Changes for https://github.com/dart-lang/sdk/issues/27742 mark tear-offs using the id#x syntax as d…

runtime/vm/parser.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/parser.h"
 #include "vm/flags.h"
 
 #ifndef DART_PRECOMPILED_RUNTIME
 
 #include "lib/invocation_mirror.h"
@@ skipping 27 matching lines @@
 #include "vm/tags.h"
 #include "vm/timeline.h"
 #include "vm/timer.h"
 #include "vm/zone.h"
 
 namespace dart {
 
 DEFINE_FLAG(bool, enable_debug_break, false, "Allow use of break \"message\".");
 DEFINE_FLAG(bool, trace_parser, false, "Trace parser operations.");
 DEFINE_FLAG(bool, warn_mixin_typedef, true, "Warning on legacy mixin typedef.");
+DEFINE_FLAG(bool, warn_new_tearoff_syntax, true, "Warning on new tear off.");
 // TODO(floitsch): remove the conditional-directive flag, once we publicly
 // committed to the current version.
 DEFINE_FLAG(bool,
             conditional_directives,
             true,
             "Enable conditional directives");
 DEFINE_FLAG(bool, generic_method_syntax, false, "Enable generic functions.");
 DEFINE_FLAG(bool,
             initializing_formal_access,
             false,
@@ skipping 11600 matching lines @@
       return left;
     }
     ASSERT(selector != NULL);
     left = selector;
   }
 }
 
 
 // Closurization e#m of getter, setter, method or operator.
 AstNode* Parser::ParseClosurization(AstNode* primary) {
+  if (FLAG_warn_new_tearoff_syntax) {
+    ReportWarning(
+        "Tear-offs using the x#id syntax is a deprecated feature,"
+        "it will not be supported in the next release");
+  }
   ExpectToken(Token::kHASH);
   TokenPosition property_pos = TokenPos();
   bool is_setter_name = false;
 
   String& extractor_name = String::ZoneHandle(Z);
   if (IsIdentifier()) {
     extractor_name = CurrentLiteral()->raw();
     ConsumeToken();
     if (CurrentToken() == Token::kASSIGN) {
       ConsumeToken();
@@ skipping 1565 matching lines @@
       (la3 == Token::kLT) || (la3 == Token::kPERIOD) || (la3 == Token::kHASH);
   LibraryPrefix& prefix = LibraryPrefix::ZoneHandle(Z);
   AbstractType& type =
       AbstractType::Handle(Z, ParseType(ClassFinalizer::kCanonicalizeWellFormed,
                                         true,  // allow deferred type
                                         consume_unresolved_prefix, &prefix));
   // A constructor tear-off closure can only have been created for a
   // type that is loaded.
   ASSERT(prefix.IsNull() || prefix.is_loaded());
   ASSERT(!type.IsMalformed() && !type.IsTypeParameter());
+  if (FLAG_warn_new_tearoff_syntax) {
+    ReportWarning(
+        "Tear-offs using the x#id syntax is a deprecated feature,"
+        "it will not be supported in the next release");
+  }
   ExpectToken(Token::kHASH);
   String* named_constructor = NULL;
   if (IsIdentifier()) {
     named_constructor = CurrentLiteral();
     ConsumeToken();
   }
   // Resolve the type and optional identifier to a constructor or factory.
   Class& type_class = Class::Handle(Z, type.type_class());
   String& type_class_name = String::Handle(Z, type_class.Name());
   *type_arguments = type.arguments();
@@ skipping 78 matching lines @@
   // The type can be followed by an optional named constructor identifier.
   // Note that we tell ParseType() above not to consume it as part of
   // a misinterpreted qualified identifier. Only a valid library
   // prefix is accepted as qualifier.
   String* named_constructor = NULL;
   const bool is_tearoff_expression = (CurrentToken() == Token::kHASH);
   if (is_tearoff_expression) {
     if (is_const) {
       ReportError("tear-off closure not allowed with const allocation");
     }
+    if (FLAG_warn_new_tearoff_syntax) {
+      ReportWarning(
+          "Tear-offs using the x#id syntax is a deprecated feature,"
+          "and will not be supported in the next release");
+    }
     ConsumeToken();
     if (IsIdentifier()) {
       named_constructor = ExpectIdentifier("name of constructor expected");
     }
   } else if (CurrentToken() == Token::kPERIOD) {
     ConsumeToken();
     named_constructor = ExpectIdentifier("name of constructor expected");
   }
 
   // Parse constructor parameters.
@@ skipping 421 matching lines @@
     // The name of a literal function is visible from inside the function, but
     // must not collide with names in the scope declaring the literal.
     OpenBlock();
     primary = ParseFunctionStatement(true);
     CloseBlock();
   } else if (IsIdentifier()) {
     TokenPosition qual_ident_pos = TokenPos();
     const LibraryPrefix& prefix = LibraryPrefix::ZoneHandle(Z, ParsePrefix());
     if (!prefix.IsNull()) {
       if (CurrentToken() == Token::kHASH) {
+        if (FLAG_warn_new_tearoff_syntax) {
+          ReportWarning(
+              "Tear-offs using the x#id syntax is a deprecated feature,"
+              "it will not be supported in the next release");
+        }
         // Closurization of top-level entity in prefix scope.
         return new (Z) LiteralNode(qual_ident_pos, prefix);
       } else {
         ExpectToken(Token::kPERIOD);
       }
     }
     String& ident = *CurrentLiteral();
     ConsumeToken();
     if (prefix.IsNull()) {
       intptr_t primary_func_level = 0;
@@ skipping 683 matching lines @@
     const ArgumentListNode& function_args,
     const LocalVariable* temp_for_last_arg,
     bool is_super_invocation) {
   UNREACHABLE();
   return NULL;
 }
 
 }  // namespace dart
 
 #endif  // DART_PRECOMPILED_RUNTIME