Repository: sqlfluff/sqlfluff
Issue category: Bug Report

Issue:
Unrecoverable failure in Jinja templating: `RelationEmulator` is not safely callable.
### Search before asking

- [X] I searched the [issues](https://github.com/sqlfluff/sqlfluff/issues) and found no similar issues.

- #3998 is similar, but not quite the same as it is related to custom macros.
- #6253 is the source of this issue.

### What Happened

When using `this.some_function()` in DBT models, SQLFLuff crashes with the following error:

```
Unrecoverable failure in Jinja templating:
<sqlfluff.core.templaters.jinja.JinjaTemplater._generate_dbt_builtins.<locals>.RelationEmulator
object at 0x109cfeef0> is not safely callable. Have you
correctly configured your variables?
https://docs.sqlfluff.com/en/latest/perma/variables.html
```

Is there any way to make the object "safely callable"?

### Expected Behaviour

It works.

### Observed Behaviour

It crashes.

### How to reproduce

Just lint a simple model like this:

```sql
{{ this.include(database = False) }}
```

### Dialect

Snowflake (but the issue should apply to all dialects using the Jinja templater)

### Version

==== sqlfluff ====
sqlfluff:                3.2.4 python:                 3.10.7
implementation:        cpython verbosity:                   1
dialect:             snowflake templater:               jinja
rules:                                all

### Configuration

[sqlfluff]
templater = jinja
dialect = snowflake

### Are you willing to work on and submit a PR to address the issue?

- [x] Yes I am willing to submit a PR!

### Code of Conduct

- [X] I agree to follow this project's [Code of Conduct](https://github.com/sqlfluff/sqlfluff/blob/main/CODE_OF_CONDUCT.md)



Hints:
I just found [this](https://github.com/pallets/jinja/blob/main/src/jinja2/sandbox.py#L268) in the Jinja codebase.

Perhaps the issue could be fixed by adding `unsafe_callable = False` and `alters_data = False` to `RelationEmulator`?

Not sure what would be the best way to test this though. 🤔 

Are there any tests for the Jinja templater which could be updated with this scenario?

Patch:
diff --git a/src/sqlfluff/core/templaters/jinja.py b/src/sqlfluff/core/templaters/jinja.py
index bae8649f733..d6ea7841a94 100644
--- a/src/sqlfluff/core/templaters/jinja.py
+++ b/src/sqlfluff/core/templaters/jinja.py
@@ -61,9 +61,8 @@ class UndefinedRecorder:
     """Similar to jinja2.StrictUndefined, but remembers, not fails."""
 
     # Tell Jinja this object is safe to call and does not alter data.
-    # https://jinja.palletsprojects.com/en/2.9.x/sandbox/#jinja2.sandbox.SandboxedEnvironment.is_safe_callable
-    unsafe_callable = False
     # https://jinja.palletsprojects.com/en/3.0.x/sandbox/#jinja2.sandbox.SandboxedEnvironment.is_safe_callable
+    unsafe_callable = False
     alters_data = False
 
     def __init__(self, name: str, undefined_set: Set[str]) -> None:
@@ -317,6 +316,11 @@ def _generate_dbt_builtins() -> Dict[str, Any]:
         class RelationEmulator:
             """A class which emulates the `this` class from dbt."""
 
+            # Tell Jinja this object is safe to call and does not alter data.
+            # https://jinja.palletsprojects.com/en/3.0.x/sandbox/#jinja2.sandbox.SandboxedEnvironment.is_safe_callable
+            unsafe_callable = False
+            alters_data = False
+
             identifier = "this_model"
             schema = "this_schema"
             database = "this_database"


Test patch:
diff --git a/test/core/templaters/jinja_test.py b/test/core/templaters/jinja_test.py
index 0180f1df8d1..30e69597ec2 100644
--- a/test/core/templaters/jinja_test.py
+++ b/test/core/templaters/jinja_test.py
@@ -703,6 +703,7 @@ def assert_structure(yaml_loader, path, code_only=True, include_meta=False):
         ("jinja_c_dbt/dbt_builtins_ref", True, False),
         ("jinja_c_dbt/dbt_builtins_source", True, False),
         ("jinja_c_dbt/dbt_builtins_this", True, False),
+        ("jinja_c_dbt/dbt_builtins_this_callable", True, False),
         ("jinja_c_dbt/dbt_builtins_var_default", True, False),
         ("jinja_c_dbt/dbt_builtins_test", True, False),
         # do directive
diff --git a/test/fixtures/templater/jinja_c_dbt/dbt_builtins_this_callable.sql b/test/fixtures/templater/jinja_c_dbt/dbt_builtins_this_callable.sql
new file mode 100644
index 00000000000..1085e31493d
--- /dev/null
+++ b/test/fixtures/templater/jinja_c_dbt/dbt_builtins_this_callable.sql
@@ -0,0 +1,2 @@
+SELECT col1
+FROM {{ this.render() }}
diff --git a/test/fixtures/templater/jinja_c_dbt/dbt_builtins_this_callable.yml b/test/fixtures/templater/jinja_c_dbt/dbt_builtins_this_callable.yml
new file mode 100644
index 00000000000..5ad4fc0374b
--- /dev/null
+++ b/test/fixtures/templater/jinja_c_dbt/dbt_builtins_this_callable.yml
@@ -0,0 +1,15 @@
+file:
+  statement:
+    select_statement:
+      select_clause:
+      - keyword: SELECT
+      - select_clause_element:
+          column_reference:
+            naked_identifier: col1
+      from_clause:
+        keyword: FROM
+        from_expression:
+          from_expression_element:
+            table_expression:
+              table_reference:
+                naked_identifier: this_model