On Wed, 14 Jan 2026 at 16:59, Peter Eisentraut <[email protected]> wrote:
I think this module should have a runtime test, too. Otherwise you
don't know that you got the linkage correct, or whether this works at
all. It doesn't have to do much, like it could literally be a + b, and
it could evolve in the future to test hooks, _PG_init, etc.
Done
Let's put a README file in the module's directory instead of putting the
explanation into the Makefile/meson.build.
Done
I wonder if the module's build integration would work correctly in the
autoconf/makefile case if no C++ is available. AFAICT, it would fail to
build with g++ not found or similar.
Changed this to check that if CXX is g++, the command is also actually
available before including the module for the build.
AFAICT, the minimum changes to get a minimum test module to work are
- fix for "restrict", recently committed
- disable warning about zero-length arrays, seems trivial
- named designated initializers
Correct, I've now restructured the commits to have the module
introduction as the first one. Then all the other commits, both fix a
macro to work in C++ and add some usage of those macros as coverage to
the previously added module.
I learned that named designated initializers in C++ are not allowed to
be specified out of order, so they are not a full equivalent to the C
syntax. This could be a problem for example if someone wanted in the
future to have something like
PG_MODULE_MAGIC_EXT(.threads_supported = true)
(while not specifying the leading .name and .version fields).
This would still work fine, because fields are left out. The problem
occurs when defining values for fields, but in a different order than
the fields are specified in the struct (so e.g. by putting .version
before .name). The reason for that is related to destructor ordering.
I think for now the easiest fix would be to just not use the named
initializers in the definition of PG_MODULE_MAGIC_DATA. Then we don't
need to require C++20 and have that additional code. In the future, we
might need a different solution more suitable for C++.
There is a small problem with this though. Using both designated an
non-designated initializers, is not valid standard C++. I even get a
warning (but no error) about that with clang:
../src/test/modules/test_cplusplusext/test_cplusplusext.cpp:24:2: warning:
mixture of designated and non-designated initializers in the same initializer
list is a C99 extension [-Wc99-designator]
In C mixing them is allowed just fine.
Sadly that means that C++ extensions (even when compiled for C++20)
shouldn't use PG_MODULE_MAGIC_EXT with designated initializers at all.
I've updated the documentation to reflect that. I agree that it's better
to avoid requiring C++20 on MSVC (at least for now).
The use of -std=c++11 for CI is a valid idea; I have often wanted that
for C as well. But conversely we also want to allow testing optional
extension and future C standard features. So we need a comprehensive
solution there that covers both ends and both languages. Let's leave
that out for now and think about it separately.
Removed
From 6ece40b64ad1dcf44746680b07618ee783dd7e3b Mon Sep 17 00:00:00 2001
From: Jelte Fennema-Nio <[email protected]>
Date: Fri, 2 Jan 2026 22:31:05 +0100
Subject: [PATCH v6 1/5] tests: Add a test C++ extension module
While we already test that our headers are valid C++ using headerscheck,
it turns out that the macros we define might still expand to invalid
C++ code. This adds a minimal test extension that is compiled using C++
to test that it's actually possible to build and run extensions written
in C++. Future commits will improve C++ compatibility of some of our
macros and add usage of them to this extension make sure that they don't
regress in the future.
To get CI green, this also fixes an issue when compiling C++ extensions
on MSVC: Our use of designated initializers in PG_MODULE_MAGIC_DATA
caused it to only be possible. This reverts to using positional
initializers instead. Sadly that means that using designated
initializers in C++20 is still not allowed in PG_MODULE_MAGIC_EXT
because mixing designated an positional initializers is a C only
feature.
---
doc/src/sgml/xfunc.sgml | 6 +++
meson.build | 4 ++
src/include/fmgr.h | 12 +++---
src/test/modules/Makefile | 11 ++++++
src/test/modules/meson.build | 1 +
src/test/modules/test_cplusplusext/.gitignore | 3 ++
src/test/modules/test_cplusplusext/Makefile | 26 +++++++++++++
src/test/modules/test_cplusplusext/README | 10 +++++
.../expected/test_cplusplusext.out | 14 +++++++
.../modules/test_cplusplusext/meson.build | 37 +++++++++++++++++++
.../sql/test_cplusplusext.sql | 6 +++
.../test_cplusplusext--1.0.sql | 8 ++++
.../test_cplusplusext.control | 4 ++
.../test_cplusplusext/test_cplusplusext.cpp | 37 +++++++++++++++++++
14 files changed, 174 insertions(+), 5 deletions(-)
create mode 100644 src/test/modules/test_cplusplusext/.gitignore
create mode 100644 src/test/modules/test_cplusplusext/Makefile
create mode 100644 src/test/modules/test_cplusplusext/README
create mode 100644 src/test/modules/test_cplusplusext/expected/test_cplusplusext.out
create mode 100644 src/test/modules/test_cplusplusext/meson.build
create mode 100644 src/test/modules/test_cplusplusext/sql/test_cplusplusext.sql
create mode 100644 src/test/modules/test_cplusplusext/test_cplusplusext--1.0.sql
create mode 100644 src/test/modules/test_cplusplusext/test_cplusplusext.control
create mode 100644 src/test/modules/test_cplusplusext/test_cplusplusext.cpp
diff --git a/doc/src/sgml/xfunc.sgml b/doc/src/sgml/xfunc.sgml
index 70e815b8a2c..143f87a253a 100644
--- a/doc/src/sgml/xfunc.sgml
+++ b/doc/src/sgml/xfunc.sgml
@@ -1973,6 +1973,12 @@ PG_MODULE_MAGIC_EXT(
.name = "my_module_name",
.version = "1.2.3"
);
+</programlisting>
+
+ In C++ code, use positional arguments instead of designated initializers:
+
+<programlisting>
+PG_MODULE_MAGIC_EXT("my_module_name", "1.2.3");
</programlisting>
Subsequently the name and version can be examined via
diff --git a/meson.build b/meson.build
index 6d304f32fb0..aef791da7c3 100644
--- a/meson.build
+++ b/meson.build
@@ -2211,6 +2211,10 @@ if cc.get_id() == 'msvc'
'/w24777', # 'function' : format string 'string' requires an argument of type 'type1', but variadic argument number has type 'type2' [like -Wformat]
]
+ cxxflags_warn += [
+ '/wd4200', # nonstandard extension used: zero-sized array in struct/union
+ ]
+
cppflags += [
'/DWIN32',
'/DWINDOWS',
diff --git a/src/include/fmgr.h b/src/include/fmgr.h
index eabbc78b280..1ab8749cee1 100644
--- a/src/include/fmgr.h
+++ b/src/include/fmgr.h
@@ -497,13 +497,15 @@ typedef struct
}
/*
- * Macro to fill a magic block. If any arguments are given, they should
- * be field initializers.
+ * Macro to fill a magic block. If any arguments are given, they should be
+ * field initializers. These can be designated initialzers, or non-designated
+ * initializers. If they're non-designated, they are applied after the ABI
+ * fields.
*/
#define PG_MODULE_MAGIC_DATA(...) \
{ \
- .len = sizeof(Pg_magic_struct), \
- .abi_fields = PG_MODULE_ABI_DATA, \
+ sizeof(Pg_magic_struct), \
+ PG_MODULE_ABI_DATA, \
__VA_ARGS__ \
}
@@ -524,7 +526,7 @@ extern PGDLLEXPORT const Pg_magic_struct *PG_MAGIC_FUNCTION_NAME(void); \
const Pg_magic_struct * \
PG_MAGIC_FUNCTION_NAME(void) \
{ \
- static const Pg_magic_struct Pg_magic_data = PG_MODULE_MAGIC_DATA(.name = NULL); \
+ static const Pg_magic_struct Pg_magic_data = PG_MODULE_MAGIC_DATA(); \
return &Pg_magic_data; \
} \
extern int no_such_variable
diff --git a/src/test/modules/Makefile b/src/test/modules/Makefile
index 4c6d56d97d8..c90b1bd0dc0 100644
--- a/src/test/modules/Makefile
+++ b/src/test/modules/Makefile
@@ -75,5 +75,16 @@ else
ALWAYS_SUBDIRS += ldap_password_func
endif
+# test_cplusplusext requires a working C++ compiler. If CXX is set to g++, then
+# that could be because g++ is AC_PROG_CXX's fallback when no C++ compiler is
+# found. So in that case we do check to see if it actually exists.
+ifneq ($(CXX),g++)
+SUBDIRS += test_cplusplusext
+else ifneq ($(shell command -v $(CXX)),)
+SUBDIRS += test_cplusplusext
+else
+ALWAYS_SUBDIRS += test_cplusplusext
+endif
+
$(recurse)
$(recurse_always)
diff --git a/src/test/modules/meson.build b/src/test/modules/meson.build
index 1b31c5b98d6..0c7e8ad4856 100644
--- a/src/test/modules/meson.build
+++ b/src/test/modules/meson.build
@@ -19,6 +19,7 @@ subdir('test_aio')
subdir('test_binaryheap')
subdir('test_bitmapset')
subdir('test_bloomfilter')
+subdir('test_cplusplusext')
subdir('test_cloexec')
subdir('test_copy_callbacks')
subdir('test_custom_rmgrs')
diff --git a/src/test/modules/test_cplusplusext/.gitignore b/src/test/modules/test_cplusplusext/.gitignore
new file mode 100644
index 00000000000..913175ff6e6
--- /dev/null
+++ b/src/test/modules/test_cplusplusext/.gitignore
@@ -0,0 +1,3 @@
+/log/
+/results/
+/tmp_check/
diff --git a/src/test/modules/test_cplusplusext/Makefile b/src/test/modules/test_cplusplusext/Makefile
new file mode 100644
index 00000000000..88cd4403823
--- /dev/null
+++ b/src/test/modules/test_cplusplusext/Makefile
@@ -0,0 +1,26 @@
+# src/test/modules/test_cplusplusext/Makefile
+
+MODULE_big = test_cplusplusext
+OBJS = \
+ $(WIN32RES) \
+ test_cplusplusext.o
+PGFILEDESC = "test_cplusplusext - test C++ compatibility of PostgreSQL headers"
+
+EXTENSION = test_cplusplusext
+DATA = test_cplusplusext--1.0.sql
+
+REGRESS = test_cplusplusext
+
+# Use C++ compiler for linking because this module includes C++ files
+override COMPILER = $(CXX) $(CXXFLAGS)
+
+ifdef USE_PGXS
+PG_CONFIG = pg_config
+PGXS := $(shell $(PG_CONFIG) --pgxs)
+include $(PGXS)
+else
+subdir = src/test/modules/test_cplusplusext
+top_builddir = ../../../..
+include $(top_builddir)/src/Makefile.global
+include $(top_srcdir)/contrib/contrib-global.mk
+endif
diff --git a/src/test/modules/test_cplusplusext/README b/src/test/modules/test_cplusplusext/README
new file mode 100644
index 00000000000..c7a54fe8e7f
--- /dev/null
+++ b/src/test/modules/test_cplusplusext/README
@@ -0,0 +1,10 @@
+test_cplusplusext - Test C++ Extension Compatibility
+====================================================
+
+This test module verifies that PostgreSQL headers and macros work correctly
+when compiled with a C++ compiler.
+
+While PostgreSQL already tests that headers are syntactically valid C++ using
+headerscheck, the macros defined in those headers might still expand to invalid
+C++ code. This module catches such issues by actually compiling and running an
+extension that's written in C++.
diff --git a/src/test/modules/test_cplusplusext/expected/test_cplusplusext.out b/src/test/modules/test_cplusplusext/expected/test_cplusplusext.out
new file mode 100644
index 00000000000..25600cfd1b4
--- /dev/null
+++ b/src/test/modules/test_cplusplusext/expected/test_cplusplusext.out
@@ -0,0 +1,14 @@
+CREATE EXTENSION test_cplusplusext;
+SELECT test_cplusplus_add(1, 2);
+ test_cplusplus_add
+--------------------
+ 3
+(1 row)
+
+SELECT module_name, version FROM pg_get_loaded_modules()
+ WHERE module_name = 'test_cplusplusext';
+ module_name | version
+-------------------+---------
+ test_cplusplusext | 1.2
+(1 row)
+
diff --git a/src/test/modules/test_cplusplusext/meson.build b/src/test/modules/test_cplusplusext/meson.build
new file mode 100644
index 00000000000..0ddb67978ef
--- /dev/null
+++ b/src/test/modules/test_cplusplusext/meson.build
@@ -0,0 +1,37 @@
+# Copyright (c) 2025-2026, PostgreSQL Global Development Group
+
+if not add_languages('cpp', required: false, native: false)
+ subdir_done()
+endif
+
+test_cplusplusext_sources = files(
+ 'test_cplusplusext.cpp',
+)
+
+if host_system == 'windows'
+ test_cplusplusext_sources += rc_lib_gen.process(win32ver_rc, extra_args: [
+ '--NAME', 'test_cplusplusext',
+ '--FILEDESC', 'test_cplusplusext - test C++ compatibility of PostgreSQL headers',])
+endif
+
+test_cplusplusext = shared_module('test_cplusplusext',
+ test_cplusplusext_sources,
+ kwargs: pg_test_mod_args,
+)
+test_install_libs += test_cplusplusext
+
+test_install_data += files(
+ 'test_cplusplusext.control',
+ 'test_cplusplusext--1.0.sql',
+)
+
+tests += {
+ 'name': 'test_cplusplusext',
+ 'sd': meson.current_source_dir(),
+ 'bd': meson.current_build_dir(),
+ 'regress': {
+ 'sql': [
+ 'test_cplusplusext',
+ ],
+ },
+}
diff --git a/src/test/modules/test_cplusplusext/sql/test_cplusplusext.sql b/src/test/modules/test_cplusplusext/sql/test_cplusplusext.sql
new file mode 100644
index 00000000000..693910ba637
--- /dev/null
+++ b/src/test/modules/test_cplusplusext/sql/test_cplusplusext.sql
@@ -0,0 +1,6 @@
+CREATE EXTENSION test_cplusplusext;
+
+SELECT test_cplusplus_add(1, 2);
+
+SELECT module_name, version FROM pg_get_loaded_modules()
+ WHERE module_name = 'test_cplusplusext';
diff --git a/src/test/modules/test_cplusplusext/test_cplusplusext--1.0.sql b/src/test/modules/test_cplusplusext/test_cplusplusext--1.0.sql
new file mode 100644
index 00000000000..c54acb76823
--- /dev/null
+++ b/src/test/modules/test_cplusplusext/test_cplusplusext--1.0.sql
@@ -0,0 +1,8 @@
+/* src/test/modules/test_cplusplusext/test_cplusplusext--1.0.sql */
+
+-- complain if script is sourced in psql, rather than via CREATE EXTENSION
+\echo Use "CREATE EXTENSION test_cplusplusext" to load this file. \quit
+
+CREATE FUNCTION test_cplusplus_add(int4, int4) RETURNS int4
+AS 'MODULE_PATHNAME'
+LANGUAGE C STRICT;
diff --git a/src/test/modules/test_cplusplusext/test_cplusplusext.control b/src/test/modules/test_cplusplusext/test_cplusplusext.control
new file mode 100644
index 00000000000..640a0a51f35
--- /dev/null
+++ b/src/test/modules/test_cplusplusext/test_cplusplusext.control
@@ -0,0 +1,4 @@
+comment = 'Test module for C++ extension compatibility'
+default_version = '1.0'
+module_pathname = '$libdir/test_cplusplusext'
+relocatable = true
diff --git a/src/test/modules/test_cplusplusext/test_cplusplusext.cpp b/src/test/modules/test_cplusplusext/test_cplusplusext.cpp
new file mode 100644
index 00000000000..7108e5b1cc5
--- /dev/null
+++ b/src/test/modules/test_cplusplusext/test_cplusplusext.cpp
@@ -0,0 +1,37 @@
+/*--------------------------------------------------------------------------
+ *
+ * test_cplusplusext.cpp
+ * Test that PostgreSQL headers compile with a C++ compiler.
+ *
+ * This file is compiled with a C++ compiler to verify that PostgreSQL
+ * headers remain compatible with C++ extensions.
+ *
+ * Copyright (c) 2025-2026, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ * src/test/modules/test_cplusplusext/test_cplusplusext.cpp
+ *
+ * -------------------------------------------------------------------------
+ */
+
+extern "C" {
+#include "postgres.h"
+#include "fmgr.h"
+
+PG_MODULE_MAGIC_EXT("test_cplusplusext", "1.2");
+
+PG_FUNCTION_INFO_V1(test_cplusplus_add);
+}
+
+/*
+ * Simple function that returns the sum of two integers. This verifies that
+ * C++ extension modules can be loaded and called correctly at runtime.
+ */
+extern "C" Datum
+test_cplusplus_add(PG_FUNCTION_ARGS)
+{
+ int32 a = PG_GETARG_INT32(0);
+ int32 b = PG_GETARG_INT32(1);
+
+ PG_RETURN_INT32(a + b);
+}
base-commit: 6831cd9e3b082d7b830c3196742dd49e3540c49b
--
2.52.0
From 923e443ff3724188ba13c93337b07378e4860d9a Mon Sep 17 00:00:00 2001
From: Jelte Fennema-Nio <[email protected]>
Date: Fri, 5 Dec 2025 15:37:59 +0100
Subject: [PATCH v6 2/5] Support using copyObject in C++
Calling copyObject in C++ without GNU extensions fails with an error
like this:
error: use of undeclared identifier 'typeof'; did you mean 'typeid'
This is due to the C compiler supporting used to compile postgres
supporting typeof, but that function actually not being present in the
C++ compiler. This fixes that by defining pg_exprtype which maps to
typeof or decltype depending on the compiler. While pg_typeof would have
been a more natural name, that name is already taken in our codebase as
the implementation of the pg_typeof UDF.
---
src/include/c.h | 13 +++++++++++++
src/include/nodes/nodes.h | 4 ++--
.../modules/test_cplusplusext/test_cplusplusext.cpp | 6 ++++++
3 files changed, 21 insertions(+), 2 deletions(-)
diff --git a/src/include/c.h b/src/include/c.h
index 7136102e5ff..a0b1261f7d3 100644
--- a/src/include/c.h
+++ b/src/include/c.h
@@ -412,6 +412,19 @@
#define unlikely(x) ((x) != 0)
#endif
+/*
+ * pg_exprtype
+ * Get the type of an expression at compile time.
+ *
+ * In C++ we use decltype since typeof is not standard C++, while in C we use
+ * typeof when available.
+ */
+#if defined(__cplusplus)
+#define pg_exprtype(x) decltype(x)
+#elif defined(HAVE_TYPEOF)
+#define pg_exprtype(x) typeof(x)
+#endif
+
/*
* CppAsString
* Convert the argument to a string, using the C preprocessor.
diff --git a/src/include/nodes/nodes.h b/src/include/nodes/nodes.h
index b6ad28618ab..f5e17e670b7 100644
--- a/src/include/nodes/nodes.h
+++ b/src/include/nodes/nodes.h
@@ -226,8 +226,8 @@ extern int16 *readAttrNumberCols(int numCols);
extern void *copyObjectImpl(const void *from);
/* cast result back to argument type, if supported by compiler */
-#ifdef HAVE_TYPEOF
-#define copyObject(obj) ((typeof(obj)) copyObjectImpl(obj))
+#ifdef pg_exprtype
+#define copyObject(obj) ((pg_exprtype(obj)) copyObjectImpl(obj))
#else
#define copyObject(obj) copyObjectImpl(obj)
#endif
diff --git a/src/test/modules/test_cplusplusext/test_cplusplusext.cpp b/src/test/modules/test_cplusplusext/test_cplusplusext.cpp
index 7108e5b1cc5..48741f27949 100644
--- a/src/test/modules/test_cplusplusext/test_cplusplusext.cpp
+++ b/src/test/modules/test_cplusplusext/test_cplusplusext.cpp
@@ -17,6 +17,7 @@
extern "C" {
#include "postgres.h"
#include "fmgr.h"
+#include "nodes/parsenodes.h"
PG_MODULE_MAGIC_EXT("test_cplusplusext", "1.2");
@@ -32,6 +33,11 @@ test_cplusplus_add(PG_FUNCTION_ARGS)
{
int32 a = PG_GETARG_INT32(0);
int32 b = PG_GETARG_INT32(1);
+ RangeTblRef *node = makeNode(RangeTblRef);
+ RangeTblRef *copy = copyObject(node);
+
+ pfree(copy);
+ pfree(node);
PG_RETURN_INT32(a + b);
}
--
2.52.0
From ac5cbcfc21a2b91f646fbd636e94c79c5bc2f9b8 Mon Sep 17 00:00:00 2001
From: Jelte Fennema-Nio <[email protected]>
Date: Mon, 8 Dec 2025 08:13:51 +0100
Subject: [PATCH v6 3/5] Use pg_exprtype instead of typeof
The previous commit introduced pg_exprtype. This starts using that in a
few more places.
---
src/include/c.h | 8 ++++----
src/include/utils/relptr.h | 8 ++++----
2 files changed, 8 insertions(+), 8 deletions(-)
diff --git a/src/include/c.h b/src/include/c.h
index a0b1261f7d3..65173b9d9fd 100644
--- a/src/include/c.h
+++ b/src/include/c.h
@@ -978,10 +978,10 @@ pg_noreturn extern void ExceptionalCondition(const char *conditionName,
*/
#ifdef HAVE__BUILTIN_TYPES_COMPATIBLE_P
#define AssertVariableIsOfType(varname, typename) \
- StaticAssertStmt(__builtin_types_compatible_p(__typeof__(varname), typename), \
+ StaticAssertStmt(__builtin_types_compatible_p(pg_exprtype(varname), typename), \
CppAsString(varname) " does not have type " CppAsString(typename))
#define AssertVariableIsOfTypeMacro(varname, typename) \
- (StaticAssertExpr(__builtin_types_compatible_p(__typeof__(varname), typename), \
+ (StaticAssertExpr(__builtin_types_compatible_p(pg_exprtype(varname), typename), \
CppAsString(varname) " does not have type " CppAsString(typename)))
#else /* !HAVE__BUILTIN_TYPES_COMPATIBLE_P */
#define AssertVariableIsOfType(varname, typename) \
@@ -1229,11 +1229,11 @@ typedef struct PGAlignedXLogBlock
#define unvolatize(underlying_type, expr) const_cast<underlying_type>(expr)
#elif defined(HAVE__BUILTIN_TYPES_COMPATIBLE_P)
#define unconstify(underlying_type, expr) \
- (StaticAssertExpr(__builtin_types_compatible_p(__typeof(expr), const underlying_type), \
+ (StaticAssertExpr(__builtin_types_compatible_p(pg_exprtype(expr), const underlying_type), \
"wrong cast"), \
(underlying_type) (expr))
#define unvolatize(underlying_type, expr) \
- (StaticAssertExpr(__builtin_types_compatible_p(__typeof(expr), volatile underlying_type), \
+ (StaticAssertExpr(__builtin_types_compatible_p(pg_exprtype(expr), volatile underlying_type), \
"wrong cast"), \
(underlying_type) (expr))
#else
diff --git a/src/include/utils/relptr.h b/src/include/utils/relptr.h
index aeb17fa24a5..3e03d34d9ad 100644
--- a/src/include/utils/relptr.h
+++ b/src/include/utils/relptr.h
@@ -38,10 +38,10 @@
#define relptr_declare(type, relptrtype) \
typedef relptr(type) relptrtype
-#ifdef HAVE_TYPEOF
+#ifdef pg_exprtype
#define relptr_access(base, rp) \
(AssertVariableIsOfTypeMacro(base, char *), \
- (typeof((rp).relptr_type)) ((rp).relptr_off == 0 ? NULL : \
+ (pg_exprtype((rp).relptr_type)) ((rp).relptr_off == 0 ? NULL : \
(base) + (rp).relptr_off - 1))
#else
#define relptr_access(base, rp) \
@@ -68,10 +68,10 @@ relptr_store_eval(char *base, char *val)
}
}
-#ifdef HAVE_TYPEOF
+#ifdef pg_exprtype
#define relptr_store(base, rp, val) \
(AssertVariableIsOfTypeMacro(base, char *), \
- AssertVariableIsOfTypeMacro(val, typeof((rp).relptr_type)), \
+ AssertVariableIsOfTypeMacro(val, pg_exprtype((rp).relptr_type)), \
(rp).relptr_off = relptr_store_eval((base), (char *) (val)))
#else
#define relptr_store(base, rp, val) \
--
2.52.0
From 67f5f506dd13bac5e54790e864511c9eb3f5d88b Mon Sep 17 00:00:00 2001
From: Jelte Fennema-Nio <[email protected]>
Date: Sat, 17 Jan 2026 14:51:36 +0100
Subject: [PATCH v6 4/5] Support using StaticAssert macros in C++
StaticAssertExpr didn't work in MSVC C++. This adds a dedicated C++
definition which uses an inline lamdbda, that calls only the static
assert. Since this results in empty lambda, the actual call will be
removed by any compiler that does some optimization.
---
src/include/c.h | 8 ++++++--
src/test/modules/test_cplusplusext/test_cplusplusext.cpp | 5 +++++
2 files changed, 11 insertions(+), 2 deletions(-)
diff --git a/src/include/c.h b/src/include/c.h
index 65173b9d9fd..03764571dc8 100644
--- a/src/include/c.h
+++ b/src/include/c.h
@@ -956,13 +956,17 @@ pg_noreturn extern void ExceptionalCondition(const char *conditionName,
static_assert(condition, errmessage)
#define StaticAssertStmt(condition, errmessage) \
do { static_assert(condition, errmessage); } while(0)
-#ifdef HAVE_STATEMENT_EXPRESSIONS
+#ifdef __cplusplus
+/* C++11 lambdas provide a convenient way to use static_assert as an expression */
+#define StaticAssertExpr(condition, errmessage) \
+ ((void) ([](){ static_assert(condition, errmessage); }(), 0))
+#elif defined(HAVE_STATEMENT_EXPRESSIONS)
#define StaticAssertExpr(condition, errmessage) \
((void) ({ static_assert(condition, errmessage); true; }))
#else
#define StaticAssertExpr(condition, errmessage) \
((void) sizeof(struct { int static_assert_failure : (condition) ? 1 : -1; }))
-#endif /* HAVE_STATEMENT_EXPRESSIONS */
+#endif
/*
diff --git a/src/test/modules/test_cplusplusext/test_cplusplusext.cpp b/src/test/modules/test_cplusplusext/test_cplusplusext.cpp
index 48741f27949..bb9c310504e 100644
--- a/src/test/modules/test_cplusplusext/test_cplusplusext.cpp
+++ b/src/test/modules/test_cplusplusext/test_cplusplusext.cpp
@@ -24,6 +24,8 @@ PG_MODULE_MAGIC_EXT("test_cplusplusext", "1.2");
PG_FUNCTION_INFO_V1(test_cplusplus_add);
}
+StaticAssertDecl(sizeof(int32) == 4, "int32 should be 4 bytes");
+
/*
* Simple function that returns the sum of two integers. This verifies that
* C++ extension modules can be loaded and called correctly at runtime.
@@ -36,6 +38,9 @@ test_cplusplus_add(PG_FUNCTION_ARGS)
RangeTblRef *node = makeNode(RangeTblRef);
RangeTblRef *copy = copyObject(node);
+ StaticAssertStmt(sizeof(int32) == 4, "int32 should be 4 bytes");
+ (void) StaticAssertExpr(sizeof(int64) == 8, "int64 should be 8 bytes");
+
pfree(copy);
pfree(node);
--
2.52.0
From fb4f07ba3ce998c5c2358e2434fea6825fe3edbe Mon Sep 17 00:00:00 2001
From: Jelte Fennema-Nio <[email protected]>
Date: Sat, 17 Jan 2026 14:55:28 +0100
Subject: [PATCH v6 5/5] Support using list_make macros in C++
The list_make_xxx_cell macros were using designated initializers and
these are only officially available in C++20. GCC and Clang allow them
in earlier C++ versions too, but MSVC is strict about it. Since we want
to support C++11 this changes these macros to use inline functions
instead, which work across both C and C++.
---
src/include/nodes/pg_list.h | 43 ++++++++++++++++---
.../test_cplusplusext/test_cplusplusext.cpp | 14 ++++++
2 files changed, 52 insertions(+), 5 deletions(-)
diff --git a/src/include/nodes/pg_list.h b/src/include/nodes/pg_list.h
index ae80975548f..ba43d36bc89 100644
--- a/src/include/nodes/pg_list.h
+++ b/src/include/nodes/pg_list.h
@@ -202,12 +202,45 @@ list_length(const List *l)
#define llast_node(type,l) castNode(type, llast(l))
/*
- * Convenience macros for building fixed-length lists
+ * Convenience functions for building fixed-length lists. These cannot be
+ * macros with designated initializers, because we want these functions to be
+ * usable from C++ versions below C++20.
*/
-#define list_make_ptr_cell(v) ((ListCell) {.ptr_value = (v)})
-#define list_make_int_cell(v) ((ListCell) {.int_value = (v)})
-#define list_make_oid_cell(v) ((ListCell) {.oid_value = (v)})
-#define list_make_xid_cell(v) ((ListCell) {.xid_value = (v)})
+static inline ListCell
+list_make_ptr_cell(void *v)
+{
+ ListCell c;
+
+ c.ptr_value = v;
+ return c;
+}
+
+static inline ListCell
+list_make_int_cell(int v)
+{
+ ListCell c;
+
+ c.int_value = v;
+ return c;
+}
+
+static inline ListCell
+list_make_oid_cell(Oid v)
+{
+ ListCell c;
+
+ c.oid_value = v;
+ return c;
+}
+
+static inline ListCell
+list_make_xid_cell(TransactionId v)
+{
+ ListCell c;
+
+ c.xid_value = v;
+ return c;
+}
#define list_make1(x1) \
list_make1_impl(T_List, list_make_ptr_cell(x1))
diff --git a/src/test/modules/test_cplusplusext/test_cplusplusext.cpp b/src/test/modules/test_cplusplusext/test_cplusplusext.cpp
index bb9c310504e..2bdf2c3d057 100644
--- a/src/test/modules/test_cplusplusext/test_cplusplusext.cpp
+++ b/src/test/modules/test_cplusplusext/test_cplusplusext.cpp
@@ -17,6 +17,7 @@
extern "C" {
#include "postgres.h"
#include "fmgr.h"
+#include "nodes/pg_list.h"
#include "nodes/parsenodes.h"
PG_MODULE_MAGIC_EXT("test_cplusplusext", "1.2");
@@ -41,6 +42,19 @@ test_cplusplus_add(PG_FUNCTION_ARGS)
StaticAssertStmt(sizeof(int32) == 4, "int32 should be 4 bytes");
(void) StaticAssertExpr(sizeof(int64) == 8, "int64 should be 8 bytes");
+ List *list = list_make1(node);
+
+ foreach_ptr(RangeTblRef, rtr, list)
+ {
+ (void) rtr;
+ }
+
+ foreach_node(RangeTblRef, rtr, list)
+ {
+ (void) rtr;
+ }
+
+ list_free(list);
pfree(copy);
pfree(node);
--
2.52.0
