fix(optimizer): handle ColumnDef in typed table alias columns

[tobymao]

Summary

• qualify_tables._set_alias unconditionally called exp.to_identifier(c) on every entry in TableAlias.columns, which only accepts str/Identifier. Typed table-function signatures like FROM fn() AS t(col INT) produce ColumnDef nodes and tripped ValueError: Name needs to be a string or an Identifier, got: <class '...ColumnDef'> when the column-assignment branch ran (e.g. under canonicalize_table_aliases=True).
• Route only strings through to_identifier; copy any other expression (Identifier, ColumnDef) to preserve the original copy-before-reparent semantics.

Repro (before):

qualify_tables(
    sqlglot.parse_one('SELECT * FROM JSON_TO_RECORDSET(z) AS y("rank" INT)'),
    canonicalize_table_aliases=True,
)
# ValueError: Name needs to be a string or an Identifier, got: <class '...ColumnDef'>

After: SELECT * FROM JSON_TO_RECORDSET(z) AS _0("rank" INT)

Test plan

• New test_qualify_tables_copies_typed_alias_columns exercises the ColumnDef path via canonicalize_table_aliases=True and asserts the column is preserved as ColumnDef, is a different object than the original (the copy check), and has identical SQL.
• Confirmed the test fails on a reverted-copy variant and passes with the fix.
• python -m unittest tests.test_optimizer — 77 tests pass.

[github-actions]

SQLGlot Integration Test Results

Comparing:

• this branch (sqlglot:fix/qualify-tables-typed-alias-columns, sqlglot version: fix/qualify-tables-typed-alias-columns)
• baseline (main, sqlglot version: 0.0.1.dev1)

By Dialect

dialect	main	sqlglot:fix/qualify-tables-typed-alias-columns	transitions	links
bigquery -> bigquery	24645/24650 passed (100.0%)	23495/23495 passed (100.0%)	No change	full result / delta
bigquery -> duckdb	867/1154 passed (75.1%)	0/0 passed (0.0%)	Results not found	full result / delta
duckdb -> duckdb	5823/5823 passed (100.0%)	0/0 passed (0.0%)	Results not found	full result / delta
snowflake -> duckdb	1063/1961 passed (54.2%)	0/0 passed (0.0%)	Results not found	full result / delta
snowflake -> snowflake	65133/65133 passed (100.0%)	63027/63027 passed (100.0%)	No change	full result / delta
databricks -> databricks	1370/1370 passed (100.0%)	1370/1370 passed (100.0%)	No change	full result / delta
postgres -> postgres	6042/6042 passed (100.0%)	6042/6042 passed (100.0%)	No change	full result / delta
redshift -> redshift	7101/7101 passed (100.0%)	7101/7101 passed (100.0%)	No change	full result / delta

Overall

main: 113234 total, 112044 passed (pass rate: 98.9%), sqlglot version: 0.0.1.dev1

sqlglot:fix/qualify-tables-typed-alias-columns: 101035 total, 101035 passed (pass rate: 100.0%), sqlglot version: fix/qualify-tables-typed-alias-columns

Transitions:
No change

Dialect pair changes: 0 previous results not found, 3 current results not found

✅ 32 test(s) passed