Fix bug in type analysis for ComprehensionNodes.

Cython/Compiler/ExprNodes.py

@@ -3988,6 +3988,9 @@ class ComprehensionNode(ScopedExprNode):
         if not self.has_local_scope:
             self.loop.analyse_expressions(env)
 
+    def analyse_expressions(self, env):
+        self.analyse_types(env)
+
     def analyse_scoped_expressions(self, env):
         if self.has_local_scope:
             self.loop.analyse_expressions(env)

tests/run/list_comprehension.pyx

+
+def foo():
+    """
+    >>> foo()
+    [[], [-1], [-1, 0], [-1, 0, 1]]
+    """
+    result = [[a-1 for a in range(b)] for b in range(4)]
+    return result