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

Patch by Jonathan Hosmer.

diff --cc Misc/ACKS
Simple merge

diff --cc Misc/NEWS
index 4fd4f174ac1f728134e344af6eb15d43d6e9b199,564750451b6e96567df7a5df5e43c5db196f2c42..182942abfd84efeb65daa59943dd05b4cfe3d9d3
--- 1/Misc/NEWS
--- 2/Misc/NEWS
+++ b/Misc/NEWS
@@@ -977,34 -780,10 +977,37 @@@ IDL
  Build
  -----
  
 -- The Windows build now includes OpenSSL 1.0.1g
++- Issue #16537: Check whether self.extensions is empty in setup.py. Patch by
++  Jonathan Hosmer.
+ 
 -- Issue #21285: Refactor and fix curses configure check to always search
 -  in a ncursesw directory.
 +- Issue #22359: Remove incorrect uses of recursive make.  Patch by Jonas
 +  Wagner.
 +
 +- Issue #21958: Define HAVE_ROUND when building with Visual Studio 2013 and
 +  above.  Patch by Zachary Turner.
 +
 +- Issue #18093: the programs that embed the CPython runtime are now in a
 +  separate "Programs" directory, rather than being kept in the Modules
 +  directory.
 +
 +- Issue #15759: "make suspicious", "make linkcheck" and "make doctest" in Doc/
 +  now display special message when and only when there are failures.
 +
 +- Issue #21141: The Windows build process no longer attempts to find Perl,
 +  instead relying on OpenSSL source being configured and ready to build.  The
 +  ``PCbuild\build_ssl.py`` script has been re-written and re-named to
 +  ``PCbuild\prepare_ssl.py``, and takes care of configuring OpenSSL source
 +  for both 32 and 64 bit platforms.  OpenSSL sources obtained from
 +  svn.python.org will always be pre-configured and ready to build.
 +
 +- Issue #21037: Add a build option to enable AddressSanitizer support.
 +
 +- Issue #19962: The Windows build process now creates "python.bat" in the
 +  root of the source tree, which passes all arguments through to the most
 +  recently built interpreter.
 +
 +- Issue #21285: Refactor and fix curses configure check to always search
 +  in a ncursesw directory.
  
  - Issue #15234: For BerkelyDB and Sqlite, only add the found library and
    include directories if they aren't already being searched. This avoids

diff --cc setup.py
index 016c45568925e2d2aa59d253c6084bbc88c6f0f5,6f6da7156c35ab841c0855bc960e2b0483882981..a0a22a5f9dc59857dc035573d1b40c5fa2f6eadb
--- 1/setup.py
--- 2/setup.py
+++ b/setup.py
@@@ -260,13 -252,11 +260,15 @@@ class PyBuildExt(build_ext)
  
          build_ext.build_extensions(self)
  
-         longest = max([len(e.name) for e in self.extensions])
 +        for ext in self.extensions:
 +            self.check_extension_import(ext)
 +
 -        if self.failed:
 -            longest = max(longest, max([len(name) for name in self.failed]))
+         longest = 0
+         if self.extensions:
+             longest = max([len(e.name) for e in self.extensions])
 +        if self.failed or self.failed_on_import:
 +            all_failed = self.failed + self.failed_on_import
 +            longest = max(longest, max([len(name) for name in all_failed]))
  
          def print_three_column(lst):
              lst.sort(key=str.lower)