Define _GNU_SOURCE at compiler invocation

Author: fangerer

graalpython/com.oracle.graal.python.cext/posix/fork_exec.c

@@ -3,8 +3,8 @@
  *
  * Licensed under the PYTHON SOFTWARE FOUNDATION LICENSE VERSION 2
  */
-#ifdef __gnu_linux__
-#define _GNU_SOURCE
+#if defined(__gnu_linux__) && !defined(_GNU_SOURCE)
+#define _GNU_SOURCE 1
 #endif
 
 #include <unistd.h>

graalpython/com.oracle.graal.python.cext/posix/posix.c

@@ -44,8 +44,8 @@
 
 // This file uses GNU extensions. Functions that require non-GNU versions (e.g. strerror_r)
 // need to go to posix_no_gnu.c
-#ifdef __gnu_linux__
-#define _GNU_SOURCE
+#if defined(__gnu_linux__) && !defined(_GNU_SOURCE)
+#define _GNU_SOURCE 1
 #endif
 
 #include <arpa/inet.h>

graalpython/com.oracle.graal.python.cext/setup.py

@@ -473,6 +473,9 @@ def build_nativelibsupport(capi_home, subdir, libname, deps=[], **kwargs):
 def build_libposix(capi_home):
     src_dir = os.path.join(__dir__, "posix")
     files = [os.path.abspath(os.path.join(src_dir, f)) for f in os.listdir(src_dir) if f.endswith(".c")]
+    no_gnu_source = get_config_var("USE_GNU_SOURCE")
+    if no_gnu_source:
+        get_config_vars()["CFLAGS"] = get_config_var("CFLAGS_DEFAULT")
     module = Extension(libposix_name,
                        sources=files,
                        libraries=['crypt'] if not darwin_native else [],
@@ -486,6 +489,8 @@ def build_libposix(capi_home):
         description="Graal Python's Native support for the POSIX library",
         ext_modules=[module],
     )
+    if no_gnu_source:
+        get_config_vars()["CFLAGS"] = get_config_var("CFLAGS_DEFAULT") + " " + get_config_var("USE_GNU_SOURCE")
 
 
 def build_builtin_exts(capi_home):

graalpython/lib-graalpython/_sysconfig.py

@@ -84,7 +84,11 @@ def _get_posix_vars():
     g['OPT'] = "-stdlib=libc++ -DNDEBUG"
     g['CONFINCLUDEPY'] = get_python_inc()
     g['CPPFLAGS'] = '-I. -I' + get_python_inc()
-    g['CFLAGS'] = "-Wno-unused-command-line-argument -stdlib=libc++ -DNDEBUG -DGRAALVM_PYTHON_LLVM"
+    gnu_source = "-D_GNU_SOURCE=1"
+    g['USE_GNU_SOURCE'] = gnu_source
+    cflags_default = "-Wno-unused-command-line-argument -stdlib=libc++ -DNDEBUG -DGRAALVM_PYTHON_LLVM"
+    g['CFLAGS_DEFAULT'] = cflags_default
+    g['CFLAGS'] = cflags_default + " " + gnu_source
     g['LDFLAGS'] = ""
     g['CCSHARED'] = "-fPIC"
     g['LDSHARED_LINUX'] = "%s -shared -fPIC" % __graalpython__.get_toolchain_tool_path('CC')