Serialize typedef parameters (including function typed ones) to Kernel and use it to resynthesize t…

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

Index: pkg/analyzer/lib/src/dart/element/element.dart
diff --git a/pkg/analyzer/lib/src/dart/element/element.dart b/pkg/analyzer/lib/src/dart/element/element.dart
index dbff10ebee74a66d83473c08b8d2c53d74dbab38..ebd1f63a559a4f28940bff5542e05217321b9137 100644
--- a/pkg/analyzer/lib/src/dart/element/element.dart
+++ b/pkg/analyzer/lib/src/dart/element/element.dart
@@ -1683,6 +1683,11 @@ class CompilationUnitElementImpl extends UriReferencedElementImpl
 
   @override
   List<FunctionTypeAliasElement> get functionTypeAliases {
+    if (_kernelContext != null) {
+      _typeAliases ??= _kernelContext.library.typedefs
+          .map((k) => new FunctionTypeAliasElementImpl.forKernel(this, k))
+          .toList(growable: false);
+    }
     if (_unlinkedUnit != null) {
       _typeAliases ??= _unlinkedUnit.typedefs.map((t) {
         if (t.style == TypedefStyle.functionType) {
@@ -4921,6 +4926,11 @@ class FunctionTypeAliasElementImpl extends ElementImpl
   final UnlinkedTypedef _unlinkedTypedef;
 
   /**
+   * The kernel of the element.
+   */
+  final kernel.Typedef _kernel;
+
+  /**
    * A list containing all of the parameters defined by this type alias.
    */
   List<ParameterElement> _parameters;
@@ -4944,13 +4954,23 @@ class FunctionTypeAliasElementImpl extends ElementImpl
    */
   FunctionTypeAliasElementImpl(String name, int nameOffset)
       : _unlinkedTypedef = null,
+        _kernel = null,
         super(name, nameOffset);
 
   /**
+   * Initialize using the given kernel.
+   */
+  FunctionTypeAliasElementImpl.forKernel(
+      CompilationUnitElementImpl enclosingUnit, this._kernel)
+      : _unlinkedTypedef = null,
+        super.forSerialized(enclosingUnit);
+
+  /**
    * Initialize a newly created type alias element to have the given [name].
    */
   FunctionTypeAliasElementImpl.forNode(Identifier name)
       : _unlinkedTypedef = null,
+        _kernel = null,
         super.forNode(name);
 
   /**
@@ -4958,7 +4978,8 @@ class FunctionTypeAliasElementImpl extends ElementImpl
    */
   FunctionTypeAliasElementImpl.forSerialized(
       this._unlinkedTypedef, CompilationUnitElementImpl enclosingUnit)
-      : super.forSerialized(enclosingUnit);
+      : _kernel = null,
+        super.forSerialized(enclosingUnit);
 
   @override
   int get codeLength {
@@ -4999,7 +5020,7 @@ class FunctionTypeAliasElementImpl extends ElementImpl
       _enclosingElement as CompilationUnitElementImpl;
 
   @override
-  List<kernel.TypeParameter> get kernelTypeParams => null;
+  List<kernel.TypeParameter> get kernelTypeParams => _kernel?.typeParameters;
 
   @override
   ElementKind get kind => ElementKind.FUNCTION_TYPE_ALIAS;
@@ -5015,6 +5036,9 @@ class FunctionTypeAliasElementImpl extends ElementImpl
 
   @override
   String get name {
+    if (_kernel != null) {
+      return _kernel.name;
+    }
     if (_unlinkedTypedef != null) {
       return _unlinkedTypedef.name;
     }
@@ -5032,6 +5056,13 @@ class FunctionTypeAliasElementImpl extends ElementImpl
 
   @override
   List<ParameterElement> get parameters {
+    if (_kernel != null) {
+      _parameters ??= ParameterElementImpl.forKernelParameters(
+          this,
+          _kernel.requiredParameterCount,
+          _kernel.positionalParameters,
+          _kernel.namedParameters);
+    }
     if (_unlinkedTypedef != null) {
       _parameters ??= ParameterElementImpl.resynthesizeList(
           _unlinkedTypedef.parameters, this);
@@ -5054,10 +5085,17 @@ class FunctionTypeAliasElementImpl extends ElementImpl
 
   @override
   DartType get returnType {
-    if (_unlinkedTypedef != null && _returnType == null) {
-      _returnType = enclosingUnit.resynthesizerContext.resolveTypeRef(
-          this, _unlinkedTypedef.returnType,
-          declaredType: true);
+    if (_returnType == null) {
+      if (_kernel != null) {
+        var type = _kernel.type as kernel.FunctionType;
+        _returnType =
+            enclosingUnit._kernelContext.getType(this, type.returnType);
+      }
+      if (_unlinkedTypedef != null) {
+        _returnType = enclosingUnit.resynthesizerContext.resolveTypeRef(
+            this, _unlinkedTypedef.returnType,
+            declaredType: true);
+      }
     }
     return _returnType;
   }
@@ -5069,8 +5107,10 @@ class FunctionTypeAliasElementImpl extends ElementImpl
 
   @override
   FunctionType get type {
-    if (_unlinkedTypedef != null && _type == null) {
-      _type = new FunctionTypeImpl.forTypedef(this);
+    if (_type == null) {
+      if (_kernel != null || _unlinkedTypedef != null) {
+        _type = new FunctionTypeImpl.forTypedef(this);
+      }
     }
     return _type;
   }