bpo-38078: IDLE: Don't run internal code in the user namespace

Lib/idlelib/pyshell.py

@@ -749,7 +749,7 @@ class ModifiedInterpreter(InteractiveInterpreter):
             self.display_executing_dialog()
             return 0
         if self.rpcclt:
-            self.rpcclt.remotequeue("exec", "runcode", (code,), {})
+            self.rpcclt.remotequeue("exec", "runcommand", (code,), {})
         else:
             exec(code, self.locals)
         return 1

Lib/idlelib/run.py

@@ -539,13 +539,13 @@ class Executive(object):
         self.calltip = calltip.Calltip()
         self.autocomplete = autocomplete.AutoComplete()
 
-    def runcode(self, code):
+    def runcode(self, code, user=True):
         global interruptable
         try:
             self.usr_exc_info = None
             interruptable = True
             try:
-                exec(code, self.locals)
+                exec(code, self.locals if user else {})
             finally:
                 interruptable = False
         except SystemExit as e:
@@ -565,6 +565,9 @@ class Executive(object):
         else:
             flush_stdout()
 
+    def runcommand(self, code):
+        return self.runcode(code, user=False)
+
     def interrupt_the_server(self):
         if interruptable:
             thread.interrupt_main()

Misc/NEWS.d/next/IDLE/2020-05-11-16-32-30.bpo-38078.FbnK9O.rst

@@ -0,0 +1 @@
+Stop running internal IDLE code in the user namespace.