+## ----------------- ##
+## Compiler issues. ##
+## ----------------- ##
+
+# b4_attribute_define
+# -------------------
+# Provide portability for __attribute__.
+m4_define([b4_attribute_define],
+[#ifndef __attribute__
+/* This feature is available in gcc versions 2.5 and later. */
+# if (! defined __GNUC__ || __GNUC__ < 2 \
+ || (__GNUC__ == 2 && __GNUC_MINOR__ < 5))
+# define __attribute__(Spec) /* empty */
+# endif
+#endif
+
+/* Suppress unused-variable warnings by "using" E. */
+#if ! defined lint || defined __GNUC__
+# define YYUSE(E) ((void) (E))
+#else
+# define YYUSE(E) /* empty */
+#endif
+
+#if defined __GNUC__ && 407 <= __GNUC__ * 100 + __GNUC_MINOR__
+/* Suppress an incorrect diagnostic about yylval being uninitialized. */
+# define YY_IGNORE_MAYBE_UNINITIALIZED_BEGIN \
+ _Pragma ("GCC diagnostic push") \
+ _Pragma ("GCC diagnostic ignored \"-Wuninitialized\"")\
+ _Pragma ("GCC diagnostic ignored \"-Wmaybe-uninitialized\"")
+# define YY_IGNORE_MAYBE_UNINITIALIZED_END \
+ _Pragma ("GCC diagnostic pop")
+#else
+# define YY_INITIAL_VALUE(Value) Value
+#endif
+#ifndef YY_IGNORE_MAYBE_UNINITIALIZED_BEGIN
+# define YY_IGNORE_MAYBE_UNINITIALIZED_BEGIN
+# define YY_IGNORE_MAYBE_UNINITIALIZED_END
+#endif
+#ifndef YY_INITIAL_VALUE
+# define YY_INITIAL_VALUE(Value) /* Nothing. */
+#endif
+])
+
+