BEGIN {
    HAVE_SYS_CDEFS_H = 0
    HAVE_SYS_CDEFS_BEGIN_END_DECLS = 0
    HAVE_SYS_CDEFS_NONNULL = 0
    HAVE_SYS_CDEFS_THROW = 0
}
END {
    if (!HAVE_SYS_CDEFS_H &&
        (HAVE_SYS_CDEFS_BEGIN_END_DECLS ||
         HAVE_SYS_CDEFS_NONNULL ||
         HAVE_SYS_CDEFS_THROW)) {
        print "config.h is inconsistent" > "/dev/stderr"
        close("/dev/stderr")
        exit 1
    }
}
FILENAME ~ /config\.h$/ {
    if ($0 ~ /^#define HAVE_SYS_CDEFS_H 1$/) {
        HAVE_SYS_CDEFS_H = 1
    } else if ($0 ~ /^#define HAVE_SYS_CDEFS_BEGIN_END_DECLS 1$/) {
        HAVE_SYS_CDEFS_BEGIN_END_DECLS = 1
    } else if ($0 ~ /^#define HAVE_SYS_CDEFS_NONNULL 1$/) {
        HAVE_SYS_CDEFS_NONNULL = 1
    } else if ($0 ~ /^#define HAVE_SYS_CDEFS_THROW 1$/) {
        HAVE_SYS_CDEFS_THROW = 1
    }
}
FILENAME !~ /config\.h$/ {
    if ($0 ~ /^\/\*HEADER\*\/$/) {
        if (HAVE_SYS_CDEFS_H) {
            print "#include <sys/cdefs.h>"
        }
        if (!HAVE_SYS_CDEFS_THROW) {
            print "#define __THROW /* nothing */"
        }
        if (!HAVE_SYS_CDEFS_NONNULL) {
            print "#define __nonnull(arg) /* nothing */"
        }
        print ""
        if (HAVE_SYS_CDEFS_BEGIN_END_DECLS) {
            print "__BEGIN_DECLS"
        } else {
            print "#ifdef __cplusplus"
            print "extern \"C\" {"
            print "#endif"
        }

    } else if ($0 ~ /^\/\*TRAILER\*\/$/) {
        if (HAVE_SYS_CDEFS_BEGIN_END_DECLS) {
            print "__END_DECLS"
        } else {
            print "#ifdef __cplusplus"
            print "} /* extern \"C\" */"
            print "#endif"
        }

    } else {
        print;
    }
}