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Fix Enum Constructor Specialization in Generic Types #8996

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Fix Enum Constructor Specialization in Generic Types #8996

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9ac5b28
Check nullptr before accssing the generic inner return val
gtong-nv Nov 12, 2025
061665a
Test usage of enum inside generic
gtong-nv Nov 12, 2025
84e4147
Specialize generics in witness table entry
gtong-nv Nov 21, 2025
f222d6e
Use default DefaultDeclRef for enum syn init
gtong-nv Nov 22, 2025
d0f2dd9
clean up
gtong-nv Nov 22, 2025
7f3d41a
address review comment
gtong-nv Nov 25, 2025
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5 changes: 2 additions & 3 deletions source/slang/slang-check-decl.cpp
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Expand Up @@ -6681,9 +6681,8 @@ bool SemanticsVisitor::trySynthesizeEnumTypeMethodRequirementWitness(
context->parentDecl->addDirectMemberDecl(synFunc);

addModifier(synFunc, intrinsicOpModifier);
witnessTable->add(
funcDeclRef.getDecl(),
RequirementWitness(m_astBuilder->getDirectDeclRef(synFunc)));
DeclRef<Decl> memberDeclRef = getDefaultDeclRef(synFunc);
witnessTable->add(funcDeclRef.getDecl(), RequirementWitness(memberDeclRef));
return true;
}

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19 changes: 12 additions & 7 deletions source/slang/slang-ir-dce.cpp
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Expand Up @@ -587,17 +587,22 @@ bool shouldInstBeLiveIfParentIsLive(IRInst* inst, IRDeadCodeEliminationOptions o
break;
}
}
for (auto decor : innerInst->getDecorations())

if (innerInst)
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@tangent-vector tangent-vector Nov 24, 2025

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Do we think this conditional is still good/necessary?

Unless we have a reason to believe that innerInst could be null for valid input code, I would rather see a SLANG_ASSERT(innerInst) than an if(innerInst). Either way, this code seems unrelated to the actual fix.

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@gtong-nv gtong-nv Nov 25, 2025

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Looks like we still need to keep this conditional check.
As the innerInst = findInnerMostGenericReturnVal(genInst); could return nullptr for the generic that doesn't have return val ( enum in this case?)

The genInst causing the trouble has only a basic block contains a T Op_Param.
We would have to keep check, unless this inst should not be here in the first place..

{
switch (decor->getOp())
for (auto decor : innerInst->getDecorations())
{
case kIROp_ForwardDerivativeDecoration:
case kIROp_UserDefinedBackwardDerivativeDecoration:
case kIROp_PrimalSubstituteDecoration:
shouldKeptAliveIfImported = true;
break;
switch (decor->getOp())
{
case kIROp_ForwardDerivativeDecoration:
case kIROp_UserDefinedBackwardDerivativeDecoration:
case kIROp_PrimalSubstituteDecoration:
shouldKeptAliveIfImported = true;
break;
}
}
}

if (isImported && shouldKeptAliveIfImported)
return true;
}
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25 changes: 3 additions & 22 deletions source/slang/slang-ir-specialize.cpp
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Expand Up @@ -880,7 +880,9 @@ struct SpecializationContext
IRInst* satisfyingVal = nullptr;

if (witnessTable)
satisfyingVal = findWitnessVal(witnessTable, requirementKey);
{
satisfyingVal = findWitnessTableEntry(witnessTable, requirementKey);
}
else
{
// If we are specializing ThisTypeWitness, the result of the specialization
Expand Down Expand Up @@ -935,27 +937,6 @@ struct SpecializationContext
return instChanged;
}

// The above subroutine needed a way to look up
// the satisfying value for a given requirement
// key in a concrete witness table, so let's
// define that now.
//
IRInst* findWitnessVal(IRWitnessTable* witnessTable, IRInst* requirementKey)
{
// A witness table is basically just a container
// for key-value pairs, and so the best we can
// do for now is a naive linear search.
//
for (auto entry : witnessTable->getEntries())
{
if (requirementKey == entry->getRequirementKey())
{
return entry->getSatisfyingVal();
}
}
return nullptr;
}

template<typename TDict>
void _readSpecializationDictionaryImpl(TDict& dict, IRInst* dictInst)
{
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2 changes: 1 addition & 1 deletion source/slang/slang-ir-strip.cpp
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Expand Up @@ -67,7 +67,7 @@ void stripImportedWitnessTable(IRModule* module)
default:
continue;
}
if (inst->getOp() != kIROp_WitnessTable)
if (!inst || inst->getOp() != kIROp_WitnessTable)
continue;
if (!globalInst->findDecoration<IRImportDecoration>())
continue;
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29 changes: 29 additions & 0 deletions tests/language-feature/enums/nested-enum.slang
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Expand Up @@ -62,6 +62,33 @@ int test(int val)
return result;
}

struct OuterGeneric<T>
{
enum Channel
{
Red,
Green,
Blue,
Alpha,
};
T value;
Channel channel;
}

int testGeneric(int val)
{
OuterGeneric<int> outer;
outer.value = val;
outer.channel = OuterGeneric<int>.Channel(val);
int result = 0;
if (outer.channel == OuterGeneric<int>.Channel.Red) result += 1;
if (outer.channel == OuterGeneric<int>.Channel.Green) result += 2;
if (outer.channel == OuterGeneric<int>.Channel.Blue) result += 3;
if (outer.channel == OuterGeneric<int>.Channel.Alpha) result += 4;

return result;
}

//TEST_INPUT:ubuffer(data=[0 0 0 0], stride=4):out,name=outputBuffer
RWStructuredBuffer<int> outputBuffer;

Expand All @@ -80,5 +107,7 @@ void computeMain(int3 dispatchThreadID : SV_DispatchThreadID)
int tid = dispatchThreadID.x;
int inVal = tid;
int outVal = test(inVal) + value * 2 + int(anotherValue) * 4;

outVal += testGeneric(inVal);
outputBuffer[tid] = outVal;
}
8 changes: 4 additions & 4 deletions tests/language-feature/enums/nested-enum.slang.expected.txt
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Original file line number Diff line number Diff line change
@@ -1,4 +1,4 @@
1071
1060
1170
70
1072
1062
1173
74