Export witness table and RTTI objects in compiled libraries. (#1514)

* Export witness table objects in compiled code.

- Ensure that witness tables are preceeded with `extern "C"` modifier in the generated C++ code.
- RTTI objects use the mangled name of the type directly, so that can be queried using the type's mangled name directly from the resulting DLL.
- Expose `Linkage::getTypeConformanceWitnessMangledName` to return the mangled name of witness tables to the host.
- Ensure that all witness tables (including those for associated types) have proper mangled name.

* Fix GCC error in Slang generated code.

1 files changed, 7 insertions, 0 deletions

diff --git a/slang.h b/slang.h
index e00b813a8..1b79f97ab 100644
--- a/slang.h
+++ b/slang.h
@@ -3102,6 +3102,13 @@ namespace slang
             LayoutRules     rules = LayoutRules::Default,
             ISlangBlob**    outDiagnostics = nullptr) = 0;
 
+            /** Get the mangled name for a type witness.
+            */
+        virtual SLANG_NO_THROW SlangResult SLANG_MCALL getTypeConformanceWitnessMangledName(
+            TypeReflection* type,
+            TypeReflection* interfaceType,
+            ISlangBlob** outNameBlob) = 0;
+
             /** Create a request to load/compile front-end code.
             */
         virtual SLANG_NO_THROW SlangResult SLANG_MCALL createCompileRequest(