Fixed #4702: Throwing DistutilsPlatformError instead of IOError under win32 if MSVC is not found

Lib/distutils/msvc9compiler.py

@@ -247,7 +247,7 @@ def query_vcvarsall(version, arch="x86"):
     result = {}
 
     if vcvarsall is None:
-        raise IOError("Unable to find vcvarsall.bat")
+        raise DistutilsPlatformError("Unable to find vcvarsall.bat")
     log.debug("Calling 'vcvarsall.bat %s' (version=%s)", arch, version)
     popen = subprocess.Popen('"%s" %s & set' % (vcvarsall, arch),
                              stdout=subprocess.PIPE,
@@ -255,7 +255,7 @@ def query_vcvarsall(version, arch="x86"):
 
     stdout, stderr = popen.communicate()
     if popen.wait() != 0:
-        raise IOError(stderr.decode("mbcs"))
+        raise DistutilsPlatformError(stderr.decode("mbcs"))
 
     stdout = stdout.decode("mbcs")
     for line in stdout.split("\n"):

Lib/distutils/tests/test_msvc9compiler.py

@@ -0,0 +1,33 @@
+"""Tests for distutils.msvc9compiler."""
+import sys
+import unittest
+
+from distutils.errors import DistutilsPlatformError
+
+class msvc9compilerTestCase(unittest.TestCase):
+
+    def test_no_compiler(self):
+        # makes sure query_vcvarsall throws
+        # a DistutilsPlatformError if the compiler
+        # is not found
+        if sys.platform != 'win32':
+            # this test is only for win32
+            return
+        from distutils.msvc9compiler import query_vcvarsall
+        def _find_vcvarsall(version):
+            return None
+
+        from distutils import msvc9compiler
+        old_find_vcvarsall = msvc9compiler.find_vcvarsall
+        msvc9compiler.find_vcvarsall = _find_vcvarsall
+        try:
+            self.assertRaises(DistutilsPlatformError, query_vcvarsall,
+                             'wont find this version')
+        finally:
+            msvc9compiler.find_vcvarsall = old_find_vcvarsall
+
+def test_suite():
+    return unittest.makeSuite(msvc9compilerTestCase)
+
+if __name__ == "__main__":
+    unittest.main(defaultTest="test_suite")

Misc/NEWS

@@ -100,6 +100,9 @@ Core and Builtins
 Library
 -------
 
+- Issue #4702: Throwing a DistutilsPlatformError instead of IOError in case 
+  no MSVC compiler is found under Windows. Original patch by Philip Jenvey. 
+
 - Issue #4646: distutils was choking on empty options arg in the setup 
   function. Original patch by Thomas Heller.