Use autoconf FLEXIBLE_ARRAY_MEMBER when available

configure.ac

@@ -11,6 +11,8 @@ AC_PROG_LIBTOOL dnl ([1.4]) Don't remove!
 AC_PROG_CC
 AC_PROG_CXX
 
+AC_C_FLEXIBLE_ARRAY_MEMBER
+
 AC_CHECK_FUNCS(mprotect sysconf getpagesize)
 AC_CHECK_HEADERS(unistd.h sys/mman.h)
 

src/hb-ot-layout-gpos-private.hh

@@ -35,8 +35,8 @@
 
 typedef SHORT Value;
 
-typedef Value ValueRecord[VAR];
-ASSERT_SIZE_VAR (Value, 0, ValueRecord);
+typedef Value ValueRecord[VAR0];
+ASSERT_SIZE_VAR (ValueRecord, 0, Value);
 
 struct ValueFormat : USHORT
 {

src/hb-private.h

@@ -148,11 +148,18 @@ typedef int hb_mutex_t;
 
 #define ASSERT_SIZE(_type, _size) ASSERT_STATIC (sizeof (_type) == (_size))
 
-#define VAR 1 /* Size signifying variable-sized array */
+/* Size signifying variable-sized array */
+#ifdef FLEXIBLE_ARRAY_MEMBER
+#define VAR FLEXIBLE_ARRAY_MEMBER
+#else
+#define VAR 1
+#endif
+
+#define VAR0 (VAR+0)
 #define ASSERT_SIZE_VAR(_type, _size, _var_type) \
-	ASSERT_STATIC (sizeof (_type) == (_size) + VAR * sizeof (_var_type))
+	ASSERT_STATIC (sizeof (_type) == (_size) + VAR0 * sizeof (_var_type))
 #define ASSERT_SIZE_VAR2(_type, _size, _var_type1, _var_type2) \
-	ASSERT_STATIC (sizeof (_type) == (_size) + VAR * sizeof (_var_type1) + VAR * sizeof (_var_type2))
+	ASSERT_STATIC (sizeof (_type) == (_size) + VAR0 * sizeof (_var_type1) + VAR0 * sizeof (_var_type2))
 
 #if defined(__GNUC__) && (__GNUC__ > 2) && defined(__OPTIMIZE__)
 #define _HB_BOOLEAN_EXPR(expr) \