mrhhsg opened a new pull request, #67713:
URL: https://github.com/apache/doris/pull/67713
### What problem does this PR solve?
Issue Number: None
Problem Summary:
A lambda body may reference the columns of the enclosing query, but this
only worked for a single level of high-order function. As soon as the
lambda was nested inside another lambda, the reference failed to bind:
```sql
WITH t2 AS (SELECT c IS NULL AS dict_flag, ARRAY('A') AS arr1, ARRAY('a') AS
arr2 FROM t)
SELECT ARRAY_MAP(arg1 -> ARRAY_SUM(ARRAY_MAP(arg2 -> IF(dict_flag, 1, 0),
arr2)), arr1) FROM t2;
-- ERROR 1105 (HY000): Unknown lambda slot 'dict_flag in lambda
arguments[arg2]
```
The same happened with `array_sortby`, `array_filter` and any other
high-order function used as the inner lambda.
Root cause: `ExpressionAnalyzer` analyzes every lambda body with a
nested analyzer whose scope only holds the lambda arguments and whose
outer scope is the enclosing scope. Slot binding intentionally looks at
most one level up (the outer scope is meant for correlated subqueries).
With two nested lambdas the scope chain became
`inner arguments -> outer arguments -> query columns`, so the query
columns were out of reach for the inner lambda body.
Fix: when the enclosing analyzer is itself analyzing a lambda body, the
scope of the nested lambda merges the enclosing lambda arguments (a
same-named inner argument still shadows the outer one) and keeps the
query scope as its outer scope. Every nesting depth therefore sees the
same names as a single-level lambda: all enclosing lambda arguments plus
the columns of the query. Single-level lambdas and correlated subquery
binding are unchanged.
### Release note
None
### Check List (For Author)
- Test:
- Unit Test: `BindFunctionTest` covers query-column capture in nested
`array_map`/`array_sortby`/three-level lambdas, visibility of all
enclosing lambda arguments, same-name shadowing and the unknown
slot error.
- Regression test: `test_nested_array_map` adds nested lambdas that
capture query columns (plain column, CTE alias, together with the
enclosing lambda argument, three levels deep).
- Behavior changed: No
- Does this need documentation: No
https://claude.ai/code/session_016A7UJu7EA7j4NkGz3yjkt6
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