Fix a bug in the ``compiler`` package that caused invalid code to be

generated for generator expressions.

5 files changed, 26 insertions, 9 deletions

diff --git a/Lib/compiler/ast.py b/Lib/compiler/ast.py
index 8dcdf68..93437d6 100644
--- a/Lib/compiler/ast.py
+++ b/Lib/compiler/ast.py
@@ -583,11 +583,9 @@ class GenExpr(Node):
     def __init__(self, code, lineno=None):
         self.code = code
         self.lineno = lineno
-        self.argnames = ['[outmost-iterable]']
+        self.argnames = ['.0']
         self.varargs = self.kwargs = None
 
-
-
     def getChildren(self):
         return self.code,
 
diff --git a/Lib/compiler/pycodegen.py b/Lib/compiler/pycodegen.py
index e3667b5..009438d 100644
--- a/Lib/compiler/pycodegen.py
+++ b/Lib/compiler/pycodegen.py
@@ -658,18 +658,19 @@ class CodeGenerator:
 
         stack = []
         for i, for_ in zip(range(len(node.quals)), node.quals):
-            start, anchor = self.visit(for_)
+            start, anchor, end = self.visit(for_)
             cont = None
             for if_ in for_.ifs:
                 if cont is None:
                     cont = self.newBlock()
                 self.visit(if_, cont)
-            stack.insert(0, (start, cont, anchor))
+            stack.insert(0, (start, cont, anchor, end))
 
         self.visit(node.expr)
         self.emit('YIELD_VALUE')
+        self.emit('POP_TOP')
 
-        for start, cont, anchor in stack:
+        for start, cont, anchor, end in stack:
             if cont:
                 skip_one = self.newBlock()
                 self.emit('JUMP_FORWARD', skip_one)
@@ -678,14 +679,22 @@ class CodeGenerator:
                 self.nextBlock(skip_one)
             self.emit('JUMP_ABSOLUTE', start)
             self.startBlock(anchor)
+            self.emit('POP_BLOCK')
+            self.setups.pop()
+            self.startBlock(end)
+
         self.emit('LOAD_CONST', None)
 
     def visitGenExprFor(self, node):
         start = self.newBlock()
         anchor = self.newBlock()
+        end = self.newBlock()
+
+        self.setups.push((LOOP, start))
+        self.emit('SETUP_LOOP', end)
 
         if node.is_outmost:
-            self.loadName('[outmost-iterable]')
+            self.loadName('.0')
         else:
             self.visit(node.iter)
             self.emit('GET_ITER')
@@ -695,7 +704,7 @@ class CodeGenerator:
         self.emit('FOR_ITER', anchor)
         self.nextBlock()
         self.visit(node.assign)
-        return start, anchor
+        return start, anchor, end
 
     def visitGenExprIf(self, node, branch):
         self.set_lineno(node, force=True)
diff --git a/Lib/compiler/symbols.py b/Lib/compiler/symbols.py
index 8eb5fce..8f62980 100644
--- a/Lib/compiler/symbols.py
+++ b/Lib/compiler/symbols.py
@@ -188,7 +188,7 @@ class GenExprScope(Scope):
         i = self.__counter
         self.__counter += 1
         self.__super_init("generator expression<%d>"%i, module, klass)
-        self.add_param('[outmost-iterable]')
+        self.add_param('.0')
 
     def get_names(self):
         keys = Scope.get_names(self)
diff --git a/Lib/test/test_compiler.py b/Lib/test/test_compiler.py
index 1efb6a6..81f2ea8 100644
--- a/Lib/test/test_compiler.py
+++ b/Lib/test/test_compiler.py
@@ -116,6 +116,13 @@ class CompilerTest(unittest.TestCase):
         exec c in dct
         self.assertEquals(dct.get('result'), 3)
 
+    def testGenExp(self):
+        c = compiler.compile('list((i,j) for i in range(3) if i < 3'
+                             '           for j in range(4) if j > 2)',
+                             '<string>',
+                             'eval')
+        self.assertEquals(eval(c), [(0, 3), (1, 3), (2, 3)])
+
 
 NOLINENO = (compiler.ast.Module, compiler.ast.Stmt, compiler.ast.Discard)
 
diff --git a/Misc/NEWS b/Misc/NEWS
index b3a3e7d..c482411 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -64,6 +64,9 @@ Core and builtins
 Library
 -------
 
+- Fix a bug in the ``compiler`` package that caused invalid code to be
+  generated for generator expressions.
+
 - The distutils version has been changed to 2.5.0. The change to
   keep it programmatically in sync with the Python version running
   the code (introduced in 2.5b3) has been reverted. It will continue