# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1266194117 -3600
# Node ID 505512c40ea55c716f9ace2a66c07f86f300d093
# Parent  9f1f0b79c182ff1dc67b57218d5d718db22e319b
Fixed usage merging where names are defined below the current level in the
control-flow hierarchy.
Fixed alternative usage retrieval when generating guards, adding a test for
conflicting types deduced from attribute usage.

diff -r 9f1f0b79c182 -r 505512c40ea5 micropython/data.py
--- a/micropython/data.py	Sun Feb 14 23:49:17 2010 +0100
+++ b/micropython/data.py	Mon Feb 15 01:35:17 2010 +0100
@@ -483,6 +483,10 @@
 
         self.speculative_shelves[-1].append(speculative)
 
+        # NOTE: Could record contributing usage as speculative usage.
+
+        #self.speculative_shelves[-1].append(usage)
+
         # Forget about any nodes which defined names employing attributes in
         # this branch if the branch is abandoned.
 
@@ -564,7 +568,13 @@
 
         for shelved_users in self.user_shelves.pop():
             for name, nodes in shelved_users.items():
-                users[name].update(nodes)
+
+                # Handle cases where the name is not known at this level.
+
+                if users.has_key(name):
+                    users[name].update(nodes)
+                else:
+                    users[name] = nodes
 
         # Where each shelved set of definitions is a superset of the eventual
         # definitions for a name, record these specialised sets of usage.
diff -r 9f1f0b79c182 -r 505512c40ea5 micropython/trans.py
--- a/micropython/trans.py	Sun Feb 14 23:49:17 2010 +0100
+++ b/micropython/trans.py	Mon Feb 15 01:35:17 2010 +0100
@@ -319,7 +319,7 @@
 
             if node._alternative_attrnames.has_key(name):
                 all_names_used = set()
-                all_names_used.update(node._alternative_attrnames)
+                all_names_used.update(node._alternative_attrnames[name])
                 all_names_used.add(tuple(names_used))
             else:
                 all_names_used = [names_used]
@@ -327,14 +327,31 @@
             # Get the names of all object types supporting these names.
 
             targets = set()
+            common_targets = None
+
             for names_used in all_names_used:
-                targets.update(self.objtable.all_possible_objects_plus_status(names_used))
+                found_targets = self.objtable.all_possible_objects_plus_status(names_used)
+                found_target_names = [target_name for (target_name, is_static) in found_targets]
+                targets.update(found_targets)
+
+                if common_targets is None:
+                    common_targets = set(found_target_names)
+                else:
+                    common_targets.intersection_update(found_target_names)
+
+            # Report cases where no common targets can be found.
+
+            if not common_targets:
+                raise TranslateError(self.module.full_name(), node, "No common types found for expected attribute usage.")
+
+            # NOTE: Need to merge targets using the same type but suggesting
+            # NOTE: different kinds of attributes.
 
             # Where only one object type is suggested, produce a guard.
             # NOTE: This only supports classes as types, not modules.
 
             if len(targets) == 1:
-                target_name, is_static = targets[0]
+                target_name, is_static = list(targets)[0]
 
                 # Access the object table to get the attribute.
                 # NOTE: This depends on the special entry in the table
diff -r 9f1f0b79c182 -r 505512c40ea5 tests/attribute_access_type_restriction_multiple_candidates.py
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/tests/attribute_access_type_restriction_multiple_candidates.py	Mon Feb 15 01:35:17 2010 +0100
@@ -0,0 +1,34 @@
+#!/usr/bin/env python
+
+"""
+This test attempts to cause the recording of the usage of 'C' in the function
+'f', alongside the expectation that 'D' might be used instead. A guard
+stipulating constraints for all of 'f' cannot therefore be generated. Meanwhile,
+the method 'E.h' should be eliminated.
+"""
+
+class C:
+    def f(self):
+        return 1
+
+class D:
+    def g(self):
+        return 2
+
+class E:
+    def h(self):    # unused
+        return 3
+
+def f(c):
+    if 1:
+        if 1:
+            x = c.f()
+        return x
+    return c.g()
+
+c = C()
+d = D()
+e = E()
+result1_1 = f(c)
+
+# vim: tabstop=4 expandtab shiftwidth=4