Could lang=regex syntax handling apply to consts that are later used in a recognized location?

[stephentoub]

Today if I have:

new Regex("someRegex")

I get nice syntax coloring / IntelliSense support for that "someRegex" string. Same applies anywhere [StringSyntax("Regex")] is used, or if /* lang=regex */ is applied.

Frequently, though, I'll see code that has:

private const string SomePattern = "someRegex";
...
... = new Regex(SomePattern);

and that "someRegex" doesn't get the nice support.

Could Roslyn see that SomePattern is passed somewhere that accepts [StringSyntax("Regex")] and implicitly treat it as if it had /* lang=regex */ applied?

cc: @CyrusNajmabadi

[CyrusNajmabadi]

Yes, it could. We already do this for locals. It would not be out of bounds to do this.

Question: in your cases, is the constant and the regex usage located in the file? or do you sometimes put them in different partial parts. I'm wary about the expense of looking into different parts during the classification pass. So it would be nice if this only applied to one part at a time.

If your pattern is to have them in distinct parts, i'll def look into supporting that, but it's more complex :)

[stephentoub]

Question: in your cases, is the constant and the regex usage located in the file?

The 90% case is they're in the same file.

[CyrusNajmabadi]

Ok. We can start with that and see if that's sufficient :)