Check for circular dependencies between .gyp files....

pylib/gyp/input.py

Index: pylib/gyp/input.py
===================================================================
--- pylib/gyp/input.py	(revision 784)
+++ pylib/gyp/input.py	(working copy)
@@ -1304,6 +1304,57 @@
   return [dependency_nodes, flat_list]
 
 
+def VerifyNoGYPFileCircularDependencies(targets):
+  # Create a DependencyGraphNode for each gyp file containing a target.  Put
+  # it into a dict for easy access.
+  dependency_nodes = {}
+  for target in targets.iterkeys():
+    build_file = gyp.common.BuildFile(target)
+    if not build_file in dependency_nodes:
+      dependency_nodes[build_file] = DependencyGraphNode(build_file)
+
+  # Set up the dependency links.
+  for target, spec in targets.iteritems():
+    build_file = gyp.common.BuildFile(target)
+    build_file_node = dependency_nodes[build_file]
+    target_dependencies = spec.get('dependencies', [])
+    for dependency in target_dependencies:
+      try:
+        dependency_build_file = gyp.common.BuildFile(dependency)
+        if dependency_build_file == build_file:
+          # A .gyp file is allowed to refer back to itself.
+          continue
+        dependency_node = dependency_nodes[dependency_build_file]
+        if dependency_node not in build_file_node.dependencies:
+          build_file_node.dependencies.append(dependency_node)
+          dependency_node.dependents.append(build_file_node)
+      except KeyError, e:
+        gyp.common.ExceptionAppend(
+            e, 'while computing dependencies of .gyp file %s' % build_file)
+        raise
+
+  # Files that have no dependencies are treated as dependent on root_node.
+  root_node = DependencyGraphNode(None)
+  for build_file_node in dependency_nodes.itervalues():
+    if len(build_file_node.dependencies) == 0:
+      build_file_node.dependencies.append(root_node)
+      root_node.dependents.append(build_file_node)
+
+  flat_list = root_node.FlattenToList()
+
+  # If there's anything left unvisited, there must be a circular dependency
+  # (cycle).
+  if len(flat_list) != len(dependency_nodes):
+    bad_files = []
+    for file in dependency_nodes.iterkeys():
+      if not file in flat_list:
+        bad_files.append(file)
+    raise DependencyGraphNode.CircularException, \
+        'Some files not reachable, cycle in .gyp file dependency graph ' + \
+        'detected involving some or all of: ' + \
+        ' '.join(bad_files)
+
+
 def DoDependentSettings(key, flat_list, targets, dependency_nodes):
   # key should be one of all_dependent_settings, direct_dependent_settings,
   # or link_settings.
@@ -1966,7 +2017,8 @@
       TurnIntIntoStrInList(item)
 
 
-def Load(build_files, variables, includes, depth, generator_input_info, check):
+def Load(build_files, variables, includes, depth, generator_input_info, check,
+         circular_check):
   # Set up path_sections and non_configuration_keys with the default data plus
   # the generator-specifc data.
   global path_sections
@@ -2022,6 +2074,11 @@
   # Expand dependencies specified as build_file:*.
   ExpandWildcardDependencies(targets, data)
 
+  if circular_check:
+    # Make sure that any targets in a.gyp don't contain dependencies in other
+    # .gyp files that further depend on a.gyp.
+    VerifyNoGYPFileCircularDependencies(targets)
+
   [dependency_nodes, flat_list] = BuildDependencyList(targets)
 
   # Handle dependent settings of various types.