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

pkg/front_end/lib/src/fasta/kernel/kernel_function_type_alias_builder.dart

Index: pkg/front_end/lib/src/fasta/kernel/kernel_function_type_alias_builder.dart
diff --git a/pkg/front_end/lib/src/fasta/kernel/kernel_function_type_alias_builder.dart b/pkg/front_end/lib/src/fasta/kernel/kernel_function_type_alias_builder.dart
index f8c928d71fca40d3834266ce3e85311abbe1aad9..419d9c67ed0a4a1dd8c135a26d6005dda7cd75c4 100644
--- a/pkg/front_end/lib/src/fasta/kernel/kernel_function_type_alias_builder.dart
+++ b/pkg/front_end/lib/src/fasta/kernel/kernel_function_type_alias_builder.dart
@@ -4,6 +4,8 @@
 
 library fasta.kernel_function_type_alias_builder;
 
+import 'package:front_end/src/fasta/kernel/kernel_function_type_builder.dart';
+import 'package:front_end/src/fasta/kernel/kernel_shadow_ast.dart';
 import 'package:kernel/ast.dart'
     show
         DartType,
@@ -11,15 +13,15 @@ import 'package:kernel/ast.dart'
         FunctionType,
         InvalidType,
         TypeParameter,
-        Typedef;
-
+        Typedef,
+        VariableDeclaration;
 import 'package:kernel/type_algebra.dart' show substitute;
 
 import '../fasta_codes.dart' show templateCyclicTypedef;
-
 import 'kernel_builder.dart'
     show
         FunctionTypeAliasBuilder,
+        KernelFormalParameterBuilder,
         KernelFunctionTypeBuilder,
         KernelTypeBuilder,
         KernelTypeVariableBuilder,
@@ -61,6 +63,7 @@ class KernelFunctionTypeAliasBuilder
       return thisType;
     }
     thisType = const InvalidType();
+
     DartType builtType = type?.build(library) ?? const DynamicType();
     if (typeVariables != null) {
       for (KernelTypeVariableBuilder tv in typeVariables) {
@@ -68,6 +71,9 @@ class KernelFunctionTypeAliasBuilder
         target.typeParameters.add(tv.parameter..parent = target);
       }
     }
+
+    _buildParameters(library);
+
     return thisType = builtType;
   }
 
@@ -103,4 +109,23 @@ class KernelFunctionTypeAliasBuilder
     }
     return buildTypesWithBuiltArguments(library, builtArguments);
   }
+
+  /// Build and set formal parameters of this typedef.
+  void _buildParameters(LibraryBuilder library) {
+    int requiredCount = 0;
+    final positional = <VariableDeclaration>[];
+    final named = <VariableDeclaration>[];
+    if (type.formals != null) {
+      for (KernelFormalParameterBuilder formal in type.formals) {
+        KernelVariableDeclaration parameter = formal.build(library);
+        if (formal.isPositional) {
+          positional.add(parameter);
+          if (formal.isRequired) requiredCount++;
+        } else if (formal.isNamed) {
+          named.add(parameter);
+        }
+      }
+      target.setParameters(requiredCount, positional, named);
+    }
+  }
 }