603a3af19b
When the extractor can't prove that control flow will never reach the end of a non-`void`-returning function without reaching an explicit `return` statement, it inserts an implicit `return` without an operand. If control actually reaches this point, the behavior is undefined. We were previously generating invalid IR for these implicit `return` statements, because the lack of an operand meant that there was no definition of the return value variable along that path. Instead, I've changed the IR generation to emit an `Unreached` instruction for the implicit `return`. This ensures that we don't create a control flow edge from the end of the body to the function epilogue. The change to the range analysis test avoids having that test depend on the previous bad IR behavior, while still preserving the original spirit of the test.
CodeQL
This open source repository contains the standard CodeQL libraries and queries that power LGTM and the other CodeQL products that GitHub makes available to its customers worldwide.
How do I learn CodeQL and run queries?
There is extensive documentation on getting started with writing CodeQL. You can use the interactive query console on LGTM.com or the CodeQL for Visual Studio Code extension to try out your queries on any open source project that's currently being analyzed.
Contributing
We welcome contributions to our standard library and standard checks. Do you have an idea for a new check, or how to improve an existing query? Then please go ahead and open a pull request! Before you do, though, please take the time to read our contributing guidelines. You can also consult our style guides to learn how to format your code for consistency and clarity, how to write query metadata, and how to write query help documentation for your query.
License
The code in this repository is licensed under the MIT License by GitHub.