[bugfix] #4958 & #4810

exist-core/src/main/java/org/exist/xquery/GeneralComparison.java

@@ -648,6 +648,9 @@ protected Sequence nodeSetCompare( NodeSet nodes, Sequence contextSequence ) thr
                     }
                 }
             }
+            if (result.isEmpty()) {
+                return BooleanValue.FALSE;
+            }
         }
 
         if( context.getProfiler().traceFunctions() ) {

exist-core/src/main/java/org/exist/xquery/Predicate.java

@@ -36,6 +36,7 @@
 import org.exist.xquery.value.SequenceIterator;
 import org.exist.xquery.value.Type;
 import org.exist.xquery.value.ValueSequence;
+import org.exist.xquery.value.BooleanValue;
 
 import javax.annotation.Nullable;
 import java.util.Set;
@@ -377,7 +378,14 @@ private Sequence selectByNodeSet(final Sequence contextSequence) throws XPathExc
         final NodeSet contextSet = contextSequence.toNodeSet();
         final boolean contextIsVirtual = contextSet instanceof VirtualNodeSet;
         contextSet.setTrackMatches(false);
-        final NodeSet nodes = super.eval(contextSet, null).toNodeSet();
+        final Sequence res = super.eval(contextSet, null);
+        if(!(res instanceof NodeSet)) {
+            if(res == BooleanValue.FALSE)
+                return NodeSet.EMPTY_SET;
+            return res;
+        }
+        final NodeSet nodes = res.toNodeSet();
+
         /*
          * if the predicate expression returns results from the cache we can
          * also return the cached result.

exist-core/src/test/xquery/emptySeq.xq

@@ -0,0 +1,38 @@
+xquery version "3.1";
+
+module namespace t="http://exist-db.org/xquery/test";
+
+declare namespace test="http://exist-db.org/xquery/xqsuite";
+
+declare variable $t:XML := document {
+    <F id="1"/>
+};
+
+declare
+    %test:setUp
+function t:setup() {
+    xmldb:create-collection("/db", "test"),
+    xmldb:store("/db/test", "test.xml", $t:XML)
+};
+
+declare
+    %test:tearDown
+function t:tearDown() {
+    xmldb:remove("/db/test")
+};
+
+declare
+    %test:assertTrue
+function t:test-db() {
+    exists(
+        doc("/db/test/test.xml")//F[boolean(count(@id >= 2))]
+    )
+};
+
+declare
+    %test:assertTrue
+function t:test-mem() {
+    exists(
+        $t:XML//F[boolean(count(@id >= 2))]
+    )
+};

exist-core/src/test/xquery/startWithComp.xq

@@ -0,0 +1,32 @@
+xquery version "3.1";
+
+module namespace t="http://exist-db.org/xquery/test";
+
+declare namespace test="http://exist-db.org/xquery/xqsuite";
+
+declare variable $t:XML := document {
+    <Y1 id="1">
+        <H1 id="2" a2="2">true</H1>
+    </Y1>
+};
+
+declare
+    %test:setUp
+function t:setup() {
+    let $testCol := xmldb:create-collection("/db", "test")
+    return
+        xmldb:store("/db/test", "test.xml", $t:XML)
+};
+
+declare
+    %test:tearDown
+function t:tearDown() {
+    xmldb:remove("/db/test")
+};
+
+declare
+    %test:assertTrue
+function t:test() {
+    doc("/db/test/test.xml")//*[starts-with(@a2, "1") = false()]
+    => exists()
+};