Confusing and dangerous String->int conversion

this is no bug, this is the intended behavior. That is because groovy doesn't know characters, but handles characters as Strings of length 1. The ways I see to solve the problem above is to introduce chars or to forbid the handling of Strings of length 1 as chars when not explicitly converted to chars before.

String s = "5"
int x = s

would then throw an runtime exception.

String s = "5"
char c = s
int x = c

would not.

String s = "10"
int x = s

and String s = "10"
char c = s

would both cause an exception during runtime.

BTW, after the String is created, there is no way to know it was a liteal String.

Is there a downside to your second solution ("forbid the handling of Strings of length 1 as chars without explicit conversion")?

You could resolve literals at parse time, whenever possible. So:

int x = "5"

would be the same as int x = '5' in Java, but

int x = foo

would fail at runtime whenever foo is a String of any length.

there are always downsides... for example old code will behave different. More weight does have that it will not be possible to do something like this:

def foo(char c){}

foo("a")

This must fail then, because "a" is a String and no char.

adding special handling for

int x="5"

is no good idea. People normally don't care much about String constants and String references when coming from Java. And it will be hard to explain them, that

int x="5"

behaves different from

def foo()

int x = foo()

I don't have any good ideas, so I guess I'll close this issue. I'm assuming that's OK - if it's the assignee's job to close it I apologize.