[PATCH v6 02/13] selftests: Add -D_GNU_SOURCE= to CFLAGS in lib.mk

[Edward Liaw]

Centralizes the _GNU_SOURCE definition to CFLAGS in lib.mk.

This uses the form "-D_GNU_SOURCE=", which is equivalent to
"#define _GNU_SOURCE".

Otherwise using "-D_GNU_SOURCE" is equivalent to "-D_GNU_SOURCE=1" and
"#define _GNU_SOURCE 1", which is less commonly seen in source code and
would require many changes in selftests to avoid redefinition warnings.

Suggested-by: John Hubbard <jhubbard at nvidia.com>
Signed-off-by: Edward Liaw <edliaw at google.com>
---
 tools/testing/selftests/lib.mk | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/tools/testing/selftests/lib.mk b/tools/testing/selftests/lib.mk
index 7b299ed5ff45..d6edcfcb5be8 100644
--- a/tools/testing/selftests/lib.mk
+++ b/tools/testing/selftests/lib.mk
@@ -196,6 +196,9 @@ endef
 clean: $(if $(TEST_GEN_MODS_DIR),clean_mods_dir)
 	$(CLEAN)
 
+# Build with _GNU_SOURCE by default
+CFLAGS += -D_GNU_SOURCE=
+
 # Enables to extend CFLAGS and LDFLAGS from command line, e.g.
 # make USERCFLAGS=-Werror USERLDFLAGS=-static
 CFLAGS += $(USERCFLAGS)
-- 
2.45.2.741.gdbec12cfda-goog