Deprecate DartType.displayName, use getDisplayString() instead.

We call it with `withNullability: false` almost everywhere.
My attempt to update all places turned out to be a long chain of
changes. So, instead I will make decisions and updates in separate
CLs, starting with ErrorReporter.

R=brianwilkerson@google.com, paulberry@google.com

Change-Id: I9d72475577ba2934bed1c06a4808ab620e92a20e
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/127441
Reviewed-by: Paul Berry <paulberry@google.com>
Commit-Queue: Konstantin Shcheglov <scheglov@google.com>

Author: scheglov

pkg/analysis_server/lib/src/computer/computer_signature.dart

@@ -81,7 +81,7 @@ class DartUnitSignatureComputer {
             ? ParameterKind.OPTIONAL
             : param.isPositional ? ParameterKind.REQUIRED : ParameterKind.NAMED,
         param.displayName,
-        param.type.displayName,
+        param.type.getDisplayString(withNullability: false),
         defaultValue: param.defaultValueCode);
   }
 }

pkg/analysis_server/lib/src/protocol_server.dart

@@ -66,7 +66,9 @@ String getReturnTypeString(engine.Element element) {
     }
   } else if (element is engine.VariableElement) {
     engine.DartType type = element.type;
-    return type != null ? type.displayName : 'dynamic';
+    return type != null
+        ? type.getDisplayString(withNullability: false)
+        : 'dynamic';
   } else if (element is engine.FunctionTypeAliasElement) {
     return element.function.returnType.toString();
   } else {

pkg/analysis_server/lib/src/services/completion/dart/arglist_contributor.dart

@@ -171,7 +171,7 @@ class ArgListContributor extends DartCompletionContributor {
   void _addNamedParameterSuggestion(List<String> namedArgs,
       ParameterElement parameter, bool appendColon, bool appendComma) {
     String name = parameter.name;
-    String type = parameter.type?.displayName;
+    String type = parameter.type?.getDisplayString(withNullability: false);
     if (name != null && name.isNotEmpty && !namedArgs.contains(name)) {
       String completion = name;
       if (appendColon) {

pkg/analysis_server/lib/src/services/completion/dart/suggestion_builder.dart

@@ -63,7 +63,9 @@ CompletionSuggestion createSuggestion(Element element,
         element.parameters.map((ParameterElement parameter) {
       DartType paramType = parameter.type;
       // Gracefully degrade if type not resolved yet
-      return paramType != null ? paramType.displayName : 'var';
+      return paramType != null
+          ? paramType.getDisplayString(withNullability: false)
+          : 'var';
     }).toList();
 
     Iterable<ParameterElement> requiredParameters = element.parameters

pkg/analysis_server/lib/src/services/completion/postfix/postfix_completion.dart

@@ -505,7 +505,7 @@ class PostfixCompletionProcessor {
     if (astNode is ThrowExpression) {
       ThrowExpression expr = astNode;
       var type = expr.expression.staticType;
-      return type.displayName;
+      return type.getDisplayString(withNullability: false);
     }
     return 'Exception';
   }

pkg/analysis_server/lib/src/services/completion/token_details/token_detail_builder.dart

@@ -116,7 +116,7 @@ class TokenDetailBuilder {
     } else if (type is InterfaceType) {
       Element element = type.element;
       if (element == null || element.isSynthetic) {
-        buffer.write(type.displayName);
+        buffer.write(type.getDisplayString(withNullability: false));
       } else {
 //        String uri = element.library.source.uri.toString();
         String name = element.name;
@@ -134,7 +134,7 @@ class TokenDetailBuilder {
       }
     } else {
       // Handle `void` and `dynamic`.
-      buffer.write(type.displayName);
+      buffer.write(type.getDisplayString(withNullability: false));
     }
   }
 }

pkg/analysis_server/lib/src/services/correction/fix_internal.dart

@@ -1325,8 +1325,13 @@ class FixProcessor extends BaseProcessor {
               });
             });
             _addFixFromBuilder(
-                changeBuilder, DartFixKind.CHANGE_TYPE_ANNOTATION,
-                args: [typeNode.type, newType.displayName]);
+              changeBuilder,
+              DartFixKind.CHANGE_TYPE_ANNOTATION,
+              args: [
+                typeNode.type,
+                newType.getDisplayString(withNullability: false),
+              ],
+            );
           }
         }
       }

pkg/analysis_server/lib/src/services/correction/util.dart

@@ -184,17 +184,16 @@ CompilationUnitElement getCompilationUnitElement(Element element) {
 
 String getDefaultValueCode(DartType type) {
   if (type != null) {
-    String typeName = type.displayName;
-    if (typeName == "bool") {
+    if (type.isDartCoreBool) {
       return "false";
     }
-    if (typeName == "int") {
+    if (type.isDartCoreInt) {
       return "0";
     }
-    if (typeName == "double") {
+    if (type.isDartCoreDouble) {
       return "0.0";
     }
-    if (typeName == "String") {
+    if (type.isDartCoreString) {
       return "''";
     }
   }
@@ -1327,7 +1326,7 @@ class CorrectionUtils {
       return _invertCondition0(expression.unParenthesized);
     }
     DartType type = expression.staticType;
-    if (type.displayName == "bool") {
+    if (type.isDartCoreBool) {
       return _InvertedCondition._simple("!${getNodeText(expression)}");
     }
     return _InvertedCondition._simple(getNodeText(expression));

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

@@ -32,6 +32,7 @@ abstract class DartType {
   ///
   /// Clients should not depend on the content of the returned value as it will
   /// be changed if doing so would improve the UX.
+  @deprecated
   String get displayName;
 
   /// Return the element representing the declaration of this type, or `null` if

pkg/analyzer/lib/error/listener.dart

@@ -206,7 +206,7 @@ class ErrorReporter {
           return buffer.toString();
         }
       }
-      return type.displayName;
+      return type.getDisplayString(withNullability: false);
     }
 
     Map<String, List<_TypeToConvert>> typeGroups = {};