Add optional FunctionType.positionalParameterNames and use them to resynthesize function-type forma…

pkg/analyzer/lib/src/dart/element/element.dart

 // Copyright (c) 2014, 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.
 
 library analyzer.src.dart.element.element;
 
 import 'dart:collection';
 import 'dart:math' show min;
 
 import 'package:analyzer/dart/ast/ast.dart';
@@ skipping 8085 matching lines @@
    */
   void set parameters(List<ParameterElement> parameters) {
     for (ParameterElement parameter in parameters) {
       (parameter as ParameterElementImpl).enclosingElement = this;
     }
     this._parameters = parameters;
   }
 
   @override
   DartType get type {
-    if (_kernel != null) {
-      return _type ??= enclosingUnit._kernelContext.getType(this, _kernel.type);
-    }
     _resynthesizeTypeAndParameters();
     return super.type;
   }
 
   @override
   TopLevelInferenceError get typeInferenceError {
     if (_unlinkedParam != null) {
       return enclosingUnit.resynthesizerContext
           .getTypeInferenceError(_unlinkedParam.inferredTypeSlot);
     }
@@ skipping 91 matching lines @@
   void visitChildren(ElementVisitor visitor) {
     super.visitChildren(visitor);
     safelyVisitChildren(parameters, visitor);
   }
 
   /**
    * If this element is resynthesized, and its type and parameters have not
    * been build yet, build them and remember in the corresponding fields.
    */
   void _resynthesizeTypeAndParameters() {
+    if (_kernel != null && _type == null) {
+      kernel.DartType type = _kernel.type;
+      _type = enclosingUnit._kernelContext.getType(this, type);
+      if (type is kernel.FunctionType) {
+        _parameters = new List<ParameterElement>(
+            type.positionalParameters.length + type.namedParameters.length);
+        int index = 0;
+        for (int i = 0; i < type.positionalParameters.length; i++) {
+          String name = i < type.positionalParameterNames.length
+              ? type.positionalParameterNames[i]
+              : null;
+          _parameters[index++] = new ParameterElementImpl.forKernel(
+              enclosingElement,
+              new kernel.VariableDeclaration(name,
+                  type: type.positionalParameters[i]),
+              i < type.requiredParameterCount
+                  ? ParameterKind.REQUIRED
+                  : ParameterKind.POSITIONAL);
+        }
+        for (int i = 0; i < type.namedParameters.length; i++) {
+          _parameters[index++] = new ParameterElementImpl.forKernel(
+              enclosingElement,
+              new kernel.VariableDeclaration(type.namedParameters[i].name,
+                  type: type.namedParameters[i].type),
+              ParameterKind.NAMED);
+        }
+      } else {
+        _parameters = const <ParameterElement>[];
+      }
+    }
     if (_unlinkedParam != null && _declaredType == null && _type == null) {
       if (_unlinkedParam.isFunctionTyped) {
         CompilationUnitElementImpl enclosingUnit = this.enclosingUnit;
         FunctionElementImpl parameterTypeElement =
             new FunctionElementImpl_forFunctionTypedParameter(
                 enclosingUnit, this);
         if (!isSynthetic) {
           parameterTypeElement.enclosingElement = this;
         }
         List<ParameterElement> subParameters = ParameterElementImpl
@@ skipping 1477 matching lines @@
 
   @override
   DartObject computeConstantValue() => null;
 
   @override
   void visitChildren(ElementVisitor visitor) {
     super.visitChildren(visitor);
     _initializer?.accept(visitor);
   }
 }