse-checkout: enable `set` to initialize sparse-checkout mode sparse-checkout: split out code for tweaking settings config sparse-checkout: disallow --no-stdin as an argument to set sparse-checkout: add sanity-checks on initial sparsity state sparse-checkout: break apart functions for sparse_checkout_(set|add) sparse-checkout: pass use_stdin as a parameter instead of as a global
2021-12-15Documentation: clarify/correct a few sparsity related statementsLibravatar Elijah Newren1-1/+1
Reviewed-by: Derrick Stolee <dstolee@microsoft.com> Reviewed-by: Victoria Dye <vdye@github.com> Signed-off-by: Elijah Newren <newren@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-12-15git-sparse-checkout.txt: update to document init/set/reapply changesLibravatar Elijah Newren1-43/+55
As noted in the previous commit, using separate `init` and `set` steps with sparse-checkout result in a number of issues. The previous commits made `set` able to handle the work of both commands, and enabled reapply to tweak the {cone,sparse-index} settings. Update the documentation to reflect this, and mark `init` as deprecated. Reviewed-by: Derrick Stolee <dstolee@microsoft.com> Reviewed-by: Victoria Dye <vdye@github.com> Signed-off-by: Elijah Newren <newren@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-12-10Merge branch 'ja/doc-cleanup'Libravatar Junio C Hamano1-1/+1
Doc update. * ja/doc-cleanup: init doc: --shared=0xxx does not give umask but perm bits doc: git-init: clarify file modes in octal. doc: git-http-push: describe the refs as pattern pairs doc: uniformize <URL> placeholders' case doc: use three dots for indicating repetition instead of star doc: git-ls-files: express options as optional alternatives doc: use only hyphens as word separators in placeholders doc: express grammar placeholders between angle brackets doc: split placeholders as individual tokens doc: fix git credential synopsis
2021-11-09doc: express grammar placeholders between angle bracketsLibravatar Jean-Noël Avila1-1/+1
This discerns user inputs from verbatim options in the synopsis. Signed-off-by: Jean-Noël Avila <jn.avila@free.fr> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-09-07sparse-checkout: clear tracked sparse dirsLibravatar Derrick Stolee1-0/+10
When changing the scope of a sparse-checkout using cone mode, we might have some tracked directories go out of scope. The current logic removes the tracked files from within those directories, but leaves the ignored files within those directories. This is a bit unexpected to users who have given input to Git saying they don't need those directories anymore. This is something that is new to the cone mode pattern type: the user has explicitly said "I want these directories and _not_ those directories." The typical sparse-checkout patterns more generally apply to "I want files with with these patterns" so it is natural to leave ignored files as they are. This focus on directories in cone mode provides us an opportunity to change the behavior. Leaving these ignored files in the sparse directories makes it impossible to gain performance benefits in the sparse index. When we track into these directories, we need to know if the files are ignored or not, which might depend on the _tracked_ .gitignore file(s) within the sparse directory. This depends on the indexed version of the file, so the sparse directory must be expanded. We must take special care to look for untracked, non-ignored files in these directories before deleting them. We do not want to delete any meaningful work that the users were doing in those directories and perhaps forgot to add and commit before switching sparse-checkout definitions. Since those untracked files might be code files that generated ignored build output, also do not delete any ignored files from these directories in that case. The users can recover their state by resetting their sparse-checkout definition to include that directory and continue. Alternatively, they can see the warning that is presented and delete the directory themselves to regain the performance they expect. By deleting the sparse directories when changing scope (or running 'git sparse-checkout reapply') we regain these performance benefits as if the repository was in a clean state. Since these ignored files are frequently build output or helper files from IDEs, the users should not need the files now that the tracked files are removed. If the tracked files reappear, then they will have newer timestamps than the build artifacts, so the artifacts will need to be regenerated anyway. Use the sparse-index as a data structure in order to find the sparse directories that can be safely deleted. Re-expand the index to a full one if it was full before. Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Reviewed-by: Elijah Newren <newren@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-03-30sparse-checkout: toggle sparse index from builtinLibravatar Derrick Stolee1-0/+14
The sparse index extension is used to signal that index writes should be in sparse mode. This was only updated using GIT_TEST_SPARSE_INDEX=1. Add a '--[no-]sparse-index' option to 'git sparse-checkout init' that specifies if the sparse index should be used. It also updates the index to use the correct format, either way. Add a warning in the documentation that the use of a repository extension might reduce compatibility with third-party tools. 'git sparse-checkout init' already sets extension.worktreeConfig, which places most sparse-checkout users outside of the scope of most third-party tools. Update t1092-sparse-checkout-compatibility.sh to use this CLI instead of GIT_TEST_SPARSE_INDEX=1. Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-06-22Merge branch 'en/sparse-with-submodule-doc'Libravatar Junio C Hamano1-4/+26
The effect of sparse checkout settings on submodules is documented. * en/sparse-with-submodule-doc: git-sparse-checkout: clarify interactions with submodules
2020-06-12git-sparse-checkout: clarify interactions with submodulesLibravatar Elijah Newren1-4/+26
Ignoring the sparse-checkout feature momentarily, if one has a submodule and creates local branches within it with unpushed changes and maybe adds some untracked files to it, then we would want to avoid accidentally removing such a submodule. So, for example with git.git, if you run git checkout v2.13.0 then the sha1collisiondetection/ submodule is NOT removed even though it did not exist as a submodule until v2.14.0. Similarly, if you only had v2.13.0 checked out previously and ran git checkout v2.14.0 the sha1collisiondetection/ submodule would NOT be automatically initialized despite being part of v2.14.0. In both cases, git requires submodules to be initialized or deinitialized separately. Further, we also have special handling for submodules in other commands such as clean, which requires two --force flags to delete untracked submodules, and some commands have a --recurse-submodules flag. sparse-checkout is very similar to checkout, as evidenced by the similar name -- it adds and removes files from the working copy. However, for the same avoid-data-loss reasons we do not want to remove a submodule from the working copy with checkout, we do not want to do it with sparse-checkout either. So submodules need to be separately initialized or deinitialized; changing sparse-checkout rules should not automatically trigger the removal or vivification of submodules. I believe the previous wording in git-sparse-checkout.txt about submodules was only about this particular issue. Unfortunately, the previous wording could be interpreted to imply that submodules should be considered active regardless of sparsity patterns. Update the wording to avoid making such an implication. It may be helpful to consider two example situations where the differences in wording become important: In the future, we want users to be able to run commands like git clone --sparse=moduleA --recurse-submodules $REPO_URL and have sparsity paths automatically set up and have submodules *within the sparsity paths* be automatically initialized. We do not want all submodules in any path to be automatically initialized with that command. Similarly, we want to be able to do things like git -c sparse.restrictCmds grep --recurse-submodules $REV $PATTERN and search through $REV for $PATTERN within the recorded sparsity patterns. We want it to recurse into submodules within those sparsity patterns, but do not want to recurse into directories that do not match the sparsity patterns in search of a possible submodule. Signed-off-by: Elijah Newren <newren@gmail.com> Reviewed-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-05-18git-sparse-checkout.txt: add missing 'Libravatar Martin Ågren1-1/+1
Where we explain the 'reapply' command, we don't properly wrap it in single quote marks like we do with the other commands: We omit the closing mark ("'reapply") and this ends up being rendered literally as "'reapply". Add the missing "'". Signed-off-by: Martin Ågren <martin.agren@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-03-27sparse-checkout: provide a new reapply subcommandLibravatar Elijah Newren1-0/+10
If commands like merge or rebase materialize files as part of their work, or a previous sparse-checkout command failed to update individual files due to dirty changes, users may want a command to simply 'reapply' the sparsity rules. Provide one. Reviewed-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Elijah Newren <newren@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-03-05Merge branch 'ds/sparse-add'Libravatar Junio C Hamano1-0/+7
"git sparse-checkout" learned a new "add" subcommand. * ds/sparse-add: sparse-checkout: allow one-character directories in cone mode sparse-checkout: work with Windows paths sparse-checkout: create 'add' subcommand sparse-checkout: extract pattern update from 'set' subcommand sparse-checkout: extract add_patterns_from_input()
2020-02-14Merge branch 'ds/sparse-checkout-harden'Libravatar Junio C Hamano1-4/+15
Some rough edges in the sparse-checkout feature, especially around the cone mode, have been cleaned up. * ds/sparse-checkout-harden: sparse-checkout: fix cone mode behavior mismatch sparse-checkout: improve docs around 'set' in cone mode sparse-checkout: escape all glob characters on write sparse-checkout: use C-style quotes in 'list' subcommand sparse-checkout: unquote C-style strings over --stdin sparse-checkout: write escaped patterns in cone mode sparse-checkout: properly match escaped characters sparse-checkout: warn on globs in cone patterns sparse-checkout: detect short patterns sparse-checkout: cone mode does not recognize "**" sparse-checkout: fix documentation typo for core.sparseCheckoutCone clone: fix --sparse option with URLs sparse-checkout: create leading directories t1091: improve here-docs t1091: use check_files to reduce boilerplate
2020-02-11sparse-checkout: create 'add' subcommandLibravatar Derrick Stolee1-0/+7
When using the sparse-checkout feature, a user may want to incrementally grow their sparse-checkout pattern set. Allow adding patterns using a new 'add' subcommand. This is not much different from the 'set' subcommand, because we still want to allow the '--stdin' option and interpret inputs as directories when in cone mode and patterns otherwise. When in cone mode, we are growing the cone. This may actually reduce the set of patterns when adding directory A when A/B is already a directory in the cone. Test the different cases: siblings, parents, ancestors. When not in cone mode, we can only assume the patterns should be appended to the sparse-checkout file. Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-01-31sparse-checkout: improve docs around 'set' in cone modeLibravatar Derrick Stolee1-3/+14
The existing documentation does not clarify how the 'set' subcommand changes when core.sparseCheckoutCone is enabled. Correct this by changing some language around the "A/B/C" example. Also include a description of the input format matching the output of 'git ls-tree --name-only'. Helped-by: Jeff King <peff@peff.net> Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-01-24sparse-checkout: fix documentation typo for core.sparseCheckoutConeLibravatar Jeff King1-1/+1
Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-01-23doc: sparse-checkout: mention --cone optionLibravatar Matheus Tavares1-0/+4
In af09ce2 ("sparse-checkout: init and set in cone mode", 2019-11-21), the '--cone' option was added to 'git sparse-checkout init'. Document it. Signed-off-by: Matheus Tavares <matheus.bernardino@usp.br> Acked-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-01-06Merge branch 'ds/sparse-cone'Libravatar Junio C Hamano1-1/+1
Code cleanup. * ds/sparse-cone: Documentation/git-sparse-checkout.txt: fix a typo sparse-checkout: use extern for global variables
2020-01-04Documentation/git-sparse-checkout.txt: fix a typoLibravatar Taylor Blau1-1/+1
This typo was introduced in 94c0956b60 (sparse-checkout: create builtin with 'list' subcommand, 2019-11-21). Signed-off-by: Taylor Blau <me@ttaylorr.com> Acked-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-12-30sparse-checkout: document interactions with submodulesLibravatar Derrick Stolee1-0/+10
Using 'git submodule (init|deinit)' a user can select a subset of submodules to populate. This behaves very similar to the sparse-checkout feature, but those directories contain their own .git directory including an object database and ref space. To have the sparse-checkout file also determine if those files should exist would easily cause problems. Therefore, keeping these features independent in this way is the best way forward. Also create a test that demonstrates this behavior to make sure it doesn't change as the sparse-checkout feature evolves. Reported-by: Junio C Hamano <gitster@pobox.com> Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-12-30sparse-checkout: list directories in cone modeLibravatar Derrick Stolee1-1/+10
When core.sparseCheckoutCone is enabled, the 'git sparse-checkout set' command takes a list of directories as input, then creates an ordered list of sparse-checkout patterns such that those directories are recursively included and all sibling entries along the parent directories are also included. Listing the patterns is less user-friendly than the directories themselves. In cone mode, and as long as the patterns match the expected cone-mode pattern types, change the output of 'git sparse-checkout list' to only show the directories that created the patterns. With this change, the following piped commands would not change the working directory: git sparse-checkout list | git sparse-checkout set --stdin The only time this would not work is if core.sparseCheckoutCone is true, but the sparse-checkout file contains patterns that do not match the expected pattern types for cone mode. Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-12-13sparse-checkout: respect core.ignoreCase in cone modeLibravatar Derrick Stolee1-0/+5
When a user uses the sparse-checkout feature in cone mode, they add patterns using "git sparse-checkout set <dir1> <dir2> ..." or by using "--stdin" to provide the directories line-by-line over stdin. This behaviour naturally looks a lot like the way a user would type "git add <dir1> <dir2> ..." If core.ignoreCase is enabled, then "git add" will match the input using a case-insensitive match. Do the same for the sparse-checkout feature. Perform case-insensitive checks while updating the skip-worktree bits during unpack_trees(). This is done by changing the hash algorithm and hashmap comparison methods to optionally use case- insensitive methods. When this is enabled, there is a small performance cost in the hashing algorithm. To tease out the worst possible case, the following was run on a repo with a deep directory structure: git ls-tree -d -r --name-only HEAD | git sparse-checkout set --stdin The 'set' command was timed with core.ignoreCase disabled or enabled. For the repo with a deep history, the numbers were core.ignoreCase=false: 62s core.ignoreCase=true: 74s (+19.3%) For reproducibility, the equivalent test on the Linux kernel repository had these numbers: core.ignoreCase=false: 3.1s core.ignoreCase=true: 3.6s (+16%) Now, this is not an entirely fair comparison, as most users will define their sparse cone using more shallow directories, and the performance improvement from eb42feca97 ("unpack-trees: hash less in cone mode" 2019-11-21) can remove most of the hash cost. For a more realistic test, drop the "-r" from the ls-tree command to store only the first-level directories. In that case, the Linux kernel repository takes 0.2-0.25s in each case, and the deep repository takes one second, plus or minus 0.05s, in each case. Thus, we _can_ demonstrate a cost to this change, but it is unlikely to matter to any reasonable sparse-checkout cone. Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-11-22sparse-checkout: use in-process update for disable subcommandLibravatar Derrick Stolee1-2/+4
The 'git sparse-checkout disable' subcommand returns a user to a full working directory. The old process for doing this required updating the sparse-checkout file with the "/*" pattern and then updating the working directory with core.sparseCheckout enabled. Finally, the sparse-checkout file could be removed and the config setting disabled. However, it is valuable to keep a user's sparse-checkout file intact so they can re-enable the sparse-checkout they previously used with 'git sparse-checkout init'. This is now possible with the in-process mechanism for updating the working directory. Reported-by: Szeder Gábor <szeder.dev@gmail.com> Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-11-22sparse-checkout: add 'cone' modeLibravatar Derrick Stolee1-1/+54
The sparse-checkout feature can have quadratic performance as the number of patterns and number of entries in the index grow. If there are 1,000 patterns and 1,000,000 entries, this time can be very significant. Create a new Boolean config option, core.sparseCheckoutCone, to indicate that we expect the sparse-checkout file to contain a more limited set of patterns. This is a separate config setting from core.sparseCheckout to avoid breaking older clients by introducing a tri-state option. The config option does nothing right now, but will be expanded upon in a later commit. Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-11-22sparse-checkout: create 'disable' subcommandLibravatar Derrick Stolee1-15/+12
The instructions for disabling a sparse-checkout to a full working directory are complicated and non-intuitive. Add a subcommand, 'git sparse-checkout disable', to perform those steps for the user. Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-11-22sparse-checkout: add '--stdin' option to set subcommandLibravatar Derrick Stolee1-0/+3
The 'git sparse-checkout set' subcommand takes a list of patterns and places them in the sparse-checkout file. Then, it updates the working directory to match those patterns. For a large list of patterns, the command-line call can get very cumbersome. Add a '--stdin' option to instead read patterns over standard in. Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-11-22sparse-checkout: 'set' subcommandLibravatar Derrick Stolee1-0/+6
The 'git sparse-checkout set' subcommand takes a list of patterns as arguments and writes them to the sparse-checkout file. Then, it updates the working directory using 'git read-tree -mu HEAD'. The 'set' subcommand will replace the entire contents of the sparse-checkout file. The write_patterns_and_update() method is extracted from cmd_sparse_checkout() to make it easier to implement 'add' and/or 'remove' subcommands in the future. If the core.sparseCheckout config setting is disabled, then enable the config setting in the worktree config. If we set the config this way and the sparse-checkout fails, then re-disable the config setting. Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-11-22sparse-checkout: create 'init' subcommandLibravatar Derrick Stolee1-0/+11
Getting started with a sparse-checkout file can be daunting. Help users start their sparse enlistment using 'git sparse-checkout init'. This will set 'core.sparseCheckout=true' in their config, write an initial set of patterns to the sparse-checkout file, and update their working directory. Make sure to use the `extensions.worktreeConfig` setting and write the sparse checkout config to the worktree-specific config file. This avoids confusing interactions with other worktrees. The use of running another process for 'git read-tree' is sub- optimal. This will be removed in a later change. Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-11-22sparse-checkout: create builtin with 'list' subcommandLibravatar Derrick Stolee1-0/+89
The sparse-checkout feature is mostly hidden to users, as its only documentation is supplementary information in the docs for 'git read-tree'. In addition, users need to know how to edit the .git/info/sparse-checkout file with the right patterns, then run the appropriate 'git read-tree -mu HEAD' command. Keeping the working directory in sync with the sparse-checkout file requires care. Begin an effort to make the sparse-checkout feature a porcelain feature by creating a new 'git sparse-checkout' builtin. This builtin will be the preferred mechanism for manipulating the sparse-checkout file and syncing the working directory. The documentation provided is adapted from the "git read-tree" documentation with a few edits for clarity in the new context. Extra sections are added to hint toward a future change to a more restricted pattern set. Helped-by: Elijah Newren <newren@gmail.com> Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>