From 655ed68acf1aa396770aafb2f6a95927deb15ef6 Mon Sep 17 00:00:00 2001
From: Laurettta <okolielauretta0715@gmail.com>
Date: Tue, 3 Nov 2026 09:30:53 +0000
Subject: [PATCH] [hotfix] report the first wrong let variable type Closes
 https://github.com/eXist-db/exist/issues/5315

---
 .../main/java/org/exist/xquery/LetExpr.java   |  3 +--
 .../java/org/exist/xquery/XQueryTest.java     | 25 +++++++++++++++++++
 2 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/exist-core/src/main/java/org/exist/xquery/LetExpr.java b/exist-core/src/main/java/org/exist/xquery/LetExpr.java
index 50f08b6014..b4bb263395 100644
--- a/exist-core/src/main/java/org/exist/xquery/LetExpr.java
+++ b/exist-core/src/main/java/org/exist/xquery/LetExpr.java
@@ -108,8 +108,6 @@ public Sequence eval(Sequence contextSequence, Item contextItem)
                 var.setContextDocs(inputSequence.getContextDocSet());
                 registerUpdateListener(in);
 
-                resultSequence = returnExpr.eval(contextSequence, null);
-
                 if (sequenceType != null) {
                     Cardinality actualCardinality;
                     if (var.getValue().isEmpty()) {actualCardinality = Cardinality.EMPTY_SEQUENCE;}
@@ -166,6 +164,7 @@ public Sequence eval(Sequence contextSequence, Item contextItem)
                         }
                     }
                 }
+                resultSequence = returnExpr.eval(contextSequence, null);
             } finally {
                 // Restore the local variable stack
                 context.popLocalVariables(mark, resultSequence);
diff --git a/exist-core/src/test/java/org/exist/xquery/XQueryTest.java b/exist-core/src/test/java/org/exist/xquery/XQueryTest.java
index 0d0372f762..b06dc77204 100644
--- a/exist-core/src/test/java/org/exist/xquery/XQueryTest.java
+++ b/exist-core/src/test/java/org/exist/xquery/XQueryTest.java
@@ -2233,6 +2233,31 @@ public void noErrorNeOperatorWithSequence_1740883() {
         }
     }
 
+    @Test
+    public void letTypeErrorReportedOnFirstVariable () throws XMLDBException {
+        try{
+            final String query = "let $input as xs:string := () " +
+                    "let $output as xs:string := $input " +
+                    "return $output";
+
+            try (final Collection testCollection = getTestCollection()) {
+                final XPathQueryService service = testCollection.getService(XPathQueryService.class);
+
+                try(final EXistResourceSet result = (EXistResourceSet) service.query(query)) {
+                    // needed to ensure that result is closed
+
+                }
+
+                fail("Expected XPTY0004 error for $input");
+            }
+        } catch (XMLDBException e) {
+            if (!e.getMessage().contains("$input")) {
+                LOG.error(e.getMessage(), e);
+                fail(e.getMessage());
+            }
+        }
+    }
+
     /**
      * <a href="http://sourceforge.net/support/tracker.php?aid=1740885">http://sourceforge.net/support/tracker.php?aid=1740885</a>
      */