Any call to .AtName(), .AtListIndex(), etc. removes the root flag on root expressions

[detro]

Module version

0.10.0

Description

For a terraform configuration like:

provider "tls" {
  proxy {
    // url: conflicting with `from_env`
    from_env = true
  }
}

If we need to express that url conflicts with from_env, we need to write in the schema of the provider something like:

Validators: []tfsdk.AttributeValidator{					
  // using an "absolute path"
  schemavalidator.ConflictsWith(path.MatchRoot("proxy").AtName("from_env")),
  // using a "relative path"
  schemavalidator.ConflictsWith(path.MatchRelative().AtParent().AtName("from_env")),
}						},

Both approaches should work, but unfortunately the calls to AtName() (and any other .At* method on a path.Expression) make use .Copy(), and that call inadvertently modifies the expression so that, if internally it contained the flag root: true, by virtue of Golang default values, it gets turned to root: false:

func (e Expression) Copy() Expression {
	return Expression{
		steps: e.Steps().Copy(),
	}
}

Because of this, the provider validation logic triggers an error when using the "absolute path" approach:

Error: Invalid Path Expression for Schema Data
        
          with provider["registry.terraform.io/hashicorp/tls"],
          on terraform_plugin_test.tf line 2, in provider "tls":
           2: 					provider "tls" {
        
        The Terraform Provider unexpectedly matched no paths with the given path
        expression and current schema data. This can happen if the path expression
        does not correctly follow the schema in structure or types. Please report
        this to the provider developers.
        
        Path Expression: proxy.url.proxy.from_env

Expected Behavior

Validation should be express-able via "absolute" as well as "relative" paths.
The choice should be left to the provider developer.

Actual Behavior

Any "absolute" path expression (i.e. created via .MatchRoot(), i.e. that contain internally the root: true flag), when deeper than 1 level, assemble an incorrect expression, where the "root-ness" gets lost.

[github-actions]

I'm going to lock this issue because it has been closed for 30 days ⏳. This helps our maintainers find and focus on the active issues.
If you have found a problem that seems similar to this, please open a new issue and complete the issue template so we can capture all the details necessary to investigate further.