fix(spark): return error from ELT coerce_types when fewer than 2 args#23164
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davidlghellin wants to merge 1 commit into
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fix(spark): return error from ELT coerce_types when fewer than 2 args#23164davidlghellin wants to merge 1 commit into
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Pull request overview
Fixes a planning-time validation bug in the Spark elt scalar UDF: when fewer than 2 arguments were provided, an error was constructed but never returned, allowing invalid arities to proceed.
Changes:
- Return the
plan_datafusion_err!result fromSparkElt::coerce_typeswhenarg_types.len() < 2, properly short-circuiting invalid calls.
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| let length = arg_types.len(); | ||
| if length < 2 { | ||
| plan_datafusion_err!( | ||
| return Err(plan_datafusion_err!( | ||
| "ELT function expects at least 2 arguments: index, value1" | ||
| ); | ||
| )); | ||
| } |
alamb
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Jun 24, 2026
alamb
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Nice catch -- thank you @davidlghellin
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Which issue does this PR close?
Rationale for this change
SparkElt::coerce_typesvalidates that ELT receives at least 2 arguments (index + value1), but the error was never returned: it was built withplan_datafusion_err!(...)as an expression statement whose value was discarded. SinceDataFusionErroris not#[must_use], the compiler didn't warn, so the function fell through and continued with fewer arguments than required instead of failing with a clear plan-time error.What changes are included in this PR?
In datafusion/spark/src/function/string/elt.rs, the argument-count check is wrapped in return Err(plan_datafusion_err!(...)) so the validation actually short-circuits when fewer than 2 arguments are provided.
Are these changes tested?
This change restores an error path that was previously dropped silently. ELT's normal behavior is already covered by the existing tests in elt.rs. The invalid-arity branch had no coverage because it was never actually exercised.
Are there any user-facing changes?
ELT now returns a plan-time error when invoked with fewer than 2 arguments, instead of silently continuing. No public API changes.