Hide warnings from Python headers when using gcc-compatible compiler.

Like commit 388e801, use "#pragma GCC system_header" to silence
warnings appearing within the Python headers, since newer Python
versions no longer worry about some restrictions we still use like
-Wdeclaration-after-statement.

This patch improves on 388e801 by inventing a separate wrapper
header file, allowing the pragma to be tightly scoped to just
the Python headers and not other stuff we have laying about in
plpython.h.  I applied the same technique to plperl for the same
reason: the original patch suppressed warnings for a good deal
of our own code, not only the Perl headers.

Like the previous commit, back-patch to supported branches.

Peter Eisentraut and Tom Lane

Discussion: https://postgr.es/m/ae523163-6d2a-4b81-a875-832e48dec502@eisentraut.org

Author: tglsfdc

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
 

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,
 )

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);