Whoops -- that #include <cxxabi.h> wasn't supposed to sneak in there. If present, it may already define a __cxxabiv1::__guard that we could use, but that file comes from libstdc++, and I don't think the NuttX buildroot-based toolchain would have that, which is why we need libxx in the first place.

libc/netdb/lib_gethostbynamer.c

@@ -546,7 +546,7 @@ static int lib_dns_lookup(FAR const char *name, FAR struct hostent *host,
       ptr                 += addrlen;
       buflen              -= addrlen;
 
-      /* And copy name */
+      /* And copy the name */
 
       namelen = strlen(name);
       if (addrlen + namelen + 1 > buflen)

libxx/libxx_cxa_guard.cxx

@@ -38,7 +38,6 @@
 //***************************************************************************
 
 #include <nuttx/compiler.h>
-#include <cxxabi.h>
 
 //***************************************************************************
 // Pre-processor Definitions