microsoft / microsoft/DirectXShaderCompiler

Zero initializing array of struct causes error: cast<X>() argument of incompatible type!

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bug crash
Dominant language
C++
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Merged PRs (30d)
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Description

Description
Compiling the following HLSL causes an internal compiler error:

repro.hlsl:

struct s {
  float f;
  float2x4 m;
};

struct t {
  s a[1];
};


static t g = (t)0;
[numthreads(1, 1, 1)]
void main() {
  s h = g.a[0u];
}

Steps to Reproduce
dxc -T cs_6_6 repro.hlsl

Godbolt repro: https://godbolt.org/z/1Pqb7odes

Actual Behavior
error: cast<X>() argument of incompatible type!

Environment

  • DXC version: libdxcompiler.dylib: 1.10(dev;5155-60a1c856); libdxil.dylib: 1.10
  • Host Operating System: macOS

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by saving the supplied code as repro.hlsl and running dxc -T cs_6_6 repro.hlsl to reproduce the incompatible-type error. Trace the compiler path handling the zero cast for the nested struct and array, then verify that the repro compiles without the internal error.

Written by the indexing model from the issue text.

Assessment

Tech stack
cpp
Domain
compilers
Issue type
Bug
Difficulty
3/5
Estimated time
1-2 days
Activity status
Stale
Clarity
Clearly specified
Newbie friendliness
48/100

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