[typetraits] Tuple type name confusion

[kaushalmodi]

Hello,

I don't know how to correctly describe this bug.. see the below examples to understand the issue.

import strformat, typetraits
type Person = tuple[name: string, age: int]
let 
  person1: Person = ("Peter", 30)
  person2 = (name : "Peter", age : 30)
echo fmt"Tuple person1 of type {$person1.type} = {person1}"
echo fmt"Tuple person2 of type {$person2.type} = {person2}"

Tuple person1 of type Person = (name: "Peter", age: 30)
Tuple person2 of type Person = (name: "Peter", age: 30)
                      ^^^^^^ <-- was expecting "tuple[name: string, age: int]" here

import strformat, typetraits
type Person = tuple[name: string, age: int]
let 
  person1 = (name : "Peter", age : 30)
  person2: Person = ("Peter", 30)
echo fmt"Tuple person1 of type {$person1.type} = {person1}"
echo fmt"Tuple person2 of type {$person2.type} = {person2}"

Tuple person1 of type tuple[name: string, age: int] = (name: "Peter", age: 30)
Tuple person2 of type tuple[name: string, age: int] = (name: "Peter", age: 30)
                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ <- was expecting "Person" here

---

As Person is type tuple[name: string, age: int], the type "name" gets stuck to the first type I use to declare the variable.

[Vindaar]

It actually seems to be even weirder (at least to me). It's not the order in which you declare the variable, but the order in which you print the names:

import strformat, typetraits
type Person = tuple[name: string, age: int]
let 
  person1: Person = ("Peter", 30)
  person2 = (name : "Peter", age : 30)
echo fmt"Tuple person1 of type {$person1.type} = {person1}"
echo fmt"Tuple person2 of type {$person2.type} = {person2}"

prints them both as Person, whereas

import strformat, typetraits
type Person = tuple[name: string, age: int]
let 
  person1: Person = ("Peter", 30)
  person2 = (name : "Peter", age : 30)
echo fmt"Tuple person1 of type {$person2.type} = {person2}"  # simply moved up
echo fmt"Tuple person2 of type {$person1.type} = {person1}"

prints them as tuple. But if instead of $ one directly calls name it works just fine:

import strformat, typetraits
type Person = tuple[name: string, age: int]
let 
  person1: Person = ("Peter", 30)
  person2 = (name : "Peter", age : 30)
echo fmt"Tuple person1 of type {name(person1.type)} = {person1}"
echo fmt"Tuple person2 of type {name(person2.type)} = {person2}"

prints the first as Person and the second as tuple as one would expect.

[timotheecour]

see this comment #8569 (comment)

[kaushalmodi]

Interesting, I just rebuilt Nim devel (a1e268e) and looks like this issue got fixed by a positive side-effect of some commit :D

@timotheecour @Araq If you guys know which commit could have fixed this, please link that commit here for future reference. Thanks to whoever fixed this 👍

[timotheecour]

@kaushalmodi @Araq I verified that it was as a side effect of my recent PR #10071; not exactly sure why though.
I'm adding a test case so we avoid future regressions (we should always add a test case before closing!)=> see PR #10169

[kaushalmodi]

This issue has been fixed for a while; closing it.