Cfg: Add support for unless and until statements#21980
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Pull request overview
Adds shared-CFG support for until loops and unless-style conditionals (modeled as if statements without a then branch), to enable consistent control-flow construction across language frontends (motivated by Ruby).
Changes:
- Extends the shared AST signature and CFG construction to recognize
UntilStmtand treat it analogously toWhileStmt(with inverted condition semantics). - Updates
IfStmtCFG construction to handle conditionals with missingthenbranches (supportingunless-style constructs). - Adds placeholder
UntilStmtbindings in Java and C# CFG AST adapters (as unsupported stubs) to satisfy the shared AST signature.
Show a summary per file
| File | Description |
|---|---|
| shared/controlflow/codeql/controlflow/ControlFlowGraph.qll | Adds UntilStmt to the shared AST signature and updates shared CFG edge construction for until and unless-style conditionals. |
| java/ql/lib/semmle/code/java/ControlFlowGraph.qll | Introduces a stub UntilStmt in the Java AST adapter to match the shared signature. |
| csharp/ql/lib/semmle/code/csharp/controlflow/internal/ControlFlowGraph.qll | Introduces a stub UntilStmt in the C# AST adapter to match the shared signature. |
Copilot's findings
- Files reviewed: 3/3 changed files
- Comments generated: 2
Comment on lines
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| /** Gets the boolean condition of this `until` loop. */ | ||
| Expr getCondition(); |
Comment on lines
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| not exists(ifstmt.getThen()) and | ||
| n2.isAfter(ifstmt) |
michaelnebel
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Jun 12, 2026
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LGTM!
Easy to review after your CFG talk 😄
hvitved
approved these changes
Jun 12, 2026
owen-mc
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Jun 12, 2026
owen-mc
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It's a shame that it needs a little bit of boilerplate for languages that don't have this feature.
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This adds support for
unlessanduntilstatements (motivated by Ruby). Theunlessstatements are particularly simple, since they're merelyifstatements without athenbranch.