Source location for StringConcatenation node for interpolation points to the end of the string.

[nshahan]

In the kernel AST for the following code the location for the StringConcatenation node is pointing to the column where the carrot is pointing.

String foo() => 'hello';
String bar() => 'world';

void main() {
  var s = '${foo()} ${bar()}';
  //                        ^
  print(s);
}

I noticed this when working on some problems with source mapped locations in JavaScript output from DDC. I'm working around it for now but most other nodes have a location that point to the beginning of their corresponding source code. Would it make sense if StringConcatenation did too?

cc @johnniwinther

[johnniwinther]

I think it makes more sense to point to the start of the string literal. @jensjoha do you see a problem in making such a change?

[jensjoha]

A StringConcatenation is created via createStringConcatenation which is called twice:

• push(forest.createStringConcatenation(offsetForToken(endToken), expressions));
• push(forest.createStringConcatenation(offsetForToken(startToken), expressions ?? parts));

So it's only somtimes it's the end token. Generally I think we just give it what we have available, but yeah, making it the start instead would make more sense.
I'll add it to my todo list.