BC_IMPOSSIBLE_DOWNCAST_OF_TOARRAY not detected fix#3871
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Pull request overview
This PR fixes issue #3752 where SpotBugs failed to detect impossible downcasts of the return value from Stream.toArray() and Collection.toArray() methods. The fix ensures that the BC_IMPOSSIBLE_DOWNCAST_OF_TOARRAY warning is correctly raised when developers attempt to cast the Object[] return value to more specific array types like String[].
Changes:
- Modified the cast detection logic to continue analysis for Object[] casts instead of skipping them
- Extracted the toArray downcast check into a reusable method to handle both normal and exception cases
- Updated documentation to reflect that the warning applies to both collections and streams
Reviewed changes
Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.
| File | Description |
|---|---|
| spotbugsTestCases/src/java/ghIssues/Issue3752.java | Adds test cases demonstrating the bug with both Stream.toArray() and Collection.toArray() |
| spotbugs/src/main/java/edu/umd/cs/findbugs/detect/FindBadCast2.java | Updates detection logic to avoid skipping Object[] casts and extracts check into reusable method |
| spotbugs/etc/messages.xml | Updates documentation to mention streams in addition to collections |
| spotbugs-tests/src/test/java/edu/umd/cs/findbugs/detect/Issue3752Test.java | Adds integration test verifying both test cases are detected |
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| if (!operandTypeIsExact && "Ljava/lang/Object;".equals(refSig2)) { | ||
| if (!operandTypeIsExact | ||
| && "Ljava/lang/Object;".equals(refSig2) | ||
| // Keep inspecting this instruction if casting an Object[] because it might from a toArray() call |
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Grammar issue in comment: "it might from a toArray()" should be "it might be from a toArray()"
Suggested change
| // Keep inspecting this instruction if casting an Object[] because it might from a toArray() call | |
| // Keep inspecting this instruction if casting an Object[] because it might be from a toArray() call |
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BC_IMPOSSIBLE_DOWNCAST_OF_TOARRAYisn't raised when casting the return of a Stream (or a Collection) toArray().This should fix #3752