Convert Slice into typed SliceT.

artiq/compiler/asttyped.py

@@ -36,6 +36,9 @@ class ExceptHandlerT(ast.ExceptHandler):
     _fields = ("filter", "name", "body") # rename ast.ExceptHandler.type
     _types = ("name_type",)
 
+class SliceT(ast.Slice, commontyped):
+    pass
+
 class AttributeT(ast.Attribute, commontyped):
     pass
 class BinOpT(ast.BinOp, commontyped):

artiq/compiler/transforms/asttyped_rewriter.py

@@ -276,6 +276,15 @@ class ASTTypedRewriter(algorithm.Transformer):
                                    dot_loc=node.dot_loc, attr_loc=node.attr_loc, loc=node.loc)
         return self.visit(node)
 
+    def visit_Slice(self, node):
+        node = self.generic_visit(node)
+        node = asttyped.SliceT(type=types.TVar(),
+                               lower=node.lower, upper=node.upper, step=node.step,
+                               bound_colon_loc=node.bound_colon_loc,
+                               step_colon_loc=node.step_colon_loc,
+                               loc=node.loc)
+        return self.visit(node)
+
     def visit_Subscript(self, node):
         node = self.generic_visit(node)
         node = asttyped.SubscriptT(type=types.TVar(),

artiq/compiler/transforms/inferencer.py

@@ -119,10 +119,12 @@ class Inferencer(algorithm.Visitor):
             self._unify(value.type, builtins.TInt(),
                         value.loc, None)
 
-    def visit_Slice(self, node):
+    def visit_SliceT(self, node):
+        self._unify(node.type, builtins.TInt(),
+                    node.loc, None)
         for operand in (node.lower, node.upper, node.step):
             if operand is not None:
-                self._unify(operand.type, builtins.TInt(),
+                self._unify(operand.type, node.type,
                             operand.loc, None)
 
     def visit_ExtSlice(self, node):