Java: Update the CFG for assert statements to make them proper guards. #19733
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Pull Request Overview
This PR refines how Java assert statements are represented in the control‐flow graph, treating them as true guards and incorporating the optional message expression into the flow.
- Expanded the assertion framework predicates to include
AssertStmtnodes. - Removed direct handling of
AssertStmtin nullness flow in favor of the updated CFG. - Enhanced
ControlFlowGraph.qllto generate throw and normal edges for asserts, update boolean contexts, and record thrown types.
Reviewed Changes
Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.
| File | Description |
|---|---|
| java/ql/lib/semmle/code/java/frameworks/Assertions.qll | Added AssertStmt cases to the assert‐failure guard |
| java/ql/lib/semmle/code/java/dataflow/Nullness.qll | Removed direct AssertStmt null‐guard branch |
| java/ql/lib/semmle/code/java/ControlFlowGraph.qll | Integrated assert into CFG edges and completions |
| java/ql/lib/change-notes/2025-06-12-assert-cfg.md | Documented CFG change for assert analysis |
Comments suppressed due to low confidence (2)
java/ql/lib/semmle/code/java/dataflow/Nullness.qll:143
- Removing the direct
AssertStmtnull‐guard branch may break nullness inference for plainassertstatements. Ensure that the new CFG paths fully cover this case or reintroduce null‐guard logic forAssertStmt.
result.asStmt().(AssertStmt).getExpr() = nullGuard(v, true, false)
java/ql/lib/semmle/code/java/ControlFlowGraph.qll:1119
- It would be beneficial to add unit tests that verify both normal and exceptional CFG edges for
assertstatements (with and without messages), to ensure the new logic behaves as expected.
exists(AssertStmt assertstmt | assertstmt = n |
|
I've spot-checked a bunch of the changed results. The removed results were FPs, and the new results were typically redundant checks - e.g. both asserting a condition and then also checking it in an |
hvitved
reviewed
Jun 13, 2025
Co-authored-by: Tom Hvitved <hvitved@github.com>
hvitved
approved these changes
Jun 13, 2025
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This upgrades the CFG for Java assert statements to be proper guards and includes the message part, which was previously a CFG orphan, in the CFG. That is, the false edge of the condition now leads to an exception edge rather than simply ignoring the value.
For things like nullness, this is definitely what we want, and in general it's probably fine to assume that asserts are evaluated (even though they technically can be disabled).