Printer incorrectly adding line break when emitting node list with non-synthesized nodes as of TS 4.3

[devversion]

Bug Report

🔎 Search Terms

printer, line break, ts 4.3, beta, for non-synthesized nodes, line separator, new line.

🕗 Version & Regression Information

Started as of v4.3-dev.

⏯ Playground Link

Specific to the compiler API; not reproduce in the playground.

💻 Code

Reproduction repository: https://github.com/devversion/ts-4.3-emitter-node-list-line-breaks

Consider an input file as the followed:

const FirstSymbol = Symbol();
const SecondSymbol = Symbol();

Assume we have the AST for this source file and have access to these variables. i.e. firstVarNode and secondVarNode. If we construct a new array literal containing the names of these variables and print the array literal, the array literal will be multi-line.

const arrayLiteral = ts.createArrayLiteral([
    firstVarNode.name,
    secondVarNode.name
]);

console.log(printer.printNode(ts.EmitHint.Unspecified, arrayLiteral, testFile));

the output will be:

[FirstSymbol,
    SecondSymbol]

while I'd expect it to be [FirstSymbol, SecondSymbol] unless I specify multiLine = true for the array literal expression.

Additional information

This seems to have changed with 3c32f6e. The printer now checks if the non-synthesized nodes are on the same line, even if they do not have the same parent.