Disconnect SPI at end of Function_create

Issue #544 presented a mystery where the regression test for trigger
transition tables would succeed with check_function_bodies on, but fail
with check_function_bodies off.

In the 'on' case, the function would be ready to use ahead of its first
invocation (the validator having done all the necessary work). The first
invocation would find the function cached and invoke it, with SPI not yet
connected. On the function's first use of SPI, Invocation_assertConnect
sees there is a TriggerData associated with the invocation, and registers
the transition tables to make them visible by the expected names.

In the 'off' case, the function's first invocation requires Function_create
to do its work, which may involve an SPI connection from PL/Java's class
loader. Taking place before the invocation has been recognized as handling
a trigger, this connection is made without registering the transition
tables. By the time the function itself first uses SPI, the TriggerData
has been associated with the invocation, but no registration occurs because
SPI is already connected.

Ending any SPI connection that Function_create may have made ensures that
the first use of SPI by the function itself makes a new SPI connection
that is appropriately set up.

It is a bug for check_function_bodies to have an effect on a function's
runtime behavior and not just on its validation. To catch such behavior
in the future, the regression test script now repeats the example jar
installation and test execution with check_function_bodies set to off.

Author: jcflack

CI/common

@@ -279,4 +279,32 @@ boolean loadExamplesAndTest(Connection c) throws Exception
   );
 }
 
+/*
+ * Unloads the PL/Java example and Saxon jars, returning true if that produced
+ * the expected sequence of results (not necessarily meaning success, unless
+ * results.get("ng") is also zero afterward.
+ */
+boolean unloadExamples(Connection c) throws Exception
+{
+  return stateMachine(
+    "remove example and saxon jars",
+    null,
+
+    Stream.concat(
+      Node.removeJar(c, "examples", true),
+      Node.removeJar(c, "saxon", false)
+    )
+    .flatMap(Node::semiFlattenDiagnostics)
+    .peek(Node::peek),
+
+    (o,p,q) -> isDiagnostic(o, Set.of("error")) ? 1 : -2,
+    (o,p,q) -> isVoidResultSet(o, 1, 1) ? 3 : false,
+
+    (o,p,q) -> isDiagnostic(o, Set.of("error")) ? 3 : -4,
+    (o,p,q) -> isVoidResultSet(o, 1, 1) ? 5 : false,
+
+    (o,p,q) -> null == o
+  );
+}
+
 int pgMajorVersion;

CI/integration

@@ -205,18 +205,27 @@ try (
     /*
      * Also confirm that the generated undeploy actions work.
      */
-    succeeding &= stateMachine(
-      "remove jar void result",
-      null,
+    unloadExamples(c);
 
-      q(c, "SELECT sqlj.remove_jar('examples', true)")
-      .flatMap(Node::semiFlattenDiagnostics)
-      .peek(Node::peek),
+    /*
+     * Repeat the regression tests with check_function_bodies off (issue 544).
+     */
+    try ( Connection c2 = n1.connect() )
+    {
+      succeeding &= stateMachine(
+	"check_function_bodies off",
+	null,
 
-      (o,p,q) -> isDiagnostic(o, Set.of("error")) ? 1 : -2,
-      (o,p,q) -> isVoidResultSet(o, 1, 1) ? 3 : false,
-      (o,p,q) -> null == o
-    );
+	q(c2, "SET check_function_bodies TO off")
+	.flatMap(Node::semiFlattenDiagnostics)
+	.peek(Node::peek),
+
+	(o,p,q) -> isDiagnostic(o, Set.of("error")) ? 1 : -2,
+	NOTHING_OR_PGJDBC_ZERO_COUNT,
+	(o,p,q) -> null == o
+      );
+      succeeding &= loadExamplesAndTest(c2) && unloadExamples(c2);
+    }
 
     /*
      * Get another new connection and make sure the extension can be

pljava-so/src/main/c/Function.c

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2004-2025 Tada AB and other contributors, as listed below.
+ * Copyright (c) 2004-2026 Tada AB and other contributors, as listed below.
  *
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the The BSD 3-Clause License
@@ -789,6 +789,7 @@ static Function Function_create(
 			funcOid);
 	}
 
+	Invocation_assertDisconnect(); /* func may make its own connection */
 	return self;
 }