[stringtemplate-interest] [ST4 Beta4] NullPointerException when redefining embedded region

[Udo Borkowski]

The following template raises an NullPointerException:

------------
main() ::= <<
<@r>a<@end>
<@r()>
>>
------------

The NPE is caught by ST4 and reported through the ErrorManager.


TestCase:

	public void testIt() throws Exception {
		STMessageTextCollector messages = new STMessageTextCollector();

		String templates = "main() ::= <<\n<@r>a<@end>\n<@r()>\n>>";
		writeFile(tmpdir, "t.stg", templates);
		org.stringtemplate.v4.STGroup group = new org.stringtemplate.v4.STGroupFile(
				tmpdir + "/t.stg");
		group.errMgr = new ErrorManager(messages);

		// Force the compilation (this led to an NPE earlier that is reported in
		// the error messages)
		org.stringtemplate.v4.ST st = group.getInstanceOf("main");

		// A proper error messages should be written
		Assert.assertEquals(
				"0:-1: region main.r is embedded and thus already implicitly defined\n",
				messages.getText());
	}


CodeFix:

I don't have a fix for this. I implemented a workaround in ErrorManager#compileTimeError, however the cause for the problem is deeper inside the ST4 code, possibly related to STGroup#rawDefineTemplate and its callers.


Udo

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