Support indirection for struct and tuple field access

When we have a fat pointer to a structure the GCC needs to know the RECORD
or UNION type of the type before it can access fields, this can be
supported by C'stye indirection such as '->'.

This might get updated when we support the autoderef mechanism and if the
type supports the deref trait.

Addresses #241

4 files changed, 92 insertions, 11 deletions

diff --git a/gcc/rust/backend/rust-compile-expr.h b/gcc/rust/backend/rust-compile-expr.h
index ac33ccd..d0c0b74 100644
--- a/gcc/rust/backend/rust-compile-expr.h
+++ b/gcc/rust/backend/rust-compile-expr.h
@@ -46,6 +46,26 @@ public:
     TupleIndex index = expr.get_tuple_index ();
 
     Bexpression *receiver_ref = CompileExpr::Compile (tuple_expr, ctx);
+
+    TyTy::BaseType *tuple_expr_ty = nullptr;
+    bool ok = ctx->get_tyctx ()->lookup_type (
+      tuple_expr->get_mappings ().get_hirid (), &tuple_expr_ty);
+    rust_assert (ok);
+
+    // do we need to add an indirect reference
+    if (tuple_expr_ty->get_kind () == TyTy::TypeKind::REF)
+      {
+	TyTy::ReferenceType *r
+	  = static_cast<TyTy::ReferenceType *> (tuple_expr_ty);
+	TyTy::BaseType *tuple_type = r->get_base ();
+	Btype *tuple_tyty = TyTyResolveCompile::compile (ctx, tuple_type);
+
+	Bexpression *indirect
+	  = ctx->get_backend ()->indirect_expression (tuple_tyty, receiver_ref,
+						      true, expr.get_locus ());
+	receiver_ref = indirect;
+      }
+
     translated
       = ctx->get_backend ()->struct_field_expression (receiver_ref, index,
 						      expr.get_locus ());
@@ -606,6 +626,9 @@ public:
 
   void visit (HIR::FieldAccessExpr &expr) override
   {
+    Bexpression *receiver_ref
+      = CompileExpr::Compile (expr.get_receiver_expr ().get (), ctx);
+
     // resolve the receiver back to ADT type
     TyTy::BaseType *receiver = nullptr;
     if (!ctx->get_tyctx ()->lookup_type (
@@ -615,17 +638,31 @@ public:
 		       "unresolved type for receiver");
 	return;
       }
-    rust_assert (receiver->get_kind () == TyTy::TypeKind::ADT);
-    TyTy::ADTType *adt = static_cast<TyTy::ADTType *> (receiver);
 
-    size_t index = 0;
-    adt->get_field (expr.get_field_name (), &index);
+    size_t field_index = 0;
+    if (receiver->get_kind () == TyTy::TypeKind::ADT)
+      {
+	TyTy::ADTType *adt = static_cast<TyTy::ADTType *> (receiver);
+	adt->get_field (expr.get_field_name (), &field_index);
+      }
+    else if (receiver->get_kind () == TyTy::TypeKind::REF)
+      {
+	TyTy::ReferenceType *r = static_cast<TyTy::ReferenceType *> (receiver);
+	TyTy::BaseType *b = r->get_base ();
+	rust_assert (b->get_kind () == TyTy::TypeKind::ADT);
 
-    Bexpression *struct_ref
-      = CompileExpr::Compile (expr.get_receiver_expr ().get (), ctx);
+	TyTy::ADTType *adt = static_cast<TyTy::ADTType *> (b);
+	adt->get_field (expr.get_field_name (), &field_index);
+	Btype *adt_tyty = TyTyResolveCompile::compile (ctx, adt);
+
+	Bexpression *indirect
+	  = ctx->get_backend ()->indirect_expression (adt_tyty, receiver_ref,
+						      true, expr.get_locus ());
+	receiver_ref = indirect;
+      }
 
     translated
-      = ctx->get_backend ()->struct_field_expression (struct_ref, index,
+      = ctx->get_backend ()->struct_field_expression (receiver_ref, field_index,
 						      expr.get_locus ());
   }
 
diff --git a/gcc/rust/lint/rust-lint-marklive.cc b/gcc/rust/lint/rust-lint-marklive.cc
index f383d48..0871291 100644
--- a/gcc/rust/lint/rust-lint-marklive.cc
+++ b/gcc/rust/lint/rust-lint-marklive.cc
@@ -214,9 +214,22 @@ MarkLive::visit (HIR::FieldAccessExpr &expr)
       rust_error_at (expr.get_receiver_expr ()->get_locus (),
 		     "unresolved type for receiver");
     }
-  bool ok = receiver->get_kind () == TyTy::TypeKind::ADT;
-  rust_assert (ok);
-  TyTy::ADTType *adt = static_cast<TyTy::ADTType *> (receiver);
+
+  TyTy::ADTType *adt = nullptr;
+  if (receiver->get_kind () == TyTy::TypeKind::ADT)
+    {
+      adt = static_cast<TyTy::ADTType *> (receiver);
+    }
+  else if (receiver->get_kind () == TyTy::TypeKind::REF)
+    {
+      TyTy::ReferenceType *r = static_cast<TyTy::ReferenceType *> (receiver);
+      TyTy::BaseType *b = r->get_base ();
+      rust_assert (b->get_kind () == TyTy::TypeKind::ADT);
+
+      adt = static_cast<TyTy::ADTType *> (b);
+    }
+
+  rust_assert (adt != nullptr);
 
   // get the field index
   size_t index = 0;
@@ -228,6 +241,7 @@ MarkLive::visit (HIR::FieldAccessExpr &expr)
 		     adt->get_name ().c_str (), index);
       return;
     }
+
   // get the field hir id
   HirId field_id = adt->get_field (index)->get_ref ();
   mark_hir_id (field_id);
diff --git a/gcc/rust/typecheck/rust-hir-type-check-expr.h b/gcc/rust/typecheck/rust-hir-type-check-expr.h
index 2744516..31c8909 100644
--- a/gcc/rust/typecheck/rust-hir-type-check-expr.h
+++ b/gcc/rust/typecheck/rust-hir-type-check-expr.h
@@ -64,13 +64,20 @@ public:
   {
     auto resolved
       = TypeCheckExpr::Resolve (expr.get_tuple_expr ().get (), inside_loop);
-    if (resolved == nullptr)
+    if (resolved->get_kind () == TyTy::TypeKind::ERROR)
       {
 	rust_error_at (expr.get_tuple_expr ()->get_locus (),
 		       "failed to resolve TupleIndexExpr receiver");
 	return;
       }
 
+    // FIXME does this require autoderef here?
+    if (resolved->get_kind () == TyTy::TypeKind::REF)
+      {
+	TyTy::ReferenceType *r = static_cast<TyTy::ReferenceType *> (resolved);
+	resolved = r->get_base ();
+      }
+
     bool is_valid_type = resolved->get_kind () == TyTy::TypeKind::ADT
 			 || resolved->get_kind () == TyTy::TypeKind::TUPLE;
     if (!is_valid_type)
@@ -902,6 +909,14 @@ public:
     auto struct_base
       = TypeCheckExpr::Resolve (expr.get_receiver_expr ().get (), false);
 
+    // FIXME does this require autoderef here?
+    if (struct_base->get_kind () == TyTy::TypeKind::REF)
+      {
+	TyTy::ReferenceType *r
+	  = static_cast<TyTy::ReferenceType *> (struct_base);
+	struct_base = r->get_base ();
+      }
+
     bool is_valid_type = struct_base->get_kind () == TyTy::TypeKind::ADT;
     if (!is_valid_type)
       {
diff --git a/gcc/testsuite/rust/compile/torture/autoderef1.rs b/gcc/testsuite/rust/compile/torture/autoderef1.rs
new file mode 100644
index 0000000..0cf070f
--- /dev/null
+++ b/gcc/testsuite/rust/compile/torture/autoderef1.rs
@@ -0,0 +1,15 @@
+struct Foo(i32, bool);
+struct Bar {
+    a: i32,
+    b: bool,
+}
+
+fn main() {
+    let a = &Foo(123, false);
+    let _b: i32 = a.0;
+    let _c: bool = a.1;
+
+    let a = &Bar { a: 456, b: false };
+    let _b: i32 = a.a;
+    let _c: bool = a.b;
+}