6 files changed, 48 insertions, 9 deletions

diff --git a/gcc/rust/backend/rust-compile-context.h b/gcc/rust/backend/rust-compile-context.h
index 3fefd8d..4bade5c 100644
--- a/gcc/rust/backend/rust-compile-context.h
+++ b/gcc/rust/backend/rust-compile-context.h
@@ -307,6 +307,11 @@ public:
     return mangler.mangle_item (ty, path);
   }
 
+  std::vector<tree> &get_type_decls () { return type_decls; }
+  std::vector<::Bvariable *> &get_var_decls () { return var_decls; }
+  std::vector<tree> &get_const_decls () { return const_decls; }
+  std::vector<tree> &get_func_decls () { return func_decls; }
+
 private:
   ::Backend *backend;
   Resolver::Resolver *resolver;
diff --git a/gcc/rust/backend/rust-compile-expr.cc b/gcc/rust/backend/rust-compile-expr.cc
index 6d50c3f..03e3c2e 100644
--- a/gcc/rust/backend/rust-compile-expr.cc
+++ b/gcc/rust/backend/rust-compile-expr.cc
@@ -1339,18 +1339,22 @@ CompileExpr::visit (HIR::IdentifierExpr &expr)
   Bvariable *var = nullptr;
   if (ctx->lookup_const_decl (ref, &translated))
     {
+      TREE_USED (translated) = 1;
       return;
     }
   else if (ctx->lookup_function_decl (ref, &fn))
     {
+      TREE_USED (fn) = 1;
       translated = address_expression (fn, expr.get_locus ());
     }
   else if (ctx->lookup_var_decl (ref, &var))
     {
+      // TREE_USED is setup in the gcc abstraction here
       translated = ctx->get_backend ()->var_expression (var, expr.get_locus ());
     }
   else if (ctx->lookup_pattern_binding (ref, &translated))
     {
+      TREE_USED (translated) = 1;
       return;
     }
   else
@@ -1371,6 +1375,11 @@ CompileExpr::visit (HIR::IdentifierExpr &expr)
       else
 	translated = CompileItem::compile (resolved_item, ctx, lookup, true,
 					   expr.get_locus ());
+
+      if (translated != error_mark_node)
+	{
+	  TREE_USED (translated) = 1;
+	}
     }
 }
 
diff --git a/gcc/rust/backend/rust-compile-item.cc b/gcc/rust/backend/rust-compile-item.cc
index d42cc1e..21cbb1c 100644
--- a/gcc/rust/backend/rust-compile-item.cc
+++ b/gcc/rust/backend/rust-compile-item.cc
@@ -73,6 +73,10 @@ CompileItem::visit (HIR::StaticItem &var)
 void
 CompileItem::visit (HIR::ConstantItem &constant)
 {
+  if (ctx->lookup_const_decl (constant.get_mappings ().get_hirid (),
+			      &reference))
+    return;
+
   // resolve the type
   TyTy::BaseType *resolved_type = nullptr;
   bool ok
diff --git a/gcc/rust/backend/rust-compile-resolve-path.cc b/gcc/rust/backend/rust-compile-resolve-path.cc
index e41ee7f..09f3860 100644
--- a/gcc/rust/backend/rust-compile-resolve-path.cc
+++ b/gcc/rust/backend/rust-compile-resolve-path.cc
@@ -23,6 +23,8 @@
 #include "rust-hir-trait-resolve.h"
 #include "rust-hir-path-probe.h"
 
+#include "print-tree.h"
+
 namespace Rust {
 namespace Compile {
 
@@ -117,12 +119,18 @@ ResolvePathRef::resolve (const HIR::PathIdentSegment &final_segment,
   // might be a constant
   tree constant_expr;
   if (ctx->lookup_const_decl (ref, &constant_expr))
-    return constant_expr;
+    {
+      TREE_USED (constant_expr) = 1;
+      return constant_expr;
+    }
 
   // this might be a variable reference or a function reference
   Bvariable *var = nullptr;
   if (ctx->lookup_var_decl (ref, &var))
-    return ctx->get_backend ()->var_expression (var, expr_locus);
+    {
+      // TREE_USED is setup in the gcc abstraction here
+      return ctx->get_backend ()->var_expression (var, expr_locus);
+    }
 
   // it might be a function call
   if (lookup->get_kind () == TyTy::TypeKind::FNDEF)
@@ -131,13 +139,19 @@ ResolvePathRef::resolve (const HIR::PathIdentSegment &final_segment,
       tree fn = NULL_TREE;
       if (ctx->lookup_function_decl (fntype->get_ty_ref (), &fn))
 	{
+	  TREE_USED (fn) = 1;
 	  return address_expression (fn, expr_locus);
 	}
     }
 
   // let the query system figure it out
-  return query_compile (ref, lookup, final_segment, mappings, expr_locus,
-			is_qualified_path);
+  tree resolved_item = query_compile (ref, lookup, final_segment, mappings,
+				      expr_locus, is_qualified_path);
+  if (resolved_item != error_mark_node)
+    {
+      TREE_USED (resolved_item) = 1;
+    }
+  return resolved_item;
 }
 
 tree
diff --git a/gcc/rust/backend/rust-compile-stmt.h b/gcc/rust/backend/rust-compile-stmt.h
index 0f69fb0..ad34253 100644
--- a/gcc/rust/backend/rust-compile-stmt.h
+++ b/gcc/rust/backend/rust-compile-stmt.h
@@ -81,6 +81,7 @@ public:
     bool ok = ctx->get_tyctx ()->lookup_type (
       stmt.get_init_expr ()->get_mappings ().get_hirid (), &actual);
     rust_assert (ok);
+    tree stmt_type = TyTyResolveCompile::compile (ctx, ty);
 
     Location lvalue_locus = stmt.get_pattern ()->get_locus ();
     Location rvalue_locus = stmt.get_init_expr ()->get_locus ();
@@ -90,8 +91,14 @@ public:
     auto fnctx = ctx->peek_fn ();
     if (ty->is_unit ())
       {
-	// FIXME this feels wrong
 	ctx->add_statement (init);
+
+	auto unit_type_init_expr
+	  = ctx->get_backend ()->constructor_expression (stmt_type, false, {},
+							 -1, rvalue_locus);
+	auto s = ctx->get_backend ()->init_statement (fnctx.fndecl, var,
+						      unit_type_init_expr);
+	ctx->add_statement (s);
       }
     else
       {
diff --git a/gcc/rust/backend/rust-compile-tyty.h b/gcc/rust/backend/rust-compile-tyty.h
index a3720f8..52ad2f9 100644
--- a/gcc/rust/backend/rust-compile-tyty.h
+++ b/gcc/rust/backend/rust-compile-tyty.h
@@ -54,10 +54,10 @@ public:
 
   void visit (TyTy::TupleType &type) override
   {
-    if (type.num_fields () == 0)
-      translated = backend->unit_type ();
-    else
-      gcc_unreachable ();
+    // this interface is only for unit-type the -type interface takes into
+    // account the context
+    rust_assert (type.num_fields () == 0);
+    translated = backend->unit_type ();
   }
 
   void visit (TyTy::ArrayType &) override { gcc_unreachable (); }