fixes #25477, downward inference of generic methods

pkg/analyzer/lib/src/dart/ast/ast.dart

Index: pkg/analyzer/lib/src/dart/ast/ast.dart
diff --git a/pkg/analyzer/lib/src/dart/ast/ast.dart b/pkg/analyzer/lib/src/dart/ast/ast.dart
index 4a9826ee757dc032867fbdddfca18f88e424ee9c..6357be298e20fdce81f957919e638f1737288aaf 100644
--- a/pkg/analyzer/lib/src/dart/ast/ast.dart
+++ b/pkg/analyzer/lib/src/dart/ast/ast.dart
@@ -5054,7 +5054,7 @@ class FunctionExpressionImpl extends ExpressionImpl
  * > functionExpressionInvocation ::=
  * >     [Expression] [TypeArgumentList]? [ArgumentList]
  */
-class FunctionExpressionInvocationImpl extends ExpressionImpl
+class FunctionExpressionInvocationImpl extends InvocationExpressionImpl
     implements FunctionExpressionInvocation {
   /**
    * The expression producing the function being invoked.
@@ -5062,17 +5062,6 @@ class FunctionExpressionInvocationImpl extends ExpressionImpl
   Expression _function;
 
   /**
-   * The type arguments to be applied to the method being invoked, or `null` if
-   * no type arguments were provided.
-   */
-  TypeArgumentList _typeArguments;
-
-  /**
-   * The list of arguments to the function.
-   */
-  ArgumentList _argumentList;
-
-  /**
    * The element associated with the function being invoked based on static type
    * information, or `null` if the AST structure has not been resolved or the
    * function could not be resolved.
@@ -5080,16 +5069,6 @@ class FunctionExpressionInvocationImpl extends ExpressionImpl
   ExecutableElement staticElement;
 
   /**
-   * The function type of the method invocation, or `null` if the AST
-   * structure has not been resolved, or if the invoke could not be resolved.
-   *
-   * This will usually be a [FunctionType], but it can also be an
-   * [InterfaceType] with a `call` method, `dynamic`, `Function`, or a `@proxy`
-   * interface type that implements `Function`.
-   */
-  DartType staticInvokeType;
-
-  /**
    * The element associated with the function being invoked based on propagated
    * type information, or `null` if the AST structure has not been resolved or
    * the function could not be resolved.
@@ -5097,26 +5076,12 @@ class FunctionExpressionInvocationImpl extends ExpressionImpl
   ExecutableElement propagatedElement;
 
   /**
-   * Like [staticInvokeType], but reflects propagated type information.
-   */
-  DartType propagatedInvokeType;
-
-  /**
    * Initialize a newly created function expression invocation.
    */
   FunctionExpressionInvocationImpl(Expression function,
-      TypeArgumentList typeArguments, ArgumentList argumentList) {
+      TypeArgumentList typeArguments, ArgumentList argumentList)
+      : super(typeArguments, argumentList) {
     _function = _becomeParentOf(function);
-    _typeArguments = _becomeParentOf(typeArguments);
-    _argumentList = _becomeParentOf(argumentList);
-  }
-
-  @override
-  ArgumentList get argumentList => _argumentList;
-
-  @override
-  void set argumentList(ArgumentList argumentList) {
-    _argumentList = _becomeParentOf(argumentList);
   }
 
   @override
@@ -5150,14 +5115,6 @@ class FunctionExpressionInvocationImpl extends ExpressionImpl
   int get precedence => 15;
 
   @override
-  TypeArgumentList get typeArguments => _typeArguments;
-
-  @override
-  void set typeArguments(TypeArgumentList typeArguments) {
-    _typeArguments = _becomeParentOf(typeArguments);
-  }
-
-  @override
   accept(AstVisitor visitor) => visitor.visitFunctionExpressionInvocation(this);
 
   @override
@@ -6167,6 +6124,55 @@ class InterpolationStringImpl extends InterpolationElementImpl
 }
 
 /**
+ * Common base class for [FunctionExpressionInvocationImpl] and
+ * [MethodInvocationImpl].
+ */
+abstract class InvocationExpressionImpl extends ExpressionImpl
+    implements InvocationExpression {
+  /**
+   * The type arguments to be applied to the method being invoked, or `null` if
+   * no type arguments were provided.
+   */
+  TypeArgumentList _typeArguments;
+
+  /**
+   * The list of arguments to the function.
+   */
+  ArgumentList _argumentList;
+
+  @override
+  DartType propagatedInvokeType;
+
+  @override
+  DartType staticInvokeType;
+
+  /**
+   * Initialize a newly created invocation.
+   */
+  InvocationExpressionImpl(
+      TypeArgumentList typeArguments, ArgumentList argumentList) {
+    _typeArguments = _becomeParentOf(typeArguments);
+    _argumentList = _becomeParentOf(argumentList);
+  }
+
+  @override
+  ArgumentList get argumentList => _argumentList;
+
+  @override
+  void set argumentList(ArgumentList argumentList) {
+    _argumentList = _becomeParentOf(argumentList);
+  }
+
+  @override
+  TypeArgumentList get typeArguments => _typeArguments;
+
+  @override
+  void set typeArguments(TypeArgumentList typeArguments) {
+    _typeArguments = _becomeParentOf(typeArguments);
+  }
+}
+
+/**
  * An is expression.
  *
  * > isExpression ::=
@@ -6959,7 +6965,8 @@ class MethodDeclarationImpl extends ClassMemberImpl
  * > methodInvocation ::=
  * >     ([Expression] '.')? [SimpleIdentifier] [TypeArgumentList]? [ArgumentList]
  */
-class MethodInvocationImpl extends ExpressionImpl implements MethodInvocation {
+class MethodInvocationImpl extends InvocationExpressionImpl
+    implements MethodInvocation {
   /**
    * The expression producing the object on which the method is defined, or
    * `null` if there is no target (that is, the target is implicitly `this`).
@@ -6980,32 +6987,6 @@ class MethodInvocationImpl extends ExpressionImpl implements MethodInvocation {
   SimpleIdentifier _methodName;
 
   /**
-   * The type arguments to be applied to the method being invoked, or `null` if
-   * no type arguments were provided.
-   */
-  TypeArgumentList _typeArguments;
-
-  /**
-   * The list of arguments to the method.
-   */
-  ArgumentList _argumentList;
-
-  /**
-   * The function type of the method invocation, or `null` if the AST
-   * structure has not been resolved, or if the invoke could not be resolved.
-   *
-   * This will usually be a [FunctionType], but it can also be an
-   * [InterfaceType] with a `call` method, `dynamic`, `Function`, or a `@proxy`
-   * interface type that implements `Function`.
-   */
-  DartType staticInvokeType;
-
-  /**
-   * Like [staticInvokeType], but reflects propagated type information.
-   */
-  DartType propagatedInvokeType;
-
-  /**
    * Initialize a newly created method invocation. The [target] and [operator]
    * can be `null` if there is no target.
    */
@@ -7014,19 +6995,10 @@ class MethodInvocationImpl extends ExpressionImpl implements MethodInvocation {
       this.operator,
       SimpleIdentifier methodName,
       TypeArgumentList typeArguments,
-      ArgumentList argumentList) {
+      ArgumentList argumentList)
+      : super(typeArguments, argumentList) {
     _target = _becomeParentOf(target);
     _methodName = _becomeParentOf(methodName);
-    _typeArguments = _becomeParentOf(typeArguments);
-    _argumentList = _becomeParentOf(argumentList);
-  }
-
-  @override
-  ArgumentList get argumentList => _argumentList;
-
-  @override
-  void set argumentList(ArgumentList argumentList) {
-    _argumentList = _becomeParentOf(argumentList);
   }
 
   @override
@@ -7050,6 +7022,9 @@ class MethodInvocationImpl extends ExpressionImpl implements MethodInvocation {
   Token get endToken => _argumentList.endToken;
 
   @override
+  Expression get function => methodName;
+
+  @override
   bool get isCascaded =>
       operator != null && operator.type == TokenType.PERIOD_PERIOD;
 
@@ -7088,14 +7063,6 @@ class MethodInvocationImpl extends ExpressionImpl implements MethodInvocation {
   }
 
   @override
-  TypeArgumentList get typeArguments => _typeArguments;
-
-  @override
-  void set typeArguments(TypeArgumentList typeArguments) {
-    _typeArguments = _becomeParentOf(typeArguments);
-  }
-
-  @override
   accept(AstVisitor visitor) => visitor.visitMethodInvocation(this);
 
   @override