tonumber() does not support 0x prefixed hexadecimal strings

[joe-bowman]

Terraform Version

0.12.7

Terraform Configuration Files

variable "v1" {
    default = "0x99"
}
output "input-v1" {
    value = tonumber(var.v1)
}

Expected Behavior

Hex string is parsed, and converted to a number (decimal 153).

Actual Behavior

Error: Invalid function argument

  on main.tf line 5, in output "input-v1":
   5:     value = tonumber(var.v1)
    |----------------
    | var.v1 is "0x99"

Invalid value for "v" parameter: cannot convert "0x99" to number; given string
must be a decimal representation of a number.

Additional Context

The above example is a reduced case. In the real life use case, the hex string is generated from the substring of a hash to deterministically determine AZ placement without placement changing if other nodes are torn down (i.e. can't use index.count) - so this must be represented as a string and converted to a number for lookup in a list. Worked under 0.11 and previous, so considered a bug in 0.12.

[ghost]

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