From 87f7dd589bc8f47ad2bff8b8a1b6a6b20b03b262 Mon Sep 17 00:00:00 2001
From: Giulio Eulisse <10544+ktf@users.noreply.github.com>
Date: Wed, 2 Oct 2024 15:32:20 +0200
Subject: [PATCH] Add --only-deps option for caching

---
 alibuild_helpers/args.py  | 2 ++
 alibuild_helpers/build.py | 6 ++++++
 tests/test_build.py       | 1 +
 3 files changed, 9 insertions(+)

diff --git a/alibuild_helpers/args.py b/alibuild_helpers/args.py
index 8f48bc42..da45b0bc 100644
--- a/alibuild_helpers/args.py
+++ b/alibuild_helpers/args.py
@@ -107,6 +107,8 @@ def doParseArgs():
                                   "in multiple packages. The comment will only be stored if "
                                   "PACKAGE is compiled or downloaded during this run; if it "
                                   "already exists, this does not happen."))
+  build_parser.add_argument("--only-deps", dest="onlyDeps", default=False, action="store_true",
+                            help="Only build dependencies, not the main package (e.g. for caching)")
 
   build_docker = build_parser.add_argument_group(title="Build inside a container", description="""\
   Builds can be done inside a Docker container, to make it easier to get a
diff --git a/alibuild_helpers/build.py b/alibuild_helpers/build.py
index 2716bf14..3ef98a8f 100644
--- a/alibuild_helpers/build.py
+++ b/alibuild_helpers/build.py
@@ -697,6 +697,12 @@ def doBuild(args, parser):
     deps=",".join(buildOrder[:-1]),
   ), args.architecture)
 
+  # If we are building only the dependencies, the last package in
+  # the build order can be considered done.
+  if args.onlyDeps and len(buildOrder) > 1:
+    mainPackage = buildOrder.pop()
+    warning("Not rebuilding %s because --only-deps option provided.", mainPackage)
+
   while buildOrder:
     p = buildOrder[0]
     spec = specs[p]
diff --git a/tests/test_build.py b/tests/test_build.py
index a4b48358..a18a8441 100644
--- a/tests/test_build.py
+++ b/tests/test_build.py
@@ -285,6 +285,7 @@ def test_coverDoBuild(self, mock_debug, mock_listdir, mock_warning, mock_sys, mo
             environment={},
             autoCleanup=False,
             noDevel=[],
+            onlyDeps=False,
             fetchRepos=False,
             forceTracked=False,
             plugin="legacy"