feat: add missing return detection for funcs with return values #550

aofei · 2025-12-12T03:29:49Z

Add isTerminating check (based on go/types/return.go from Go stdlib) to detect funcs that have return values but do not terminate properly. This enables reporting "missing return" errors during code generation rather than at runtime.

Updates goplus/builder#2576

gemini-code-assist · 2025-12-12T03:30:03Z

Summary of Changes

Hello @aofei, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request introduces a significant improvement to the code generation process by adding static analysis for missing return statements in functions that are expected to return values. By integrating a termination check based on the Go standard library's approach, the system can now identify and report these errors at compile-time rather than allowing them to manifest as runtime failures, thereby enhancing the reliability and correctness of generated code.

Highlights

Missing Return Detection: Implemented a new static analysis check to detect functions that are declared to return values but do not properly terminate with a return statement across all execution paths.
Early Error Reporting: This new detection mechanism allows 'missing return' errors to be reported during code generation, preventing potential runtime issues and improving code quality.
Go Standard Library Adaptation: The core logic for determining statement termination (isTerminating) is adapted from the go/types/return.go package in the Go standard library, ensuring robust and accurate analysis.

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codecov · 2025-12-12T03:30:55Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 96.00%. Comparing base (d8e0fc9) to head (da2476a).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #550   +/-   ##
=======================================
  Coverage   95.99%   96.00%           
=======================================
  Files          23       23           
  Lines        6474     6482    +8     
=======================================
+ Hits         6215     6223    +8     
  Misses        193      193           
  Partials       66       66

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gemini-code-assist

Code Review

This pull request introduces a 'missing return' detection mechanism for functions with return values, which is a great feature to catch errors at code generation time. The implementation is based on the Go standard library's return analysis, which is a solid approach. The changes include the core logic in func.go, the termination analysis in a new return.go file, and updates to existing tests to accommodate the new checks, plus new tests for the feature itself.

My review identified a critical correctness issue in the isTerminating logic for select statements in return.go. I've also suggested a refactoring for one of the new test functions in error_msg_test.go to improve its maintainability. Apart from these points, the changes look good and the tests are comprehensive.

return.go

error_msg_test.go

Copilot

Pull request overview

This pull request adds missing return detection for functions with return values by implementing an isTerminating check based on go/types/return.go from the Go standard library. This enhancement enables the detection of functions that have return values but do not properly terminate, allowing "missing return" errors to be reported during code generation rather than at runtime.

Key changes:

New return.go file implementing terminating statement detection logic
Integration of the check into func.go to validate functions before code generation
Updated existing tests to add proper return statements to previously incomplete function bodies

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 4 comments.

File	Description
return.go	New file implementing `isTerminating` and supporting functions to detect whether statements properly terminate control flow (returns, panics, infinite loops, etc.)
func.go	Integrates the missing return check in the `End()` method to validate functions with return values properly terminate before code generation
package_test.go	Adds return statements to test functions that now require them due to the new validation
error_msg_test.go	Adds comprehensive test coverage for missing return detection, including error cases and valid scenarios

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return.go

error_msg_test.go

return.go

Add `isTerminating` check (based on go/types/return.go from Go stdlib) to detect funcs that have return values but do not terminate properly. This enables reporting "missing return" errors during code generation rather than at runtime. Updates goplus/builder#2576 Signed-off-by: Aofei Sheng <[email protected]>

- Update gogen to include missing return detection for funcs with return values[^]1, enabling "missing return" errors to be reported in the editor rather than only at runtime - Use `RangeForPosEnd` instead of `RangeForPos` to properly report both start and end positions from `gogen.CodeError` - Use `codeError.Msg` instead of `codeError.Error` to avoid duplicate position info in message - Add `MissingReturn` test case for diagnostic detection - Skip empty diagnosticss in `inspectDiagnosticsAnalyzers` Fixes goplus/builder#2576 [^1]: goplus/gogen#550 Signed-off-by: Aofei Sheng <[email protected]>

- Update gogen to include missing return detection for funcs with return values[^1], enabling "missing return" errors to be reported in the editor rather than only at runtime - Use `RangeForPosEnd` instead of `RangeForPos` to properly report both start and end positions from `gogen.CodeError` - Use `codeError.Msg` instead of `codeError.Error` to avoid duplicate position info in message - Add `MissingReturn` test case for diagnostic detection - Skip empty diagnosticss in `inspectDiagnosticsAnalyzers` Fixes goplus/builder#2576 [^1]: goplus/gogen#550 Signed-off-by: Aofei Sheng <[email protected]>

- Bump gogen to include missing return detection for funcs with return values[^1], enabling "missing return" errors to be reported in the editor rather than only at runtime - Use `RangeForPosEnd` instead of `RangeForPos` to properly report both start and end positions from `gogen.CodeError` - Use `codeError.Msg` instead of `codeError.Error` to avoid duplicate position info in message - Add `MissingReturn` test case for diagnostic detection - Skip empty diagnosticss in `inspectDiagnosticsAnalyzers` Fixes goplus/builder#2576 [^1]: goplus/gogen#550 Signed-off-by: Aofei Sheng <[email protected]>

Copilot AI review requested due to automatic review settings December 12, 2025 03:29

Copilot started reviewing on behalf of aofei December 12, 2025 03:31 View session

gemini-code-assist bot reviewed Dec 12, 2025

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aofei force-pushed the missing-return branch 2 times, most recently from 2938d96 to 94cde8f Compare December 12, 2025 05:26

aofei force-pushed the missing-return branch from 94cde8f to da2476a Compare December 12, 2025 05:33

Copilot AI mentioned this pull request Dec 12, 2025

fix: detect missing return errors in diagnostics goplus/xgolsw#242

Merged

xushiwei merged commit 03c926d into goplus:main Dec 13, 2025
23 checks passed

aofei deleted the missing-return branch December 13, 2025 03:19

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feat: add missing return detection for funcs with return values #550

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aofei commented Dec 12, 2025

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feat: add missing return detection for funcs with return values #550

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aofei commented Dec 12, 2025

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gemini-code-assist bot commented Dec 12, 2025

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codecov bot commented Dec 12, 2025 •

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