terragrunt does not support provider functions and fails during input-validate

[cordula-grau]

Describe the bug

When using provider functions terragrunt validate-inputs fails with the following error:
Invalid 'for' expression: Extra characters after the end of the 'for' expression. (and 1 other messages)

offending line is:
condition = var.subnet.enable_ipv6 == false || anytrue([ for prefix in self.address_prefixes: provider::assert::cidrv6(prefix) ])

Log Output

09:38:27.973 INFO   Downloading Terraform configurations from file://../../../../../source into ./.terragrunt-cache/GH_-yqcqatzOk6TOWWxlk8evAns/Zl8COh10InqCrREuxj5EItMHqpM
09:38:27.978 DEBUG  Copying files from . into ./.terragrunt-cache/GH_-yqcqatzOk6TOWWxlk8evAns/Zl8COh10InqCrREuxj5EItMHqpM/components/dns
09:38:27.979 DEBUG  Setting working directory to ./.terragrunt-cache/GH_-yqcqatzOk6TOWWxlk8evAns/Zl8COh10InqCrREuxj5EItMHqpM/components/dns
09:38:27.979 DEBUG  The file path ./.terragrunt-cache/GH_-yqcqatzOk6TOWWxlk8evAns/Zl8COh10InqCrREuxj5EItMHqpM/components/dns/provider.tf already exists, but was a previously generated file by terragrunt. Since if_exists for code generation is set to "overwrite_terragrunt", regenerating file.
09:38:27.979 DEBUG  Generated file ./.terragrunt-cache/GH_-yqcqatzOk6TOWWxlk8evAns/Zl8COh10InqCrREuxj5EItMHqpM/components/dns/provider.tf.
09:38:27.980 DEBUG  The file path ./.terragrunt-cache/GH_-yqcqatzOk6TOWWxlk8evAns/Zl8COh10InqCrREuxj5EItMHqpM/components/dns/remotestate.tf already exists, but was a previously generated file by terragrunt. Since if_exists for code generation is set to "overwrite_terragrunt", regenerating file.
09:38:27.980 DEBUG  Generated file ./.terragrunt-cache/GH_-yqcqatzOk6TOWWxlk8evAns/Zl8COh10InqCrREuxj5EItMHqpM/components/dns/remotestate.tf.
09:38:28.078 DEBUG  tfconfig.Diagnostics Invalid 'for' expression: Extra characters after the end of the 'for' expression.
/home/circleci/project/terraform/terraform.go:56 (0x100f473fd)
/home/circleci/project/cli/commands/validate-inputs/action.go:33 (0x10143de54)
/home/circleci/project/cli/commands/terraform/target.go:85 (0x10142f684)
/home/circleci/project/cli/commands/terraform/action.go:215 (0x10142f669)
/home/circleci/project/cli/commands/terraform/action.go:87 (0x10143ddf0)
/home/circleci/project/cli/commands/validate-inputs/action.go:29 (0x10143ddf1)
/home/circleci/project/cli/commands/validate-inputs/command.go:31 (0x101440368)
/home/circleci/project/cli/app.go:239 (0x101a74078)
/home/circleci/go/pkg/mod/golang.org/x/[email protected]/errgroup/errgroup.go:78 (0x100f47dd8)
/usr/local/go/src/runtime/asm_arm64.s:1222 (0x10031db74)

09:38:28.078 ERROR  Invalid 'for' expression: Extra characters after the end of the 'for' expression.
09:38:28.078 ERROR  Unable to determine underlying exit code, so Terragrunt will exit with error code 1

Steps To Reproduce

terraform {
  required_version = "~> 1.8"
  required_providers {
    assert = {
      source  = "hashicorp/assert"
      version = "~> 0.13"
    }
    azurerm = {
      source  = "hashicorp/azurerm"
      version = "~> 3.8"
    }
  }
}

data "azurerm_subnet" "main" {
  name                 = var.subnet.name
  resource_group_name  = var.subnet.resource_group_name
  virtual_network_name = var.subnet.virtual_network_name

  lifecycle {
    postcondition {
      condition     = var.subnet.enable_ipv6 == false || anytrue([ for prefix in self.address_prefixes: provider::assert::cidrv6(prefix) ])
      error_message = "Subnet does not contain valid IPv6 CIDR. Either use a subnet that contains a valid IPv6 CIDR or disable IPv6 support."
    }
  }
}

variable "subnet" {
   type =    object({
      name                 = string
      virtual_network_name = string
      resource_group_name  = string
      enable_ipv6          = optional(bool, false)
    })
}

Expected behavior

terragrunt validate-inputs should run properly

Nice to haves

• Terminal output
• Screenshots

Versions

• Terragrunt version: v0.67.10
• OpenTofu/Terraform version: v1.9.6
• Environment details (Ubuntu 20.04, Windows 10, etc.): MacOS 15.0 / Ubuntu 24.04

Additional context

Add any other context about the problem here.