The MS resource compiler simply cannot be convinced to do arithmetic

correctly.  So field3.py is a Python program that can.  This injects
another manual step into the Python release process for Windows; so
it goes.

PC/python_nt.rc

@@ -19,9 +19,29 @@
 #endif
 
 /* Nothing below this should need to be changed except for copyright
- * notices and company name.
+ * notices, company name, and FIELD3.  Unfortunately, all attempts
+ * to get the resource compiler to do arithmetic in macros have
+ * failed miserably -- it gives syntax errors, ignores operators,
+ * or does stuff that's simply bizarre.
  */
 
+
+/* This is what we'd like FIELD3 to be:
+ *
+ * #define FIELD3 (PY_MICRO_VERSION*1000 + PY_RELEASE_LEVEL*10 + PY_RELEASE_SERIAL)
+ *
+ * but that neither gives an error nor comes anywhere close to working.  The
+ * following comment and #define are output from PCbuild\field3.py:
+ *
+ * For 2.3a0,
+ * PY_MICRO_VERSION = 0
+ * PY_RELEASE_LEVEL = 'alpha' = 0xa
+ * PY_RELEASE_SERIAL = 1
+ *
+ * and 0*1000 + 10*10 + 1 = 101
+ */
+#define FIELD3 101
+
 /* e.g., 2.1a2
  * PY_VERSION comes from patchevel.h
  */
@@ -37,7 +57,6 @@
 #if PY_RELEASE_SERIAL > 9
 #   error "PY_RELEASE_SERIAL > 9"
 #endif
-#define FIELD3 (PY_MICRO_VERSION*1000 + PY_RELEASE_LEVEL*10 + PY_RELEASE_SERIAL)
 #define PYVERSION64 PY_MAJOR_VERSION, PY_MINOR_VERSION, FIELD3, PYTHON_API_VERSION
 
 // String Tables

PCbuild/field3.py

@@ -0,0 +1,35 @@
+# An absurd workaround for the lack of arithmetic in MS's resource compiler.
+# After building Python, run this, then paste the output into the appropriate
+# part of PC\python_nt.rc.
+# Example output:
+#
+# * For 2.3a0,
+# * PY_MICRO_VERSION = 0
+# * PY_RELEASE_LEVEL = 'alpha' = 0xA
+# * PY_RELEASE_SERIAL = 1
+# *
+# * and 0*1000 + 10*10 + 1 = 101.
+# */
+# #define FIELD3 101
+
+import sys
+
+major, minor, micro, level, serial = sys.version_info
+levelnum = {'alpha': 0xA,
+            'beta': 0xB,
+            'candidate': 0xC,
+            'final': 0xF,
+           }[level]
+string = sys.version.split()[0] # like '2.3a0'
+
+print " * For %s," % string
+print " * PY_MICRO_VERSION = %d" % micro
+print " * PY_RELEASE_LEVEL = %r = %s" % (level, hex(levelnum))
+print " * PY_RELEASE_SERIAL = %d" % serial
+print " *"
+
+field3 = micro * 1000 + levelnum * 10 + serial
+
+print " * and %d*1000 + %d*10 + %d = %d" % (micro, levelnum, serial, field3)
+print " */"
+print "#define FIELD3", field3