Adding cython v0.20.2 in third-party.

third_party/cython/src/Cython/Compiler/FlowControl.pxd

Index: third_party/cython/src/Cython/Compiler/FlowControl.pxd
diff --git a/third_party/cython/src/Cython/Compiler/FlowControl.pxd b/third_party/cython/src/Cython/Compiler/FlowControl.pxd
new file mode 100644
index 0000000000000000000000000000000000000000..fa47853db9ddc850b11a21dd9ab39bb50c00298b
--- /dev/null
+++ b/third_party/cython/src/Cython/Compiler/FlowControl.pxd
@@ -0,0 +1,105 @@
+cimport cython
+
+from Cython.Compiler.Visitor cimport CythonTransform, TreeVisitor
+
+cdef class ControlBlock:
+     cdef public set children
+     cdef public set parents
+     cdef public set positions
+     cdef public list stats
+     cdef public dict gen
+     cdef public set bounded
+     cdef public dict input
+     cdef public dict output
+
+     # Big integer it bitsets
+     cdef public object i_input
+     cdef public object i_output
+     cdef public object i_gen
+     cdef public object i_kill
+     cdef public object i_state
+
+     cpdef bint empty(self)
+     cpdef detach(self)
+     cpdef add_child(self, block)
+
+cdef class ExitBlock(ControlBlock):
+     cpdef bint empty(self)
+
+cdef class NameAssignment:
+    cdef public bint is_arg
+    cdef public bint is_deletion
+    cdef public object lhs
+    cdef public object rhs
+    cdef public object entry
+    cdef public object pos
+    cdef public set refs
+    cdef public object bit
+    cdef public object inferred_type
+
+cdef class AssignmentList:
+    cdef public object bit
+    cdef public object mask
+    cdef public list stats
+
+cdef class AssignmentCollector(TreeVisitor):
+    cdef list assignments
+
+@cython.final
+cdef class ControlFlow:
+     cdef public set blocks
+     cdef public set entries
+     cdef public list loops
+     cdef public list exceptions
+
+     cdef public ControlBlock entry_point
+     cdef public ExitBlock exit_point
+     cdef public ControlBlock block
+
+     cdef public dict assmts
+
+     cpdef newblock(self, ControlBlock parent=*)
+     cpdef nextblock(self, ControlBlock parent=*)
+     cpdef bint is_tracked(self, entry)
+     cpdef bint is_statically_assigned(self, entry)
+     cpdef mark_position(self, node)
+     cpdef mark_assignment(self, lhs, rhs, entry)
+     cpdef mark_argument(self, lhs, rhs, entry)
+     cpdef mark_deletion(self, node, entry)
+     cpdef mark_reference(self, node, entry)
+
+     @cython.locals(block=ControlBlock, parent=ControlBlock, unreachable=set)
+     cpdef normalize(self)
+
+     @cython.locals(bit=object, assmts=AssignmentList,
+                    block=ControlBlock)
+     cpdef initialize(self)
+
+     @cython.locals(assmts=AssignmentList, assmt=NameAssignment)
+     cpdef set map_one(self, istate, entry)
+
+     @cython.locals(block=ControlBlock, parent=ControlBlock)
+     cdef reaching_definitions(self)
+
+cdef class Uninitialized:
+     pass
+
+cdef class Unknown:
+    pass
+
+@cython.locals(dirty=bint, block=ControlBlock, parent=ControlBlock,
+               assmt=NameAssignment)
+cdef check_definitions(ControlFlow flow, dict compiler_directives)
+
+@cython.final
+cdef class ControlFlowAnalysis(CythonTransform):
+    cdef object gv_ctx
+    cdef set reductions
+    cdef list env_stack
+    cdef list stack
+    cdef object env
+    cdef ControlFlow flow
+    cdef bint in_inplace_assignment
+
+    cpdef mark_assignment(self, lhs, rhs=*)
+    cpdef mark_position(self, node)