fix doc and broken api (apache#15602)

Author: logan-keede

datafusion/common/src/functional_dependencies.rs

@@ -47,11 +47,13 @@ impl Constraints {
  Constraints::new_unverified(vec![])
  }
 
- /// Create a new `Constraints` object from the given `constraints`.
- /// Users should use the `empty` or `new_from_table_constraints` functions
- /// for constructing `Constraints`. This constructor is for internal
+ /// Create a new [`Constraints`] object from the given `constraints`.
+ /// Users should use the [`Constraints::empty`] or [`SqlToRel::new_constraint_from_table_constraints`] functions
+ /// for constructing [`Constraints`]. This constructor is for internal
  /// purposes only and does not check whether the argument is valid. The user
- /// is responsible for supplying a valid vector of `Constraint` objects.
+ /// is responsible for supplying a valid vector of [`Constraint`] objects.
+ ///
+ /// [`SqlToRel::new_constraint_from_table_constraints`]: https://docs.rs/datafusion/latest/datafusion/sql/planner/struct.SqlToRel.html#method.new_constraint_from_table_constraints
  pub fn new_unverified(constraints: Vec<Constraint>) -> Self {
  Self { inner: constraints }
  }

datafusion/sql/src/statement.rs

@@ -1547,7 +1547,7 @@ impl<S: ContextProvider> SqlToRel<'_, S> {
  }
 
  /// Convert each [TableConstraint] to corresponding [Constraint]
- fn new_constraint_from_table_constraints(
+ pub fn new_constraint_from_table_constraints(
  &self,
  constraints: &[TableConstraint],
  df_schema: &DFSchemaRef,