Merge branch 'jx/clean-interactive'

Add "interactive" mode to "git clean".

The early part to refactor relative path related helper functions
looked sensible.

* jx/clean-interactive:
  test: run testcases with POSIX absolute paths on Windows
  test: add t7301 for git-clean--interactive
  git-clean: add documentation for interactive git-clean
  git-clean: add ask each interactive action
  git-clean: add select by numbers interactive action
  git-clean: add filter by pattern interactive action
  git-clean: use a git-add-interactive compatible UI
  git-clean: add colors to interactive git-clean
  git-clean: show items of del_list in columns
  git-clean: add support for -i/--interactive
  git-clean: refactor git-clean into two phases
  write_name{_quoted_relative,}(): remove redundant parameters
  quote_path_relative(): remove redundant parameter
  quote.c: substitute path_relative with relative_path
  path.c: refactor relative_path(), not only strip prefix
  test: add test cases for relative_path

Documentation/config.txt

@@ -879,16 +879,17 @@ The values of these variables may be specified as in color.branch.<slot>.
 
 color.interactive::
 	When set to `always`, always use colors for interactive prompts
-	and displays (such as those used by "git-add --interactive").
-	When false (or `never`), never.  When set to `true` or `auto`, use
-	colors only when the output is to the terminal. Defaults to false.
+	and displays (such as those used by "git-add --interactive" and
+	"git-clean --interactive"). When false (or `never`), never.
+	When set to `true` or `auto`, use colors only when the output is
+	to the terminal. Defaults to false.
 
 color.interactive.<slot>::
-	Use customized color for 'git add --interactive'
-	output. `<slot>` may be `prompt`, `header`, `help` or `error`, for
-	four distinct types of normal output from interactive
-	commands.  The values of these variables may be specified as
-	in color.branch.<slot>.
+	Use customized color for 'git add --interactive' and 'git clean
+	--interactive' output. `<slot>` may be `prompt`, `header`, `help`
+	or `error`, for four distinct types of normal output from
+	interactive commands.  The values of these variables may be
+	specified as in color.branch.<slot>.
 
 color.pager::
 	A boolean to enable/disable colored output when the pager is in
@@ -973,6 +974,10 @@ column.branch::
 	Specify whether to output branch listing in `git branch` in columns.
 	See `column.ui` for details.
 
+column.clean::
+	Specify the layout when list items in `git clean -i`, which always
+	shows files and directories in columns. See `column.ui` for details.
+
 column.status::
 	Specify whether to output untracked files in `git status` in columns.
 	See `column.ui` for details.

Documentation/git-clean.txt

@@ -8,7 +8,7 @@ git-clean - Remove untracked files from the working tree
 SYNOPSIS
 --------
 [verse]
-'git clean' [-d] [-f] [-n] [-q] [-e <pattern>] [-x | -X] [--] <path>...
+'git clean' [-d] [-f] [-i] [-n] [-q] [-e <pattern>] [-x | -X] [--] <path>...
 
 DESCRIPTION
 -----------
@@ -34,7 +34,13 @@ OPTIONS
 -f::
 --force::
 	If the Git configuration variable clean.requireForce is not set
-	to false, 'git clean' will refuse to run unless given -f or -n.
+	to false, 'git clean' will refuse to run unless given -f, -n or
+	-i.
+
+-i::
+--interactive::
+	Show what would be done and clean files interactively. See
+	``Interactive mode'' for details.
 
 -n::
 --dry-run::
@@ -63,6 +69,67 @@ OPTIONS
 	Remove only files ignored by Git.  This may be useful to rebuild
 	everything from scratch, but keep manually created files.
 
+Interactive mode
+----------------
+When the command enters the interactive mode, it shows the
+files and directories to be cleaned, and goes into its
+interactive command loop.
+
+The command loop shows the list of subcommands available, and
+gives a prompt "What now> ".  In general, when the prompt ends
+with a single '>', you can pick only one of the choices given
+and type return, like this:
+
+------------
+    *** Commands ***
+	1: clean                2: filter by pattern    3: select by numbers
+	4: ask each             5: quit                 6: help
+    What now> 1
+------------
+
+You also could say `c` or `clean` above as long as the choice is unique.
+
+The main command loop has 6 subcommands.
+
+clean::
+
+   Start cleaning files and directories, and then quit.
+
+filter by pattern::
+
+   This shows the files and directories to be deleted and issues an
+   "Input ignore patterns>>" prompt. You can input space-seperated
+   patterns to exclude files and directories from deletion.
+   E.g. "*.c *.h" will excludes files end with ".c" and ".h" from
+   deletion. When you are satisfied with the filtered result, press
+   ENTER (empty) back to the main menu.
+
+select by numbers::
+
+   This shows the files and directories to be deleted and issues an
+   "Select items to delete>>" prompt. When the prompt ends with double
+   '>>' like this, you can make more than one selection, concatenated
+   with whitespace or comma.  Also you can say ranges.  E.g. "2-5 7,9"
+   to choose 2,3,4,5,7,9 from the list.  If the second number in a
+   range is omitted, all remaining patches are taken.  E.g. "7-" to
+   choose 7,8,9 from the list.  You can say '*' to choose everything.
+   Also when you are satisfied with the filtered result, press ENTER
+   (empty) back to the main menu.
+
+ask each::
+
+  This will start to clean, and you must confirm one by one in order
+  to delete items. Please note that this action is not as efficient
+  as the above two actions.
+
+quit::
+
+  This lets you quit without do cleaning.
+
+help::
+
+  Show brief usage of interactive git-clean.
+
 SEE ALSO
 --------
 linkgit:gitignore[5]