Diagnostic for no type conformance + bug fix. (#1985)

* Diagnostic for no type conformance + bug fix.

* Fixes.

* Fix.

* Include heterogeneous example only with --enable-experimental-projects premake flag

Co-authored-by: Yong He <yhe@nvidia.com>
Co-authored-by: jsmall-nvidia <jsmall@nvidia.com>

1 files changed, 32 insertions, 0 deletions

diff --git a/source/slang/slang-ir-lower-generics.cpp b/source/slang/slang-ir-lower-generics.cpp
index 241827561..95046787a 100644
--- a/source/slang/slang-ir-lower-generics.cpp
+++ b/source/slang/slang-ir-lower-generics.cpp
@@ -117,6 +117,36 @@ namespace Slang
         cleanUpInterfaceTypes(sharedContext);
     }
 
+    void checkTypeConformanceExists(SharedGenericsLoweringContext* context)
+    {
+        HashSet<IRInst*> implementedInterfaces;
+
+        // Add all interface type that are implemented by at least one type to a set.
+        for (auto inst : context->module->getGlobalInsts())
+        {
+            if (inst->getOp() == kIROp_WitnessTable)
+            {
+                auto interfaceType = cast<IRWitnessTableType>(inst->getDataType())->getConformanceType();
+                implementedInterfaces.Add(interfaceType);
+            }
+        }
+        // Check if an interface type has any implementations.
+        workOnModule(context, [&](IRInst* inst)
+            {
+                if (auto lookupWitnessMethod = as<IRLookupWitnessMethod>(inst))
+                {
+                    auto witnessTableType = lookupWitnessMethod->getWitnessTable()->getDataType();
+                    auto interfaceType = cast<IRWitnessTableType>(witnessTableType)->getConformanceType();
+                    if (!implementedInterfaces.Contains(interfaceType))
+                    {
+                        context->sink->diagnose(interfaceType->sourceLoc, Diagnostics::noTypeConformancesFoundForInterface, interfaceType);
+                        // Add to set to prevent duplicate diagnostic messages.
+                        implementedInterfaces.Add(interfaceType);
+                    }
+                }
+            });
+    }
+
     void lowerGenerics(
         TargetRequest*          targetReq,
         IRModule*               module,
@@ -127,6 +157,8 @@ namespace Slang
         sharedContext.module = module;
         sharedContext.sink = sink;
 
+        checkTypeConformanceExists(&sharedContext);
+
         // Replace all `makeExistential` insts with `makeExistentialWithRTTI`
         // before making any other changes. This is necessary because a parameter of
         // generic type will be lowered into `AnyValueType`, and after that we can no longer