Fix top-level inference with ForElement and NNBD.

Change-Id: I7b656ad4af600a82ec13f007dbad3465cd502a3a
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/137020
Commit-Queue: Konstantin Shcheglov <scheglov@google.com>
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>

pkg/analyzer/lib/src/dart/resolver/flow_analysis_visitor.dart

@@ -339,7 +339,7 @@ class TypeSystemTypeOperations
 /// The visitor that gathers local variables that are potentially assigned
 /// in corresponding statements, such as loops, `switch` and `try`.
 class _AssignedVariablesVisitor extends RecursiveAstVisitor<void> {
-  final AssignedVariables assignedVariables;
+  final AssignedVariables<AstNode, PromotableElement> assignedVariables;
 
   _AssignedVariablesVisitor(this.assignedVariables);
 

pkg/analyzer/lib/src/summary2/ast_resolver.dart

@@ -16,21 +16,13 @@ class AstResolver {
   final CompilationUnitElement _unitElement;
   final Scope _nameScope;
 
-  /// This field is set if the library is non-nullable by default.
-  FlowAnalysisHelper flowAnalysis;
-
-  AstResolver(this._linker, this._unitElement, this._nameScope) {
-    if (_unitElement.library.isNonNullableByDefault) {
-      flowAnalysis = FlowAnalysisHelper(
-        _unitElement.library.typeSystem,
-        false,
-      );
-    }
-  }
+  AstResolver(this._linker, this._unitElement, this._nameScope);
 
   void resolve(
     AstNode node,
     AstNode Function() getNode, {
+    bool buildElements = true,
+    bool isTopLevelVariableInitializer = false,
     ClassElement enclosingClassElement,
     ExecutableElement enclosingExecutableElement,
     FunctionBody enclosingFunctionBody,
@@ -38,24 +30,37 @@ class AstResolver {
     var featureSet = node.thisOrAncestorOfType<CompilationUnit>().featureSet;
     var errorListener = AnalysisErrorListener.NULL_LISTENER;
 
-    node.accept(
-      ResolutionVisitor(
-        unitElement: _unitElement,
-        featureSet: featureSet,
-        nameScope: _nameScope,
-        errorListener: errorListener,
-      ),
-    );
-    node = getNode();
+    if (buildElements) {
+      node.accept(
+        ResolutionVisitor(
+          unitElement: _unitElement,
+          featureSet: featureSet,
+          nameScope: _nameScope,
+          errorListener: errorListener,
+        ),
+      );
+      node = getNode();
 
-    var variableResolverVisitor = VariableResolverVisitor(
-      _unitElement.library,
-      _unitElement.source,
-      _unitElement.library.typeProvider,
-      errorListener,
-      nameScope: _nameScope,
-    );
-    node.accept(variableResolverVisitor);
+      var variableResolverVisitor = VariableResolverVisitor(
+        _unitElement.library,
+        _unitElement.source,
+        _unitElement.library.typeProvider,
+        errorListener,
+        nameScope: _nameScope,
+      );
+      node.accept(variableResolverVisitor);
+    }
+
+    FlowAnalysisHelper flowAnalysis;
+    if (isTopLevelVariableInitializer) {
+      if (_unitElement.library.isNonNullableByDefault) {
+        flowAnalysis = FlowAnalysisHelper(
+          _unitElement.library.typeSystem,
+          false,
+        );
+        flowAnalysis.topLevelDeclaration_enter(node.parent, null, null);
+      }
+    }
 
     var resolverVisitor = ResolverVisitor(
       _linker.inheritance,
@@ -78,5 +83,9 @@ class AstResolver {
     }
 
     node.accept(resolverVisitor);
+
+    if (isTopLevelVariableInitializer) {
+      flowAnalysis?.topLevelDeclaration_exit();
+    }
   }
 }

pkg/analyzer/lib/src/summary2/top_level_inference.dart

@@ -20,6 +20,7 @@ import 'package:analyzer/src/summary2/lazy_ast.dart';
 import 'package:analyzer/src/summary2/link.dart';
 import 'package:analyzer/src/summary2/linking_node_scope.dart';
 import 'package:analyzer/src/task/strong_mode.dart';
+import 'package:meta/meta.dart';
 
 DartType _dynamicIfNull(DartType type) {
   if (type == null || type.isBottom || type.isDartCoreNull) {
@@ -399,7 +400,7 @@ class _VariableInferenceNode extends _InferenceNode {
 
   @override
   List<_InferenceNode> computeDependencies() {
-    _resolveInitializer();
+    _resolveInitializer(forDependencies: true);
 
     var collector = _InferenceDependenciesCollector();
     _node.initializer.accept(collector);
@@ -427,7 +428,7 @@ class _VariableInferenceNode extends _InferenceNode {
 
   @override
   void evaluate() {
-    _resolveInitializer();
+    _resolveInitializer(forDependencies: false);
 
     if (LazyAst.getType(_node) == null) {
       var initializerType = _node.initializer.staticType;
@@ -458,9 +459,13 @@ class _VariableInferenceNode extends _InferenceNode {
     isEvaluated = true;
   }
 
-  void _resolveInitializer() {
+  void _resolveInitializer({@required bool forDependencies}) {
     var astResolver = AstResolver(_walker._linker, _unitElement, _scope);
-    astResolver.flowAnalysis?.topLevelDeclaration_enter(_node, null, null);
-    astResolver.resolve(_node.initializer, () => _node.initializer);
+    astResolver.resolve(
+      _node.initializer,
+      () => _node.initializer,
+      buildElements: forDependencies,
+      isTopLevelVariableInitializer: true,
+    );
   }
 }

pkg/analyzer/test/src/dart/resolution/type_inference/list_literal_test.dart

@@ -258,7 +258,13 @@ f() async {
   var a = [1, ...?await futureNull, 2];
 }
 ''');
-    assertType(findNode.listLiteral('['), 'List<int>');
+    assertType(
+      findNode.listLiteral('['),
+      typeStringByNullability(
+        nullable: 'List<int?>',
+        legacy: 'List<int>',
+      ),
+    );
   }
 
   test_noContext_noTypeArgs_spread_nullAware_onlyNull() async {
@@ -302,7 +308,7 @@ var a = <num>[];
 }
 
 @reflectiveTest
-class ListLiteralWithNnbdTest extends DriverResolutionTest {
+class ListLiteralWithNnbdTest extends ListLiteralTest {
   @override
   AnalysisOptionsImpl get analysisOptions => AnalysisOptionsImpl()
     ..contextFeatures = FeatureSet.forTesting(

pkg/analyzer/test/src/dart/resolution/type_inference/map_literal_test.dart

@@ -271,7 +271,13 @@ f() async {
   a;
 }
 ''');
-    assertType(setOrMapLiteral('{1'), 'Map<int, String>');
+    assertType(
+      setOrMapLiteral('{1'),
+      typeStringByNullability(
+        nullable: 'Map<int?, String?>',
+        legacy: 'Map<int, String>',
+      ),
+    );
   }
 
   test_noContext_noTypeArgs_spread_nullAware_nullAndNotNull_set() async {
@@ -282,7 +288,13 @@ f() async {
   a;
 }
 ''');
-    assertType(setOrMapLiteral('{1'), 'Set<int>');
+    assertType(
+      setOrMapLiteral('{1'),
+      typeStringByNullability(
+        nullable: 'Set<int?>',
+        legacy: 'Set<int>',
+      ),
+    );
   }
 
   test_noContext_noTypeArgs_spread_nullAware_onlyNull() async {
@@ -343,7 +355,7 @@ var a = <num, String>{};
 }
 
 @reflectiveTest
-class MapLiteralWithNnbdTest extends DriverResolutionTest {
+class MapLiteralWithNnbdTest extends MapLiteralTest {
   @override
   AnalysisOptionsImpl get analysisOptions => AnalysisOptionsImpl()
     ..contextFeatures = FeatureSet.fromEnableFlags(
@@ -353,15 +365,6 @@ class MapLiteralWithNnbdTest extends DriverResolutionTest {
   @override
   bool get typeToStringWithNullability => true;
 
-  AstNode setOrMapLiteral(String search) => findNode.setOrMapLiteral(search);
-
-  test_context_noTypeArgs_noEntries() async {
-    await resolveTestCode('''
-Map<String, String> a = {};
-''');
-    assertType(setOrMapLiteral('{'), 'Map<String, String>');
-  }
-
   test_context_noTypeArgs_noEntries_typeParameterNullable() async {
     await resolveTestCode('''
 class C<T extends Object?> {

pkg/analyzer/test/src/dart/resolution/type_inference/set_literal_test.dart

@@ -267,7 +267,7 @@ var a = <num>{};
 }
 
 @reflectiveTest
-class SetLiteralWithNnbdTest extends DriverResolutionTest {
+class SetLiteralWithNnbdTest extends SetLiteralTest {
   @override
   AnalysisOptionsImpl get analysisOptions => AnalysisOptionsImpl()
     ..contextFeatures = FeatureSet.fromEnableFlags(