1 files changed, 22 insertions, 8 deletions

diff --git a/source/slang/slang-ir-specialize-target-switch.cpp b/source/slang/slang-ir-specialize-target-switch.cpp
index f4cb6bfa7..fac1dd484 100644
--- a/source/slang/slang-ir-specialize-target-switch.cpp
+++ b/source/slang/slang-ir-specialize-target-switch.cpp
@@ -7,13 +7,15 @@
 
 namespace Slang
 {
-    void specializeTargetSwitch(TargetRequest* target, IRGlobalValueWithCode* code)
+    void specializeTargetSwitch(TargetRequest* target, IRGlobalValueWithCode* code, DiagnosticSink* sink)
     {
         bool changed = false;
         for (auto block : code->getBlocks())
         {
+            bool failedImplies = false;
             if (auto targetSwitch = as<IRTargetSwitch>(block->getTerminator()))
             {
+                bool isEqual;
                 CapabilitySet bestCapSet = CapabilitySet::makeInvalid();
                 IRBlock* targetBlock = nullptr;
                 for (UInt i = 0; i < targetSwitch->getCaseCount(); i++)
@@ -22,14 +24,22 @@ namespace Slang
                     if (target->getTargetCaps().isIncompatibleWith(cap))
                         continue;
                     CapabilitySet capSet;
-                    if (cap == CapabilityName::Invalid)
+                    if (cap == CapabilityName::Invalid) // `default` case
                         capSet = CapabilitySet::makeEmpty();
                     else
                         capSet = CapabilitySet(cap);
-                    if (capSet.isBetterForTarget(bestCapSet, target->getTargetCaps()))
+                    bool isBetterForTarget = capSet.isBetterForTarget(bestCapSet, target->getTargetCaps(), isEqual);
+                    if (isBetterForTarget)
                     {
-                        targetBlock = targetSwitch->getCaseBlock(i);
-                        bestCapSet = capSet;
+                        bool targetImpliesCapSet = (target->getTargetCaps().implies(capSet, true) || capSet.isEmpty());
+                        if (targetImpliesCapSet)
+                        {
+                            // Now check if bestCapSet contains targetCaps. If it does not then this is an invalid target
+                            targetBlock = targetSwitch->getCaseBlock(i);
+                            bestCapSet = capSet;
+                        }
+                        else
+                            failedImplies = true;
                     }
                 }
                 IRBuilder builder(targetSwitch);
@@ -40,6 +50,10 @@ namespace Slang
                 }
                 else
                 {
+                    // only error if we have the chance of setting a valid target switch, but did not due to incompatability within same `target` atom.
+                    // Otherwise we will have an issue when we process a `__target_switch() { case metal: return; }` for glsl targets.
+                    if(failedImplies)
+                        sink->diagnose(targetSwitch->sourceLoc, Diagnostics::profileIncompatibleWithTargetSwitch, target->getTargetCaps());
                     builder.emitMissingReturn();
                 }
                 targetSwitch->removeAndDeallocate();
@@ -53,19 +67,19 @@ namespace Slang
         }
     }
 
-    void specializeTargetSwitch(TargetRequest* target, IRModule* module)
+    void specializeTargetSwitch(TargetRequest* target, IRModule* module, DiagnosticSink* sink)
     {
         for (auto globalInst : module->getGlobalInsts())
         {
             if (auto code = as<IRGlobalValueWithCode>(globalInst))
             {
-                specializeTargetSwitch(target, code);
+                specializeTargetSwitch(target, code, sink);
                 if (auto gen = as<IRGeneric>(code))
                 {
                     auto retVal = findGenericReturnVal(gen);
                     if (auto innerCode = as<IRGlobalValueWithCode>(retVal))
                     {
-                        specializeTargetSwitch(target, innerCode);
+                        specializeTargetSwitch(target, innerCode, sink);
                     }
                 }
             }