From fc3261b284b7abf737818abcc693360d40124d37 Mon Sep 17 00:00:00 2001
From: Viktor Szakats <commit@vsz.me>
Date: Mon, 6 Apr 2026 21:52:20 +0200
Subject: [PATCH] cmake: pre-fill `HAVE_PIPE2` for two more platforms

For DragonFlyBSD and SunOS.

Also opt-in `BSD`, which is covering those listed explicitly, when using
CMake 3.25+.

Follow-up to 131a2fd5aaa1a809211695d2ef8151ffadbebc0c #16987

Closes #21243
---
 CMake/unix-cache.cmake | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/CMake/unix-cache.cmake b/CMake/unix-cache.cmake
index e8a7df1cbc..8ecd206186 100644
--- a/CMake/unix-cache.cmake
+++ b/CMake/unix-cache.cmake
@@ -194,9 +194,12 @@ if(APPLE OR
    CYGWIN)
   set(HAVE_PIPE2 0)
 elseif(CMAKE_SYSTEM_NAME STREQUAL "Linux" OR
+       BSD OR
+       CMAKE_SYSTEM_NAME STREQUAL "DragonFlyBSD" OR
        CMAKE_SYSTEM_NAME STREQUAL "FreeBSD" OR
        CMAKE_SYSTEM_NAME STREQUAL "NetBSD" OR
-       CMAKE_SYSTEM_NAME STREQUAL "OpenBSD")
+       CMAKE_SYSTEM_NAME STREQUAL "OpenBSD" OR
+       CMAKE_SYSTEM_NAME STREQUAL "SunOS")
   set(HAVE_PIPE2 1)
 endif()
 set(HAVE_POLL 1)