Description: Make generate-id() return identifiers in a deterministic way
 generate-id() used to return identifiers based on the memory address of
 the node object. This unfortunately prevents documentation to be built
 reproducily. Instead, we now increment a static counter and store its
 value in the node _private on the first invocation of generate-id().
Author: Jérémy Bobbio <lunar@debian.org>

Index: libxslt-1.1.29/libxslt/functions.c
===================================================================
--- libxslt-1.1.29.orig/libxslt/functions.c
+++ libxslt-1.1.29/libxslt/functions.c
@@ -661,10 +661,10 @@ xsltFormatNumberFunction(xmlXPathParserC
  */
 void
 xsltGenerateIdFunction(xmlXPathParserContextPtr ctxt, int nargs){
-    static char base_address;
+    static unsigned long next_id = 1;
     xmlNodePtr cur = NULL;
     xmlXPathObjectPtr obj = NULL;
-    long val;
+    unsigned long val;
     xmlChar str[30];
 
     if (nargs == 0) {
@@ -702,12 +702,16 @@ xsltGenerateIdFunction(xmlXPathParserCon
     if (obj)
         xmlXPathFreeObject(obj);
 
-    val = (long)((char *)cur - (char *)&base_address);
-    if (val >= 0) {
-      snprintf((char *)str, sizeof(str), "idp%ld", val);
-    } else {
-      snprintf((char *)str, sizeof(str), "idm%ld", -val);
+    if (cur->_private == NULL) {
+        cur->_private = xmlMalloc(sizeof (unsigned long));
+        if (cur->_private == NULL) {
+            xmlGenericError(xmlGenericErrorContext, "malloc failed !\n");
+        }
+        *((unsigned long *)cur->_private) = next_id++;
     }
+    val = *((unsigned long *)cur->_private);
+
+    sprintf((char *)str, "id%lu", val);
     valuePush(ctxt, xmlXPathNewString(str));
 }