From 5b9a58d6801dfea2bb0ac0d1556d729d97a7ae70 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ion=20Gazta=C3=B1aga?= <igaztanaga@gmail.com>
Date: Sun, 25 Aug 2024 23:09:45 +0200
Subject: [PATCH] Add check to make sure POSIX functions are available in
 Cygwin.

---
 include/boost/interprocess/detail/workaround.hpp | 4 ++++
 test/Jamfile.v2                                  | 2 +-
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/include/boost/interprocess/detail/workaround.hpp b/include/boost/interprocess/detail/workaround.hpp
index e6793e8..02528ce 100644
--- a/include/boost/interprocess/detail/workaround.hpp
+++ b/include/boost/interprocess/detail/workaround.hpp
@@ -34,6 +34,10 @@
 #else
    #include <unistd.h>
 
+   #if defined (__CYGWIN__) && (!defined(_POSIX_C_SOURCE) && (_POSIX_C_SOURCE < 200112L))
+   #error "Error: Compiling on Cygwin without POSIX is not supported. Please define _XOPEN_SOURCE >= 600 or _POSIX_C_SOURCE >= 200112 when compiling"
+   #endif
+
    //////////////////////////////////////////////////////
    //Check for XSI shared memory objects. They are available in nearly all UNIX platforms
    //////////////////////////////////////////////////////
diff --git a/test/Jamfile.v2 b/test/Jamfile.v2
index 9b530a6..d22a419 100644
--- a/test/Jamfile.v2
+++ b/test/Jamfile.v2
@@ -25,7 +25,7 @@ project : requirements
     <target-os>hpux,<toolset>gcc:<linkflags>"-Wl,+as,mpas"
     <target-os>windows,<toolset>clang:<linkflags>"-lole32 -loleaut32 -lpsapi -ladvapi32"
     <target-os>linux:<linkflags>"-lrt"
-    #cygwin with -std=c++XX does not include POSIX
+    #cygwin with -std=c++XX does not include POSIX features, so always request them
     <target-os>cygwin:<define>_XOPEN_SOURCE=600
     ;