From: Azat Khuzhin <a3at.mail@gmail.com>
Date: Sun, 5 Mar 2017 21:30:21 +0000 (+0300)
Subject: cmake: detect _GNU_SOURCE not by __GNU_LIBRARY__ only (fallback to _GNU_SOURCE)
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=71a56bd3a7f4f74ded331fdd4156b680c7e2fc9b;p=libevent

cmake: detect _GNU_SOURCE not by __GNU_LIBRARY__ only (fallback to _GNU_SOURCE)

Fixes pipe2() on Android-9/armv7-a

Refs: #475
---

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 1eabc243..a861e7d9 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -224,7 +224,14 @@ if (SOLARIS)
 endif()
 
 # Check if _GNU_SOURCE is available.
-CHECK_SYMBOL_EXISTS(__GNU_LIBRARY__ "features.h" _GNU_SOURCE)
+if (NOT _GNU_SOURCE)
+  CHECK_SYMBOL_EXISTS(__GNU_LIBRARY__ "features.h" _GNU_SOURCE)
+
+  if (NOT _GNU_SOURCE)
+    unset(_GNU_SOURCE CACHE)
+    CHECK_SYMBOL_EXISTS(_GNU_SOURCE "features.h" _GNU_SOURCE)
+  endif()
+endif()
 
 if (_GNU_SOURCE)
     add_definitions(-D_GNU_SOURCE)