environment.py: write lockfile last (#30039)

This makes it easier to write `spack.lock: spack.yaml` type of rules in `Makefiles`.

1 files changed, 6 insertions, 2 deletions

diff --git a/lib/spack/spack/environment/environment.py b/lib/spack/spack/environment/environment.py
index b6875653df..720819695b 100644
--- a/lib/spack/spack/environment/environment.py
+++ b/lib/spack/spack/environment/environment.py
@@ -1897,10 +1897,14 @@ class Environment(object):
                     fs.mkdirp(pkg_dir)
                     spack.repo.path.dump_provenance(dep, pkg_dir)
 
-            # write the lock file last
+            self._update_and_write_manifest(raw_yaml_dict, yaml_dict)
+
+            # Write the lock file last. This is useful for Makefiles
+            # with `spack.lock: spack.yaml` rules, where the target
+            # should be newer than the prerequisite to avoid
+            # redundant re-concretization.
             with fs.write_tmp_and_move(self.lock_path) as f:
                 sjson.dump(self._to_lockfile_dict(), stream=f)
-            self._update_and_write_manifest(raw_yaml_dict, yaml_dict)
         else:
             with fs.safe_remove(self.lock_path):
                 self._update_and_write_manifest(raw_yaml_dict, yaml_dict)