From 18e3d334d480a05103d6dde46d511775fd987f84 Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Tue, 18 Nov 2025 08:43:13 +0100
Subject: [PATCH 6/6] Use static_assert inside StaticAssert* macros

For C23 alignment and to unify the C and C++ definitions.
---
 src/include/c.h               | 19 +++++++++----------
 src/include/regex/regcustom.h |  1 +
 2 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/src/include/c.h b/src/include/c.h
index d462ebbebd1..e5779ee5c26 100644
--- a/src/include/c.h
+++ b/src/include/c.h
@@ -59,6 +59,7 @@
 #include "pg_config_os.h"		/* config from include/port/PORTNAME.h */
 
 /* System header files that should be available everywhere in Postgres */
+#include <assert.h>
 #include <inttypes.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -863,7 +864,6 @@ typedef NameData *Name;
 
 #elif defined(FRONTEND)
 
-#include <assert.h>
 #define Assert(p) assert(p)
 #define AssertMacro(p)	((void) assert(p))
 
@@ -914,22 +914,21 @@ pg_noreturn extern void ExceptionalCondition(const char *conditionName,
  * If the "condition" (a compile-time-constant expression) evaluates to false,
  * throw a compile error using the "errmessage" (a string literal).
  *
- * We require C11 and C++11, so _Static_assert()/static_assert() are expected
- * to be there.  For portability, we wrap it into StaticAssertDecl().
- * _Static_assert() is a "declaration", and so it must be placed where for
- * example a variable declaration would be valid.  As long as we compile with
+ * We require C11 and C++11, so static_assert() is expected to be there.
+ * StaticAssertDecl() was previously used for portability, but it's now just a
+ * plain wrapper and doesn't need to be used in new code.  static_assert() is
+ * a "declaration", and so it must be placed where for example a variable
+ * declaration would be valid.  As long as we compile with
  * -Wno-declaration-after-statement, that also means it cannot be placed after
  * statements in a function.  The macro StaticAssertExpr() makes it safe to
  * use in an expression.
  */
-#ifndef __cplusplus
 #define StaticAssertDecl(condition, errmessage) \
-	_Static_assert(condition, errmessage)
+	static_assert(condition, errmessage)
+#ifndef __cplusplus
 #define StaticAssertExpr(condition, errmessage) \
-	((void) sizeof(struct {_Static_assert(condition, errmessage); char a;}))
+	((void) sizeof(struct {static_assert(condition, errmessage); char a;}))
 #else							/* C++ */
-#define StaticAssertDecl(condition, errmessage) \
-	static_assert(condition, errmessage)
 #define StaticAssertExpr(condition, errmessage) \
 	({ static_assert(condition, errmessage); })
 #endif							/* C++ */
diff --git a/src/include/regex/regcustom.h b/src/include/regex/regcustom.h
index 1c0e92f168f..4557e7a62c0 100644
--- a/src/include/regex/regcustom.h
+++ b/src/include/regex/regcustom.h
@@ -53,6 +53,7 @@
 #define FREE(p)			pfree(VS(p))
 #define REALLOC(p,n)	repalloc_extended(VS(p),(n), MCXT_ALLOC_NO_OOM)
 #define INTERRUPT(re)	CHECK_FOR_INTERRUPTS()
+#undef assert
 #define assert(x)		Assert(x)
 
 /* internal character type and related */
-- 
2.51.0