microsoft / microsoft/DirectXShaderCompiler
Assertion `MaybeODRUseExprs.empty() && "Leftover expressions for odr-use checking"` in heavily templated code
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Description
Description
We do some very simple metaprogramming consteval math for attributes
Steps to Reproduce
These sorts of bugs are a problem to reproduce on your official Godbolt as you don't have assertions/exception enabled builds:
https://godbolt.org/z/EnnPxqbfa
We have our own instance with a Debug build, but outside of a debugger you can't see the assertion being raised
our short links don't work yet
Actual Behavior
One assertion per compilation:
Error: assert(MaybeODRUseExprs.empty() && "Leftover expressions for odr-use checking")
File:
D:\work\Nabla\3rdparty\dxc\dxc\tools\clang\lib\Sema\SemaDecl.cpp(11119)
Func: clang::Sema::ActOnFinishFunctionBody
Environment
- DXC version: latest trunk as of Nov 04
- Host Operating System: godbolt
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Reproduce the assertion with the linked metaprogramming example using an assertion-enabled DXC build. Start in dxc/tools/clang/lib/Sema/SemaDecl.cpp at ActOnFinishFunctionBody around line 11119, then trace how the reproduced function body leaves expressions for ODR-use checking. Done means the example compiles without the assertion and the relevant compiler behavior is covered by a regression test.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- cpp
- Domain
- compilers
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 30/100