Issue #16537: Check whether self.extensions is empty in setup.py.

Patch by Jonathan Hosmer.

Misc/ACKS

@@ -588,6 +588,7 @@ Randall Hopper
 Nadav Horesh
 Alon Horev
 Jan Hosang
+Jonathan Hosmer
 Alan Hourihane
 Ken Howard
 Brad Howes

Misc/NEWS

@@ -15,6 +15,12 @@ Library
 - Issue #22448: Improve canceled timer handles cleanup to prevent
   unbound memory usage. Patch by Joshua Moore-Oliva.
 
+Build
+-----
+
+- Issue #16537: Check whether self.extensions is empty in setup.py. Patch by
+  Jonathan Hosmer.
+
 
 What's New in Python 3.4.2?
 ===========================

setup.py

@@ -252,7 +252,9 @@ class PyBuildExt(build_ext):
 
         build_ext.build_extensions(self)
 
-        longest = max([len(e.name) for e in self.extensions])
+        longest = 0
+        if self.extensions:
+            longest = max([len(e.name) for e in self.extensions])
         if self.failed:
             longest = max(longest, max([len(name) for name in self.failed]))