`format_int` bad output type

[JTKU]

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Problem

The output type of format_int seems to be integer instead of string.

Probably caused by its TypeDef being integer instead of bytes:

vrl/src/stdlib/format_int.rs

Line 103 in 07cd43a

TypeDef::integer().fallible()

Since the tests also use the same TypeDef::integer() type :

vrl/src/stdlib/format_int.rs

Line 147 in 07cd43a

tdef: TypeDef::integer().fallible(),

, they actually pass, even though declared types are different from that of the actual values.

This is also in contradiction with vector's documentation: https://github.com/vectordotdev/vector/blob/2a85007ce5c0ea05cdb408f4d6c898049c33f055/website/cue/reference/remap/functions/format_int.cue#L27.

VRL Program

b, err_b = format_int(.b.value, 2)
c, err_c = to_string(.c.value)

# both are considered strings
.b.is_string = is_string(b)
.c.is_string = is_string(c)

# not ints
.b.is_int = is_integer(b)
.c.is_int = is_integer(c)

# cannot fail so no error catching needed
if is_null(err_c) {
   .c.string = string(c)
}

# can fail, although its return type is the same as `to_string`
if is_null(err_b) {
   .b.string = string(b)
}

VRL and/or Vector Version

vrl 0.22 (vector 0.45.0)

Debug Output

error[E103]: unhandled fallible assignment
   ┌─ :19:16
   │
19 │    .b.string = string(b)
   │    ----------- ^^^^^^^^^ this expression is fallible because at least one argument's type cannot be verified to be valid
   │    │
   │    or change this to an infallible assignment:
   │    .b.string, err = string(b)
   │
   = see documentation about error handling at https://errors.vrl.dev/#handling
   = see functions characteristics documentation at https://vrl.dev/expressions/#function-call-characteristics
   = learn more about error code 103 at https://errors.vrl.dev/103
   = see language documentation at https://vrl.dev
   = try your code in the VRL REPL, learn more at https://vrl.dev/examples

Example

https://playground.vrl.dev/?state=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%3D%3D

Additional Context

No response

References

Possible solution: https://github.com/JTKU/vrl/tree/fix_format_int_output_type