From 21eafefd28fa3d24bc03acce2f05ebfc078547a9 Mon Sep 17 00:00:00 2001
From: whitequark <whitequark@whitequark.org>
Date: Sat, 18 Jul 2015 08:13:49 +0300
Subject: [PATCH] Fix inference for globals.

---
 artiq/compiler/asttyped.py                     | 2 +-
 artiq/compiler/transforms/asttyped_rewriter.py | 4 ++--
 lit-test/compiler/inferencer/scoping.py        | 7 ++++---
 3 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/artiq/compiler/asttyped.py b/artiq/compiler/asttyped.py
index 7d38bd823..e24003aba 100644
--- a/artiq/compiler/asttyped.py
+++ b/artiq/compiler/asttyped.py
@@ -18,7 +18,7 @@ class scoped(object):
     :ivar typing_env: (dict with string keys and :class:`.types.Type` values)
         map of variable names to variable types
     :ivar globals_in_scope: (set of string keys)
-        list of variables resolved as globals
+        set of variables resolved as globals
     """
 
 # Typed versions of untyped nodes
diff --git a/artiq/compiler/transforms/asttyped_rewriter.py b/artiq/compiler/transforms/asttyped_rewriter.py
index 244f99fd0..d05a73cd1 100644
--- a/artiq/compiler/transforms/asttyped_rewriter.py
+++ b/artiq/compiler/transforms/asttyped_rewriter.py
@@ -151,8 +151,8 @@ class LocalExtractor(algorithm.Visitor):
                continue
 
             self.global_.add(name)
-            self._assignable(name)
-            self.env_stack[1][name] = self.typing_env[name]
+            if name in self.env_stack[1]:
+                self.typing_env[name] = self.env_stack[1][name]
 
     def visit_Nonlocal(self, node):
         for name, loc in zip(node.names, node.name_locs):
diff --git a/lit-test/compiler/inferencer/scoping.py b/lit-test/compiler/inferencer/scoping.py
index 595daecf6..604b2425d 100644
--- a/lit-test/compiler/inferencer/scoping.py
+++ b/lit-test/compiler/inferencer/scoping.py
@@ -1,8 +1,9 @@
 # RUN: %python -m artiq.compiler.testbench.inferencer %s >%t
 # RUN: OutputCheck %s --file-to-check=%t
 
+# CHECK-L: []:list(elt=int(width='a))
+x = []
+
 def f():
     global x
-    x = 1
-# CHECK-L: [x:int(width='a)]
-[x]
+    x[0] = 1