Initial implementation for decl-tree reflection API (#4666)

* Initial implementation for decl-tree reflection API

This patch adds Slang API methods for walking all the declarations in the AST.

We expose this functionality through an abstract `DeclReflection` class that can be a type, function or a variable declaration.
We also provide ways to cast the decl to a `FunctionReflection`, `TypeReflection` or `VariableReflection` and traverse through the child nodes (for instance, a struct type will have component variable declarations)

This patch also adds `ISlangInternal` as an internal COM interface to allow us to cast IGlobalSession to the internal Session pointer while bypassing any wrappers (such as the capture interface)

* Update slang.h

* Remove `ISlangInternal` (its causing a diamond pattern w.r.t `ISlangUnknown`) and use `ComPtr` for proper ref management.

* Update unit-test-decl-tree-reflection.cpp

* Change `FunctionDeclBase` to use `DeclRef` instead of directly using the decl.

* Update slang-reflection-api.cpp

1 files changed, 8 insertions, 0 deletions

diff --git a/source/slang-capture-replay/slang-module.cpp b/source/slang-capture-replay/slang-module.cpp
index 8a1a80126..273faa59d 100644
--- a/source/slang-capture-replay/slang-module.cpp
+++ b/source/slang-capture-replay/slang-module.cpp
@@ -27,6 +27,14 @@ namespace SlangCapture
             return nullptr;
     }
 
+    SLANG_NO_THROW slang::DeclReflection* ModuleCapture::getModuleReflection()
+    {
+        // No need to capture this call as it is just a query.
+        slangCaptureLog(LogLevel::Verbose, "%s\n", __PRETTY_FUNCTION__);
+        slang::DeclReflection* res = (slang::DeclReflection*)m_actualModule->getModuleReflection();
+        return res;
+    }
+
     SLANG_NO_THROW SlangResult ModuleCapture::findEntryPointByName(
         char const*     name,
         slang::IEntryPoint**   outEntryPoint)