greenlight/xml fails to compile

[skinkie]

go run cmd/*go 
# github.com/concreteit/greenlight/xml
lxml.c: In function ‘validationErrorFunc’:
lxml.c:16:14: warning: implicit declaration of function ‘malloc’ [-Wimplicit-function-declaration]
   16 |     msgStr = malloc(strlen(error->message));
      |              ^~~~~~
lxml.c:7:1: note: include ‘<stdlib.h>’ or provide a declaration of ‘malloc’
    6 | #include "lxml.h"
  +++ |+#include <stdlib.h>
    7 | 
lxml.c:16:14: warning: incompatible implicit declaration of built-in function ‘malloc’ [-Wbuiltin-declaration-mismatch]
   16 |     msgStr = malloc(strlen(error->message));
      |              ^~~~~~
lxml.c:16:14: note: include ‘<stdlib.h>’ or provide a declaration of ‘malloc’
lxml.c:21:21: warning: incompatible implicit declaration of built-in function ‘malloc’ [-Wbuiltin-declaration-mismatch]
   21 |   errMessage *msg = malloc(sizeof(errMessage));
      |                     ^~~~~~
lxml.c:21:21: note: include ‘<stdlib.h>’ or provide a declaration of ‘malloc’
lxml.c: In function ‘newValidationResult’:
lxml.c:48:35: warning: incompatible implicit declaration of built-in function ‘malloc’ [-Wbuiltin-declaration-mismatch]
   48 |         res = (validationResult*) malloc(sizeof(validationResult));
      |                                   ^~~~~~
lxml.c:48:35: note: include ‘<stdlib.h>’ or provide a declaration of ‘malloc’
lxml.c: In function ‘freeValidationResult’:
lxml.c:60:7: warning: implicit declaration of function ‘free’ [-Wimplicit-function-declaration]
   60 |       free(res->errors[i]);
      |       ^~~~
lxml.c:60:7: note: include ‘<stdlib.h>’ or provide a declaration of ‘free’
lxml.c:60:7: warning: incompatible implicit declaration of built-in function ‘free’ [-Wbuiltin-declaration-mismatch]
lxml.c:60:7: note: include ‘<stdlib.h>’ or provide a declaration of ‘free’
lxml.c:63:3: warning: incompatible implicit declaration of built-in function ‘free’ [-Wbuiltin-declaration-mismatch]
   63 |   free(res);
      |   ^~~~
lxml.c:63:3: note: include ‘<stdlib.h>’ or provide a declaration of ‘free’
lxml.c: In function ‘validateStream’:
lxml.c:82:42: warning: passing argument 2 of ‘xmlSchemaSetValidStructuredErrors’ from incompatible pointer type [-Wincompatible-pointer-types]
   82 |   xmlSchemaSetValidStructuredErrors(ctx, validationErrorFunc, res);
      |                                          ^~~~~~~~~~~~~~~~~~~
      |                                          |
      |                                          void (*)(void *, xmlError *) {aka void (*)(void *, struct _xmlError *)}
In file included from lxml.c:5:
/usr/include/libxml2/libxml/xmlschemas.h:185:65: note: expected ‘xmlStructuredErrorFunc’ {aka ‘void (*)(void *, const struct _xmlError *)’} but argument is of type ‘void (*)(void *, xmlError *)’ {aka ‘void (*)(void *, struct _xmlError *)’}
  185 |                                          xmlStructuredErrorFunc serror,
      |                                          ~~~~~~~~~~~~~~~~~~~~~~~^~~~~~
NeTEx/Siri validation tool