fix(presto): iterate over copy in eliminate_semi_and_anti_joins

[Evgeniy-Sinyak]

Summary

When a SELECT has multiple SEMI or ANTI joins, eliminate_semi_and_anti_joins only rewrites every other one. The remaining joins leak into the generated SQL as bare ANTI JOIN / SEMI JOIN — invalid syntax for dialects like Presto/Trino.

Root cause: the transform iterates over expression.args.get("joins") while calling join.pop() inside the loop. After popping index i, the next element shifts into position i, but the iterator has already advanced to i+1 — so that element is never visited.

Fix: iterate over list(...) so removals don't shift unvisited elements. Same approach as #4364 which fixed the identical pattern in unnest_to_explode.

Minimal reproduction

from sqlglot import exp

select = (
    exp.Select()
    .select(exp.column("id", table="t1"))
    .from_("t1")
    .join("t2", on=exp.EQ(this=exp.column("id", table="t1"),
                           expression=exp.column("id", table="t2")))
    .join("t3", join_type="anti",
          on=exp.EQ(this=exp.column("id", table="t1"),
                    expression=exp.column("id", table="t3")))
    .join("t4", join_type="anti",
          on=exp.EQ(this=exp.column("id", table="t1"),
                    expression=exp.column("id", table="t4")))
)

print(select.sql(dialect="presto", pretty=True))

Before (bug): t4 leaks as bare ANTI JOIN

SELECT
  t1.id
FROM t1
JOIN t2
  ON t1.id = t2.id
ANTI JOIN t4
  ON t1.id = t4.id
WHERE
  NOT EXISTS(SELECT 1 FROM t3 WHERE t1.id = t3.id)

After (fix): both rewritten to NOT EXISTS

SELECT
  t1.id
FROM t1
JOIN t2
  ON t1.id = t2.id
WHERE
  NOT EXISTS(SELECT 1 FROM t3 WHERE t1.id = t3.id)
  AND NOT EXISTS(SELECT 1 FROM t4 WHERE t1.id = t4.id)

Changes

• sqlglot/transforms.py: iterate over list(expression.args.get("joins") or []) instead of the original list
• tests/test_transforms.py: add tests for single, double, and triple ANTI/SEMI joins

Made with Cursor

[Evgeniy-Sinyak]

@georgesittas This is the same iterate-and-mutate pattern you fixed in #4364 for unnest_to_explode, but in eliminate_semi_and_anti_joins. One-line fix + tests.

[georgesittas]

thanks!