| Issue |
169561
|
| Summary |
[HLSL][Matrix] Failure to initalize vector via implicit or explit cast of a matrix to vector
|
| Labels |
HLSL
|
| Assignees |
|
| Reporter |
farzonl
|
The code below is failing in `clang/lib/Sema/SemaInit.cpp` via a `FK_ConversionFailed` in clang when it works fine in DXC.
https://godbolt.org/z/r9G7fYzcj
```hlsl
export float4 fn(float2x2 m) {
float4 v = m;
return v;
}
```
Note the explicit cast version only works on: https://github.com/llvm/llvm-project/pull/168915
```hlsl
export float4 fn(float2x2 m) {
float4 v = (float4)m;
return v;
}
```
```bash
error: cannot initialize a variable of type 'float4' (aka 'vector<float, 4>') with an rvalue of type 'float2x2' (aka 'matrix<float, 2, 2>')
2 | float4 v = (float4)m;
| ^ ~~~~~~~~~~~
```
The bug is happening because we are not hitting this block in `InitializationSequence::InitializeFrom`
```cpp
// For HLSL ext vector types we allow list initialization behavior for C++
// functional cast expressions which look like constructor syntax. This is
// accomplished by converting initialization arguments to InitListExpr.
if (S.getLangOpts().HLSL && Args.size() > 1 &&
(DestType->isExtVectorType() || DestType->isConstantMatrixType()) &&
(SourceType.isNull() ||
!Context.hasSameUnqualifiedType(SourceType, DestType))) {
InitListExpr *ILE = new (Context)
InitListExpr(S.getASTContext(), Args.front()->getBeginLoc(), Args,
Args.back()->getEndLoc());
ILE->setType(DestType);
Args[0] = ILE;
TryListInitialization(S, Entity, Kind, ILE, *this,
TreatUnavailableAsInvalid);
return;
}
```
We can see if we did every thing would work fine:
https://godbolt.org/z/GMej3Kvvr
```hlsl
export float4 fn(float2x2 m) {
float4 v = {m};
return v;
}
```
Ie if we did vector initalization via matrix inside an initalizer list everthing would work just fine.
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