[cfe] Create explicit internal ast nodes for extension access

This adds explicit internal ast nodes for the various kinds of extension access in order to avoid lowering during body building and to make the encoding directly match the information from the source code.

TEST=existing

Change-Id: Ic831b2871ed0e66221a7ca5dadde4333647c2d3c
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/446381
Commit-Queue: Johnni Winther <[email protected]>
Reviewed-by: Chloe Stefantsova <[email protected]>
Reviewed-by: Alexander Markov <[email protected]>
Reviewed-by: Erik Ernst <[email protected]>

Author: johnniwinther

pkg/front_end/lib/src/kernel/body_builder.dart

@@ -1137,6 +1137,10 @@ class BodyBuilder extends StackListenerImpl
     } else {
       Expression value = toValue(node);
       if (!forest.isThrow(node)) {
+        // TODO(johnniwinther): Derive the message position from the [node]
+        // and not the [value].  For instance this occurs for `super()?.foo()`
+        // in an initializer list, pointing to `foo` as expecting an
+        // initializer.
         value = wrapInProblem(
             value, cfe.codeExpectedAnInitializer, value.fileOffset, noLength);
       }
@@ -1161,13 +1165,11 @@ class BodyBuilder extends StackListenerImpl
         if (formal.isNamed) {
           (superParametersAsArguments ??= <Object>[]).add(new NamedExpression(
               formal.name,
-              createVariableGet(formal.variable!, formal.fileOffset,
-                  forNullGuardedAccess: false))
+              createVariableGet(formal.variable!, formal.fileOffset))
             ..fileOffset = formal.fileOffset);
         } else {
-          (superParametersAsArguments ??= <Object>[]).add(createVariableGet(
-              formal.variable!, formal.fileOffset,
-              forNullGuardedAccess: false));
+          (superParametersAsArguments ??= <Object>[])
+              .add(createVariableGet(formal.variable!, formal.fileOffset));
         }
       }
     }
@@ -1853,18 +1855,16 @@ class BodyBuilder extends StackListenerImpl
           if (formal.isNamed) {
             NamedExpression superParameterAsArgument = new NamedExpression(
                 formal.name,
-                createVariableGet(formal.variable!, formal.fileOffset,
-                    forNullGuardedAccess: false))
+                createVariableGet(formal.variable!, formal.fileOffset))
               ..fileOffset = formal.fileOffset;
             (namedSuperParametersAsArguments ??= <NamedExpression>[])
                 .add(superParameterAsArgument);
             (namedSuperParameterNames ??= <String>{}).add(formal.name);
             (superParametersAsArguments ??= <Object>[])
                 .add(superParameterAsArgument);
           } else {
-            Expression superParameterAsArgument = createVariableGet(
-                formal.variable!, formal.fileOffset,
-                forNullGuardedAccess: false);
+            Expression superParameterAsArgument =
+                createVariableGet(formal.variable!, formal.fileOffset);
             (positionalSuperParametersAsArguments ??= <Expression>[])
                 .add(superParameterAsArgument);
             (superParametersAsArguments ??= <Object>[])
@@ -1929,11 +1929,9 @@ class BodyBuilder extends StackListenerImpl
         if (_context.isEnumClass && libraryFeatures.enhancedEnums.isEnabled) {
           ArgumentsImpl arguments = last.arguments as ArgumentsImpl;
           List<Expression> enumSyntheticArguments = [
-            new VariableGetImpl(function.positionalParameters[0],
-                forNullGuardedAccess: false)
+            new VariableGet(function.positionalParameters[0])
               ..parent = last.arguments,
-            new VariableGetImpl(function.positionalParameters[1],
-                forNullGuardedAccess: false)
+            new VariableGet(function.positionalParameters[1])
               ..parent = last.arguments
           ];
           arguments.positional.insertAll(0, enumSyntheticArguments);
@@ -1981,10 +1979,8 @@ class BodyBuilder extends StackListenerImpl
             function.positionalParameters[0].name == "#index" &&
             function.positionalParameters[1].name == "#name");
         (positionalArguments ??= <Expression>[]).insertAll(0, [
-          new VariableGetImpl(function.positionalParameters[0],
-              forNullGuardedAccess: false),
-          new VariableGetImpl(function.positionalParameters[1],
-              forNullGuardedAccess: false)
+          new VariableGet(function.positionalParameters[0]),
+          new VariableGet(function.positionalParameters[1])
         ]);
       }
 
@@ -3227,15 +3223,12 @@ class BodyBuilder extends StackListenerImpl
   /// Helper method to create a [VariableGet] of the [variable] using
   /// [charOffset] as the file offset.
   @override
-  VariableGet createVariableGet(VariableDeclaration variable, int charOffset,
-      {bool forNullGuardedAccess = false}) {
+  VariableGet createVariableGet(VariableDeclaration variable, int charOffset) {
     if (!(variable as VariableDeclarationImpl).isLocalFunction &&
         !variable.isWildcard) {
       typeInferrer.assignedVariables.read(variable);
     }
-    return new VariableGetImpl(variable,
-        forNullGuardedAccess: forNullGuardedAccess)
-      ..fileOffset = charOffset;
+    return new VariableGet(variable)..fileOffset = charOffset;
   }
 
   /// Helper method to create a [ReadOnlyAccessGenerator] on the [variable]
@@ -3433,7 +3426,7 @@ class BodyBuilder extends StackListenerImpl
                 this,
                 nameToken,
                 extensionBuilder.extension,
-                name,
+                memberName,
                 thisVariable!,
                 thisTypeParameters,
                 getable as MemberBuilder?,
@@ -3516,7 +3509,7 @@ class BodyBuilder extends StackListenerImpl
                 this,
                 nameToken,
                 extensionBuilder.extension,
-                name,
+                memberName,
                 thisVariable!,
                 thisTypeParameters,
                 getable as MemberBuilder?,
@@ -6248,60 +6241,29 @@ class BodyBuilder extends StackListenerImpl
     }
   }
 
-  @override
-  Expression buildExtensionMethodInvocation(
-      int fileOffset, Procedure target, Arguments arguments,
-      {required bool isTearOff}) {
-    List<TypeParameter> typeParameters = target.function.typeParameters;
-    LocatedMessage? argMessage = checkArgumentsForFunction(
-        target.function, arguments, fileOffset, typeParameters,
-        isExtensionMemberInvocation: true);
-    if (argMessage != null) {
-      return buildUnresolvedError(target.name.text, fileOffset,
-          arguments: arguments,
-          candidate: target,
-          message: argMessage,
-          kind: UnresolvedKind.Method);
-    }
-
-    Expression node;
-    if (isTearOff) {
-      node = new ExtensionTearOff(target, arguments);
-    } else {
-      node = new StaticInvocation(target, arguments);
-    }
-    node.fileOffset = fileOffset;
-    return node;
-  }
-
   @override
   LocatedMessage? checkArgumentsForFunction(FunctionNode function,
       Arguments arguments, int offset, List<TypeParameter> typeParameters,
-      {bool isExtensionMemberInvocation = false}) {
-    int requiredPositionalParameterCountToReport =
-        function.requiredParameterCount;
-    int positionalParameterCountToReport = function.positionalParameters.length;
-    int positionalArgumentCountToReport =
-        forest.argumentsPositional(arguments).length;
-    if (isExtensionMemberInvocation) {
+      {Extension? extension}) {
+    int typeParameterCount = typeParameters.length;
+    int requiredParameterCount = function.requiredParameterCount;
+    int positionalParameterCount = function.positionalParameters.length;
+    int positionalArgumentsCount = arguments.positional.length;
+    if (extension != null) {
       // Extension member invocations have additional synthetic parameter for
       // `this`.
-      --requiredPositionalParameterCountToReport;
-      --positionalParameterCountToReport;
-      --positionalArgumentCountToReport;
+      --requiredParameterCount;
+      --positionalParameterCount;
+      typeParameterCount -= extension.typeParameters.length;
     }
-    if (forest.argumentsPositional(arguments).length <
-        function.requiredParameterCount) {
+    if (positionalArgumentsCount < requiredParameterCount) {
       return cfe.codeTooFewArguments
-          .withArguments(requiredPositionalParameterCountToReport,
-              positionalArgumentCountToReport)
+          .withArguments(requiredParameterCount, positionalArgumentsCount)
           .withLocation(uri, arguments.fileOffset, noLength);
     }
-    if (forest.argumentsPositional(arguments).length >
-        function.positionalParameters.length) {
+    if (positionalArgumentsCount > positionalParameterCount) {
       return cfe.codeTooManyArguments
-          .withArguments(
-              positionalParameterCountToReport, positionalArgumentCountToReport)
+          .withArguments(positionalParameterCount, positionalArgumentsCount)
           .withLocation(uri, arguments.fileOffset, noLength);
     }
     List<NamedExpression> named = forest.argumentsNamed(arguments);
@@ -6329,16 +6291,16 @@ class BodyBuilder extends StackListenerImpl
       }
     }
 
-    List<DartType> types = forest.argumentsTypeArguments(arguments);
-    if (typeParameters.length != types.length) {
+    List<DartType> types = arguments.types;
+    if (typeParameterCount != types.length) {
       if (types.length == 0) {
         // Expected `typeParameters.length` type arguments, but none given, so
         // we use type inference.
       } else {
         // A wrong (non-zero) amount of type arguments given. That's an error.
         // TODO(jensj): Position should be on type arguments instead.
         return cfe.codeTypeArgumentMismatch
-            .withArguments(typeParameters.length)
+            .withArguments(typeParameterCount)
             .withLocation(uri, offset, noLength);
       }
     }
@@ -7808,8 +7770,7 @@ class BodyBuilder extends StackListenerImpl
         ///       body;
         ///     }
         elements.syntheticAssignment = lvalue.buildAssignment(
-            new VariableGetImpl(variable, forNullGuardedAccess: false)
-              ..fileOffset = inToken.offset,
+            new VariableGet(variable)..fileOffset = inToken.offset,
             voidContext: true);
       } else if (lvalue is Pattern) {
         /// We are in the case where `lvalue` is a pattern:
@@ -7824,9 +7785,7 @@ class BodyBuilder extends StackListenerImpl
         ///     }
         elements.syntheticAssignment = null;
         elements.expressionEffects = forest.createPatternVariableDeclaration(
-            inToken.offset,
-            lvalue,
-            new VariableGetImpl(variable, forNullGuardedAccess: false),
+            inToken.offset, lvalue, new VariableGet(variable),
             isFinal: false);
       } else if (lvalue is InvalidExpression) {
         // Coverage-ignore-block(suite): Not run.