Resynthesize return types lazily.

[email protected]
BUG=

Review URL: https://codereview.chromium.org/2007323006 .

Author: scheglov

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

@@ -1681,6 +1681,9 @@ class ConstructorElementImpl extends ExecutableElementImpl
   @override
   ElementKind get kind => ElementKind.CONSTRUCTOR;
 
+  @override
+  DartType get returnType => enclosingElement.type;
+
   @override
   accept(ElementVisitor visitor) => visitor.visitConstructorElement(this);
 
@@ -2806,7 +2809,7 @@ abstract class ExecutableElementImpl extends ElementImpl
   /**
    * The return type defined by this executable element.
    */
-  DartType returnType;
+  DartType _returnType;
 
   /**
    * The type of function defined by this executable element.
@@ -3039,6 +3042,26 @@ abstract class ExecutableElementImpl extends ElementImpl
     this._parameters = parameters;
   }
 
+  @override
+  DartType get returnType {
+    if (serializedExecutable != null && _returnType == null) {
+      bool isSetter =
+          serializedExecutable.kind == UnlinkedExecutableKind.setter;
+      _returnType = enclosingUnit.resynthesizerContext.resolveLinkedType(
+              serializedExecutable.inferredReturnTypeSlot,
+              typeParameterContext) ??
+          enclosingUnit.resynthesizerContext.resolveTypeRef(
+              serializedExecutable.returnType, typeParameterContext,
+              defaultVoid: isSetter && context.analysisOptions.strongMode);
+    }
+    return _returnType;
+  }
+
+  void set returnType(DartType returnType) {
+    assert(serializedExecutable == null);
+    _returnType = returnType;
+  }
+
   @override
   TypeParameterizedElementMixin get typeParameterContext => this;
 
@@ -3631,7 +3654,7 @@ class FunctionTypeAliasElementImpl extends ElementImpl
   /**
    * The return type defined by this type alias.
    */
-  DartType returnType;
+  DartType _returnType;
 
   /**
    * The type of function defined by this type alias.
@@ -3761,6 +3784,20 @@ class FunctionTypeAliasElementImpl extends ElementImpl
     this._parameters = parameters;
   }
 
+  @override
+  DartType get returnType {
+    if (_unlinkedTypedef != null && _returnType == null) {
+      _returnType = enclosingUnit.resynthesizerContext
+          .resolveTypeRef(_unlinkedTypedef.returnType, this);
+    }
+    return _returnType;
+  }
+
+  void set returnType(DartType returnType) {
+    assert(_unlinkedTypedef == null);
+    _returnType = returnType;
+  }
+
   @override
   TypeParameterizedElementMixin get typeParameterContext => this;
 

pkg/analyzer/lib/src/summary/resynthesize.dart

@@ -1879,7 +1879,6 @@ class _UnitResynthesizer {
       currentConstructor.periodOffset = serializedExecutable.periodOffset;
     }
     constructors[serializedExecutable.name] = currentConstructor;
-    currentConstructor.returnType = classElement.type;
     buildExecutableCommonParts(currentConstructor, serializedExecutable);
     currentConstructor.constantInitializers = serializedExecutable
         .constantInitializers
@@ -2107,17 +2106,6 @@ class _UnitResynthesizer {
         executableElement.parameters = parameters;
       }
     }
-    if (serializedExecutable.kind == UnlinkedExecutableKind.constructor) {
-      // Caller handles setting the return type.
-      assert(serializedExecutable.returnType == null);
-    } else {
-      bool isSetter =
-          serializedExecutable.kind == UnlinkedExecutableKind.setter;
-      executableElement.returnType = buildLinkedType(
-              serializedExecutable.inferredReturnTypeSlot, executableElement) ??
-          buildType(serializedExecutable.returnType, executableElement,
-              defaultVoid: isSetter && summaryResynthesizer.strongMode);
-    }
     executableElement.type = new FunctionTypeImpl.elementWithNameAndArgs(
         executableElement, null, getCurrentTypeArguments(skipLevels: 1), false);
     {
@@ -2456,8 +2444,6 @@ class _UnitResynthesizer {
     functionTypeAliasElement.parameters = serializedTypedef.parameters
         .map((p) => buildParameter(p, functionTypeAliasElement))
         .toList();
-    functionTypeAliasElement.returnType =
-        buildType(serializedTypedef.returnType, functionTypeAliasElement);
     functionTypeAliasElement.type =
         new FunctionTypeImpl.forTypedef(functionTypeAliasElement);
     unitHolder.addTypeAlias(functionTypeAliasElement);