Fix:

error: incompatible function pointer types passing 'void (void *, xmlErrorPtr)' (aka 'void (void *, struct _xmlError *)') to parameter of type 'xmlStructuredErrorFunc' (aka 'void (*)(void *, const struct _xmlError *)') [-Wincompatible-function-pointer-types]
error: incompatible function pointer types passing 'void (void *, void *, xmlChar *)' (aka 'void (void *, void *, unsigned char *)') to parameter of type 'xmlHashScanner' (aka 'void (*)(void *, void *, const unsigned char *)') [-Wincompatible-function-pointer-types]

https://sourceforge.net/p/xmlstar/patches/22/
--- src/xml.c
+++ src/xml.c
@@ -104,7 +104,7 @@ void reportGenericError(void* ctx, const char * msg, ...) {
 /* by default all errors are reported */
 static ErrorInfo errorInfo = { NULL, NULL, VERBOSE, CONTINUE };
 
-void reportError(void *ptr, xmlErrorPtr error)
+void reportError(void *ptr, const xmlError *error)
 {
     ErrorInfo *errorInfo = (ErrorInfo*) ptr;
     assert(errorInfo);
--- src/xml_elem.c
+++ src/xml_elem.c
@@ -186,7 +186,7 @@ typedef struct {
  * put @name into @data->array[@data->offset]
  */
 static void
-hash_key_put(void *payload, void *data, xmlChar *name)
+hash_key_put(void *payload, void *data, const xmlChar *name)
 {
     ArrayDest *dest = data;
     dest->array[dest->offset++] = name;
--- src/xmlstar.h
+++ src/xmlstar.h
@@ -32,7 +32,7 @@ typedef struct _errorInfo {
     ErrorStop stop;
 } ErrorInfo;
 
-void reportError(void *ptr, xmlErrorPtr error);
+void reportError(void *ptr, const xmlError *error);
 void suppressErrors(void);
 
 typedef struct _gOptions {