[modular] Create repro of issue building full dills from summaries.

Change-Id: I67db9eefe508ddbe072238e8773109c7b7f25d1a
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/222560
Reviewed-by: Sigmund Cherem <sigmund@google.com>
Commit-Queue: Joshua Litt <joshualitt@google.com>

pkg/compiler/lib/src/compiler.dart

@@ -344,8 +344,8 @@ abstract class Compiler {
         }
         frontendStrategy.registerModuleData(data);
 
-        // After we've deserialized modular data, we set and verify the main
-        // method as well as trim the component of any unnecessary dependencies.
+        // After we've deserialized modular data, we trim the component of any
+        // unnecessary dependencies.
         // Note: It is critical we wait to trim the dill until after we've
         // deserialized modular data because some of this data may reference
         // 'trimmed' elements.
@@ -354,14 +354,7 @@ abstract class Compiler {
             dumpUnusedLibraries(result);
           }
           if (options.entryUri != null) {
-            result.setMainAndTrimComponent(options.entryUri);
-          }
-          if (result.component.mainMethod == null) {
-            // TODO(sigmund): move this so that we use the same error template
-            // from the CFE.
-            _reporter.reportError(_reporter.createMessage(NO_LOCATION_SPANNABLE,
-                MessageKind.GENERIC, {'text': "No 'main' method found."}));
-            return;
+            result.trimComponent(options.entryUri);
           }
         }
         if (options.cfeOnly) {

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

@@ -52,6 +52,37 @@ class KernelLoaderTask extends CompilerTask {
   @override
   String get name => 'kernel loader';
 
+  static Library _findEntryLibrary(Component component, Uri entryUri) {
+    var entryLibrary = component.libraries
+        .firstWhere((l) => l.fileUri == entryUri, orElse: () => null);
+    if (entryLibrary == null) {
+      throw ArgumentError('Entry uri $entryUri not found in dill.');
+    }
+    return entryLibrary;
+  }
+
+  static ir.Reference _findMainMethod(Library entryLibrary) {
+    var mainMethod = entryLibrary.procedures
+        .firstWhere((p) => p.name.text == 'main', orElse: () => null);
+
+    // In some cases, a main method is defined in another file, and then
+    // exported. In these cases, we search for the main method in
+    // [additionalExports].
+    ir.Reference mainMethodReference;
+    if (mainMethod == null) {
+      mainMethodReference = entryLibrary.additionalExports.firstWhere(
+          (p) => p.canonicalName.name == 'main',
+          orElse: () => null);
+    } else {
+      mainMethodReference = mainMethod.reference;
+    }
+    if (mainMethodReference == null) {
+      throw ArgumentError(
+          'Entry uri ${entryLibrary.fileUri} has no main method.');
+    }
+    return mainMethodReference;
+  }
+
   /// Loads an entire Kernel [Component] from a file on disk.
   Future<KernelResult> load() {
     return measure(() async {
@@ -128,6 +159,18 @@ class KernelLoaderTask extends CompilerTask {
             await read(dependency);
           }
         }
+
+        if (_options.entryUri != null) {
+          var entryLibrary = _findEntryLibrary(component, _options.entryUri);
+          var mainMethod = _findMainMethod(entryLibrary);
+          component.setMainMethodAndMode(mainMethod, true, component.mode);
+        }
+        if (!_options.modularMode && component.mainMethod == null) {
+          // TODO(sigmund): move this so that we use the same error template
+          // from the CFE.
+          _reporter.reportError(_reporter.createMessage(NO_LOCATION_SPANNABLE,
+              MessageKind.GENERIC, {'text': "No 'main' method found."}));
+        }
       } else {
         bool verbose = false;
         Target target =
@@ -250,40 +293,7 @@ class KernelResult {
   KernelResult(this.component, this.rootLibraryUri, this.libraries,
       this.moduleLibraries);
 
-  static Library _findEntryLibrary(Component component, Uri entryUri) {
-    var entryLibrary = component.libraries
-        .firstWhere((l) => l.fileUri == entryUri, orElse: () => null);
-    if (entryLibrary == null) {
-      throw ArgumentError('Entry uri $entryUri not found in dill.');
-    }
-    return entryLibrary;
-  }
-
-  static ir.Reference _findMainMethod(Library entryLibrary) {
-    var mainMethod = entryLibrary.procedures
-        .firstWhere((p) => p.name.text == 'main', orElse: () => null);
-
-    // In some cases, a main method is defined in another file, and then
-    // exported. In these cases, we search for the main method in
-    // [additionalExports].
-    ir.Reference mainMethodReference;
-    if (mainMethod == null) {
-      mainMethodReference = entryLibrary.additionalExports.firstWhere(
-          (p) => p.canonicalName.name == 'main',
-          orElse: () => null);
-    } else {
-      mainMethodReference = mainMethod.reference;
-    }
-    if (mainMethodReference == null) {
-      throw ArgumentError(
-          'Entry uri ${entryLibrary.fileUri} has no main method.');
-    }
-    return mainMethodReference;
-  }
-
-  void setMainAndTrimComponent(Uri entryUri) {
-    var entryLibrary = _findEntryLibrary(component, entryUri);
-    var mainMethod = _findMainMethod(entryLibrary);
+  void trimComponent(Uri entryUri) {
     var irLibraryMap = <Uri, Library>{};
     var irLibraries = <Library>[];
     for (var library in component.libraries) {
@@ -292,11 +302,13 @@ class KernelResult {
     for (var library in libraries) {
       irLibraries.add(irLibraryMap[library]);
     }
+    var mainMethod = component.mainMethodName;
+    var componentMode = component.mode;
     component = ir.Component(
         libraries: irLibraries,
         uriToSource: component.uriToSource,
         nameRoot: component.root);
-    component.setMainMethodAndMode(mainMethod, true, component.mode);
+    component.setMainMethodAndMode(mainMethod, true, componentMode);
   }
 
   @override

tests/modular/cross_module_constant_with_mixin/a.dart

@@ -0,0 +1,25 @@
+// Copyright (c) 2021, 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 't.dart';
+
+String _defaultStringy(String t) => t.toLowerCase();
+
+class A {
+  A({
+    double d = 3.14,
+    StringyFunction<String> s = _defaultStringy,
+  }) : this.factoryConstructor(d: d, s: s);
+
+  A.factoryConstructor({
+    double d = 3.14,
+    StringyFunction<String> s = _defaultStringy,
+  })  : d = d,
+        _s = s;
+
+  String doStringy(String i) => _s(i);
+
+  final double d;
+  final StringyFunction<String> _s;
+}

tests/modular/cross_module_constant_with_mixin/b.dart

@@ -0,0 +1,10 @@
+// Copyright (c) 2020, 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 'a.dart';
+import 'm.dart';
+
+class B extends A with M {
+  B({double d = 2.71}) : super(d: d);
+}

tests/modular/cross_module_constant_with_mixin/m.dart

@@ -0,0 +1,9 @@
+// Copyright (c) 2021, 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 'a.dart';
+
+mixin M on A {
+  m1() {}
+}

tests/modular/cross_module_constant_with_mixin/main.dart

@@ -0,0 +1,13 @@
+// Copyright (c) 2021, 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 'package:expect/expect.dart';
+
+import 'b.dart';
+
+main() {
+  var bInst = B();
+  Expect.equals(2.71, bInst.d);
+  Expect.equals('default', bInst.doStringy('DEFAULT'));
+}

tests/modular/cross_module_constant_with_mixin/modules.yaml

@@ -0,0 +1,9 @@
+# Copyright (c) 2021, 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.
+
+dependencies:
+  main: [a, b, m, expect]
+  b: [a, m]
+  m: a
+  a: t

tests/modular/cross_module_constant_with_mixin/t.dart

@@ -0,0 +1,5 @@
+// Copyright (c) 2021, 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.
+
+typedef StringyFunction<T> = String Function(T item);