apply pragma system_header to python headers
Started by Peter Eisentrautabout 2 years ago6 messages
Analogous to 388e80132c (which was for Perl) but for Python, I propose
adding #pragma GCC system_header to plpython.h. Without it, you get
tons of warnings about -Wdeclaration-after-statement, starting with
Python 3.12. (In the past, I have regularly sent feedback to Python to
fix their header files, but this is getting old, and we have an easier
solution now.)
Attachments:
0001-python-Hide-warnings-inside-Python-headers-when-usin.patchtext/plain; charset=UTF-8; name=0001-python-Hide-warnings-inside-Python-headers-when-usin.patchDownload
From 7ca9e82d3c5e30ea21fe5d428b3fa0d6e5b3e942 Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Mon, 6 Nov 2023 12:57:54 +0100
Subject: [PATCH] python: Hide warnings inside Python headers when using gcc
compatible compiler
Analogous to 388e80132c but for Python. This is necessary from Python
3.12 to get a warning-free build.
---
src/pl/plpython/plpython.h | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/src/pl/plpython/plpython.h b/src/pl/plpython/plpython.h
index 91f6f8d860..eb01e62fb6 100644
--- a/src/pl/plpython/plpython.h
+++ b/src/pl/plpython/plpython.h
@@ -25,6 +25,16 @@
*/
#define HAVE_SNPRINTF 1
+/*
+ * Newer versions of the Python headers trigger a lot of warnings with our
+ * compiler flags (at least -Wdeclaration-after-statement is known to be
+ * problematic). The system_header pragma hides warnings from within the rest
+ * of this file, if supported.
+ */
+#ifdef HAVE_PRAGMA_GCC_SYSTEM_HEADER
+#pragma GCC system_header
+#endif
+
#if defined(_MSC_VER) && defined(_DEBUG)
/* Python uses #pragma to bring in a non-default libpython on VC++ if
* _DEBUG is defined */
--
2.42.0
Re: apply pragma system_header to python headers
On 2023-11-06 Mo 07:02, Peter Eisentraut wrote:
Analogous to 388e80132c (which was for Perl) but for Python, I propose
adding #pragma GCC system_header to plpython.h. Without it, you get
tons of warnings about -Wdeclaration-after-statement, starting with
Python 3.12. (In the past, I have regularly sent feedback to Python
to fix their header files, but this is getting old, and we have an
easier solution now.)
WFM
cheers
andrew
--
Andrew Dunstan
EDB: https://www.enterprisedb.com
Re: apply pragma system_header to python headers
Peter Eisentraut <peter@eisentraut.org> writes:
Analogous to 388e80132c (which was for Perl) but for Python, I propose
adding #pragma GCC system_header to plpython.h. Without it, you get
tons of warnings about -Wdeclaration-after-statement, starting with
Python 3.12. (In the past, I have regularly sent feedback to Python to
fix their header files, but this is getting old, and we have an easier
solution now.)
+1 for the concept --- I was just noticing yesterday that my buildfarm
warning scraping script is turning up some of these. However, we ought
to try to minimize the amount of our own code that is subject to the
pragma. So I think a prerequisite ought to be to get this out of
plpython.h:
/*
* Used throughout, so it's easier to just include it everywhere.
*/
#include "plpy_util.h"
Alternatively, is there a way to reverse the effect of the
pragma after we've included what we need?
(I'm not too happy about the state of plperl.h on this point, either.)
regards, tom lane
Re: apply pragma system_header to python headers
On 2023-11-06 Mo 09:57, Tom Lane wrote:
Peter Eisentraut <peter@eisentraut.org> writes:
Analogous to 388e80132c (which was for Perl) but for Python, I propose
adding #pragma GCC system_header to plpython.h. Without it, you get
tons of warnings about -Wdeclaration-after-statement, starting with
Python 3.12. (In the past, I have regularly sent feedback to Python to
fix their header files, but this is getting old, and we have an easier
solution now.)+1 for the concept --- I was just noticing yesterday that my buildfarm
warning scraping script is turning up some of these. However, we ought
to try to minimize the amount of our own code that is subject to the
pragma. So I think a prerequisite ought to be to get this out of
plpython.h:/*
* Used throughout, so it's easier to just include it everywhere.
*/
#include "plpy_util.h"Alternatively, is there a way to reverse the effect of the
pragma after we've included what we need?
There's "GCC diagnostic push" and "GCC diagnostic pop" but I don't know
if they apply to "GCC system_header". Instead of using "GCC
system_header" we could just ignore the warnings we're seeing. e.g. "GCC
diagnostic ignored \"-Wdeclaration-after-statement\""
cheers
andrew
--
Andrew Dunstan
EDB: https://www.enterprisedb.com
Re: apply pragma system_header to python headers
Andrew Dunstan <andrew@dunslane.net> writes:
On 2023-11-06 Mo 09:57, Tom Lane wrote:
+1 for the concept --- I was just noticing yesterday that my buildfarm
warning scraping script is turning up some of these. However, we ought
to try to minimize the amount of our own code that is subject to the
pragma. So I think a prerequisite ought to be to get this out of
plpython.h:/*
* Used throughout, so it's easier to just include it everywhere.
*/
#include "plpy_util.h"Alternatively, is there a way to reverse the effect of the
pragma after we've included what we need?
There's "GCC diagnostic push" and "GCC diagnostic pop" but I don't know
if they apply to "GCC system_header". Instead of using "GCC
system_header" we could just ignore the warnings we're seeing. e.g. "GCC
diagnostic ignored \"-Wdeclaration-after-statement\""
Probably a better way is to invent a separate header "plpython_system.h"
that just includes the Python headers, to scope the pragma precisely.
(I guess it could have the fixup #defines we're wrapping those headers
in, too.)
The same idea would work in plperl.
regards, tom lane
Re: apply pragma system_header to python headers
I wrote:
Probably a better way is to invent a separate header "plpython_system.h"
that just includes the Python headers, to scope the pragma precisely.
(I guess it could have the fixup #defines we're wrapping those headers
in, too.)
The same idea would work in plperl.
After updating one of my test machines to Fedora 39, I'm seeing these
Python warnings too. So here's a fleshed-out patch proposal for doing
it like that.
regards, tom lane
Attachments:
v2-apply-system_header-pragma.patchtext/x-diff; charset=us-ascii; name=v2-apply-system_header-pragma.patchDownload
diff --git a/src/pl/plperl/GNUmakefile b/src/pl/plperl/GNUmakefile
index 975f540b3e..31fb212bf1 100644
--- a/src/pl/plperl/GNUmakefile
+++ b/src/pl/plperl/GNUmakefile
@@ -108,11 +108,11 @@ uninstall: uninstall-lib uninstall-data
install-data: installdirs
$(INSTALL_DATA) $(addprefix $(srcdir)/, $(DATA)) '$(DESTDIR)$(datadir)/extension/'
- $(INSTALL_DATA) $(srcdir)/plperl.h $(srcdir)/ppport.h '$(DESTDIR)$(includedir_server)'
+ $(INSTALL_DATA) $(srcdir)/plperl.h $(srcdir)/plperl_system.h $(srcdir)/ppport.h '$(DESTDIR)$(includedir_server)'
uninstall-data:
rm -f $(addprefix '$(DESTDIR)$(datadir)/extension'/, $(notdir $(DATA)))
- rm -f $(addprefix '$(DESTDIR)$(includedir_server)'/, plperl.h ppport.h)
+ rm -f $(addprefix '$(DESTDIR)$(includedir_server)'/, plperl.h plperl_system.h ppport.h)
.PHONY: install-data uninstall-data
diff --git a/src/pl/plperl/meson.build b/src/pl/plperl/meson.build
index 6a28f40a11..182e0fe169 100644
--- a/src/pl/plperl/meson.build
+++ b/src/pl/plperl/meson.build
@@ -71,6 +71,7 @@ install_data(
install_headers(
'plperl.h',
+ 'plperl_system.h',
'ppport.h',
install_dir: dir_include_server,
)
diff --git a/src/pl/plperl/plperl.h b/src/pl/plperl/plperl.h
index 5d8e51089a..7f338084a9 100644
--- a/src/pl/plperl/plperl.h
+++ b/src/pl/plperl/plperl.h
@@ -18,200 +18,11 @@
/* defines free() by way of system headers, so must be included before perl.h */
#include "mb/pg_wchar.h"
-/* stop perl headers from hijacking stdio and other stuff on Windows */
-#ifdef WIN32
-#define WIN32IO_IS_STDIO
-#endif /* WIN32 */
-
/*
- * Supply a value of PERL_UNUSED_DECL that will satisfy gcc - the one
- * perl itself supplies doesn't seem to.
+ * Pull in Perl headers via a wrapper header, to control the scope of
+ * the system_header pragma therein.
*/
-#define PERL_UNUSED_DECL pg_attribute_unused()
-
-/*
- * Sometimes perl carefully scribbles on our *printf macros.
- * So we undefine them here and redefine them after it's done its dirty deed.
- */
-#undef vsnprintf
-#undef snprintf
-#undef vsprintf
-#undef sprintf
-#undef vfprintf
-#undef fprintf
-#undef vprintf
-#undef printf
-
-/*
- * Perl scribbles on the "_" macro too.
- */
-#undef _
-
-/*
- * ActivePerl 5.18 and later are MinGW-built, and their headers use GCC's
- * __inline__. Translate to something MSVC recognizes. Also, perl.h sometimes
- * defines isnan, so undefine it here and put back the definition later if
- * perl.h doesn't.
- */
-#ifdef _MSC_VER
-#define __inline__ inline
-#ifdef isnan
-#undef isnan
-#endif
-/* Work around for using MSVC and Strawberry Perl >= 5.30. */
-#define __builtin_expect(expr, val) (expr)
-#endif
-
-/*
- * Regarding bool, both PostgreSQL and Perl might use stdbool.h or not,
- * depending on configuration. If both agree, things are relatively harmless.
- * If not, things get tricky. If PostgreSQL does but Perl does not, define
- * HAS_BOOL here so that Perl does not redefine bool; this avoids compiler
- * warnings. If PostgreSQL does not but Perl does, we need to undefine bool
- * after we include the Perl headers; see below.
- */
-#ifdef PG_USE_STDBOOL
-#define HAS_BOOL 1
-#endif
-
-/*
- * Newer versions of the perl headers trigger a lot of warnings with our
- * compiler flags (at least -Wdeclaration-after-statement,
- * -Wshadow=compatible-local are known to be problematic). The system_header
- * pragma hides warnings from within the rest of this file, if supported.
- */
-#ifdef HAVE_PRAGMA_GCC_SYSTEM_HEADER
-#pragma GCC system_header
-#endif
-
-/*
- * Get the basic Perl API. We use PERL_NO_GET_CONTEXT mode so that our code
- * can compile against MULTIPLICITY Perl builds without including XSUB.h.
- */
-#define PERL_NO_GET_CONTEXT
-#include "EXTERN.h"
-#include "perl.h"
-
-/*
- * We want to include XSUB.h only within .xs files, because on some platforms
- * it undesirably redefines a lot of libc functions. But it must appear
- * before ppport.h, so use a #define flag to control inclusion here.
- */
-#ifdef PG_NEED_PERL_XSUB_H
-/*
- * On Windows, win32_port.h defines macros for a lot of these same functions.
- * To avoid compiler warnings when XSUB.h redefines them, #undef our versions.
- */
-#ifdef WIN32
-#undef accept
-#undef bind
-#undef connect
-#undef fopen
-#undef fstat
-#undef kill
-#undef listen
-#undef lstat
-#undef mkdir
-#undef open
-#undef putenv
-#undef recv
-#undef rename
-#undef select
-#undef send
-#undef socket
-#undef stat
-#undef unlink
-#endif
-
-#include "XSUB.h"
-#endif
-
-/* put back our *printf macros ... this must match src/include/port.h */
-#ifdef vsnprintf
-#undef vsnprintf
-#endif
-#ifdef snprintf
-#undef snprintf
-#endif
-#ifdef vsprintf
-#undef vsprintf
-#endif
-#ifdef sprintf
-#undef sprintf
-#endif
-#ifdef vfprintf
-#undef vfprintf
-#endif
-#ifdef fprintf
-#undef fprintf
-#endif
-#ifdef vprintf
-#undef vprintf
-#endif
-#ifdef printf
-#undef printf
-#endif
-
-#define vsnprintf pg_vsnprintf
-#define snprintf pg_snprintf
-#define vsprintf pg_vsprintf
-#define sprintf pg_sprintf
-#define vfprintf pg_vfprintf
-#define fprintf pg_fprintf
-#define vprintf pg_vprintf
-#define printf(...) pg_printf(__VA_ARGS__)
-
-/*
- * Put back "_" too; but rather than making it just gettext() as the core
- * code does, make it dgettext() so that the right things will happen in
- * loadable modules (if they've set up TEXTDOMAIN correctly). Note that
- * we can't just set TEXTDOMAIN here, because this file is used by more
- * extensions than just PL/Perl itself.
- */
-#undef _
-#define _(x) dgettext(TEXTDOMAIN, x)
-
-/* put back the definition of isnan if needed */
-#ifdef _MSC_VER
-#ifndef isnan
-#define isnan(x) _isnan(x)
-#endif
-#endif
-
-/* perl version and platform portability */
-#include "ppport.h"
-
-/*
- * perl might have included stdbool.h. If we also did that earlier (see c.h),
- * then that's fine. If not, we probably rejected it for some reason. In
- * that case, undef bool and proceed with our own bool. (Note that stdbool.h
- * makes bool a macro, but our own replacement is a typedef, so the undef
- * makes ours visible again).
- */
-#ifndef PG_USE_STDBOOL
-#ifdef bool
-#undef bool
-#endif
-#endif
-
-/* supply HeUTF8 if it's missing - ppport.h doesn't supply it, unfortunately */
-#ifndef HeUTF8
-#define HeUTF8(he) ((HeKLEN(he) == HEf_SVKEY) ? \
- SvUTF8(HeKEY_sv(he)) : \
- (U32)HeKUTF8(he))
-#endif
-
-/* supply GvCV_set if it's missing - ppport.h doesn't supply it, unfortunately */
-#ifndef GvCV_set
-#define GvCV_set(gv, cv) (GvCV(gv) = cv)
-#endif
-
-/* Perl 5.19.4 changed array indices from I32 to SSize_t */
-#if PERL_BCDVERSION >= 0x5019004
-#define AV_SIZE_MAX SSize_t_MAX
-#else
-#define AV_SIZE_MAX I32_MAX
-#endif
+#include "plperl_system.h"
/* declare routines from plperl.c for access by .xs files */
HV *plperl_spi_exec(char *, int);
diff --git a/src/pl/plperl/plperl_system.h b/src/pl/plperl/plperl_system.h
new file mode 100644
index 0000000000..61550db2a5
--- /dev/null
+++ b/src/pl/plperl/plperl_system.h
@@ -0,0 +1,215 @@
+/*-------------------------------------------------------------------------
+ *
+ * plperl_system.h
+ * Pull in Perl's system header files.
+ *
+ * We break this out as a separate header file to precisely control
+ * the scope of the "system_header" pragma. No Postgres-specific
+ * declarations should be put here. However, we do include some stuff
+ * that is meant to prevent conflicts between our code and Perl.
+ *
+ * Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1995, Regents of the University of California
+ *
+ * src/pl/plperl/plperl_system.h
+ */
+
+#ifndef PL_PERL_SYSTEM_H
+#define PL_PERL_SYSTEM_H
+
+/*
+ * Newer versions of the perl headers trigger a lot of warnings with our
+ * preferred compiler flags (at least -Wdeclaration-after-statement,
+ * -Wshadow=compatible-local are known to be problematic). The system_header
+ * pragma hides warnings from within the rest of this file, if supported.
+ */
+#ifdef HAVE_PRAGMA_GCC_SYSTEM_HEADER
+#pragma GCC system_header
+#endif
+
+/* stop perl headers from hijacking stdio and other stuff on Windows */
+#ifdef WIN32
+#define WIN32IO_IS_STDIO
+#endif /* WIN32 */
+
+/*
+ * Supply a value of PERL_UNUSED_DECL that will satisfy gcc - the one
+ * perl itself supplies doesn't seem to.
+ */
+#define PERL_UNUSED_DECL pg_attribute_unused()
+
+/*
+ * Sometimes perl carefully scribbles on our *printf macros.
+ * So we undefine them here and redefine them after it's done its dirty deed.
+ */
+#undef vsnprintf
+#undef snprintf
+#undef vsprintf
+#undef sprintf
+#undef vfprintf
+#undef fprintf
+#undef vprintf
+#undef printf
+
+/*
+ * Perl scribbles on the "_" macro too.
+ */
+#undef _
+
+/*
+ * ActivePerl 5.18 and later are MinGW-built, and their headers use GCC's
+ * __inline__. Translate to something MSVC recognizes. Also, perl.h sometimes
+ * defines isnan, so undefine it here and put back the definition later if
+ * perl.h doesn't.
+ */
+#ifdef _MSC_VER
+#define __inline__ inline
+#ifdef isnan
+#undef isnan
+#endif
+/* Work around for using MSVC and Strawberry Perl >= 5.30. */
+#define __builtin_expect(expr, val) (expr)
+#endif
+
+/*
+ * Regarding bool, both PostgreSQL and Perl might use stdbool.h or not,
+ * depending on configuration. If both agree, things are relatively harmless.
+ * If not, things get tricky. If PostgreSQL does but Perl does not, define
+ * HAS_BOOL here so that Perl does not redefine bool; this avoids compiler
+ * warnings. If PostgreSQL does not but Perl does, we need to undefine bool
+ * after we include the Perl headers; see below.
+ */
+#ifdef PG_USE_STDBOOL
+#define HAS_BOOL 1
+#endif
+
+/*
+ * Get the basic Perl API. We use PERL_NO_GET_CONTEXT mode so that our code
+ * can compile against MULTIPLICITY Perl builds without including XSUB.h.
+ */
+#define PERL_NO_GET_CONTEXT
+#include "EXTERN.h"
+#include "perl.h"
+
+/*
+ * We want to include XSUB.h only within .xs files, because on some platforms
+ * it undesirably redefines a lot of libc functions. But it must appear
+ * before ppport.h, so use a #define flag to control inclusion here.
+ */
+#ifdef PG_NEED_PERL_XSUB_H
+/*
+ * On Windows, win32_port.h defines macros for a lot of these same functions.
+ * To avoid compiler warnings when XSUB.h redefines them, #undef our versions.
+ */
+#ifdef WIN32
+#undef accept
+#undef bind
+#undef connect
+#undef fopen
+#undef fstat
+#undef kill
+#undef listen
+#undef lstat
+#undef mkdir
+#undef open
+#undef putenv
+#undef recv
+#undef rename
+#undef select
+#undef send
+#undef socket
+#undef stat
+#undef unlink
+#endif
+
+#include "XSUB.h"
+#endif
+
+/* put back our *printf macros ... this must match src/include/port.h */
+#ifdef vsnprintf
+#undef vsnprintf
+#endif
+#ifdef snprintf
+#undef snprintf
+#endif
+#ifdef vsprintf
+#undef vsprintf
+#endif
+#ifdef sprintf
+#undef sprintf
+#endif
+#ifdef vfprintf
+#undef vfprintf
+#endif
+#ifdef fprintf
+#undef fprintf
+#endif
+#ifdef vprintf
+#undef vprintf
+#endif
+#ifdef printf
+#undef printf
+#endif
+
+#define vsnprintf pg_vsnprintf
+#define snprintf pg_snprintf
+#define vsprintf pg_vsprintf
+#define sprintf pg_sprintf
+#define vfprintf pg_vfprintf
+#define fprintf pg_fprintf
+#define vprintf pg_vprintf
+#define printf(...) pg_printf(__VA_ARGS__)
+
+/*
+ * Put back "_" too; but rather than making it just gettext() as the core
+ * code does, make it dgettext() so that the right things will happen in
+ * loadable modules (if they've set up TEXTDOMAIN correctly). Note that
+ * we can't just set TEXTDOMAIN here, because this file is used by more
+ * extensions than just PL/Perl itself.
+ */
+#undef _
+#define _(x) dgettext(TEXTDOMAIN, x)
+
+/* put back the definition of isnan if needed */
+#ifdef _MSC_VER
+#ifndef isnan
+#define isnan(x) _isnan(x)
+#endif
+#endif
+
+/* perl version and platform portability */
+#include "ppport.h"
+
+/*
+ * perl might have included stdbool.h. If we also did that earlier (see c.h),
+ * then that's fine. If not, we probably rejected it for some reason. In
+ * that case, undef bool and proceed with our own bool. (Note that stdbool.h
+ * makes bool a macro, but our own replacement is a typedef, so the undef
+ * makes ours visible again).
+ */
+#ifndef PG_USE_STDBOOL
+#ifdef bool
+#undef bool
+#endif
+#endif
+
+/* supply HeUTF8 if it's missing - ppport.h doesn't supply it, unfortunately */
+#ifndef HeUTF8
+#define HeUTF8(he) ((HeKLEN(he) == HEf_SVKEY) ? \
+ SvUTF8(HeKEY_sv(he)) : \
+ (U32)HeKUTF8(he))
+#endif
+
+/* supply GvCV_set if it's missing - ppport.h doesn't supply it, unfortunately */
+#ifndef GvCV_set
+#define GvCV_set(gv, cv) (GvCV(gv) = cv)
+#endif
+
+/* Perl 5.19.4 changed array indices from I32 to SSize_t */
+#if PERL_BCDVERSION >= 0x5019004
+#define AV_SIZE_MAX SSize_t_MAX
+#else
+#define AV_SIZE_MAX I32_MAX
+#endif
+
+#endif /* PL_PERL_SYSTEM_H */
diff --git a/src/pl/plpython/Makefile b/src/pl/plpython/Makefile
index ef0a5905ae..f959083a0b 100644
--- a/src/pl/plpython/Makefile
+++ b/src/pl/plpython/Makefile
@@ -39,6 +39,7 @@ DATA = $(NAME)u.control $(NAME)u--1.0.sql
# header files to install - it's not clear which of these might be needed
# so install them all.
INCS = plpython.h \
+ plpython_system.h \
plpy_cursorobject.h \
plpy_elog.h \
plpy_exec.h \
@@ -120,7 +121,7 @@ install-data: installdirs
uninstall-data:
rm -f $(addprefix '$(DESTDIR)$(datadir)/extension'/, $(notdir $(DATA)))
- rm -f $(addprefix '$(DESTDIR)$(includedir_server)'/, plpython.h plpy_util.h)
+ rm -f $(addprefix '$(DESTDIR)$(includedir_server)'/, $(INCS))
.PHONY: install-data uninstall-data
diff --git a/src/pl/plpython/meson.build b/src/pl/plpython/meson.build
index 9f4603a8b5..0071817e44 100644
--- a/src/pl/plpython/meson.build
+++ b/src/pl/plpython/meson.build
@@ -67,6 +67,7 @@ install_headers(
'plpy_typeio.h',
'plpy_util.h',
'plpython.h',
+ 'plpython_server.h',
install_dir: dir_include_server,
)
diff --git a/src/pl/plpython/plpython.h b/src/pl/plpython/plpython.h
index 91f6f8d860..f33f7b5920 100644
--- a/src/pl/plpython/plpython.h
+++ b/src/pl/plpython/plpython.h
@@ -20,27 +20,10 @@
#endif
/*
- * Python versions <= 3.8 otherwise define a replacement, causing macro
- * redefinition warnings.
+ * Pull in Python headers via a wrapper header, to control the scope of
+ * the system_header pragma therein.
*/
-#define HAVE_SNPRINTF 1
-
-#if defined(_MSC_VER) && defined(_DEBUG)
-/* Python uses #pragma to bring in a non-default libpython on VC++ if
- * _DEBUG is defined */
-#undef _DEBUG
-/* Also hide away errcode, since we load Python.h before postgres.h */
-#define errcode __msvc_errcode
-#include <Python.h>
-#undef errcode
-#define _DEBUG
-#elif defined (_MSC_VER)
-#define errcode __msvc_errcode
-#include <Python.h>
-#undef errcode
-#else
-#include <Python.h>
-#endif
+#include "plpython_system.h"
/* define our text domain for translations */
#undef TEXTDOMAIN
diff --git a/src/pl/plpython/plpython_system.h b/src/pl/plpython/plpython_system.h
new file mode 100644
index 0000000000..9532789ae2
--- /dev/null
+++ b/src/pl/plpython/plpython_system.h
@@ -0,0 +1,53 @@
+/*-------------------------------------------------------------------------
+ *
+ * plpython_system.h - pull in Python's system header files
+ *
+ * We break this out as a separate header file to precisely control
+ * the scope of the "system_header" pragma. No Postgres-specific
+ * declarations should be put here. However, we do include some stuff
+ * that is meant to prevent conflicts between our code and Python.
+ *
+ * Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/pl/plpython/plpython_system.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef PLPYTHON_SYSTEM_H
+#define PLPYTHON_SYSTEM_H
+
+/*
+ * Newer versions of the Python headers trigger a lot of warnings with our
+ * preferred compiler flags (at least -Wdeclaration-after-statement is known
+ * to be problematic). The system_header pragma hides warnings from within
+ * the rest of this file, if supported.
+ */
+#ifdef HAVE_PRAGMA_GCC_SYSTEM_HEADER
+#pragma GCC system_header
+#endif
+
+/*
+ * Python versions <= 3.8 otherwise define a replacement, causing macro
+ * redefinition warnings.
+ */
+#define HAVE_SNPRINTF 1
+
+#if defined(_MSC_VER) && defined(_DEBUG)
+/* Python uses #pragma to bring in a non-default libpython on VC++ if
+ * _DEBUG is defined */
+#undef _DEBUG
+/* Also hide away errcode, since we load Python.h before postgres.h */
+#define errcode __msvc_errcode
+#include <Python.h>
+#undef errcode
+#define _DEBUG
+#elif defined (_MSC_VER)
+#define errcode __msvc_errcode
+#include <Python.h>
+#undef errcode
+#else
+#include <Python.h>
+#endif
+
+#endif /* PLPYTHON_SYSTEM_H */