[dartdevc] Adding nnbd semantics for static and late fields.

Fixes #40375

Change-Id: I53863291a8c6a3cc694d088311a9e09b9b00a790
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/138723
Commit-Queue: Mark Zhou <markzipan@google.com>
Reviewed-by: Nicholas Shahan <nshahan@google.com>

pkg/dev_compiler/lib/src/kernel/compiler.dart

@@ -348,7 +348,7 @@ class ProgramCompiler extends ComputeOnceConstantVisitor<js_ast.Expression>
     // emitted before dart.defineLazy.
     if (_constLazyAccessors.isNotEmpty) {
       var constTableBody = runtimeStatement(
-          'defineLazy(#, { # })', [_constTable, _constLazyAccessors]);
+          'defineLazy(#, { # }, false)', [_constTable, _constLazyAccessors]);
       moduleItems.insert(_constTableInsertionIndex, constTableBody);
       _constLazyAccessors.clear();
     }
@@ -2106,10 +2106,13 @@ class ProgramCompiler extends ComputeOnceConstantVisitor<js_ast.Expression>
       }
       _staticTypeContext.leaveMember(field);
     }
-    _currentUri = _currentLibrary.fileUri;
-
     _currentUri = savedUri;
-    return runtimeStatement('defineLazy(#, { # })', [objExpr, accessors]);
+
+    return runtimeStatement('defineLazy(#, { # }, #)', [
+      objExpr,
+      accessors,
+      js.boolean(!_currentLibrary.isNonNullableByDefault)
+    ]);
   }
 
   js_ast.Fun _emitStaticFieldInitializer(Field field) {

sdk/lib/_internal/js_dev_runtime/private/ddc_runtime/operations.dart

@@ -697,7 +697,7 @@ _canonicalMember(obj, name) {
 Future loadLibrary() => Future.value();
 
 /// Defines lazy statics.
-void defineLazy(to, from) {
+void defineLazy(to, from, bool checkCycles) {
   for (var name in getOwnNamesAndSymbols(from)) {
     defineLazyField(to, name, getOwnPropertyDescriptor(from, name));
   }

sdk_nnbd/lib/_internal/js_dev_runtime/private/ddc_runtime/operations.dart

@@ -741,8 +741,89 @@ _canonicalMember(obj, name) {
 Future loadLibrary() => Future.value();
 
 /// Defines lazy statics.
-void defineLazy(to, from) {
+///
+/// TODO: Remove useOldSemantics when non-null-safe late static field behavior is
+/// deprecated.
+void defineLazy(to, from, bool useOldSemantics) {
   for (var name in getOwnNamesAndSymbols(from)) {
-    defineLazyField(to, name, getOwnPropertyDescriptor(from, name));
+    if (useOldSemantics) {
+      defineLazyFieldOld(to, name, getOwnPropertyDescriptor(from, name));
+    } else {
+      defineLazyField(to, name, getOwnPropertyDescriptor(from, name));
+    }
   }
 }
+
+/// Defines a lazy static field.
+/// After initial get or set, it will replace itself with a value property.
+// TODO(jmesserly): reusing descriptor objects has been shown to improve
+// performance in other projects (e.g. webcomponents.js ShadowDOM polyfill).
+defineLazyField(to, name, desc) => JS('', '''(() => {
+  const initializer = $desc.get;
+  let init = initializer;
+  let value = null;
+  let executed = false;
+  $desc.get = function() {
+    if (init == null) return value;
+    if (!executed) {
+      // Record the field on first execution so we can reset it later if
+      // needed (hot restart).
+      $_resetFields.push(() => {
+        init = initializer;
+        value = null;
+      });
+      executed = true;
+    }
+    value = init();
+    init = null;
+    return value;
+  };
+  $desc.configurable = true;
+  if ($desc.set != null) {
+    $desc.set = function(x) {
+      init = null;
+      value = x;
+    };
+  }
+  return ${defineProperty(to, name, desc)};
+})()''');
+
+/// Defines a lazy static field with pre-null-safety semantics.
+defineLazyFieldOld(to, name, desc) => JS('', '''(() => {
+  const initializer = $desc.get;
+  let init = initializer;
+  let value = null;
+  $desc.get = function() {
+    if (init == null) return value;
+    let f = init;
+    init = $throwCyclicInitializationError;
+    if (f === init) f($name); // throw cycle error
+
+    // On the first (non-cyclic) execution, record the field so we can reset it
+    // later if needed (hot restart).
+    $_resetFields.push(() => {
+      init = initializer;
+      value = null;
+    });
+
+    // Try to evaluate the field, using try+catch to ensure we implement the
+    // correct Dart error semantics.
+    try {
+      value = f();
+      init = null;
+      return value;
+    } catch (e) {
+      init = null;
+      value = null;
+      throw e;
+    }
+  };
+  $desc.configurable = true;
+  if ($desc.set != null) {
+    $desc.set = function(x) {
+      init = null;
+      value = x;
+    };
+  }
+  return ${defineProperty(to, name, desc)};
+})()''');

sdk_nnbd/lib/_internal/js_dev_runtime/private/ddc_runtime/utils.dart

@@ -60,49 +60,6 @@ safeGetOwnProperty(obj, name) {
     return JS<Object>('', '#[#]', obj, name);
 }
 
-/// Defines a lazy static field.
-/// After initial get or set, it will replace itself with a value property.
-// TODO(jmesserly): reusing descriptor objects has been shown to improve
-// performance in other projects (e.g. webcomponents.js ShadowDOM polyfill).
-defineLazyField(to, name, desc) => JS('', '''(() => {
-  const initializer = $desc.get;
-  let init = initializer;
-  let value = null;
-  $desc.get = function() {
-    if (init == null) return value;
-    let f = init;
-    init = $throwCyclicInitializationError;
-    if (f === init) f($name); // throw cycle error
-
-    // On the first (non-cyclic) execution, record the field so we can reset it
-    // later if needed (hot restart).
-    $_resetFields.push(() => {
-      init = initializer;
-      value = null;
-    });
-
-    // Try to evaluate the field, using try+catch to ensure we implement the
-    // correct Dart error semantics.
-    try {
-      value = f();
-      init = null;
-      return value;
-    } catch (e) {
-      init = null;
-      value = null;
-      throw e;
-    }
-  };
-  $desc.configurable = true;
-  if ($desc.set != null) {
-    $desc.set = function(x) {
-      init = null;
-      value = x;
-    };
-  }
-  return ${defineProperty(to, name, desc)};
-})()''');
-
 copyTheseProperties(to, from, names) {
   for (int i = 0, n = JS('!', '#.length', names); i < n; ++i) {
     var name = JS('', '#[#]', names, i);