gc: Introduce new command to remove old projectsv2.50.1

When projects are removed from manifest, they are only removed from
worktree and not from .repo/projects and .repo/project-objects. Keeping
data under .repo can be desired if user expects deleted projects to be
restored (e.g. checking out a release branch).

Android has ongoing effort to remove many stale projects and this change
allows users to easily free-up their disk space.

Bug: b/344018971
Bug: 40013312
Change-Id: Id23c7524a88082ee6db908f9fd69dcd5d0c4f681
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/445921
Reviewed-by: Mike Frysinger <vapier@google.com>
Commit-Queue: Josip Sokcevic <sokcevic@chromium.org>
Reviewed-by: Gavin Mak <gavinmak@google.com>
Tested-by: Josip Sokcevic <sokcevic@chromium.org>

3 files changed, 66 insertions, 2 deletions

diff --git a/man/repo-gc.1 b/man/repo-gc.1
new file mode 100644
index 00000000..e465a253
--- /dev/null
+++ b/man/repo-gc.1
@@ -0,0 +1,43 @@
+.\" DO NOT MODIFY THIS FILE!  It was generated by help2man.
+.TH REPO "1" "December 2024" "repo gc" "Repo Manual"
+.SH NAME
+repo \- repo gc - manual page for repo gc
+.SH SYNOPSIS
+.B repo
+\fI\,gc\/\fR
+.SH DESCRIPTION
+Summary
+.PP
+Cleaning up internal repo state.
+.SH OPTIONS
+.TP
+\fB\-h\fR, \fB\-\-help\fR
+show this help message and exit
+.TP
+\fB\-n\fR, \fB\-\-dry\-run\fR
+do everything except actually delete
+.TP
+\fB\-y\fR, \fB\-\-yes\fR
+answer yes to all safe prompts
+.SS Logging options:
+.TP
+\fB\-v\fR, \fB\-\-verbose\fR
+show all output
+.TP
+\fB\-q\fR, \fB\-\-quiet\fR
+only show errors
+.SS Multi\-manifest options:
+.TP
+\fB\-\-outer\-manifest\fR
+operate starting at the outermost manifest
+.TP
+\fB\-\-no\-outer\-manifest\fR
+do not operate on outer manifests
+.TP
+\fB\-\-this\-manifest\-only\fR
+only operate on this (sub)manifest
+.TP
+\fB\-\-no\-this\-manifest\-only\fR, \fB\-\-all\-manifests\fR
+operate on this manifest and its submanifests
+.PP
+Run `repo help gc` to view the detailed manual.
diff --git a/man/repo-manifest.1 b/man/repo-manifest.1
index 10ec2e75..2ee23e64 100644
--- a/man/repo-manifest.1
+++ b/man/repo-manifest.1
@@ -1,5 +1,5 @@
 .\" DO NOT MODIFY THIS FILE!  It was generated by help2man.
-.TH REPO "1" "April 2024" "repo manifest" "Repo Manual"
+.TH REPO "1" "December 2024" "repo manifest" "Repo Manual"
 .SH NAME
 repo \- repo manifest - manual page for repo manifest
 .SH SYNOPSIS
@@ -192,11 +192,13 @@ CDATA #IMPLIED>
 <!ATTLIST extend\-project remote CDATA #IMPLIED>
 <!ATTLIST extend\-project dest\-branch CDATA #IMPLIED>
 <!ATTLIST extend\-project upstream CDATA #IMPLIED>
+<!ATTLIST extend\-project base\-rev CDATA #IMPLIED>
 .IP
 <!ELEMENT remove\-project EMPTY>
 <!ATTLIST remove\-project name     CDATA #IMPLIED>
 <!ATTLIST remove\-project path     CDATA #IMPLIED>
 <!ATTLIST remove\-project optional CDATA #IMPLIED>
+<!ATTLIST remove\-project base\-rev CDATA #IMPLIED>
 .IP
 <!ELEMENT repo\-hooks EMPTY>
 <!ATTLIST repo\-hooks in\-project CDATA #REQUIRED>
@@ -495,6 +497,14 @@ project. Same syntax as the corresponding element of `project`.
 Attribute `upstream`: If specified, overrides the upstream of the original
 project. Same syntax as the corresponding element of `project`.
 .PP
+Attribute `base\-rev`: If specified, adds a check against the revision to be
+extended. Manifest parse will fail and give a list of mismatch extends if the
+revisions being extended have changed since base\-rev was set. Intended for use
+with layered manifests using hash revisions to prevent patch branches hiding
+newer upstream revisions. Also compares named refs like branches or tags but is
+misleading if branches are used as base\-rev. Same syntax as the corresponding
+element of `project`.
+.PP
 Element annotation
 .PP
 Zero or more annotation elements may be specified as children of a project or
@@ -556,6 +566,14 @@ Logic otherwise behaves like both are specified.
 Attribute `optional`: Set to true to ignore remove\-project elements with no
 matching `project` element.
 .PP
+Attribute `base\-rev`: If specified, adds a check against the revision to be
+removed. Manifest parse will fail and give a list of mismatch removes if the
+revisions being removed have changed since base\-rev was set. Intended for use
+with layered manifests using hash revisions to prevent patch branches hiding
+newer upstream revisions. Also compares named refs like branches or tags but is
+misleading if branches are used as base\-rev. Same syntax as the corresponding
+element of `project`.
+.PP
 Element repo\-hooks
 .PP
 NB: See the [practical documentation](./repo\-hooks.md) for using repo hooks.
diff --git a/man/repo.1 b/man/repo.1
index bda68c39..1c05dcfc 100644
--- a/man/repo.1
+++ b/man/repo.1
@@ -1,5 +1,5 @@
 .\" DO NOT MODIFY THIS FILE!  It was generated by help2man.
-.TH REPO "1" "April 2024" "repo" "Repo Manual"
+.TH REPO "1" "December 2024" "repo" "Repo Manual"
 .SH NAME
 repo \- repository management tool built on top of git
 .SH SYNOPSIS
@@ -79,6 +79,9 @@ Download and checkout a change
 forall
 Run a shell command in each project
 .TP
+gc
+Cleaning up internal repo state.
+.TP
 grep
 Print lines matching a pattern
 .TP