fix(dialect): guard UNWRAPPED_INTERVAL_VALUES from repeated appends

Author: Sanjays2402

sqlmesh/core/dialect.py

@@ -1174,11 +1174,12 @@ def extend_sqlglot() -> None:
                 MacroDef,
             )
 
-        generator.UNWRAPPED_INTERVAL_VALUES = (
-            *generator.UNWRAPPED_INTERVAL_VALUES,
-            MacroStrReplace,
-            MacroVar,
-        )
+        if MacroVar not in generator.UNWRAPPED_INTERVAL_VALUES:
+            generator.UNWRAPPED_INTERVAL_VALUES = (
+                *generator.UNWRAPPED_INTERVAL_VALUES,
+                MacroStrReplace,
+                MacroVar,
+            )
 
     _override(Parser, _parse_select)
     _override(Parser, _parse_statement)

tests/core/test_dialect.py

@@ -1190,6 +1190,12 @@ def test_pipe_syntax():
 def test_extend_sqlglot_is_idempotent():
     # extend_sqlglot() runs at import time; calling it again must not re-wrap the
     # already-installed overrides, otherwise they call themselves (RecursionError).
+    from sqlglot.generator import Generator
+
+    before = Generator.UNWRAPPED_INTERVAL_VALUES
+
     d.extend_sqlglot()
 
     assert parse_one("SELECT CAST(1 AS INT)").sql() == "SELECT CAST(1 AS INT)"
+    # The class-level registries must not grow on repeated calls.
+    assert Generator.UNWRAPPED_INTERVAL_VALUES == before