Activate Python "Limited API" in PL/Python

This allows building PL/Python against any Python 3.x version and
using another Python 3.x version at run time.  This is useful for
installers that want to run against a separately downloaded Python, so
that they don't have to bundle it themselves.

This builds on the earlier patch to only use APIs supported by the
Limited API.

At the moment, this is not activated on MSVC because that leads to
build failures that no one could explain or cared enough to address.
This could be done later.

Reviewed-by: Jakob Egger <[email protected]>
Discussion: https://www.postgresql.org/message-id/flat/ee410de1-1e0b-4770-b125-eeefd4726a24@eisentraut.org

diff --git a/src/pl/plpython/plpython.h b/src/pl/plpython/plpython.h
index ec822577260f863ecadd015c6acd04050f58b00b..06fc1a5440fef09e6bc40565bcfd25b61639535b 100644 (file)
--- a/src/pl/plpython/plpython.h
+++ b/src/pl/plpython/plpython.h
@@ -19,6 +19,15 @@
 #error Python.h must be included via plpython.h
 #endif
 
+/*
+ * Enable Python Limited API
+ *
+ * XXX currently not enabled on MSVC because of build failures
+ */
+#if !defined(_MSC_VER)
+#define Py_LIMITED_API 0x03020000
+#endif
+
 /*
  * Pull in Python headers via a wrapper header, to control the scope of
  * the system_header pragma therein.