From 1094aecab563e8c1601ae80caefb2e4247db87d4 Mon Sep 17 00:00:00 2001
From: David Steele <david@pgmasters.net>
Date: Tue, 25 Jun 2024 16:16:55 +0800
Subject: [PATCH] Require compiler support for __builtin_clzl() and
 __builtin_bswap64().

These functions will be useful for optimizing varint-128 functions.

Require them in the meson build before adding new code in case there are problems with packaging.
---
 doc/xml/release/2024/2.53.xml |  1 +
 meson.build                   | 10 ++++++++++
 2 files changed, 11 insertions(+)

diff --git a/doc/xml/release/2024/2.53.xml b/doc/xml/release/2024/2.53.xml
index 034cd5f01..48dd10cbb 100644
--- a/doc/xml/release/2024/2.53.xml
+++ b/doc/xml/release/2024/2.53.xml
@@ -2,6 +2,7 @@
     <release-core-list>
         <text>
             <p><b>NOTE TO PACKAGERS</b>: The <proper>lz4</proper> library is now required by the meson build.</p>
+            <p><b>NOTE TO PACKAGERS</b>: Compiler support for <code>__builtin_clzl()</code> and <code>__builtin_bswap64()</code> is now required by the meson build.</p>
         </text>
 
         <release-bug-list>
diff --git a/meson.build b/meson.build
index a88fdb37b..0808c4d39 100644
--- a/meson.build
+++ b/meson.build
@@ -135,6 +135,16 @@ add_project_arguments(cc.get_supported_arguments('-fmacro-prefix-map=@0@/test/sr
 ####################################################################################################################################
 configuration = configuration_data()
 
+# Ensure the C compiler supports __builtin_clzl()
+if not cc.links('''int main(int arg, char **argv) {__builtin_clzl(1);}''')
+    error('compiler must support __builtin_clzl()')
+endif
+
+# Ensure the C compiler supports __builtin_bswap64()
+if not cc.links('''int main(int arg, char **argv) {__builtin_bswap64(1);}''')
+    error('compiler must support __builtin_bswap64()')
+endif
+
 # Find optional backtrace library
 lib_backtrace = cc.find_library('backtrace', required: false)