Why can catch clauses not target the try_table block that declares them?

[patrick96]

I'm implementing code generation for the new exception handling proposal and found it curious that the catch clause cannot target its own try block:

The catch clauses are validated without the try block's label being added to the context.

I'm just curious, is there is a practical reason for this that I can't see?

On my side, the code I'm generating can never fall through the end of the try block anyway, so targeting the try block would save me from adding an additional labeled block because.

[titzer]

This has been asked before. It's because the label that the try_table declares isn't valid until after the immediates have been all parsed. I think it makes the most conceptual sense to think of parsing an instruction and its immediates as an atomic operation that pushes a new label.

[patrick96]

Makes sense. Thanks for clearing this up :)