microsoft / microsoft/DirectXShaderCompiler
Nonsensical error message when using undef offset in structured buffer
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bug
crash
incorrect-code
- Dominant language
- C++
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- Merged PRs (30d)
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Description
This shader
// dxc /Tps_6_0 .\rawbuf.hlsl
// error: llvm::cast<X>() argument of incompatible type!
struct S {float A[3];};
RWStructuredBuffer<S> buf;
[RootSignature("UAV(u0)")]
float main() : SV_Target
{
uint X;
return buf[0].A[X];
}
Gives an error like
error: llvm::cast() argument of incompatible type!
But it should say something like "error: using uninitialized value to access structured buffer"
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
Start by compiling the provided rawbuf.hlsl example with the dxc /Tps_6_0 command and inspect the diagnostic produced for main. Trace the handling of the uninitialized X used in buf[0].A[X]. Done means the compiler reports an informative uninitialized-value error instead of the llvm::cast() failure.
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
- 35/100