using a xml prolog leads to an error within xml literal

[JensWalter]

Description:
If I set a prolog for a xml literal, ballerina fails with "mismatched input '<'. expecting XMLLiteralEnd".
Since xml instructions are supported, setting a prolog inline should also be supported.

Steps to reproduce:
Constructing a xml literal with xml prolog leads to an error.

import ballerina/io;

function main (string... args){
    xml x1 = xml`<?xml version="1.0" encoding="UTF-8"?>`; //works
    xml x2 = xml`<root/>`; //works
    xml x3 = x1+x2; //works
    xml x4 = xml`<?xml version="1.0" encoding="UTF-8"?><root/>`; //does not work
    xml x5 = xml`<root>hallo<?char 12?></root>`; //works
}

Affected Versions:
0.976.0

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[SupunS]

Hi @JensWalter,

XML Literal (xml `some content`) only allows to parse a single xml item (a single element, text, comment or a processing instruction). However in xml x4 = xml`<?xml version="1.0" encoding="UTF-8"?><root/>`; it contains two items within the literal. Thats why it fails.

This behavior is intended. But I agree that the error message is not very intuitive, as it is thrown from the parser.

The solution is to define them separately, and concat them, as you have done with x1, x2 and x3.

[JensWalter]

This is indeed not self explanatory and very inconvenient for constructing XMLs. Is there any other way to generate the Prolog after the xml is constructed?

[SupunS]

At the moment, there's no alternative way, but to concat the prolog to the xml element..

[JensWalter]

You just added a label to this when I was about to close this issue.
From my point of view, this is a 'works as designed' case, and therefore can be closed.

[SupunS]

@JensWalter Great! Im closing the issue as per your reply. Please do reopen, if you encounter any other issue related to this.