https://github.com/php/php-src/issues/12965     Build Failure With libxml2-2.12.3 #12965
https://github.com/php/php-src/commit/0a39890   Fix libxml2 2.12 build due to API breaks
https://github.com/php/php-src/commit/8a95e61   Fix GH-12702: libxml2 2.12.0 issue building from src

--- a/ext/dom/document.c
+++ b/ext/dom/document.c
@@ -23,6 +23,7 @@
 #if defined(HAVE_LIBXML) && defined(HAVE_DOM)
 #include "php_dom.h"
 #include <libxml/SAX.h>
+#include <libxml/xmlxave.h>
 #ifdef LIBXML_SCHEMAS_ENABLED
 #include <libxml/relaxng.h>
 #include <libxml/xmlschemas.h>
--- a/ext/libxml/php_libxml.h
+++ b/ext/libxml/php_libxml.h
@@ -35,6 +35,7 @@ extern zend_module_entry libxml_module_entry;
 
 #include "zend_smart_str.h"
 #include <libxml/tree.h>
+#include <libxml/parser.h>
 
 #define LIBXML_SAVE_NOEMPTYTAG 1<<2
 
--- a/ext/soap/php_sdl.c
+++ b/ext/soap/php_sdl.c
@@ -331,7 +331,7 @@ static void load_wsdl_ex(zval *this_ptr, char *struri, sdlCtx *ctx, int include)
    sdl_restore_uri_credentials(ctx);
 
    if (!wsdl) {
-       xmlErrorPtr xmlErrorPtr = xmlGetLastError();
+       const xmlError *xmlErrorPtr = xmlGetLastError();

        if (xmlErrorPtr) {
            soap_error2(E_ERROR, "Parsing WSDL: Couldn't load from '%s' : %s", struri, xmlErrorPtr->message);
--- a/ext/libxml/libxml.c
+++ b/ext/libxml/libxml.c
@@ -481,7 +481,11 @@ static void _php_libxml_free_error(void *ptr)
        xmlResetError((xmlErrorPtr) ptr);
 }
 
-static void _php_list_set_error_structure(xmlErrorPtr error, const char *msg)
+#if LIBXML_VERSION >= 21200
+static void _php_list_set_error_structure(const xmlError *error, const char *msg)
+#else
+static void _php_list_set_error_structure(xmlError *error, const char *msg)
+#endif
 {
        xmlError error_copy;
        int ret;
@@ -732,7 +736,11 @@ PHP_LIBXML_API void php_libxml_ctx_warning(void *ctx, const char *msg, ...)
        va_end(args);
 }
 
+#if LIBXML_VERSION >= 21200
+PHP_LIBXML_API void php_libxml_structured_error_handler(void *userData, const xmlError *error)
+#else
 PHP_LIBXML_API void php_libxml_structured_error_handler(void *userData, xmlErrorPtr error)
+#endif
 {
        _php_list_set_error_structure(error, NULL);
 
--- a/ext/libxml/libxml.c
+++ b/ext/libxml/libxml.c
@@ -1044,10 +1044,8 @@
 PHP_FUNCTION(libxml_get_last_error)
 {
-   xmlErrorPtr error;
-
    ZEND_PARSE_PARAMETERS_NONE();
 
-   error = xmlGetLastError();
+   const xmlError *error = xmlGetLastError();
 
    if (error) {
        object_init_ex(return_value, libxmlerror_class_entry);