we seem to have forgotten we need __attribute__((__used__)) for idstring

Build.sh

@@ -1,5 +1,5 @@
 #!/bin/sh
-srcversion='$MirOS: src/bin/sleep/Build.sh,v 1.2 2021/07/27 20:11:53 tg Exp $'
+srcversion='$MirOS: src/bin/sleep/Build.sh,v 1.3 2021/08/13 22:29:26 tg Exp $'
 #-
 # Copyright (c) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010,
 #		2011, 2012, 2013, 2014, 2015, 2016, 2017, 2019,
@@ -1295,6 +1295,18 @@ ac_test attribute_unused '' 'for __attribute__((__unused__))' <<-'EOF'
 	    __attribute__((__unused__))) { return (isatty(0)); }
 	#endif
 EOF
+ac_test attribute_used attribute_extension 0 'for __attribute__((__used__))' <<-'EOF'
+	#if defined(__TenDRA__) || (defined(__GNUC__) && (__GNUC__ < 2))
+	extern int thiswillneverbedefinedIhope(void);
+	/* force a failure: TenDRA and gcc 1.42 have false positive here */
+	int main(void) { return (thiswillneverbedefinedIhope()); }
+	#else
+	#include <unistd.h>
+	#undef __attribute__
+	static const char fnord[] __attribute__((__used__)) = "42";
+	int main(void) { return (isatty(0)); }
+	#endif
+EOF
 
 # End of tests run with -Werror
 NOWARN=$save_NOWARN

sleep.h

@@ -76,6 +76,11 @@
 #else
 #define MKSH_A_UNUSED		/* nothing */
 #endif
+#if HAVE_ATTRIBUTE_USED
+#define MKSH_A_USED		__attribute__((__used__))
+#else
+#define MKSH_A_USED		/* nothing */
+#endif
 
 #if defined(MirBSD) && (MirBSD >= 0x09A1) && \
     defined(__ELF__) && defined(__GNUC__) && \
@@ -116,7 +121,7 @@
 #endif
 
 #ifdef EXTERN
-__RCSID("$MirOS: src/bin/sleep/sleep.h,v 1.3 2021/07/27 20:11:54 tg Exp $");
+__RCSID("$MirOS: src/bin/sleep/sleep.h,v 1.4 2021/08/13 22:29:27 tg Exp $");
 #endif
 
 #define ord(c)			((unsigned int)(unsigned char)(c))