Fix precidence between list_if and if_expr in 3.x

uncompyle6/semantics/consts.py

@@ -35,6 +35,11 @@ else:
 # Things at the top of this list below with low-value precidence will
 # tend to have parenthesis around them. Things at the bottom
 # of the list will tend not to have parenthesis around them.
+
+# Note: The values in this table tend to be even value. Inside
+# various templates we use odd values. Avoiding equal-precident comparisons
+# avoids ambiguity what to do when the precedence is equal.
+
 PRECEDENCE = {
     'list':                   0,
     'dict':                   0,

uncompyle6/semantics/customize37.py

@@ -22,7 +22,10 @@ def customize_for_version37(self, version):
     # Python 3.7+ changes
     #######################
 
-    PRECEDENCE['attribute37'] = 2
+    PRECEDENCE['attribute37'] =  2
+    PRECEDENCE['ifexp_37a']   = 28
+    PRECEDENCE['ifexp_37b']   = 28
+
     TABLE_DIRECT.update({
         'and_not':  ( '%c and not %c',
                       (0, 'expr'), (2, 'expr') ),

uncompyle6/semantics/pysource.py

@@ -1168,6 +1168,7 @@ class SourceWalker(GenericASTTraversal, object):
             self.write(' if ')
             if have_not:
                 self.write('not ')
+            self.prec = 27
             self.preorder(if_node)
             pass
         self.prec = p