Include type arguments for non-synthetic FunctionTypeImpl(s) into displayName.

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

Index: pkg/analyzer/lib/src/dart/element/type.dart
diff --git a/pkg/analyzer/lib/src/dart/element/type.dart b/pkg/analyzer/lib/src/dart/element/type.dart
index 1cfdbf8d15b30aee62cbbe56cb56e53a8437e83d..adb40bd96769adb4c784052628953aa5cf79bde9 100644
--- a/pkg/analyzer/lib/src/dart/element/type.dart
+++ b/pkg/analyzer/lib/src/dart/element/type.dart
@@ -454,13 +454,41 @@ class FunctionTypeImpl extends TypeImpl implements FunctionType {
   @override
   String get displayName {
     String name = this.name;
+
+    // Function types have an empty name when they are defined implicitly by
+    // either a closure or as part of a parameter declaration.
     if (name == null || name.length == 0) {
-      // Function types have an empty name when they are defined implicitly by
-      // either a closure or as part of a parameter declaration.
       StringBuffer buffer = new StringBuffer();
       appendTo(buffer, new Set.identity());
+      return buffer.toString();
+    }
+
+    List<DartType> typeArguments = this.typeArguments;
+
+    bool allDynamic = true;

[Brian Wilkerson, 2017/03/20 20:13:47]

Just an idea: this block of code would make a nice local function.

+    for (DartType type in typeArguments) {
+      if (type != null && !type.isDynamic) {
+        allDynamic = false;
+        break;
+      }
+    }
+
+    // If there is at least one non-dynamic type, then list them out.
+    if (!allDynamic) {
+      StringBuffer buffer = new StringBuffer();
+      buffer.write(name);
+      buffer.write("<");
+      for (int i = 0; i < typeArguments.length; i++) {
+        if (i != 0) {
+          buffer.write(", ");
+        }
+        DartType typeArg = typeArguments[i];
+        buffer.write(typeArg.displayName);
+      }
+      buffer.write(">");
       name = buffer.toString();
     }
+
     return name;
   }