String in fn definition allows any type to be used

[mojodojodev]

Bug Description

String type in fn allows any type to be used

Steps to Reproduce

Create a notebook on the playground with:

from String import String

fn add_strict(a: Int, b: Int) -> Int:
    print("\nrunning through int impl")
    return b + a

fn add_strict(a: String, b: String) -> String:
   print("\nrunning through string impl")
   return a + b

print(add_strict("should this work: ", 8))
let eight: Int = 8
print(add_strict("should this work: ", eight))
print(add_strict("should this work: ", True))
print(add_strict(5, 10))
print(add_strict(True, False))

Resulting in everything that doesn't match the (Int,Int) overload running through (String,String) and concatenating

running through string impl
should this work: 8

running through string impl
should this work: 8

running through string impl
should this work: True

running through int impl
15

running through string impl
TrueFalse

Context

With a single (Int, Int) fn trying to use any type other than Int fails to compile correctly, but having String either by itself or overloaded will allow any type through, is this intentional?

[mojodojodev]

Never mind I see there are __init__ methods for all those types in https://docs.modular.com/mojo/MojoStdlib/String.html makes sense

[dom96]

That's definitely surprising. Python's string doesn't even have this behaviour: you need to stringify explicitly.