Fallback to timestamp signatures when MD5 is not available. (Anthony Roach)

3 files changed, 13 insertions, 2 deletions

diff --git a/src/CHANGES.txt b/src/CHANGES.txt
index a5551aa..6274991 100644
--- a/src/CHANGES.txt
+++ b/src/CHANGES.txt
@@ -43,6 +43,9 @@ RELEASE 0.08 -
   - Make the drive letters on Windows always be the same case, so that
     changes in the case of drive letters don't cause a rebuild.
 
+  - Fall back to importing the SCons.TimeStamp module if the SCons.MD5
+    module can't be imported.
+
   From Zed Shaw:
 
   - Add an Append() method to Environments, to append values to
diff --git a/src/engine/SCons/Node/__init__.py b/src/engine/SCons/Node/__init__.py
index 8e3ba7e..472ec07 100644
--- a/src/engine/SCons/Node/__init__.py
+++ b/src/engine/SCons/Node/__init__.py
@@ -172,6 +172,8 @@ class Node:
             def get_contents(self):
                 return apply(self.node.builder.get_contents, (),
                              self.node.generate_build_args())
+            def get_timestamp(self):
+                return None
         return Adapter(self)
 
     def get_implicit_deps(self, env, scanner, target):
diff --git a/src/engine/SCons/Sig/__init__.py b/src/engine/SCons/Sig/__init__.py
index 40ee459..193a326 100644
--- a/src/engine/SCons/Sig/__init__.py
+++ b/src/engine/SCons/Sig/__init__.py
@@ -244,8 +244,14 @@ class Calculator:
           content signatures. (defaults to 2 days)
         """
         if module is None:
-            import MD5
-            self.module = MD5
+            try:
+                import MD5
+                self.module = MD5
+            except ImportError:
+                # fallback on timestamp signatures if MD5 is not available
+                # XXX add a warning message here
+                import TimeStamp
+                self.module = TimeStamp
         else:
             self.module = module
         self.max_drift = max_drift