From 8d8b9e371c33c9bc455245db35101585dcfb48e5 Mon Sep 17 00:00:00 2001
From: Tobias Wiese <tobias@tobiaswiese.com>
Date: Tue, 1 Mar 2022 01:11:13 +0100
Subject: Define feature test macros in Makefile

To prevent other people from copying the definition of the feature test
macro into their multi-file c project or the unlikely case that this
project will contain more than one c file at some point.
---
 Makefile   | 4 +++-
 exchange.c | 5 +----
 2 files changed, 4 insertions(+), 5 deletions(-)

diff --git a/Makefile b/Makefile
index 915330f..62226b8 100644
--- a/Makefile
+++ b/Makefile
@@ -15,7 +15,9 @@ endif
 
 INSTALL	= install
 
-CFLAGS += -Wall -DVERSION="\"$(VERSION)\"" -DBUILD_DATE="\"$(BUILD_DATE)\""
+FEATURE_TEST_MACROS = _GNU_SOURCE
+CFLAGS += -Wall $(addprefix -D, $(FEATURE_TEST_MACROS)) \
+	  -DVERSION="\"$(VERSION)\"" -DBUILD_DATE="\"$(BUILD_DATE)\""
 LDFLAGS +=
 
 TARGETS := exchange
diff --git a/exchange.c b/exchange.c
index c818606..2bc9193 100644
--- a/exchange.c
+++ b/exchange.c
@@ -1,4 +1,3 @@
-#define _GNU_SOURCE
 #include <fcntl.h>
 #include <stdio.h>
 #include <errno.h>
@@ -14,7 +13,7 @@
 #endif
 
 #ifndef VERSION
-# define VERSION ""
+# define VERSION "UNRELEASED"
 #endif
 
 #ifndef SMALL
@@ -56,8 +55,6 @@ int main(int argc, char *argv[]) {
 			!= -1)
 	{
 		switch (c) {
-			case 't':
-				break;
 			case 'h':  // help
 				usage(stdout);
 				return EXIT_SUCCESS;
-- 
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