verify that warnings are issued for bogus uses of global

Lib/test/output/test_global

+test_global
+got SyntaxWarning as expected
+got SyntaxWarning as expected
+got SyntaxWarning as expected

Lib/test/test_global.py

+"""Verify that warnings are issued for global statements following use"""
+
+from test_support import check_syntax
+
+import warnings
+
+warnings.filterwarnings("error", category=SyntaxWarning, module=__name__)
+
+def compile_and_catch_warning(text):
+    try:
+        compile(text, "<test code>", "exec")
+    except SyntaxWarning, msg:
+        print "got SyntaxWarning as expected"
+    else:
+        print "expected SyntaxWarning"
+
+prog_text_1 = """
+def wrong1():
+    a = 1
+    b = 2
+    global a
+    global b
+"""
+compile_and_catch_warning(prog_text_1)
+
+prog_text_2 = """
+def wrong2():
+    print x
+    global x
+"""
+compile_and_catch_warning(prog_text_2)
+
+prog_text_3 = """
+def wrong3():
+    print x
+    x = 2
+    global x
+"""
+compile_and_catch_warning(prog_text_3)
+