builtin/ls-files.c:add git ls-file --dedup option

I am reading the source code of git ls-files and learned that git ls-files may have duplicate files name when there are unmerged path in a branch merge or when different options are used at the same time. Users may fell confuse when they see these duplicate file names.

As Junio C Hamano said ,it have odd behaviour.

Therefore, we can provide an additional option to git ls-files to delete those repeated information.

This fixes https://github.com/gitgitgadget/git/issues/198

Thanks!

ZheNing Hu (3):
ls_files.c: bugfix for --deleted and --modified
ls_files.c: consolidate two for loops into one
ls-files.c: add --deduplicate option

 Documentation/git-ls-files.txt |  8 ++++
 builtin/ls-files.c             | 85 ++++++++++++++++++++--------------
 t/t3012-ls-files-dedup.sh      | 66 ++++++++++++++++++++++++++
 3 files changed, 124 insertions(+), 35 deletions(-)
 create mode 100755 t/t3012-ls-files-dedup.sh

base-commit: 6d3ef5b467eccd2769f1aa1c555d317d3c8dc707
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-832%2Fadlternative%2Fls-files-dedup-v7
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-832/adlternative/ls-files-dedup-v7
Pull-Request: https://github.com/gitgitgadget/git/pull/832

Range-diff vs v6:

1: fbc38ce9075 ! 1: 8b02367a359 ls_files.c: bugfix for --deleted and --modified
@@ Commit message
ie_modified() when lstat() has failed.

+ [jc: fixed misindented code]
+ Signed-off-by: Junio C Hamano <[email protected]>

## builtin/ls-files.c ##
@@ builtin/ls-files.c: static void show_files(struct repository *repo, struct dir_struct *dir)
2: 3997d390883 ! 2: f9d5e44d2c0 ls_files.c: consolidate two for loops into one
@@ Metadata
## Commit message ##
ls_files.c: consolidate two for loops into one

- Refactor the two for loops into one,skip showing the ce if it
- has the same name as the previously shown one, only when doing so
- won't lose information.
+ This will make it easier to show only one entry per filename in the
+ next step.

+ [jc: corrected the log message]
+ Signed-off-by: Junio C Hamano <[email protected]>

## builtin/ls-files.c ##
@@ builtin/ls-files.c: static void show_files(struct repository *repo, struct dir_struct *dir)
3: 07b603fd97c ! 3: 384f77a4c18 ls-files.c: add --deduplicate option
@@ Metadata
## Commit message ##
ls-files.c: add --deduplicate option

- In order to provide users a better experience
- when viewing information about files in the index
- and the working tree, the --deduplicate option will suppress
- some duplicate name under some conditions.
+ During a merge conflict, the name of a file may appear multiple
+ times in "git ls-files" output, once for each stage. If you use
+ both --delete and --modify at the same time, the output may
+ mention a deleted file twice.

- In a merge conflict, one file name of "git ls-files" output may
- appear multiple times. For example,now there is an unmerged path
- a.c,a.c will appear three times in the output of
- "git ls-files".We can use "git ls-files --deduplicate" to output
- a.c only one time.(unless --stage or --unmerged is
- used to view all the detailed information in the index)
+ When none of the '-t', '-u', or '-s' options is in use, these
+ duplicate entries do not add much value to the output.

- In addition, if you use both --delete and --modify at
- the same time, The --deduplicate option
- can also suppress file name output.
-
- Additional instructions:
- In order to display entries information,deduplicate suppresses
- the output of duplicate file names, not the output of duplicate
- entries information, so under the option of -t, --stage, --unmerge,
- --deduplicate will have no effect.
+ Introduce a new '--deduplicate' option to suppress them.

+ [jc: extended doc and rewritten commit log]
+ Signed-off-by: Junio C Hamano <[email protected]>

## Documentation/git-ls-files.txt ##
@@ Documentation/git-ls-files.txt: SYNOPSIS
@@ Documentation/git-ls-files.txt: OPTIONS
See OUTPUT below for more information.

+--deduplicate::
-+ Suppress duplicate entries when there are unmerged paths in index
-+ or --deleted and --modified are combined.
++ When only filenames are shown, suppress duplicates that may
++ come from having multiple stages during a merge, or giving
++ --deleted and --modified option at the same time.
++ When any of the -t, --unmerged, or --stage option is
++ in use, this option has no effect.
+
-x <pattern>::
--exclude=<pattern>::

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