# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1398978251 -7200
# Node ID 8dd72f06cb4a8d7f65b784fe9c5bcbfb45bca3f9
# Parent  4c2ac7cb47f72169bddfe0a0d61108f3e2b99688
Prevent guard generation when untyped instances are indicated for names.

diff -r 4c2ac7cb47f7 -r 8dd72f06cb4a micropython/deduce.py
--- a/micropython/deduce.py	Thu May 01 23:03:06 2014 +0200
+++ b/micropython/deduce.py	Thu May 01 23:04:11 2014 +0200
@@ -22,7 +22,7 @@
 from micropython.stdcompiler import compiler
 from compiler.ast import *
 
-from micropython.basicdata import Const, Constant, TypedInstance
+from micropython.basicdata import Constant, TypedInstance
 from micropython.common import ASTVisitor, used_by_unit
 from micropython.data import *
 from micropython.errors import *
@@ -568,15 +568,32 @@
         types = self.get_targets_from_type_names(node._attrtypes.get(name))
         value = node._values.get(name)
 
+        if isinstance(value, BaseAttr):
+            values = value.get_values()
+        else:
+            values = [value]
+
+        # Obtain values with identifiable types.
+
+        typed_values = set()
+
+        for v in values:
+            if isinstance(v, Instance):
+                if not isinstance(v, TypedInstance):
+                    return
+                typed_values.add(v.cls)
+            else:
+                typed_values.add(v)
+
         # Where a concrete type conflicts with deductions, the usage of
         # attributes cannot be supported and is thus impossible.
 
-        if value:
-            if types and value not in types:
+        if typed_values:
+            if types and not typed_values.intersection(types):
                 node._guard_types[name] = "impossible"
             else:
-                node._guard_types[name] = "single"
-                node._guards[name] = set([value])
+                node._guard_types[name] = len(typed_values) == 1 and "single" or "multiple"
+                node._guards[name] = typed_values
 
         # Where no concrete type is known, usage must be checked.