[GR-47858] LayoutDirDistribution does proper needsRebuild check.

PullRequest: mx/1653

common.json

@@ -4,7 +4,7 @@
     "Jsonnet files should not include this file directly but use ci/common.jsonnet instead."
   ],
 
-  "mx_version": "6.38.0",
+  "mx_version": "6.39.0",
 
   "COMMENT.jdks": "When adding or removing JDKs keep in sync with JDKs in ci/common.jsonnet",
   "jdks": {

mx.py

@@ -6462,11 +6462,6 @@ def needsUpdate(self, newestInput):
             sup = super(LayoutDistribution, self).needsUpdate(newestInput)
             if sup:
                 return sup
-        else:
-            if self.output:
-                output_up = _needsUpdate(newestInput, self.get_output())
-                if output_up:
-                    return output_up
         for destination, source in self._walk_layout():
             source_type = source['source_type']
             if source_type == 'file':
@@ -6645,6 +6640,8 @@ class LayoutDirDistribution(LayoutDistribution, ClasspathDependency):
     # A layout distribution that is not archived, useful to define the contents of a directory.
     # When added as a dependency of a JarDistribution, it is included in the jar. It is not appended to the classpath
     # unless `classpath_entries` is called with `preferProjects=True`.
+    # We use a dummy sentinel file as the "archive" such that the LayoutDistribution machinery including
+    # rebuild detection works as expected
     def __init__(self, *args, **kw_args):
         # we have *args here because some subclasses in suites have been written passing positional args to
         # LayoutDistribution.__init__ instead of keyword args. We just forward it as-is to super(), it's risky but better
@@ -6657,6 +6654,13 @@ def __init__(self, *args, **kw_args):
     def classpath_repr(self, resolve=True):
         return self.get_output()
 
+    def make_archive(self):
+        super().make_archive()
+        sentinel = self._default_path()
+        os.makedirs(os.path.abspath(os.path.dirname(sentinel)), exist_ok=True)
+        with open(sentinel, 'w'):
+            pass
+
     def getArchivableResults(self, use_relpath=True, single=False):
         if single:
             raise ValueError("{} only produces multiple output".format(self))
@@ -6668,10 +6672,10 @@ def getArchivableResults(self, use_relpath=True, single=False):
                 yield file_path, archive_path
 
     def remoteExtension(self):
-        return 'does_not_exist'
+        return 'sentinel'
 
     def localExtension(self):
-        return 'does_not_exist'
+        return 'sentinel'
 
 
 class LayoutTARDistribution(LayoutDistribution, AbstractTARDistribution):
@@ -18586,7 +18590,7 @@ def alarm_handler(signum, frame):
         abort(1, killsig=signal.SIGINT)
 
 # The version must be updated for every PR (checked in CI) and the comment should reflect the PR's issue
-version = VersionSpec("6.39.1")  # Compute java homes lazily to respect env files priority
+version = VersionSpec("6.39.2")  # LayoutDirDistribution does proper needsRebuild check
 
 _mx_start_datetime = datetime.utcnow()
 _last_timestamp = _mx_start_datetime