Patchwork Go patch committed: Lower calls to bound method expressions

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Submitter Ian Taylor
Date Aug. 29, 2011, 10:06 p.m.
Message ID <mcrk49vyish.fsf@coign.corp.google.com>
Download mbox | patch
Permalink /patch/112160/
State New
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Ian Taylor - Aug. 29, 2011, 10:06 p.m.
This patch to the Go frontend lowers calls to bound method expressions,
rather than handling them when converting to GENERIC.  Bootstrapped and
ran Go testsuite on x86_64-unknown-linux-gnu.  Committed to mainline.

Ian

Patch

diff -r 5097a3ef0927 go/expressions.cc
--- a/go/expressions.cc	Mon Aug 29 15:00:07 2011 -0700
+++ b/go/expressions.cc	Mon Aug 29 15:02:20 2011 -0700
@@ -3845,7 +3845,7 @@ 
     go_assert((et->points_to() != NULL
 		&& et->points_to()->channel_type() != NULL)
 	       || et->is_nil_type());
-  else if (t->is_unsafe_pointer_type())
+  else if (t->points_to() != NULL)
     go_assert(et->points_to() != NULL || et->is_nil_type());
   else if (et->is_unsafe_pointer_type())
     go_assert(t->points_to() != NULL);
@@ -3908,7 +3908,7 @@ 
  public:
   Unary_expression(Operator op, Expression* expr, source_location location)
     : Expression(EXPRESSION_UNARY, location),
-      op_(op), escapes_(true), expr_(expr)
+      op_(op), escapes_(true), create_temp_(false), expr_(expr)
   { }
 
   // Return the operator.
@@ -3929,6 +3929,15 @@ 
     this->escapes_ = false;
   }
 
+  // Record that this is an address expression which should create a
+  // temporary variable if necessary.  This is used for method calls.
+  void
+  set_create_temp()
+  {
+    go_assert(this->op_ == OPERATOR_AND);
+    this->create_temp_ = true;
+  }
+
   // Apply unary opcode OP to UVAL, setting VAL.  Return true if this
   // could be done, false if not.
   static bool
@@ -4004,6 +4013,9 @@ 
   // Normally true.  False if this is an address expression which does
   // not escape the current function.
   bool escapes_;
+  // True if this is an address expression which should create a
+  // temporary variable if necessary.
+  bool create_temp_;
   // The operand.
   Expression* expr_;
 };
@@ -4428,7 +4440,10 @@ 
 
     case OPERATOR_AND:
       if (!this->expr_->is_addressable())
-	this->report_error(_("invalid operand for unary %<&%>"));
+	{
+	  if (!this->create_temp_)
+	    this->report_error(_("invalid operand for unary %<&%>"));
+	}
       else
 	this->expr_->address_taken(this->escapes_);
       break;
@@ -4486,12 +4501,15 @@ 
       return fold_build1_loc(loc, BIT_NOT_EXPR, TREE_TYPE(expr), expr);
 
     case OPERATOR_AND:
-      // We should not see a non-constant constructor here; cases
-      // where we would see one should have been moved onto the heap
-      // at parse time.  Taking the address of a nonconstant
-      // constructor will not do what the programmer expects.
-      go_assert(TREE_CODE(expr) != CONSTRUCTOR || TREE_CONSTANT(expr));
-      go_assert(TREE_CODE(expr) != ADDR_EXPR);
+      if (!this->create_temp_)
+	{
+	  // We should not see a non-constant constructor here; cases
+	  // where we would see one should have been moved onto the
+	  // heap at parse time.  Taking the address of a nonconstant
+	  // constructor will not do what the programmer expects.
+	  go_assert(TREE_CODE(expr) != CONSTRUCTOR || TREE_CONSTANT(expr));
+	  go_assert(TREE_CODE(expr) != ADDR_EXPR);
+	}
 
       // Build a decl for a constant constructor.
       if (TREE_CODE(expr) == CONSTRUCTOR && TREE_CONSTANT(expr))
@@ -4510,6 +4528,22 @@ 
 	  expr = decl;
 	}
 
+      if (this->create_temp_
+	  && !TREE_ADDRESSABLE(TREE_TYPE(expr))
+	  && !DECL_P(expr)
+	  && TREE_CODE(expr) != INDIRECT_REF
+	  && TREE_CODE(expr) != COMPONENT_REF)
+	{
+	  tree tmp = create_tmp_var(TREE_TYPE(expr), get_name(expr));
+	  DECL_IGNORED_P(tmp) = 1;
+	  DECL_INITIAL(tmp) = expr;
+	  TREE_ADDRESSABLE(tmp) = 1;
+	  return build2_loc(loc, COMPOUND_EXPR,
+			    build_pointer_type(TREE_TYPE(expr)),
+			    build1_loc(loc, DECL_EXPR, void_type_node, tmp),
+			    build_fold_addr_expr_loc(loc, tmp));
+	}
+
       return build_fold_addr_expr_loc(loc, expr);
 
     case OPERATOR_MULT:
@@ -7223,7 +7257,7 @@ 
 	  this->set_is_error();
 	  return this;
 	}
-      return this->lower_varargs(gogo, function, inserter, slice_type, 2);
+      this->lower_varargs(gogo, function, inserter, slice_type, 2);
     }
 
   return this;
@@ -8805,12 +8839,14 @@ 
 Call_expression::do_lower(Gogo* gogo, Named_object* function,
 			  Statement_inserter* inserter, int)
 {
+  source_location loc = this->location();
+
   // A type cast can look like a function call.
   if (this->fn_->is_type_expression()
       && this->args_ != NULL
       && this->args_->size() == 1)
     return Expression::make_cast(this->fn_->type(), this->args_->front(),
-				 this->location());
+				 loc);
 
   // Recognize a call to a builtin function.
   Func_expression* fne = this->fn_->func_expression();
@@ -8818,7 +8854,7 @@ 
       && fne->named_object()->is_function_declaration()
       && fne->named_object()->func_declaration_value()->type()->is_builtin())
     return new Builtin_call_expression(gogo, this->fn_, this->args_,
-				       this->is_varargs_, this->location());
+				       this->is_varargs_, loc);
 
   // Handle an argument which is a call to a function which returns
   // multiple results.
@@ -8862,8 +8898,7 @@ 
 	   ++p)
 	{
 	  Temporary_statement* temp = Statement::make_temporary(p->type(),
-								NULL,
-								p->location());
+								NULL, loc);
 	  inserter->insert(temp);
 	  temps->push_back(temp);
 	}
@@ -8879,8 +8914,58 @@ 
       const Typed_identifier_list* parameters = fntype->parameters();
       go_assert(parameters != NULL && !parameters->empty());
       Type* varargs_type = parameters->back().type();
-      return this->lower_varargs(gogo, function, inserter, varargs_type,
-				 parameters->size());
+      this->lower_varargs(gogo, function, inserter, varargs_type,
+			  parameters->size());
+    }
+
+  // If this is call to a method, call the method directly passing the
+  // object as the first parameter.
+  Bound_method_expression* bme = this->fn_->bound_method_expression();
+  if (bme != NULL)
+    {
+      Named_object* method = bme->method();
+      Expression* first_arg = bme->first_argument();
+
+      // We always pass a pointer when calling a method.
+      if (first_arg->type()->points_to() == NULL
+	  && !first_arg->type()->is_error())
+	{
+	  first_arg = Expression::make_unary(OPERATOR_AND, first_arg, loc);
+	  // We may need to create a temporary variable so that we can
+	  // take the address.  We can't do that here because it will
+	  // mess up the order of evaluation.
+	  Unary_expression* ue = static_cast<Unary_expression*>(first_arg);
+	  ue->set_create_temp();
+	}
+
+      // If we are calling a method which was inherited from an
+      // embedded struct, and the method did not get a stub, then the
+      // first type may be wrong.
+      Type* fatype = bme->first_argument_type();
+      if (fatype != NULL)
+	{
+	  if (fatype->points_to() == NULL)
+	    fatype = Type::make_pointer_type(fatype);
+	  first_arg = Expression::make_unsafe_cast(fatype, first_arg, loc);
+	}
+
+      Expression_list* new_args = new Expression_list();
+      new_args->push_back(first_arg);
+      if (this->args_ != NULL)
+	{
+	  for (Expression_list::const_iterator p = this->args_->begin();
+	       p != this->args_->end();
+	       ++p)
+	    new_args->push_back(*p);
+	}
+
+      // We have to change in place because this structure may be
+      // referenced by Call_result_expressions.  We can't delete the
+      // old arguments, because we may be traversing them up in some
+      // caller.  FIXME.
+      this->args_ = new_args;
+      this->fn_ = Expression::make_func_reference(method, NULL,
+						  bme->location());
     }
 
   return this;
@@ -8893,13 +8978,13 @@ 
 // calling; the last of these parameters will be the varargs
 // parameter.
 
-Expression*
+void
 Call_expression::lower_varargs(Gogo* gogo, Named_object* function,
 			       Statement_inserter* inserter,
 			       Type* varargs_type, size_t param_count)
 {
   if (this->varargs_are_lowered_)
-    return this;
+    return;
 
   source_location loc = this->location();
 
@@ -8910,7 +8995,7 @@ 
   if (arg_count < param_count - 1)
     {
       // Not enough arguments; will be caught in check_types.
-      return this;
+      return;
     }
 
   Expression_list* old_args = this->args_;
@@ -8942,7 +9027,7 @@ 
       else if (this->is_varargs_)
 	{
 	  this->report_error(_("too many arguments"));
-	  return this;
+	  return;
 	}
       else
 	{
@@ -8960,6 +9045,7 @@ 
 	    }
 	  Expression* val =
 	    Expression::make_slice_composite_literal(varargs_type, vals, loc);
+	  gogo->lower_expression(function, inserter, &val);
 	  new_args->push_back(val);
 	}
     }
@@ -8973,12 +9059,6 @@ 
   // Builtin_call_expression which refer to them.  FIXME.
   this->args_ = new_args;
   this->varargs_are_lowered_ = true;
-
-  // Lower all the new subexpressions.
-  Expression* ret = this;
-  gogo->lower_expression(function, inserter, &ret);
-  go_assert(ret == this);
-  return ret;
 }
 
 // Get the function type.  This can return NULL in error cases.
@@ -9102,10 +9182,28 @@ 
       Typed_identifier_list::const_iterator pt;
       if (parameters != NULL)
 	pt = parameters->begin();
+      bool first = true;
       for (Expression_list::const_iterator pa = this->args_->begin();
 	   pa != this->args_->end();
 	   ++pa)
 	{
+	  if (first)
+	    {
+	      first = false;
+	      // If this is a method, the first argument is the
+	      // receiver.
+	      if (fntype != NULL && fntype->is_method())
+		{
+		  Type* rtype = fntype->receiver()->type();
+		  // The receiver is always passed as a pointer.
+		  if (rtype->points_to() == NULL)
+		    rtype = Type::make_pointer_type(rtype);
+		  Type_context subcontext(rtype, false);
+		  (*pa)->determine_type(&subcontext);
+		  continue;
+		}
+	    }
+
 	  if (parameters != NULL && pt != parameters->end())
 	    {
 	      Type_context subcontext(pt->type(), false);
@@ -9172,35 +9270,28 @@ 
       return;
     }
 
-  if (fntype->is_method())
-    {
-      // We don't support pointers to methods, so the function has to
-      // be a bound method expression.
-      Bound_method_expression* bme = this->fn_->bound_method_expression();
-      if (bme == NULL)
-	{
-	  this->report_error(_("method call without object"));
-	  return;
-	}
-      Type* first_arg_type = bme->first_argument()->type();
-      if (first_arg_type->points_to() == NULL)
-	{
-	  // When passing a value, we need to check that we are
-	  // permitted to copy it.  The language permits copying
-	  // hidden fields for a method receiver.
-	  std::string reason;
-	  if (!Type::are_assignable_hidden_ok(fntype->receiver()->type(),
-					      first_arg_type, &reason))
+  bool is_method = fntype->is_method();
+  if (is_method)
+    {
+      go_assert(this->args_ != NULL && !this->args_->empty());
+      Type* rtype = fntype->receiver()->type();
+      Expression* first_arg = this->args_->front();
+      // The language permits copying hidden fields for a method
+      // receiver.  We dereference the values since receivers are
+      // always passed as pointers.
+      std::string reason;
+      if (!Type::are_assignable_hidden_ok(rtype->deref(),
+					  first_arg->type()->deref(),
+					  &reason))
+	{
+	  if (reason.empty())
+	    this->report_error(_("incompatible type for receiver"));
+	  else
 	    {
-	      if (reason.empty())
-		this->report_error(_("incompatible type for receiver"));
-	      else
-		{
-		  error_at(this->location(),
-			   "incompatible type for receiver (%s)",
-			   reason.c_str());
-		  this->set_is_error();
-		}
+	      error_at(this->location(),
+		       "incompatible type for receiver (%s)",
+		       reason.c_str());
+	      this->set_is_error();
 	    }
 	}
     }
@@ -9215,25 +9306,30 @@ 
 	this->report_error(_("not enough arguments"));
     }
   else if (parameters == NULL)
-    this->report_error(_("too many arguments"));
+    {
+      if (!is_method || this->args_->size() > 1)
+	this->report_error(_("too many arguments"));
+    }
   else
     {
       int i = 0;
-      Typed_identifier_list::const_iterator pt = parameters->begin();
-      for (Expression_list::const_iterator pa = this->args_->begin();
-	   pa != this->args_->end();
-	   ++pa, ++pt, ++i)
-	{
-	  if (pt == parameters->end())
+      Expression_list::const_iterator pa = this->args_->begin();
+      if (is_method)
+	++pa;
+      for (Typed_identifier_list::const_iterator pt = parameters->begin();
+	   pt != parameters->end();
+	   ++pt, ++pa, ++i)
+	{
+	  if (pa == this->args_->end())
 	    {
-	      this->report_error(_("too many arguments"));
+	      this->report_error(_("not enough arguments"));
 	      return;
 	    }
 	  this->check_argument_type(i + 1, pt->type(), (*pa)->type(),
 				    (*pa)->location(), false);
 	}
-      if (pt != parameters->end())
-	this->report_error(_("not enough arguments"));
+      if (pa != this->args_->end())
+	this->report_error(_("too many arguments"));
     }
 }
 
@@ -9247,83 +9343,6 @@ 
   return this->result_count() > 0;
 }
 
-// Get the function and the first argument to use when calling a bound
-// method.
-
-tree
-Call_expression::bound_method_function(Translate_context* context,
-				       Bound_method_expression* bound_method,
-				       tree* first_arg_ptr)
-{
-  Gogo* gogo = context->gogo();
-  source_location loc = this->location();
-
-  Expression* first_argument = bound_method->first_argument();
-  tree first_arg = first_argument->get_tree(context);
-  if (first_arg == error_mark_node)
-    return error_mark_node;
-
-  // We always pass a pointer to the first argument when calling a
-  // method.
-  if (first_argument->type()->points_to() == NULL)
-    {
-      tree pointer_to_arg_type = build_pointer_type(TREE_TYPE(first_arg));
-      if (TREE_ADDRESSABLE(TREE_TYPE(first_arg))
-	  || DECL_P(first_arg)
-	  || TREE_CODE(first_arg) == INDIRECT_REF
-	  || TREE_CODE(first_arg) == COMPONENT_REF)
-	{
-	  first_arg = build_fold_addr_expr_loc(loc, first_arg);
-	  if (DECL_P(first_arg))
-	    TREE_ADDRESSABLE(first_arg) = 1;
-	}
-      else
-	{
-	  tree tmp = create_tmp_var(TREE_TYPE(first_arg),
-				    get_name(first_arg));
-	  DECL_IGNORED_P(tmp) = 0;
-	  DECL_INITIAL(tmp) = first_arg;
-	  first_arg = build2_loc(loc, COMPOUND_EXPR, pointer_to_arg_type,
-				 build1_loc(loc, DECL_EXPR, void_type_node,
-					    tmp),
-				 build_fold_addr_expr_loc(loc, tmp));
-	  TREE_ADDRESSABLE(tmp) = 1;
-	}
-      if (first_arg == error_mark_node)
-	return error_mark_node;
-    }
-
-  Type* fatype = bound_method->first_argument_type();
-  if (fatype != NULL)
-    {
-      if (fatype->points_to() == NULL)
-	fatype = Type::make_pointer_type(fatype);
-      Btype* bfatype = fatype->get_backend(gogo);
-      first_arg = fold_convert_loc(loc, type_to_tree(bfatype), first_arg);
-      if (first_arg == error_mark_node
-	  || TREE_TYPE(first_arg) == error_mark_node)
-	return error_mark_node;
-    }
-
-  *first_arg_ptr = first_arg;
-
-  Named_object* method = bound_method->method();
-  tree id = method->get_id(gogo);
-  if (id == error_mark_node)
-    return error_mark_node;
-
-  tree fndecl;
-  if (method->is_function())
-    fndecl = method->func_value()->get_or_make_decl(gogo, method, id);
-  else if (method->is_function_declaration())
-    fndecl = method->func_declaration_value()->get_or_make_decl(gogo, method,
-								id);
-  else
-    go_unreachable();
-
-  return build_fold_addr_expr_loc(loc, fndecl);
-}
-
 // Get the function and the first argument to use when calling an
 // interface method.
 
@@ -9363,35 +9382,46 @@ 
   source_location location = this->location();
 
   Func_expression* func = this->fn_->func_expression();
-  Bound_method_expression* bound_method = this->fn_->bound_method_expression();
   Interface_field_reference_expression* interface_method =
     this->fn_->interface_field_reference_expression();
   const bool has_closure = func != NULL && func->closure() != NULL;
-  const bool is_method = bound_method != NULL || interface_method != NULL;
-  go_assert(!fntype->is_method() || is_method);
+  const bool is_interface_method = interface_method != NULL;
 
   int nargs;
   tree* args;
   if (this->args_ == NULL || this->args_->empty())
     {
-      nargs = is_method ? 1 : 0;
+      nargs = is_interface_method ? 1 : 0;
       args = nargs == 0 ? NULL : new tree[nargs];
     }
+  else if (fntype->parameters() == NULL || fntype->parameters()->empty())
+    {
+      // Passing a receiver parameter.
+      go_assert(!is_interface_method
+		&& fntype->is_method()
+		&& this->args_->size() == 1);
+      nargs = 1;
+      args = new tree[nargs];
+      args[0] = this->args_->front()->get_tree(context);
+    }
   else
     {
       const Typed_identifier_list* params = fntype->parameters();
-      go_assert(params != NULL);
 
       nargs = this->args_->size();
-      int i = is_method ? 1 : 0;
+      int i = is_interface_method ? 1 : 0;
       nargs += i;
       args = new tree[nargs];
 
       Typed_identifier_list::const_iterator pp = params->begin();
-      Expression_list::const_iterator pe;
-      for (pe = this->args_->begin();
-	   pe != this->args_->end();
-	   ++pe, ++pp, ++i)
+      Expression_list::const_iterator pe = this->args_->begin();
+      if (!is_interface_method && fntype->is_method())
+	{
+	  args[i] = (*pe)->get_tree(context);
+	  ++pe;
+	  ++i;
+	}
+      for (; pe != this->args_->end(); ++pe, ++pp, ++i)
 	{
 	  go_assert(pp != params->end());
 	  tree arg_val = (*pe)->get_tree(context);
@@ -9420,14 +9450,10 @@ 
   tree fn;
   if (has_closure)
     fn = func->get_tree_without_closure(gogo);
-  else if (!is_method)
+  else if (!is_interface_method)
     fn = this->fn_->get_tree(context);
-  else if (bound_method != NULL)
-    fn = this->bound_method_function(context, bound_method, &args[0]);
-  else if (interface_method != NULL)
+  else
     fn = this->interface_method_function(context, interface_method, &args[0]);
-  else
-    go_unreachable();
 
   if (fn == error_mark_node || TREE_TYPE(fn) == error_mark_node)
     {
diff -r 5097a3ef0927 go/expressions.h
--- a/go/expressions.h	Mon Aug 29 15:00:07 2011 -0700
+++ b/go/expressions.h	Mon Aug 29 15:02:20 2011 -0700
@@ -1244,6 +1244,11 @@ 
   is_varargs() const
   { return this->is_varargs_; }
 
+  // Note that varargs have already been lowered.
+  void
+  set_varargs_are_lowered()
+  { this->varargs_are_lowered_ = true; }
+
   // Whether this call is being deferred.
   bool
   is_deferred() const
@@ -1307,7 +1312,7 @@ 
   { this->args_ = args; }
 
   // Let a builtin expression lower varargs.
-  Expression*
+  void
   lower_varargs(Gogo*, Named_object* function, Statement_inserter* inserter,
 		Type* varargs_type, size_t param_count);
 
@@ -1324,9 +1329,6 @@ 
   check_argument_type(int, const Type*, const Type*, source_location, bool);
 
   tree
-  bound_method_function(Translate_context*, Bound_method_expression*, tree*);
-
-  tree
   interface_method_function(Translate_context*,
 			    Interface_field_reference_expression*,
 			    tree*);
diff -r 5097a3ef0927 go/statements.cc
--- a/go/statements.cc	Mon Aug 29 15:00:07 2011 -0700
+++ b/go/statements.cc	Mon Aug 29 15:02:20 2011 -0700
@@ -1858,8 +1858,7 @@ 
   // If this calls something which is not a simple function, then we
   // need a thunk.
   Expression* fn = this->call_->call_expression()->fn();
-  if (fn->bound_method_expression() != NULL
-      || fn->interface_field_reference_expression() != NULL)
+  if (fn->interface_field_reference_expression() != NULL)
     return false;
 
   return true;
@@ -1914,14 +1913,6 @@ 
 	this->report_error("expected call expression");
       return;
     }
-  Function_type* fntype = ce->get_function_type();
-  if (fntype != NULL && fntype->is_method())
-    {
-      Expression* fn = ce->fn();
-      if (fn->bound_method_expression() == NULL
-	  && fn->interface_field_reference_expression() == NULL)
-	this->report_error(_("no object for method call"));
-    }
 }
 
 // The Traverse class used to find and simplify thunk statements.
@@ -2005,8 +1996,7 @@ 
   Expression* fn = ce->fn();
   if (fn->func_expression() != NULL)
     return fn->func_expression()->closure() == NULL;
-  if (fn->bound_method_expression() != NULL
-      || fn->interface_field_reference_expression() != NULL)
+  if (fn->interface_field_reference_expression() != NULL)
     return true;
   return false;
 }
@@ -2048,7 +2038,6 @@ 
     return false;
 
   Expression* fn = ce->fn();
-  Bound_method_expression* bound_method = fn->bound_method_expression();
   Interface_field_reference_expression* interface_method =
     fn->interface_field_reference_expression();
 
@@ -2071,30 +2060,6 @@ 
   if (interface_method != NULL)
     vals->push_back(interface_method->expr());
 
-  if (bound_method != NULL)
-    {
-      Expression* first_arg = bound_method->first_argument();
-
-      // We always pass a pointer when calling a method.
-      if (first_arg->type()->points_to() == NULL)
-	first_arg = Expression::make_unary(OPERATOR_AND, first_arg, location);
-
-      // If we are calling a method which was inherited from an
-      // embedded struct, and the method did not get a stub, then the
-      // first type may be wrong.
-      Type* fatype = bound_method->first_argument_type();
-      if (fatype != NULL)
-	{
-	  if (fatype->points_to() == NULL)
-	    fatype = Type::make_pointer_type(fatype);
-	  Type* unsafe = Type::make_pointer_type(Type::make_void_type());
-	  first_arg = Expression::make_cast(unsafe, first_arg, location);
-	  first_arg = Expression::make_cast(fatype, first_arg, location);
-	}
-
-      vals->push_back(first_arg);
-    }
-
   if (ce->args() != NULL)
     {
       for (Expression_list::const_iterator p = ce->args()->begin();
@@ -2186,19 +2151,6 @@ 
       fields->push_back(Struct_field(tid));
     }
 
-  // If this is a method call, pass down the expression we are
-  // calling.
-  if (fn->bound_method_expression() != NULL)
-    {
-      go_assert(fntype->is_method());
-      Type* rtype = fntype->receiver()->type();
-      // We always pass the receiver as a pointer.
-      if (rtype->points_to() == NULL)
-	rtype = Type::make_pointer_type(rtype);
-      Typed_identifier tid("receiver", rtype, location);
-      fields->push_back(Struct_field(tid));
-    }
-
   // The predeclared recover function has no argument.  However, we
   // add an argument when building recover thunks.  Handle that here.
   if (ce->is_recover_call())
@@ -2317,7 +2269,6 @@ 
   thunk_parameter = Expression::make_unary(OPERATOR_MULT, thunk_parameter,
 					   location);
 
-  Bound_method_expression* bound_method = ce->fn()->bound_method_expression();
   Interface_field_reference_expression* interface_method =
     ce->fn()->interface_field_reference_expression();
 
@@ -2335,16 +2286,7 @@ 
       next_index = 1;
     }
 
-  if (bound_method != NULL)
-    {
-      go_assert(next_index == 0);
-      Expression* r = Expression::make_field_reference(thunk_parameter, 0,
-						       location);
-      func_to_call = Expression::make_bound_method(r, bound_method->method(),
-						   location);
-      next_index = 1;
-    }
-  else if (interface_method != NULL)
+  if (interface_method != NULL)
     {
       // The main program passes the interface object.
       go_assert(next_index == 0);
@@ -2389,6 +2331,13 @@ 
 
   Call_expression* call = Expression::make_call(func_to_call, call_params,
 						false, location);
+
+  // This call expression was already lowered before entering the
+  // thunk statement.  Don't try to lower varargs again, as that will
+  // cause confusion for, e.g., method calls which already have a
+  // receiver parameter.
+  call->set_varargs_are_lowered();
+
   Statement* call_statement = Statement::make_statement(call);
 
   gogo->add_statement(call_statement);