3 files changed, 22 insertions, 1 deletions
diff --git a/src/engine/SCons/Node/FS.py b/src/engine/SCons/Node/FS.py
index 2bd68e1..883b82c 100644
--- a/src/engine/SCons/Node/FS.py
+++ b/src/engine/SCons/Node/FS.py
@@ -194,6 +194,7 @@ def get_MkdirBuilder():
         MkdirBuilder = SCons.Builder.Builder(action = Mkdir,
                                              env = None,
                                              explain = None,
+                                             is_explicit = None,
                                              name = "MkdirBuilder")
     return MkdirBuilder
 
diff --git a/src/engine/SCons/Node/NodeTests.py b/src/engine/SCons/Node/NodeTests.py
index f8cd62b..ce67781 100644
--- a/src/engine/SCons/Node/NodeTests.py
+++ b/src/engine/SCons/Node/NodeTests.py
@@ -93,10 +93,11 @@ class Environment:
         self._dict.update(dict)
 
 class Builder:
-    def __init__(self):
+    def __init__(self, is_explicit=1):
         self.env = Environment()
         self.overrides = {}
         self.action = MyAction()
+        self.is_explicit = is_explicit
     def targets(self, t):
         return [t]
     def get_actions(self):
@@ -314,6 +315,16 @@ class NodeTestCase(unittest.TestCase):
         n1.builder_set(Builder())
         assert n1.has_builder() == 1
 
+    def test_has_explicit_builder(self):
+        """Test the has_explicit_builder() method
+        """
+        n1 = SCons.Node.Node()
+        assert not n1.has_explicit_builder()
+        n1.builder_set(Builder(is_explicit=1))
+        assert n1.has_explicit_builder()
+        n1.builder_set(Builder(is_explicit=None))
+        assert not n1.has_explicit_builder()
+
     def test_multiple_side_effect_has_builder(self):
         """Test the multiple_side_effect_has_builder() method
         """
diff --git a/src/engine/SCons/Node/__init__.py b/src/engine/SCons/Node/__init__.py
index 338df07..38cff92 100644
--- a/src/engine/SCons/Node/__init__.py
+++ b/src/engine/SCons/Node/__init__.py
@@ -307,6 +307,15 @@ class Node:
             b = self.builder
         return not b is None
 
+    def has_explicit_builder(self):
+        """Return whether this Node has an explicit builder
+
+        This allows an internal Builder created by SCons to be marked
+        non-explicit, so that it can be overridden by an explicit
+        builder that the user supplies (the canonical example being
+        directories)."""
+        return self.has_builder() and self.builder.is_explicit
+
     multiple_side_effect_has_builder = has_builder
 
     def is_derived(self):