Hmm. I'm disappointed in kotlinc compiler magic.

do {
  val x = true
}
while(x)

works but

do try {
  val x = true
}
finally {}
while(x)

does not. Can i log this as a bug? Or an enhancement?

do you mean this?

do {
        try {
            val x = true
        } finally {

        }
    } while (x)
}

Kotlin parser is designed with a particular code formatting in mind. If you format your code according to Kotlin code style, then it all works. In particular, both

while

and

finally

shall be written on the same line as closing curly brace.

I guess @groostav wants to access variable

x

outside of

try

block where it is declared. But this is not possible as variable is only visible inside scope where it is declared. So solution would be to declare variable

x

outside of

try

block.

do {
    val x: Boolean
    try { 
        x = true
    } finally { 
    }
} while (x)

@Pavlo Liapota that is my workaround, but it kinda defeats the purpose of the magic in the first place. The magic is that the kotlin compiler is able to infer declared variables in hte body of a

do

block, and use them for the conditional expression in the

while

statement. Its a neat trick. Unlike the smart-casting or type-casting tricks however, this trick is not able to see through

inline

functions (or similar), because... well because the kotlin compiler team has a finite number of hours to work. Still, it does seem like a limitation more than a design choice.

Condition of

do-while

statement is located in the same scope as statement body, that’s why variable declared in a body can be access in condition expression. While

try

,

if

, lambdas, etc. create new scopes. Consider example:

if (foo) {
    val x = true
} else {
    val x = false
}

You don’t expect variable

x

to be visible outside of

if

block, right?

@groostav thanks for clarification. I did not understand what was the original problem. The scoping rules are deliberate design decisions, though.