Make Scanner::kNoSourcePos be a true sentinel value

runtime/vm/object.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/object.h"
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "vm/assembler.h"
 #include "vm/cpu.h"
@@ skipping 3431 matching lines @@
   UNREACHABLE();
 }
 
 
 void Class::set_script(const Script& value) const {
   StorePointer(&raw_ptr()->script_, value.raw());
 }
 
 
 void Class::set_token_pos(intptr_t token_pos) const {
-  ASSERT(token_pos >= 0);
+  ASSERT(Scanner::ValidSourcePosition(token_pos));

[hausner, 2016/01/05 22:30:50]

Can there be classes with kNoSourcePos?
Ditto for the other setters below.

[Cutch, 2016/01/06 15:42:19]

When first being constructed (Class::New) we set it to Scanner::kNoSourcePos.
Similarly for other objects.

   StoreNonPointer(&raw_ptr()->token_pos_, token_pos);
 }
 
 
 intptr_t Class::ComputeEndTokenPos() const {
   // Return the begin token for synthetic classes.
   if (IsSignatureClass() || IsMixinApplication() || IsTopLevel()) {
     return token_pos();
   }
   const Script& scr = Script::Handle(script());
@@ skipping 909 matching lines @@
 RawUnresolvedClass* UnresolvedClass::New() {
   ASSERT(Object::unresolved_class_class() != Class::null());
   RawObject* raw = Object::Allocate(UnresolvedClass::kClassId,
                                     UnresolvedClass::InstanceSize(),
                                     Heap::kOld);
   return reinterpret_cast<RawUnresolvedClass*>(raw);
 }
 
 
 void UnresolvedClass::set_token_pos(intptr_t token_pos) const {
-  ASSERT(token_pos >= 0);
+  ASSERT(Scanner::ValidSourcePosition(token_pos));
   StoreNonPointer(&raw_ptr()->token_pos_, token_pos);
 }
 
 
 void UnresolvedClass::set_ident(const String& ident) const {
   StorePointer(&raw_ptr()->ident_, ident.raw());
 }
 
 
 void UnresolvedClass::set_library_prefix(
@@ skipping 10172 matching lines @@
 void LanguageError::set_previous_error(const Error& value) const {
   StorePointer(&raw_ptr()->previous_error_, value.raw());
 }
 
 
 void LanguageError::set_script(const Script& value) const {
   StorePointer(&raw_ptr()->script_, value.raw());
 }
 
 
-void LanguageError::set_token_pos(intptr_t value) const {
-  ASSERT(value >= 0);
-  StoreNonPointer(&raw_ptr()->token_pos_, value);
+void LanguageError::set_token_pos(intptr_t token_pos) const {
+  ASSERT(Scanner::ValidSourcePosition(token_pos));
+  StoreNonPointer(&raw_ptr()->token_pos_, token_pos);
 }
 
 
 void LanguageError::set_kind(uint8_t value) const {
   StoreNonPointer(&raw_ptr()->kind_, value);
 }
 
 
 void LanguageError::set_message(const String& value) const {
   StorePointer(&raw_ptr()->message_, value.raw());
@@ skipping 1794 matching lines @@
   const Type& result = Type::Handle(Type::New(space));
   result.set_type_class(clazz);
   result.set_arguments(arguments);
   result.set_token_pos(token_pos);
   result.StoreNonPointer(&result.raw_ptr()->type_state_, RawType::kAllocated);
   return result.raw();
 }
 
 
 void Type::set_token_pos(intptr_t token_pos) const {
-  ASSERT(token_pos >= 0);
+  ASSERT(Scanner::ValidSourcePosition(token_pos));
   StoreNonPointer(&raw_ptr()->token_pos_, token_pos);
 }
 
 
 void Type::set_type_state(int8_t state) const {
   ASSERT((state >= RawType::kAllocated) &&
          (state <= RawType::kFinalizedUninstantiated));
   StoreNonPointer(&raw_ptr()->type_state_, state);
 }
 
@@ skipping 410 matching lines @@
   result.set_name(name);
   result.set_bound(bound);
   result.set_token_pos(token_pos);
   result.StoreNonPointer(&result.raw_ptr()->type_state_,
                          RawTypeParameter::kAllocated);
   return result.raw();
 }
 
 
 void TypeParameter::set_token_pos(intptr_t token_pos) const {
-  ASSERT(token_pos >= 0);
+  ASSERT(Scanner::ValidSourcePosition(token_pos));
   StoreNonPointer(&raw_ptr()->token_pos_, token_pos);
 }
 
 
 void TypeParameter::set_type_state(int8_t state) const {
   ASSERT((state == RawTypeParameter::kAllocated) ||
          (state == RawTypeParameter::kBeingFinalized) ||
          (state == RawTypeParameter::kFinalizedUninstantiated));
   StoreNonPointer(&raw_ptr()->type_state_, state);
 }
@@ skipping 4741 matching lines @@
                                    const Function& function,
                                    const Code& code,
                                    intptr_t frame_index) {
   const intptr_t token_pos = code.GetTokenIndexOfPC(pc);
   const Script& script = Script::Handle(zone, function.script());
   const String& function_name =
       String::Handle(zone, function.QualifiedUserVisibleName());
   const String& url = String::Handle(zone, script.url());
   intptr_t line = -1;
   intptr_t column = -1;
-  if (token_pos > 0) {
+  if (token_pos >= 0) {
     if (script.HasSource()) {
       script.GetTokenLocation(token_pos, &line, &column);
     } else {
       script.GetTokenLocation(token_pos, &line, NULL);
     }
   }
   char* chars = NULL;
   if (column >= 0) {
     chars = OS::SCreate(zone,
         "#%-6" Pd " %s (%s:%" Pd ":%" Pd ")\n",
@@ skipping 445 matching lines @@
   return tag_label.ToCString();
 }
 
 
 void UserTag::PrintJSONImpl(JSONStream* stream, bool ref) const {
   Instance::PrintJSONImpl(stream, ref);
 }
 
 
 }  // namespace dart