Remove recently introduced FunctionType vm class by merging it into class Type.

runtime/vm/raw_object.h

 // 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.
 
 #ifndef VM_RAW_OBJECT_H_
 #define VM_RAW_OBJECT_H_
 
 #include "platform/assert.h"
 #include "vm/atomic.h"
 #include "vm/globals.h"
@@ skipping 34 matching lines @@
   V(SubtypeTestCache)                                                          \
   V(Error)                                                                     \
     V(ApiError)                                                                \
     V(LanguageError)                                                           \
     V(UnhandledException)                                                      \
     V(UnwindError)                                                             \
   V(Instance)                                                                  \
     V(LibraryPrefix)                                                           \
     V(AbstractType)                                                            \
       V(Type)                                                                  \
-      V(FunctionType)                                                          \
       V(TypeRef)                                                               \
       V(TypeParameter)                                                         \
       V(BoundedType)                                                           \
       V(MixinAppType)                                                          \
     V(Closure)                                                                 \
     V(Number)                                                                  \
       V(Integer)                                                               \
         V(Smi)                                                                 \
         V(Mint)                                                                \
         V(Bigint)                                                              \
@@ skipping 795 matching lines @@
 
 class RawClosureData : public RawObject {
  private:
   RAW_HEAP_OBJECT_IMPLEMENTATION(ClosureData);
 
   RawObject** from() {
     return reinterpret_cast<RawObject**>(&ptr()->context_scope_);
   }
   RawContextScope* context_scope_;
   RawFunction* parent_function_;  // Enclosing function of this local function.
-  RawFunctionType* signature_type_;
+  RawType* signature_type_;
   RawInstance* closure_;  // Closure object for static implicit closures.
   RawObject** to() {
     return reinterpret_cast<RawObject**>(&ptr()->closure_);
   }
 
   friend class Function;
 };
 
 
 class RawRedirectionData : public RawObject {
@@ skipping 728 matching lines @@
 
 class RawType : public RawAbstractType {
  private:
   RAW_HEAP_OBJECT_IMPLEMENTATION(Type);
 
   RawObject** from() {
     return reinterpret_cast<RawObject**>(&ptr()->type_class_);
   }
   RawObject* type_class_;  // Either resolved class or unresolved class.
   RawTypeArguments* arguments_;
-  RawLanguageError* error_;  // Error object if type is malformed or malbounded.
+  // This type object represents a function type if its signature field is a
+  // non-null function object.
+  // If this type is malformed or malbounded, the signature field gets
+  // overwritten by the error object in order to save space. If the type is a
+  // function type, its signature is lost, but the message in the error object
+  // can describe the issue without needing the signature.
+  union {
+    RawFunction* signature_;  // If not null, this type is a function type.
+    RawLanguageError* error_;  // If not null, type is malformed or malbounded.
+  } sig_or_err_;
   RawObject** to() {
-    return reinterpret_cast<RawObject**>(&ptr()->error_);
+    return reinterpret_cast<RawObject**>(&ptr()->sig_or_err_.error_);
   }
   TokenPosition token_pos_;
   int8_t type_state_;
-};
-
-
-class RawFunctionType : public RawAbstractType {
- private:
-  RAW_HEAP_OBJECT_IMPLEMENTATION(FunctionType);
-
-  RawObject** from() {
-    return reinterpret_cast<RawObject**>(&ptr()->scope_class_);
-  }
-  RawClass* scope_class_;
-  RawTypeArguments* arguments_;
-  RawFunction* signature_;
-  RawLanguageError* error_;  // Error object if type is malformed or malbounded.
-  RawObject** to() {
-    return reinterpret_cast<RawObject**>(&ptr()->error_);
-  }
-  TokenPosition token_pos_;
-  int8_t type_state_;
 };
 
 
 class RawTypeRef : public RawAbstractType {
  private:
   RAW_HEAP_OBJECT_IMPLEMENTATION(TypeRef);
 
   RawObject** from() {
     return reinterpret_cast<RawObject**>(&ptr()->type_);
   }
@@ skipping 716 matching lines @@
   COMPILE_ASSERT(kExternalTypedDataInt8ArrayCid ==
                  kTypedDataInt8ArrayViewCid + 15);
   COMPILE_ASSERT(kByteBufferCid == kExternalTypedDataInt8ArrayCid + 14);
   COMPILE_ASSERT(kNullCid == kByteBufferCid + 1);
   return (kNullCid - kTypedDataInt8ArrayCid);
 }
 
 }  // namespace dart
 
 #endif  // VM_RAW_OBJECT_H_