From 0554d83f0ff7e9da5c021b57820b26a330c09129 Mon Sep 17 00:00:00 2001
From: Serhiy Storchaka <storchaka@gmail.com>
Date: Tue, 8 Mar 2016 23:35:35 +0200
Subject: Issue #15068: Avoid creating a reference loop in fileinput.

---
 Lib/fileinput.py | 28 +++++++++++++++-------------
 1 file changed, 15 insertions(+), 13 deletions(-)

diff --git a/Lib/fileinput.py b/Lib/fileinput.py
index 9f14762..d2b5206 100644
--- a/Lib/fileinput.py
+++ b/Lib/fileinput.py
@@ -207,7 +207,6 @@ class FileInput:
         self._startlineno = 0
         self._filelineno = 0
         self._file = None
-        self._readline = self._start_readline
         self._isstdin = False
         self._backupfilename = None
         # restrict mode argument to reading modes
@@ -245,15 +244,15 @@ class FileInput:
         return self
 
     def __next__(self):
-        line = self._readline()
-        if line:
-            self._filelineno += 1
-            return line
-        if not self._file:
-            raise StopIteration
-        self.nextfile()
-        # Recursive call
-        return self.__next__()
+        while True:
+            line = self._readline()
+            if line:
+                self._filelineno += 1
+                return line
+            if not self._file:
+                raise StopIteration
+            self.nextfile()
+            # repeat with next file
 
     def __getitem__(self, i):
         if i != self.lineno():
@@ -277,7 +276,10 @@ class FileInput:
         finally:
             file = self._file
             self._file = None
-            self._readline = self._start_readline
+            try:
+                del self._readline  # restore FileInput._readline
+            except AttributeError:
+                pass
             try:
                 if file and not self._isstdin:
                     file.close()
@@ -301,7 +303,7 @@ class FileInput:
             self.nextfile()
             # repeat with next file
 
-    def _start_readline(self):
+    def _readline(self):
         if not self._files:
             if 'b' in self._mode:
                 return b''
@@ -356,7 +358,7 @@ class FileInput:
                     self._file = self._openhook(self._filename, self._mode)
                 else:
                     self._file = open(self._filename, self._mode)
-        self._readline = self._file.readline
+        self._readline = self._file.readline  # hide FileInput._readline
         return self._readline()
 
     def filename(self):
-- 
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