| Issue |
53044
|
| Summary |
CastExpr conversion function decl is sometimes corrupt
|
| Labels |
new issue
|
| Assignees |
|
| Reporter |
kimgr
|
This is a problem that surfaced in IWYU recently.
I'm pretty sure it's difficult to provoke it in the compiler proper, since `CastExpr::getConversionFunction` is only called in a single place, for diagnostics. Tools built on Clang tooling and the recursive AST visitor can fall victim to it, however.
I have only been able to reproduce it on plain source code (not preprocessed), and only in conjunction with the fmt library (https://github.com/fmtlib/fmt). Attached is a minimal RAV tool and instructions to reproduce.
What makes me think this is somewhat critical is that `CastExpr::getConversionFunction` returns an `AccessSpecDecl` in this scenario, which breaks all sorts of AST and LLVM RTTI invariants. I suspect we're looking at garbage data for some reason. I have tried building ubsan+asan-instrumented LLVM/Clang, but without being able to track anything down.
Repro project: [ravrepro.tar.gz](https://github.com/llvm/llvm-project/files/7823359/ravrepro.tar.gz).
Thankful for any ideas, let me know if I can add more information.
References:
* IWYU tracking bug: https://github.com/include-what-you-use/include-what-you-use/issues/951
* Potentially same/similar issue: https://github.com/llvm/llvm-project/issues/44317
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