Don't test directly against Scanner::kNoSourcePos instead use >= 0.

runtime/vm/flow_graph_builder.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/flow_graph_builder.h"
 
 #include "lib/invocation_mirror.h"
 #include "vm/ast_printer.h"
 #include "vm/bit_vector.h"
 #include "vm/compiler.h"
@@ skipping 1098 matching lines @@
   Append(for_value);
   Value* return_value = for_value.value();
 
   // Call to stub that checks whether the debugger is in single
   // step mode. This call must happen before the contexts are
   // unchained so that captured variables can be inspected.
   // No debugger check is done in native functions or for return
   // statements for which there is no associated source position.
   const Function& function = owner()->function();
   if (FLAG_support_debugger &&
-      (node->token_pos() != Scanner::kNoSourcePos) && !function.is_native()) {
+      (node->token_pos() >= 0) && !function.is_native()) {
     AddInstruction(new(Z) DebugStepCheckInstr(node->token_pos(),
                                               RawPcDescriptors::kRuntimeCall));
   }
 
   NestedContextAdjustment context_adjustment(owner(), owner()->context_level());
 
   if (node->inlined_finally_list_length() > 0) {
     LocalVariable* temp = owner()->parsed_function().finally_return_temp_var();
     ASSERT(temp != NULL);
     Do(BuildStoreLocal(*temp, return_value));
@@ skipping 2487 matching lines @@
   // If the right hand side is an expression that does not contain
   // a safe point for the debugger to stop, add an explicit stub
   // call. Exception: don't do this when assigning to or from internal
   // variables, or for generated code that has no source position.
   if (FLAG_support_debugger) {
     if ((node->value()->IsLiteralNode() ||
         (node->value()->IsLoadLocalNode() &&
             !node->value()->AsLoadLocalNode()->local().IsInternal()) ||
         node->value()->IsClosureNode()) &&
         !node->local().IsInternal() &&
-        (node->token_pos() != Scanner::kNoSourcePos)) {
+        (node->token_pos() >= 0)) {
       AddInstruction(new(Z) DebugStepCheckInstr(
           node->token_pos(), RawPcDescriptors::kRuntimeCall));
     }
   }
 
   ValueGraphVisitor for_value(owner());
   node->value()->Visit(&for_value);
   Append(for_value);
   Value* store_value = for_value.value();
   if (Isolate::Current()->flags().type_checks()) {
@@ skipping 426 matching lines @@
     // Place a debug check at method entry to ensure breaking on a method always
     // happens, even if there are no assignments/calls/runtimecalls in the first
     // basic block. Place this check at the last parameter to ensure parameters
     // are in scope in the debugger at method entry.
     const int num_params = function.NumParameters();
     intptr_t check_pos = Scanner::kNoSourcePos;
     if (num_params > 0) {
       const LocalVariable& parameter = *scope->VariableAt(num_params - 1);
       check_pos = parameter.token_pos();
     }
-    if (check_pos == Scanner::kNoSourcePos) {
+    if (check_pos < 0) {
       // No parameters or synthetic parameters.
       check_pos = node->token_pos();
-      ASSERT(check_pos != Scanner::kNoSourcePos);
+      ASSERT(check_pos >= 0);
     }
     AddInstruction(new(Z) DebugStepCheckInstr(check_pos,
                                               RawPcDescriptors::kRuntimeCall));
   }
 
   // This check may be deleted if the generated code is leaf.
   // Native functions don't need a stack check at entry.
   if (is_top_level_sequence && !function.is_native()) {
     // Always allocate CheckOverflowInstr so that deopt-ids match regardless
     // if we inline or not.
@@ skipping 525 matching lines @@
   Report::MessageF(Report::kBailout,
                    Script::Handle(function.script()),
                    function.token_pos(),
                    "FlowGraphBuilder Bailout: %s %s",
                    String::Handle(function.name()).ToCString(),
                    reason);
   UNREACHABLE();
 }
 
 }  // namespace dart