#3761 fix: Cypher WITH *, extra AS alias dropped extra items

[robfrank]

Summary

Fixes #3761 — WITH *, expr AS alias threw "Error parsing OpenCypher query" because the alias was silently dropped during AST construction.

Root causes (three locations):

• CypherASTBuilder.visitWithClause: used if/else — when TIMES (*) was present, the returnItem() loop was skipped, so WITH *, t2 AS out2 produced items [*] only.
• WithStep.projectResult: checked items.size() == 1 && name == "*" and returned early, so a mixed list never evaluated the non-wildcard items.
• CypherSemanticValidator: when hasWildcard was true, broke out immediately without registering extra aliases in scope — causing the "undefined variable" error on the RETURN clause.

Fixes:

• CypherASTBuilder: changed if/else to if + unconditional loop so both the wildcard and any explicit items are always appended.
• WithStep.projectResult: unified loop — * copies all input properties, explicit items evaluate the expression.
• CypherSemanticValidator: when wildcard is present, still validate and register extra aliases in scope.

Test plan

• New Issue3761Test (5 cases): exact issue query, WITH * alone, computed alias, multiple aliases, alias in WHERE
• WithAndUnwindTest, OpenCypherOptionalMatchTest, OpenCypherExecutionTest, OpenCypherBasicTest, CypherTest, Issue3758Test — all green

🤖 Generated with Claude Code

[codacy-production]

Up to standards ✅

🟢 Issues 0 issues

Results:
0 new issues

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🟢 Metrics 7 complexity

Metric	Results
Complexity	7

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🟢 Coverage 95.65% diff coverage · -8.42% coverage variation

Metric	Results
Coverage variation	✅ -8.42% coverage variation
Diff coverage	✅ 95.65% diff coverage

View coverage diff in Codacy

Coverage variation details

	Coverable lines	Covered lines	Coverage
Common ancestor commit (4b31312)	115697	85582	73.97%
Head commit (06f00d6)	147055 (+31358)	96389 (+10807)	65.55% (-8.42%)

Coverage variation is the difference between the coverage for the head and common ancestor commits of the pull request branch: <coverage of head commit> - <coverage of common ancestor commit>

Diff coverage details

	Coverable lines	Covered lines	Diff coverage
Pull request (#3762)	23	22	95.65%

Diff coverage is the percentage of lines that are covered by tests out of the coverable lines that the pull request added or modified: <covered lines added or modified>/<coverable lines added or modified> * 100%

_{TIP This summary will be updated as you push new changes. Give us feedback}

[gemini-code-assist]

Code Review

This pull request fixes a bug in OpenCypher where using a wildcard in a WITH clause followed by an alias (e.g., WITH *, expr AS alias) resulted in the alias being dropped or causing parsing errors. The changes involve updating the AST builder to process all return items regardless of the wildcard, refactoring the execution step to handle both wildcard projections and explicit expressions, and adjusting the semantic validator to account for these extra aliases. A comprehensive regression test suite was also added. Feedback was provided regarding the semantic validator, specifically pointing out that aliases should not be visible within the same WITH clause and that the current implementation incorrectly skips subsequent validation logic like ORDER BY when a wildcard is present.

[gemini-code-assist]

The implementation of the hasWildcard block contains two significant issues:

1. Scope Leakage: By calling scope.add(alias) (line 395) inside the same loop that performs checkExpressionScope (line 392), you are making aliases available to subsequent items in the same WITH clause. In Cypher, an alias defined in a WITH clause should only be visible to the following clauses, not to other expressions within the same WITH clause.

2. Validation Bypass: The break statement at line 397 causes the validator to skip the ORDER BY validation logic (lines 403-433) and other subsequent checks for the WITH clause when a wildcard is present. This means queries like WITH * ORDER BY undefined_var would incorrectly pass semantic validation.

To fix this, consider validating all expressions against the incoming scope first, then performing ORDER BY validation, and finally updating the scope for the next clause.

[robfrank]

Scope leakage is a valid catch - fixed in 06f00d6 by splitting the block into two separate loops: validate all expressions first against the incoming scope, then add aliases. This matches the pattern of the non-wildcard path.

On ORDER BY bypass: the break was already there before this PR (the original code was simply break with no validation at all for WITH *). That's a pre-existing gap, not a regression introduced here.

[codecov]

Codecov Report

❌ Patch coverage is 78.26087% with 5 lines in your changes missing coverage. Please review.
✅ Project coverage is 65.15%. Comparing base (4b31312) to head (06f00d6).
⚠️ Report is 9 commits behind head on main.

Files with missing lines	Patch %	Lines
...dedb/query/opencypher/parser/CypherASTBuilder.java	57.14%	1 Missing and 2 partials ⚠️
...ery/opencypher/parser/CypherSemanticValidator.java	83.33%	0 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3762      +/-   ##
==========================================
+ Coverage   65.10%   65.15%   +0.05%     
==========================================
  Files        1580     1580              
  Lines      115697   115940     +243     
  Branches    24517    24587      +70     
==========================================
+ Hits        75329    75546     +217     
+ Misses      30142    30121      -21     
- Partials    10226    10273      +47     

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