Add the highly anticipated --debug=explain option to provide build reasoning.

2 files changed, 46 insertions, 23 deletions

diff --git a/src/engine/SCons/Sig/SigTests.py b/src/engine/SCons/Sig/SigTests.py
index f297464..98465ff 100644
--- a/src/engine/SCons/Sig/SigTests.py
+++ b/src/engine/SCons/Sig/SigTests.py
@@ -106,8 +106,12 @@ class DummyNode:
         else:
             return calc.csig(self)
 
-    def set_bsig(self, bsig):
+    def set_binfo(self, bsig, bkids, bkidsigs, bact, bactsig):
         self.bsig = bsig
+        self.bkids = bkids
+        self.bkidsigs = bkidsigs
+        self.bact = bact
+        self.bactsig = bactsig
 
     def get_bsig(self):
         return self.bsig
@@ -129,12 +133,6 @@ class DummyNode:
 
     def get_stored_implicit(self):
         return None
-
-    def store_csig(self):
-        pass
-
-    def store_bsig(self):
-        pass
     
     def store_timestamp(self):
         pass
@@ -327,8 +325,12 @@ class CalcTestCase(unittest.TestCase):
                 return 1
             def get_bsig(self):
                 return self.bsig
-            def set_bsig(self, bsig):
+            def set_binfo(self, bsig, bkids, bkidsig, bact, bactsig):
                 self.bsig = bsig
+                self.bkids = bkids
+                self.bkidsigs = bkidsigs
+                self.bact = bact
+                self.bactsig = bactsig
             def get_csig(self):
                 return self.csig
             def set_csig(self, csig):
@@ -414,7 +416,7 @@ class _SConsignTestCase(unittest.TestCase):
             path = 'not_a_valid_path'
 
         f = SCons.Sig._SConsign()
-        f.set_bsig('foo', 1)
+        f.set_binfo('foo', 1, ['f1'], ['f2'], 'foo act', 'foo actsig')
         assert f.get('foo') == (None, 1, None)
         f.set_csig('foo', 2)
         assert f.get('foo') == (None, 1, 2)
@@ -425,7 +427,7 @@ class _SConsignTestCase(unittest.TestCase):
         assert f.get_implicit('foo') == ['bar']
 
         f = SCons.Sig._SConsign(DummyModule())
-        f.set_bsig('foo', 1)
+        f.set_binfo('foo', 1, ['f1'], ['f2'], 'foo act', 'foo actsig')
         assert f.get('foo') == (None, 1, None)
         f.set_csig('foo', 2)
         assert f.get('foo') == (None, 1, 2)
@@ -446,20 +448,20 @@ class SConsignDBTestCase(unittest.TestCase):
         try:
             d1 = SCons.Sig.SConsignDB(DummyNode('dir1'))
             d1.set_timestamp('foo', 1)
-            d1.set_bsig('foo', 2)
+            d1.set_binfo('foo', 2, ['f1'], ['f2'], 'foo act', 'foo actsig')
             d1.set_csig('foo', 3)
             d1.set_timestamp('bar', 4)
-            d1.set_bsig('bar', 5)
+            d1.set_binfo('bar', 5, ['b1'], ['b2'], 'bar act', 'bar actsig')
             d1.set_csig('bar', 6)
             assert d1.get('foo') == (1, 2, 3)
             assert d1.get('bar') == (4, 5, 6)
 
             d2 = SCons.Sig.SConsignDB(DummyNode('dir1'))
             d2.set_timestamp('foo', 7)
-            d2.set_bsig('foo', 8)
+            d2.set_binfo('foo', 8, ['f3'], ['f4'], 'foo act', 'foo actsig')
             d2.set_csig('foo', 9)
             d2.set_timestamp('bar', 10)
-            d2.set_bsig('bar', 11)
+            d2.set_binfo('bar', 11, ['b3'], ['b4'], 'bar act', 'bar actsig')
             d2.set_csig('bar', 12)
             assert d2.get('foo') == (7, 8, 9)
             assert d2.get('bar') == (10, 11, 12)
@@ -480,7 +482,7 @@ class SConsignDirFileTestCase(unittest.TestCase):
             path = 'not_a_valid_path'
 
         f = SCons.Sig.SConsignDirFile(DummyNode(), DummyModule())
-        f.set_bsig('foo', 1)
+        f.set_binfo('foo', 1, ['f1'], ['f2'], 'foo act', 'foo actsig')
         assert f.get('foo') == (None, 1, None)
         f.set_csig('foo', 2)
         assert f.get('foo') == (None, 1, 2)
diff --git a/src/engine/SCons/Sig/__init__.py b/src/engine/SCons/Sig/__init__.py
index a2ebd5c..d703194 100644
--- a/src/engine/SCons/Sig/__init__.py
+++ b/src/engine/SCons/Sig/__init__.py
@@ -73,6 +73,10 @@ class SConsignEntry:
     bsig = None
     csig = None
     implicit = None
+    bkids = []
+    bkidsigs = []
+    bact = None
+    bactsig = None
 
 class _SConsign:
     """
@@ -139,9 +143,9 @@ class _SConsign:
         entry.csig = csig
         self.set_entry(filename, entry)
 
-    def set_bsig(self, filename, bsig):
+    def set_binfo(self, filename, bsig, bkids, bkidsigs, bact, bactsig):
         """
-        Set the csig .sconsign entry for a file
+        Set the build info .sconsign entry for a file
 
         filename - the filename whose signature will be set
         bsig - the file's built signature
@@ -149,11 +153,15 @@ class _SConsign:
 
         entry = self.get_entry(filename)
         entry.bsig = bsig
+        entry.bkids = bkids
+        entry.bkidsigs = bkidsigs
+        entry.bact = bact
+        entry.bactsig = bactsig
         self.set_entry(filename, entry)
 
     def set_timestamp(self, filename, timestamp):
         """
-        Set the csig .sconsign entry for a file
+        Set the timestamp .sconsign entry for a file
 
         filename - the filename whose signature will be set
         timestamp - the file's timestamp
@@ -171,12 +179,17 @@ class _SConsign:
     def set_implicit(self, filename, implicit):
         """Cache the implicit dependencies for 'filename'."""
         entry = self.get_entry(filename)
-        if SCons.Util.is_String(implicit):
+        if not SCons.Util.is_List(implicit):
             implicit = [implicit]
         implicit = map(str, implicit)
         entry.implicit = implicit
         self.set_entry(filename, entry)
 
+    def get_binfo(self, filename):
+        """Fetch the cached implicit dependencies for 'filename'"""
+        entry = self.get_entry(filename)
+        return entry.bsig, entry.bkids, entry.bkidsigs, entry.bact, entry.bactsig
+
 class SConsignDB(_SConsign):
     """
     A _SConsign subclass that reads and writes signature information
@@ -360,20 +373,28 @@ class Calculator:
             return bsig
 
         children = node.children()
+        bkids = map(str, children)
 
-        # double check bsig, because the call to childre() above may
+        # double check bsig, because the call to children() above may
         # have set it:
         bsig = cache.get_bsig()
         if bsig is not None:
             return bsig
 
         sigs = map(lambda n, c=self: n.calc_signature(c), children)
+
         if node.has_builder():
-            sigs.append(self.module.signature(node.get_executor()))
+            executor = node.get_executor()
+            bact = str(executor)
+            bactsig = self.module.signature(executor)
+            sigs.append(bactsig)
+        else:
+            bact = ""
+            bactsig = ""
 
-        bsig = self.module.collect(filter(lambda x: not x is None, sigs))
+        bsig = self.module.collect(filter(None, sigs))
 
-        cache.set_bsig(bsig)
+        cache.set_binfo(bsig, bkids, sigs, bact, bactsig)
 
         # don't store the bsig here, because it isn't accurate until
         # the node is actually built.