Merge branch 'bw/submodule-is-active'

"what URL do we want to update this submodule?" and "are we
interested in this submodule?" are split into two distinct
concepts, and then the way used to express the latter got extended,
paving a way to make it easier to manage a project with many
submodules and make it possible to later extend use of multiple
worktrees for a project with submodules.

* bw/submodule-is-active:
  submodule add: respect submodule.active and submodule.<name>.active
  submodule--helper init: set submodule.<name>.active
  clone: teach --recurse-submodules to optionally take a pathspec
  submodule init: initialize active submodules
  submodule: decouple url and submodule interest
  submodule--helper clone: check for configured submodules using helper
  submodule sync: use submodule--helper is-active
  submodule sync: skip work for inactive submodules
  submodule status: use submodule--helper is-active
  submodule--helper: add is-active subcommand

Documentation/config.txt

@@ -3013,8 +3013,9 @@ submodule.<name>.url::
 	The URL for a submodule. This variable is copied from the .gitmodules
 	file to the git config via 'git submodule init'. The user can change
 	the configured URL before obtaining the submodule via 'git submodule
-	update'. After obtaining the submodule, the presence of this variable
-	is used as a sign whether the submodule is of interest to git commands.
+	update'. If neither submodule.<name>.active or submodule.active are
+	set, the presence of this variable is used as a fallback to indicate
+	whether the submodule is of interest to git commands.
 	See linkgit:git-submodule[1] and linkgit:gitmodules[5] for details.
 
 submodule.<name>.update::
@@ -3052,6 +3053,16 @@ submodule.<name>.ignore::
 	"--ignore-submodules" option. The 'git submodule' commands are not
 	affected by this setting.
 
+submodule.<name>.active::
+	Boolean value indicating if the submodule is of interest to git
+	commands.  This config option takes precedence over the
+	submodule.active config option.
+
+submodule.active::
+	A repeated field which contains a pathspec used to match against a
+	submodule's path to determine if the submodule is of interest to git
+	commands.
+
 submodule.fetchJobs::
 	Specifies how many submodules are fetched/cloned at the same time.
 	A positive integer allows up to that number of submodules fetched

Documentation/git-clone.txt

@@ -14,7 +14,7 @@ SYNOPSIS
 	  [-o <name>] [-b <name>] [-u <upload-pack>] [--reference <repository>]
 	  [--dissociate] [--separate-git-dir <git dir>]
 	  [--depth <depth>] [--[no-]single-branch]
-	  [--recursive | --recurse-submodules] [--[no-]shallow-submodules]
+	  [--recurse-submodules] [--[no-]shallow-submodules]
 	  [--jobs <n>] [--] <repository> [<directory>]
 
 DESCRIPTION
@@ -215,10 +215,14 @@ objects from the source repository into a pack in the cloned repository.
 	branch when `--single-branch` clone was made, no remote-tracking
 	branch is created.
 
---recursive::
---recurse-submodules::
-	After the clone is created, initialize all submodules within,
-	using their default settings. This is equivalent to running
+--recurse-submodules[=<pathspec]::
+	After the clone is created, initialize and clone submodules
+	within based on the provided pathspec.  If no pathspec is
+	provided, all submodules are initialized and cloned.
+	Submodules are initialized and cloned using their default
+	settings.  The resulting clone has `submodule.active` set to
+	the provided pathspec, or "." (meaning all submodules) if no
+	pathspec is provided.  This is equivalent to running
 	`git submodule update --init --recursive` immediately after
 	the clone is finished. This option is ignored if the cloned
 	repository does not have a worktree/checkout (i.e. if any of

Documentation/git-submodule.txt

@@ -129,7 +129,9 @@ init [--] [<path>...]::
 	repository will be assumed to be upstream.
 +
 Optional <path> arguments limit which submodules will be initialized.
-If no path is specified, all submodules are initialized.
+If no path is specified and submodule.active has been configured, submodules
+configured to be active will be initialized, otherwise all submodules are
+initialized.
 +
 When present, it will also copy the value of `submodule.$name.update`.
 This command does not alter existing information in .git/config.