[kernel] Recursively number constants, avoid swallowing exceptions

Change-Id: Ie4beed397a2632e7dde9b93a9f09aa658bf4b585
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/114841
Commit-Queue: Martin Kustermann <kustermann@google.com>
Reviewed-by: Jens Johansen <jensj@google.com>

pkg/front_end/test/spell_checking_list_code.txt

@@ -208,6 +208,8 @@ demands
 demangle
 demangled
 deps
+dereferenced
+dereferencing
 descent
 deserializer
 deserializers

pkg/kernel/lib/ast.dart

@@ -6070,10 +6070,11 @@ class TearOffConstant extends Constant {
     return '${runtimeType}(${procedure})';
   }
 
-  int get hashCode => procedure.hashCode;
+  int get hashCode => procedureReference.hashCode;
 
   bool operator ==(Object other) {
-    return other is TearOffConstant && other.procedure == procedure;
+    return other is TearOffConstant &&
+        other.procedureReference == procedureReference;
   }
 
   FunctionType getType(TypeEnvironment types) =>

pkg/kernel/lib/text/ast_to_text.dart

@@ -8,8 +8,6 @@ import 'dart:core' as core show MapEntry;
 
 import 'dart:convert' show json;
 
-import 'package:kernel/type_environment.dart' show TypeEnvironment;
-
 import '../ast.dart';
 import '../import_table.dart';
 
@@ -27,49 +25,48 @@ class NormalNamer<T> extends Namer<T> {
   NormalNamer(this.prefix);
 }
 
-class FakePrintingConstant extends Constant {
-  final String id;
-  FakePrintingConstant(this.id);
-
-  @override
-  accept(ConstantVisitor v) {}
-
-  @override
-  acceptReference(Visitor v) {}
-
-  @override
-  DartType getType(TypeEnvironment types) => null;
-
-  @override
-  void visitChildren(Visitor v) {}
-
-  @override
-  String toString() {
-    return "FakePrintingConstant[$id]";
-  }
-}
-
 class ConstantNamer extends RecursiveVisitor<Null> with Namer<Constant> {
   final String prefix;
   ConstantNamer(this.prefix);
 
   String getName(Constant constant) {
-    try {
-      if (!map.containsKey(constant)) {
+    if (!map.containsKey(constant)) {
+      // When printing a non-fully linked kernel AST (i.e. some [Reference]s
+      // are not bound) to text, we need to avoid dereferencing any
+      // references.
+      //
+      // The normal visitor API causes references to be dereferenced in order
+      // to call the `visit<name>(<name>)` / `visit<name>Reference(<name>)`.
+      //
+      // We therefore handle any subclass of [Constant] which has [Reference]s
+      // specially here.
+      //
+      if (constant is InstanceConstant) {
+        // Avoid visiting `InstanceConstant.classReference`.
+        for (final value in constant.fieldValues.values) {
+          // Name everything in post-order visit of DAG.
+          getName(value);
+        }
+      } else if (constant is TearOffConstant) {
+        // We only care about naming the constants themselves. [TearOffConstant]
+        // has no Constant children.
+        // Avoid visiting `TearOffConstant.procedureReference`.
+      } else {
         // Name everything in post-order visit of DAG.
         constant.visitChildren(this);
       }
-      return super.getName(constant);
-    } catch (e) {
-      // Partial dill. Name anyway.
-      String id = "${constant.runtimeType.toString()}";
-      return super.getName(new FakePrintingConstant(id));
     }
+    return super.getName(constant);
   }
 
   defaultConstantReference(Constant constant) {
     getName(constant);
   }
+
+  defaultDartType(DartType type) {
+    // No need to recurse into dart types, we only care about naming the
+    // constants themselves.
+  }
 }
 
 class Disambiguator<T, U> {

pkg/vm/test/unlinked_ast_to_text_test.dart

@@ -0,0 +1,66 @@
+// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'dart:io';
+
+import 'package:args/args.dart';
+import 'package:expect/expect.dart';
+import 'package:kernel/kernel.dart';
+import 'package:kernel/binary/limited_ast_to_binary.dart';
+import 'package:vm/kernel_front_end.dart';
+
+main() async {
+  final outDir =
+      Directory.systemTemp.createTempSync("incremental_load_from_dill_test");
+
+  final dillFile = outDir.uri.resolve("dart2js.dart.dill").toFilePath();
+  final unlinkedDillFile =
+      outDir.uri.resolve("dart2js.dart.unlinked.dill").toFilePath();
+  final unlinkedDillTxtFile =
+      outDir.uri.resolve("dart2js.dart.unlinked dill.txt").toFilePath();
+
+  final executable = Platform.executable;
+  if (!executable.endsWith('out/ReleaseX64/dart')) {
+    return;
+  }
+
+  final platformDill = Uri.parse(executable).resolve('vm_platform.dill');
+
+  try {
+    final arguments = <String>[
+      '--no-link-platform',
+      '--platform=$platformDill',
+      '--output=$dillFile',
+      'pkg/compiler/lib/src/dart2js.dart',
+    ];
+
+    // Compile dart2js.dart.
+    final ArgParser argParser = createCompilerArgParser();
+    final int exitCode =
+        await runCompiler(argParser.parse(arguments), '<usage>');
+    Expect.equals(0, exitCode);
+
+    // Load the dart2js.dart.dill and write the unlinked version.
+    final component = loadComponentFromBinary(dillFile);
+    final IOSink sink = new File(unlinkedDillFile).openWrite();
+    final printer = new LimitedBinaryPrinter(
+        sink, (lib) => lib.importUri.scheme != 'dart', false);
+    printer.writeComponentFile(component);
+    await sink.close();
+
+    // Ensure we can load the unlinked dill file and ensure it doesn't include
+    // core libraries.
+    final unlinkedComponent = loadComponentFromBinary(unlinkedDillFile);
+    final coreLibraryCount = unlinkedComponent.libraries
+        .where(
+            (lib) => lib.importUri.scheme == 'dart' && lib.members.isNotEmpty)
+        .length;
+    Expect.equals(0, coreLibraryCount);
+
+    // Ensure we can print the unlinked kernel to text.
+    writeComponentToText(unlinkedComponent, path: unlinkedDillTxtFile);
+  } finally {
+    outDir.deleteSync(recursive: true);
+  }
+}