Fix cext for Python 2; ensure C extensions build successfully

The C extensions have been broken since cc718cccc0bf8a01abdf4068c
however CI did not find this, because the build degraded to
non-C extensions without failing.   Ensure that if cext is set,
there is no fallback to non-cext build if the C extension build
fails.

Repair C related issues introduced in cc718cccc0bf8a01abdf4068c.

As C extensions have been silently failing on 2.7 for some commits,
the callcounts also needed to be adjusted for recent performance-related
changes.  That in turn required a fix to the profiling decorator
to use signature rewriting in order to support py.test's
fixture mechanism under Python 2, usage introduced under profiling
in 89bf6d80a9.

Fixes: #5076
Change-Id: Id968f10c85d6bf489298b1c318a1f869ad3e7d80

1 files changed, 13 insertions, 10 deletions

diff --git a/lib/sqlalchemy/testing/profiling.py b/lib/sqlalchemy/testing/profiling.py
index fdf983a8f..14a6fc4ac 100644
--- a/lib/sqlalchemy/testing/profiling.py
+++ b/lib/sqlalchemy/testing/profiling.py
@@ -22,7 +22,6 @@ from . import config
 from .util import gc_collect
 from ..util import jython
 from ..util import pypy
-from ..util import update_wrapper
 from ..util import win32
 
 
@@ -232,17 +231,21 @@ def function_call_count(variance=0.05, times=1):
 
     """
 
-    def decorate(fn):
-        def wrap(*args, **kw):
-            timerange = range(times)
-            with count_functions(variance=variance):
-                for time in timerange:
-                    rv = fn(*args, **kw)
-                return rv
+    # use signature-rewriting decorator function so that py.test fixtures
+    # still work on py27.  In Py3, update_wrapper() alone is good enough,
+    # likely due to the introduction of __signature__.
 
-        return update_wrapper(wrap, fn)
+    from sqlalchemy.util import decorator
 
-    return decorate
+    @decorator
+    def wrap(fn, *args, **kw):
+        timerange = range(times)
+        with count_functions(variance=variance):
+            for time in timerange:
+                rv = fn(*args, **kw)
+            return rv
+
+    return wrap
 
 
 @contextlib.contextmanager