--- a/ChangeLog	Tue Aug 02 16:22:16 2011 +0200
+++ b/ChangeLog	Tue Aug 02 17:05:40 2011 +0200
@@ -2,7 +2,7 @@
 =================
 
 	--
-    * fix Comparison.as_string to considerer its optional attribute
+
     * add some missing operators (#72295):
 
       * % (modulo),
@@ -13,6 +13,12 @@
       * << (bitwise left shift),
       * >> (bitwise right shift)
 
+    * new #72052: optional 'optcomparisons' key in variable stinfo, containing
+      HAVING comparison nodes where it's used and optional (eg outer
+      join)
+
+    * fix Comparison.as_string to considerer its optional attribute
+
 2011-07-27  --  0.29.1
     * #70264: remove_group_var renamed into remove_group_term and fixed
       implementation

--- a/stcheck.py	Tue Aug 02 16:22:16 2011 +0200
+++ b/stcheck.py	Tue Aug 02 17:05:40 2011 +0200
@@ -528,16 +528,26 @@
             # XXX node.having is a list of size 1
             assert len(node.having) == 1
             for term in node.having[0].get_nodes(Comparison):
-                for vref in term.iget_nodes(VariableRef):
-                    vref.variable.stinfo.setdefault('having', []).append(term)
+                lhsvariables = set(vref.variable for vref in term.children[0].get_nodes(VariableRef))
+                rhsvariables = set(vref.variable for vref in term.children[1].get_nodes(VariableRef))
+                for var in lhsvariables | rhsvariables:
+                    var.stinfo.setdefault('having', []).append(term)
                 if vargraph is not None:
-                    lhsvariables = set(vref.name for vref in term.children[0].get_nodes(VariableRef))
-                    rhsvariables = set(vref.name for vref in term.children[1].get_nodes(VariableRef))
                     for v1 in lhsvariables:
+                        v1 = v1.name
                         for v2 in rhsvariables:
+                            v2 = v2.name
                             if v1 != v2:
                                 vargraph.setdefault(v1, []).append(v2)
                                 vargraph.setdefault(v2, []).append(v1)
+                if term.optional in ('left', 'both'):
+                    for var in lhsvariables:
+                        optcomps = var.stinfo['attrvar'].stinfo.setdefault('optcomparisons', set())
+                        optcomps.add(term)
+                if term.optional in ('right', 'both'):
+                    for var in rhsvariables:
+                        optcomps = var.stinfo['attrvar'].stinfo.setdefault('optcomparisons', set())
+                        optcomps.add(term)
 
     def rewrite_shared_optional(self, exists, var, identity_rel_scope=None):
         """if variable is shared across multiple scopes, need some tree