Fix NullPointerException in incomplete ternary operator parsing #3723

Copilot · 2026-01-02T07:22:43Z

The expression tree builder crashes when parsing incomplete ternary operators (e.g., Возврат ?) because it attempts to dereference null expression contexts.

Changes

buildExpressionTree: Add null guard to return early instead of passing null to visitExpression
visitTernaryOperator: Check for null sub-expressions and create ErrorExpressionNode instead of calling Objects.requireNonNull
Test coverage: Add test case for incomplete ternary operator error handling

Example

// Before: NPE when ctx is null
public static @Nullable BslExpression buildExpressionTree(BSLParser.ExpressionContext ctx) {
  var instance = new ExpressionTreeBuildingVisitor();
  instance.visitExpression(ctx);  // crashes if ctx is null
  return instance.getExpressionTree();
}

// After: Null-safe
public static @Nullable BslExpression buildExpressionTree(BSLParser.@Nullable ExpressionContext ctx) {
  if (ctx == null) {
    return null;
  }
  var instance = new ExpressionTreeBuildingVisitor();
  instance.visitExpression(ctx);
  return instance.getExpressionTree();
}

The fix maintains consistency with existing error handling patterns by treating incomplete ternary operators as error expressions rather than failing hard.

Original prompt

This section details on the original issue you should resolve

<issue_title>NullPointerException: Cannot invoke "com.github._1c_syntax.bsl.parser.BSLParser$ExpressionContext.getChildCount()" because "ctx" is null</issue_title>
<issue_description>Sentry Issue: BSL-LANGUAGE-SERVER-M2

NullPointerException: Cannot invoke "com.github._1c_syntax.bsl.parser.BSLParser$ExpressionContext.getChildCount()" because "ctx" is null
    at com.github._1c_syntax.bsl.languageserver.utils.expressiontree.ExpressionTreeBuildingVisitor.visitExpression(ExpressionTreeBuildingVisitor.java:92)
    at com.github._1c_syntax.bsl.languageserver.utils.expressiontree.ExpressionTreeBuildingVisitor.buildExpressionTree(ExpressionTreeBuildingVisitor.java:71)
    at com.github._1c_syntax.bsl.languageserver.utils.expressiontree.ExpressionTreeBuildingVisitor.makeSubexpression(ExpressionTreeBuildingVisitor.java:435)
    at com.github._1c_syntax.bsl.languageserver.utils.expressiontree.ExpressionTreeBuildingVisitor.visitTernaryOperator(ExpressionTreeBuildingVisitor.java:423)
    at com.github._1c_syntax.bsl.languageserver.utils.expressiontree.ExpressionTreeBuildingVisitor.visitTernaryOperator(ExpressionTreeBuildingVisitor.java:46)
...
(55 additional frame(s) were not displayed)
```</issue_description>

## Comments on the Issue (you are @copilot in this section)

<comments>
<comment_new><author>@nixel2007</author><body>
При вводе тернарных операторов вида:

Возврат ?

</comments>

Fixes NullPointerException: Cannot invoke "com.github._1c_syntax.bsl.parser.BSLParser$ExpressionContext.getChildCount()" because "ctx" is null #3722

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coderabbitai · 2026-01-02T07:22:48Z

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…ete ternary operators Co-authored-by: nixel2007 <[email protected]>

…erator Co-authored-by: nixel2007 <[email protected]>

Copilot

Pull request overview

This PR fixes a NullPointerException that occurs when parsing incomplete ternary operators in BSL code (e.g., when a user types Возврат ? or just ?). The fix adds defensive null checks at two key points in the expression tree building process to prevent crashes and instead create error nodes for graceful error handling.

Key changes:

Added null guard in buildExpressionTree to return null early when expression context is null
Modified visitTernaryOperator to check for null sub-expressions and create ErrorExpressionNode instead of crashing with NPE
Added test coverage for incomplete ternary operator parsing

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
ExpressionTreeBuildingVisitor.java	Added null safety checks in `buildExpressionTree` (early return) and `visitTernaryOperator` (error node creation) to prevent NPE when parsing incomplete ternary operators
ExpressionTreeBuildingVisitorTest.java	Added test case for incomplete ternary operator scenario to verify error handling works correctly without throwing exceptions

The implementation follows the existing error handling patterns in the codebase by using ErrorExpressionNode for malformed expressions, consistent with how other error cases are handled throughout the visitor (e.g., in visitNewExpression, visitParenthesis, visitMember). The fix is minimal, targeted, and maintains backward compatibility while preventing crashes during live editing scenarios.

github-actions · 2026-01-02T09:04:02Z

Test Results

312 files - 2 496 312 suites - 2 496 9m 59s ⏱️ - 43m 36s
1 150 tests + 1 1 150 ✅ + 1 0 💤 ±0 0 ❌ ±0
1 150 runs - 9 191 1 150 ✅ - 9 191 0 💤 ±0 0 ❌ ±0

Results for commit d6e3e22. ± Comparison against base commit e5b5781.

This pull request removes 8 and adds 5 tests. Note that renamed tests count towards both.

#, count=1
, count=0
, count=1
A, count=1
com.github._1c_syntax.bsl.languageserver.diagnostics.MetadataObjectNameLengthDiagnosticTest ‑ [2] content=
com.github._1c_syntax.bsl.languageserver.diagnostics.MetadataObjectNameLengthDiagnosticTest ‑ [6] content=
com.github._1c_syntax.bsl.languageserver.diagnostics.MetadataObjectNameLengthDiagnosticTest ‑ [7] content=#
com.github._1c_syntax.bsl.languageserver.diagnostics.MetadataObjectNameLengthDiagnosticTest ‑ [8] content=

com.github._1c_syntax.bsl.languageserver.diagnostics.MetadataObjectNameLengthDiagnosticTest ‑ [2] content=
, count=0
com.github._1c_syntax.bsl.languageserver.diagnostics.MetadataObjectNameLengthDiagnosticTest ‑ [6] content=
A, count=1
com.github._1c_syntax.bsl.languageserver.diagnostics.MetadataObjectNameLengthDiagnosticTest ‑ [7] content=#
, count=1
com.github._1c_syntax.bsl.languageserver.diagnostics.MetadataObjectNameLengthDiagnosticTest ‑ [8] content=
#, count=1
com.github._1c_syntax.bsl.languageserver.utils.expressiontree.ExpressionTreeBuildingVisitorTest ‑ Incomplete ternary operator - only question mark

sonarqubecloud · 2026-01-02T09:59:06Z

Quality Gate passed

Issues
1 New issue
0 Accepted issues

Measures
0 Security Hotspots
88.2% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

Initial plan

86a4354

Copilot AI assigned Copilot and nixel2007 Jan 2, 2026

Copilot started work on behalf of nixel2007 January 2, 2026 07:23 View session

Copilot AI and others added 2 commits January 2, 2026 07:30

Fix NullPointerException in ExpressionTreeBuildingVisitor for incompl…

efb4d6d

…ete ternary operators Co-authored-by: nixel2007 <[email protected]>

Improve comment explaining null expression handling in visitTernaryOp…

d6e3e22

…erator Co-authored-by: nixel2007 <[email protected]>

Copilot AI changed the title ~~[WIP] Fix NullPointerException in BSL parser~~ Fix NullPointerException in incomplete ternary operator parsing Jan 2, 2026

Copilot AI requested a review from nixel2007 January 2, 2026 07:36

Copilot finished work on behalf of nixel2007 January 2, 2026 07:36

nixel2007 marked this pull request as ready for review January 2, 2026 08:41

Copilot AI review requested due to automatic review settings January 2, 2026 08:41

nixel2007 enabled auto-merge January 2, 2026 08:41

Copilot started reviewing on behalf of nixel2007 January 2, 2026 08:47 View session

Copilot AI reviewed Jan 2, 2026

View reviewed changes

Merge branch 'develop' into copilot/fix-nullpointerexception-bsl-parser

f8eaffe

nixel2007 merged commit c6986b0 into develop Jan 2, 2026
41 checks passed

nixel2007 deleted the copilot/fix-nullpointerexception-bsl-parser branch January 2, 2026 10:05

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Fix NullPointerException in incomplete ternary operator parsing #3723

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Fix NullPointerException in incomplete ternary operator parsing #3723

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