Merging upstream version 7.1.3.

Signed-off-by: Daniel Baumann <daniel@debian.org>

sqlglot/optimizer/scope.py

@@ -1,4 +1,5 @@
 import itertools
+from collections import defaultdict
 from enum import Enum, auto
 
 from sqlglot import exp
@@ -314,6 +315,16 @@ class Scope:
             self._external_columns = [c for c in self.columns if c.table not in self.selected_sources]
         return self._external_columns
 
+    @property
+    def unqualified_columns(self):
+        """
+        Unqualified columns in the current scope.
+
+        Returns:
+             list[exp.Column]: Unqualified columns
+        """
+        return [c for c in self.columns if not c.table]
+
     @property
     def join_hints(self):
         """
@@ -403,6 +414,21 @@ class Scope:
             yield from child_scope.traverse()
         yield self
 
+    def ref_count(self):
+        """
+        Count the number of times each scope in this tree is referenced.
+
+        Returns:
+            dict[int, int]: Mapping of Scope instance ID to reference count
+        """
+        scope_ref_count = defaultdict(lambda: 0)
+
+        for scope in self.traverse():
+            for _, source in scope.selected_sources.values():
+                scope_ref_count[id(source)] += 1
+
+        return scope_ref_count
+
 
 def traverse_scope(expression):
     """