Fix embedded SDK crashing on count(*) / count(col)

[Harsh23Kashyap]

Summary

output(["count(*)"]) and output(["count(c1)"])) crashed in the embedded SDK with unknown expression type: True. sqlglot's Count node carries a big_int boolean flag (and an empty expressions list) next to its real argument, and the generic exp.Func arm fed every entry of cons.args.values() into parse_expr, crashing on the plain bool.

The arm now skips None entries, empty lists, and non-expression node flags. Non-empty list args still raise, so cases that need a dedicated arm (e.g. UNNEST) keep failing loudly. The result matches the thrift SDK: count(*) produces a count function expression with a single star column argument.

Fixes #3473

Testing

• Reproduced the crash on current main (eca7266, sqlglot 30.18.0); count(*) / count(c1) parse correctly after the change, and sum / abs / round / substring / length / upper / unnest / coalesce behavior is unchanged.
• Added test_output_embedded_count (embedded-only) to python/test_pysdk/test_condition.py.
• The full pysdk suite was not run locally (needs a built embedded engine); the change is confined to argument filtering in one traversal arm.

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📝 Walkthrough

Walkthrough

The embedded expression parser now ignores non-expression function metadata and preserves error handling for non-empty list arguments. A regression test validates parsing for count(*) and count(c1).

Changes

Embedded count parsing

Layer / File(s)	Summary
Filter function arguments and test count parsing python/infinity_embedded/local_infinity/utils.py, python/test_pysdk/test_condition.py	The parser skips None, metadata flags, and empty lists. It appends only expression arguments. The embedded regression test verifies the argument count and values for count(*) and count(c1).

Priority: ➖ Normal

Estimated code review effort: 2 (Simple) | ~10 minutes

Severity of issue fixed: Medium

Merge Risk: ⚪ Minimal · up to adc4f

Embedded SDK count output expressions now ignore parser metadata while preserving star and column arguments, with regression coverage for both count forms. No current merge-blocking risk remains.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 3 functions across 2 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly identifies the embedded SDK crash fixed for count(*) and count(col), which is the primary change.
Description check	✅ Passed	The description includes the required Summary section, explains the root cause and fix, and documents testing and limitations.
Linked Issues check	✅ Passed	The changes satisfy issue #3473 by preventing metadata flags and empty lists from reaching parse_expr, preserving errors for unsupported non-empty list arguments, and adding regression coverage for co…
Out of Scope Changes check	✅ Passed	The code changes and regression test directly support the linked issue and stated objectives. No unrelated changes are identified.

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<sub>A rabbit finds a count in the code

Star and column now travel the road

Flags stay metadata, quiet and still

Empty lists wait beyond the hill

Tests watch each argument in place

The embedded parser runs with grace</sub>

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Actionable comments posted: 1

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Inline comments:
In `@python/test_pysdk/test_condition.py`:
- Line 60: Update the test around the parsed count expressions to verify each
function has exactly one argument, assert that the count(*) result uses a star
argument, and assert that the count(c1) result references the c1 column, while
retaining the existing function-name assertion.

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• python/infinity_embedded/local_infinity/utils.py
• python/test_pysdk/test_condition.py

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