[HLSL] Resource initialization by constructors (#135120)

- Adds resource constructor that takes explicit binding for all resource
classes.
- Updates implementation of default resource constructor to initialize
resource handle to `poison`.
- Removes initialization of resource classes from Codegen.
- Initialization of `cbuffer` still needs to happen in `CGHLSLRuntime`
because it does not have a corresponding resource class type.
- Adds `ImplicitCastExpr` for builtin function calls. Sema adds these
automatically when a method of a template class is instantiated, but
some resource classes like `ByteAddressBuffer` are not templates so they
need to have this added explicitly.

Design proposal: llvm/wg-hlsl#197

Closes #134154

1 files changed, 2 insertions, 1 deletions

diff --git a/clang/lib/Sema/HLSLExternalSemaSource.cpp b/clang/lib/Sema/HLSLExternalSemaSource.cpp
index f5477ac..f09232a 100644
--- a/clang/lib/Sema/HLSLExternalSemaSource.cpp
+++ b/clang/lib/Sema/HLSLExternalSemaSource.cpp
@@ -131,7 +131,8 @@ static BuiltinTypeDeclBuilder setupBufferType(CXXRecordDecl *Decl, Sema &S,
                                               bool RawBuffer) {
   return BuiltinTypeDeclBuilder(S, Decl)
       .addHandleMember(RC, IsROV, RawBuffer)
-      .addDefaultHandleConstructor();
+      .addDefaultHandleConstructor()
+      .addHandleConstructorFromBinding();
 }
 
 // This function is responsible for constructing the constraint expression for