tools/gn: don't allow trailing junk or non-literals in "value" conversion

tools/gn/input_conversion.cc

 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "tools/gn/input_conversion.h"
 
 #include "base/strings/string_split.h"
 #include "base/strings/string_util.h"
 #include "tools/gn/build_settings.h"
 #include "tools/gn/err.h"
@@ skipping 41 matching lines @@
   } else {
     input_file->set_friendly_name("dynamic input");
   }
 
   *tokens = Tokenizer::Tokenize(input_file, err);
   if (err->has_error())
     return Value();
 
   // Parse the file according to what we're looking for.
   if (what == PARSE_VALUE)
-    *parse_root_ptr = Parser::ParseExpression(*tokens, err);
+    *parse_root_ptr = Parser::ParseValue(*tokens, err);
   else
     *parse_root_ptr = Parser::Parse(*tokens, err);  // Will return a Block.
   if (err->has_error())
     return Value();
   ParseNode* parse_root = parse_root_ptr->get();  // For nicer syntax below.
 
   // It's valid for the result to be a null pointer, this just means that the
   // script returned nothing.
   if (!parse_root)
     return Value();
 
-  // When parsing as a value, the result should either be a list or a literal,
-  // anything else is invalid.
-  if (what == PARSE_VALUE) {
-    if (!parse_root->AsList() && !parse_root->AsLiteral())
-      return Value();
-  }
-
   scoped_ptr<Scope> scope(new Scope(settings));
-
   Value result = parse_root->Execute(scope.get(), err);
   if (err->has_error())
     return Value();
 
   // When we want the result as a scope, the result is actually the scope
   // we made, rather than the result of running the block (which will be empty).
   if (what == PARSE_SCOPE) {
     DCHECK(result.type() == Value::NONE);
     result = Value(origin, scope.Pass());
   }
@@ skipping 115 matching lines @@
                           const ParseNode* origin,
                           const Value& input_conversion_value,
                           Err* err) {
   if (input_conversion_value.type() == Value::NONE)
     return Value();  // Allow null inputs to mean discard the result.
   if (!input_conversion_value.VerifyTypeIs(Value::STRING, err))
     return Value();
   return DoConvertInputToValue(settings, input, origin, input_conversion_value,
                                input_conversion_value.string_value(), err);
 }