AfterShip / clickhouse-sql-parser / 40628343801

57%

master: 57%

Pull #338

github

Fix modifier-only MODIFY COLUMN parsing

## Problem

Modifier-only `ALTER TABLE ... MODIFY COLUMN` can reject valid SQL or
store a modifier as `Column.Type`. In `parseTableColumnExpr`,
non-reserved keywords enter optional-type parsing before the modifier
parser sees them. This bug predates #337.

## Reproduction

```sql
ALTER TABLE t MODIFY COLUMN x CODEC(LZ4) COMMENT 'example' TTL ts;
```

Parsing succeeds, but `Column.Type` contains `CODEC(LZ4)` and
`Column.Codec` is nil. Starting with `COMMENT` instead fails to parse.

## Fix

Exclude COMMENT, CODEC and TTL from optional-type detection alongside
REMOVE. The existing modifier parser then fills their fields and rejects
duplicates, while explicit types follow the existing path.

## Test

Extend the modifier tests to cover omitted types in all six orders,
mixed keyword casing, compact and beautified AST round trips, and
duplicate or incomplete clauses. The new cases fail without the fix.
Add the reported SQL as fixtures with AST and formatting goldens.

- `make update_test` and `make test` pass with Go 1.26.3, including race
  and compatibility checks.
- `make lint` passes with golangci-lint 1.64.5 and Go 1.24.0.
- ClickHouse local 26.7.1.1315 executes the COMMENT, CODEC, TTL order on
  a MergeTree table. It rejects CODEC before COMMENT; arbitrary ordering
  is verified against the [26.8.34.13 parser source](https://github.com/ClickHouse/ClickHouse/blob/v26.8.34.13-lts/src/Parsers/ParserCreateQuery.h#L380-L407),
  rather than a running 26.8 binary.

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