COM interfaces with host callable (#2258)

* #include an absolute path didn't work - because paths were taken to always be relative.

* Use TerminatedUnownedStringSlice for literals in output C++.

* Remove Escape/Unescape functions used in slang-token-reader.cpp
Add target type of 'host-cpp' etc to map to the target types.

* Fix some corner cases around string encoding.

* Added unit test for string escaping.
Fixed some assorted escaping bugs.

* Updated test output.

* Added decode test.

* Stop using hex output, to get around 'greedy' aspect. Use octal instead.

* Added HostHostCallable
Small changes to use ArtifactDesc/Info instead of large switches.

* Fix C++ emit to handle arbitrary function export.

* Add options handling for callable without an output being specified.

* Can compile with COM interface. Added example using com interface.

* Use the IR Ptr type instead of hack in C++ emit for interfaces.

* Fix issue with outputting the COM call when ptr is used.

* Fix crash issue on compilation failure.

1 files changed, 14 insertions, 8 deletions

diff --git a/source/slang/slang.cpp b/source/slang/slang.cpp
index 7b22d04de..9379f3b03 100644
--- a/source/slang/slang.cpp
+++ b/source/slang/slang.cpp
@@ -670,17 +670,17 @@ SlangPassThrough Session::getDownstreamCompilerForTransition(SlangCompileTarget
         return (SlangPassThrough)m_codeGenTransitionMap.getTransition(source, target);
     }
 
+    const auto desc = ArtifactDesc::makeFromCompileTarget(inTarget);
+
     // Special case host-callable
-    if (target == CodeGenTarget::ShaderHostCallable)
+    if ((desc.kind == ArtifactKind::Callable) && 
+        (source == CodeGenTarget::CSource || source == CodeGenTarget::CPPSource))
     {
-        if (source == CodeGenTarget::CSource || source == CodeGenTarget::CPPSource)
+        // We prefer LLVM if it's available
+        DownstreamCompiler* llvm = getOrLoadDownstreamCompiler(PassThroughMode::LLVM, nullptr);
+        if (llvm)
         {
-            // We prefer LLVM if it's available
-            DownstreamCompiler* llvm = getOrLoadDownstreamCompiler(PassThroughMode::LLVM, nullptr);
-            if (llvm)
-            {
-                return SLANG_PASS_THROUGH_LLVM;
-            }
+            return SLANG_PASS_THROUGH_LLVM;
         }
     }
 
@@ -1334,6 +1334,7 @@ CapabilitySet TargetRequest::getTargetCaps()
     case CodeGenTarget::CPPSource:
     case CodeGenTarget::HostExecutable:
     case CodeGenTarget::ShaderSharedLibrary:
+    case CodeGenTarget::HostHostCallable:
     case CodeGenTarget::ShaderHostCallable:
         atoms.add(CapabilityAtom::CPP);
         break;
@@ -4711,6 +4712,11 @@ static SlangResult _getWholeProgramResult(
     auto linkage = req->getLinkage();
     auto program = req->getSpecializedGlobalAndEntryPointsComponentType();
 
+    if (!program)
+    {
+        return SLANG_FAIL;
+    }
+
     Index targetCount = linkage->targets.getCount();
     if ((targetIndex < 0) || (targetIndex >= targetCount))
     {