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

runtime/vm/debugger.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/debugger.h"
 
 #include "include/dart_api.h"
 
 #include "vm/code_generator.h"
 #include "vm/code_patcher.h"
@@ skipping 1722 matching lines @@
   ASSERT(!code.IsNull());
   PcDescriptors& desc = PcDescriptors::Handle(code.pc_descriptors());
 
   // First pass: find the safe point which is closest to the beginning
   // of the given token range.
   intptr_t best_fit_pos = INT_MAX;
   intptr_t best_column = INT_MAX;
   PcDescriptors::Iterator iter(desc, kSafepointKind);
   while (iter.MoveNext()) {
     const intptr_t pos = iter.TokenPos();
-    if ((pos == Scanner::kNoSourcePos) ||
+    if ((pos < 0) ||
         (pos < requested_token_pos) ||
         (pos > last_token_pos)) {
       // Token is not in the target range.
       continue;
     }
 
     intptr_t token_start_column = -1;
     if (requested_column >= 0) {
       intptr_t ignored = -1;
       intptr_t token_len = -1;
@@ skipping 25 matching lines @@
   // was specified) and has the lowest code address.
   if (best_fit_pos != INT_MAX) {
     const Script& script = Script::Handle(func.script());
     const TokenStream& tokens = TokenStream::Handle(script.tokens());
     const intptr_t begin_pos = best_fit_pos;
     const intptr_t end_of_line_pos = LastTokenOnLine(tokens, begin_pos);
     uword lowest_pc_offset = kUwordMax;
     PcDescriptors::Iterator iter(desc, kSafepointKind);
     while (iter.MoveNext()) {
       const intptr_t pos = iter.TokenPos();
-      if ((pos == Scanner::kNoSourcePos) ||
+      if ((pos < 0) ||
           (pos < begin_pos) ||
           (pos > end_of_line_pos)) {
         // Token is not on same line as best fit.
         continue;
       }
 
       if (requested_column >= 0) {
         intptr_t ignored = -1;
         intptr_t token_start_column = -1;
         // We look for other tokens at the best column in case there
@@ skipping 20 matching lines @@
   if (last_token_pos < func.end_token_pos()) {
     return ResolveBreakpointPos(func, last_token_pos, func.end_token_pos(),
                                 -1 /* no column */);
   }
   return -1;
 }
 
 
 void Debugger::MakeCodeBreakpointAt(const Function& func,
                                     BreakpointLocation* loc) {
-  ASSERT(loc->token_pos_ != Scanner::kNoSourcePos);
+  ASSERT(loc->token_pos_ >= 0);
   ASSERT((loc != NULL) && loc->IsResolved());
   ASSERT(!func.HasOptimizedCode());
   Code& code = Code::Handle(func.unoptimized_code());
   ASSERT(!code.IsNull());
   PcDescriptors& desc = PcDescriptors::Handle(code.pc_descriptors());
   uword lowest_pc_offset = kUwordMax;
   RawPcDescriptors::Kind lowest_kind = RawPcDescriptors::kAnyKind;
   // Find the safe point with the lowest compiled code address
   // that maps to the token position of the source breakpoint.
   PcDescriptors::Iterator iter(desc, kSafepointKind);
@@ skipping 793 matching lines @@
       // We returned from the "interesting frame", there can be no more
       // stepping breaks for it. Pause at the next appropriate location
       // and let the user set the "interesting" frame again.
       stepping_fp_ = 0;
     }
   }
 
   if (!frame->IsDebuggable()) {
     return Error::null();
   }
-  if (frame->TokenPos() == Scanner::kNoSourcePos) {
+  if (frame->TokenPos() < 0) {
     return Error::null();
   }
 
   // Don't pause for a single step if there is a breakpoint set
   // at this location.
   if (HasActiveBreakpoint(frame->pc())) {
     return Error::null();
   }
 
   if (FLAG_verbose_debug) {
@@ skipping 588 matching lines @@
 }
 
 
 void Debugger::RegisterCodeBreakpoint(CodeBreakpoint* bpt) {
   ASSERT(bpt->next() == NULL);
   bpt->set_next(code_breakpoints_);
   code_breakpoints_ = bpt;
 }
 
 }  // namespace dart