[cfe] Handle mixed if map entries

Closes #38874

Change-Id: I0122ccb9bc91d349c030955332da338830a137c3
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/121987
Reviewed-by: Aske Simon Christensen <askesc@google.com>
Commit-Queue: Johnni Winther <johnniwinther@google.com>

Author: johnniwinther

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

@@ -107,12 +107,7 @@ import '../type_inference/type_inferrer.dart' show TypeInferrer;
 import '../type_inference/type_promotion.dart'
     show TypePromoter, TypePromotionFact, TypePromotionScope;
 
-import 'collections.dart'
-    show
-        SpreadElement,
-        SpreadMapEntry,
-        convertToMapEntry,
-        isConvertibleToMapEntry;
+import 'collections.dart';
 
 import 'constness.dart' show Constness;
 
@@ -3961,12 +3956,21 @@ class BodyBuilder extends ScopeListener<JumpTarget>
       if (elseEntry is MapEntry) {
         push(forest.createIfMapEntry(
             offsetForToken(ifToken), toValue(condition), thenEntry, elseEntry));
-      } else if (elseEntry is SpreadElement) {
-        push(forest.createIfMapEntry(
-            offsetForToken(ifToken),
-            toValue(condition),
-            thenEntry,
-            new SpreadMapEntry(elseEntry.expression, elseEntry.isNullAware)));
+      } else if (elseEntry is ControlFlowElement) {
+        MapEntry elseMapEntry = elseEntry.toMapEntry();
+        if (elseMapEntry != null) {
+          push(forest.createIfMapEntry(offsetForToken(ifToken),
+              toValue(condition), thenEntry, elseMapEntry));
+        } else {
+          int offset = elseEntry is Expression
+              ? elseEntry.fileOffset
+              : offsetForToken(ifToken);
+          push(new MapEntry(
+              buildProblem(
+                  fasta.messageCantDisambiguateAmbiguousInformation, offset, 1),
+              new NullLiteral())
+            ..fileOffset = offsetForToken(ifToken));
+        }
       } else {
         int offset = elseEntry is Expression
             ? elseEntry.fileOffset
@@ -3978,12 +3982,21 @@ class BodyBuilder extends ScopeListener<JumpTarget>
           ..fileOffset = offsetForToken(ifToken));
       }
     } else if (elseEntry is MapEntry) {
-      if (thenEntry is SpreadElement) {
-        push(forest.createIfMapEntry(
-            offsetForToken(ifToken),
-            toValue(condition),
-            new SpreadMapEntry(thenEntry.expression, thenEntry.isNullAware),
-            elseEntry));
+      if (thenEntry is ControlFlowElement) {
+        MapEntry thenMapEntry = thenEntry.toMapEntry();
+        if (thenMapEntry != null) {
+          push(forest.createIfMapEntry(offsetForToken(ifToken),
+              toValue(condition), thenMapEntry, elseEntry));
+        } else {
+          int offset = thenEntry is Expression
+              ? thenEntry.fileOffset
+              : offsetForToken(ifToken);
+          push(new MapEntry(
+              buildProblem(
+                  fasta.messageCantDisambiguateAmbiguousInformation, offset, 1),
+              new NullLiteral())
+            ..fileOffset = offsetForToken(ifToken));
+        }
       } else {
         int offset = thenEntry is Expression
             ? thenEntry.fileOffset

pkg/front_end/lib/src/fasta/kernel/collections.dart

@@ -55,6 +55,11 @@ mixin ControlFlowElement on Expression {
   @override
   R accept1<R, A>(ExpressionVisitor1<R, A> v, A arg) =>
       v.defaultExpression(this, arg);
+
+  /// Returns this control flow element as a [MapEntry], or `null` if this
+  /// control flow element cannot be converted into a [MapEntry].
+  // TODO(johnniwinther): Merge this with [convertToMapEntry].
+  MapEntry toMapEntry();
 }
 
 /// A spread element in a list or set literal.
@@ -84,6 +89,11 @@ class SpreadElement extends Expression with ControlFlowElement {
       expression?.parent = this;
     }
   }
+
+  @override
+  SpreadMapEntry toMapEntry() {
+    return new SpreadMapEntry(expression, isNullAware)..fileOffset = fileOffset;
+  }
 }
 
 /// An 'if' element in a list or set literal.
@@ -120,6 +130,26 @@ class IfElement extends Expression with ControlFlowElement {
       otherwise?.parent = this;
     }
   }
+
+  @override
+  MapEntry toMapEntry() {
+    MapEntry thenEntry;
+    if (then is ControlFlowElement) {
+      ControlFlowElement thenElement = then;
+      thenEntry = thenElement.toMapEntry();
+    }
+    if (thenEntry == null) return null;
+    MapEntry otherwiseEntry;
+    if (otherwise != null) {
+      if (otherwise is ControlFlowElement) {
+        ControlFlowElement otherwiseElement = otherwise;
+        otherwiseEntry = otherwiseElement.toMapEntry();
+      }
+      if (otherwiseEntry == null) return null;
+    }
+    return new IfMapEntry(condition, thenEntry, otherwiseEntry)
+      ..fileOffset = fileOffset;
+  }
 }
 
 /// A 'for' element in a list or set literal.
@@ -157,6 +187,18 @@ class ForElement extends Expression with ControlFlowElement {
       body?.parent = this;
     }
   }
+
+  @override
+  MapEntry toMapEntry() {
+    MapEntry bodyEntry;
+    if (body is ControlFlowElement) {
+      ControlFlowElement bodyElement = body;
+      bodyEntry = bodyElement.toMapEntry();
+    }
+    if (bodyEntry == null) return null;
+    return new ForMapEntry(variables, condition, updates, bodyEntry)
+      ..fileOffset = fileOffset;
+  }
 }
 
 /// A 'for-in' element in a list or set literal.
@@ -208,6 +250,18 @@ class ForInElement extends Expression with ControlFlowElement {
       problem?.parent = this;
     }
   }
+
+  @override
+  MapEntry toMapEntry() {
+    MapEntry bodyEntry;
+    if (body is ControlFlowElement) {
+      ControlFlowElement bodyElement = body;
+      bodyEntry = bodyElement.toMapEntry();
+    }
+    if (bodyEntry == null) return null;
+    return new ForInMapEntry(variable, iterable, prologue, bodyEntry, problem)
+      ..fileOffset = fileOffset;
+  }
 }
 
 mixin ControlFlowMapEntry implements MapEntry {

pkg/front_end/testcases/text_serialization.status

@@ -1147,5 +1147,6 @@ runtime_checks_new/stub_from_interface_covariant_from_interface: TextSerializati
 runtime_checks_new/stub_from_interface_covariant_from_super: TextSerializationFailure # Was: Pass
 set_literals/disambiguation_rule: TextSerializationFailure # Was: RuntimeError
 top_level_variance_test: TextSerializationFailure
+unified_collections/mixed_entries: TextSerializationFailure
 variance/class_type_parameter_modifier: TextSerializationFailure
 variance/mixin_type_parameter_modifier: TextSerializationFailure

pkg/front_end/testcases/unified_collections/mixed_entries.dart

@@ -0,0 +1,53 @@
+// 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.
+
+bool b = false;
+
+var list = [];
+
+var map0 = {};
+var map1 = {if (b) 0: 1 else ...map0};
+var map2 = {if (b) ...map0 else 0: 1};
+var map3 = {if (b) ...map0 else ...map0};
+var map4 = {if (b) 0: 1 else for (var a in list) a: 1};
+var map5 = {if (b) for (var a in list) a: 1 else 0: 1};
+var map6 = {
+  if (b) 0: 1 else for (var a in list) ...{a: 1}
+};
+var map7 = {
+  if (b) for (var a in list) ...{a: 1} else 0: 1
+};
+var map8 = {if (b) 0: 1 else for (var i = 0; i < list.length; i++) list[i]: 1};
+var map9 = {if (b) for (var i = 0; i < list.length; i++) list[i]: 1 else 0: 1};
+var map10 = {
+  if (b) 0: 1 else for (var i = 0; i < list.length; i++) ...{list[i]: 1}
+};
+var map11 = {
+  if (b) for (var i = 0; i < list.length; i++) ...{list[i]: 1} else 0: 1
+};
+var map12 = {
+  if (b) 0: 1 else if (b) ...{0: 1}
+};
+
+var error4 = {if (b) 0: 1 else for (var a in list) a};
+var error5 = {if (b) for (var a in list) a else 0: 1};
+var error6 = {
+  if (b) 0: 1 else for (var a in list) ...{a}
+};
+var error7 = {
+  if (b) for (var a in list) ...{a} else 0: 1
+};
+var error8 = {if (b) 0: 1 else for (var i = 0; i < list.length; i++) list[i]};
+var error9 = {if (b) for (var i = 0; i < list.length; i++) list[i] else 0: 1};
+var error10 = {
+  if (b) 0: 1 else for (var i = 0; i < list.length; i++) ...{list[i]}
+};
+var error11 = {
+  if (b) for (var i = 0; i < list.length; i++) ...{list[i]} else 0: 1
+};
+var error12 = {
+  if (b) 0: 1 else if (b) ...{0}
+};
+
+main() {}

pkg/front_end/testcases/unified_collections/mixed_entries.dart.outline.expect

@@ -0,0 +1,49 @@
+library;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/unified_collections/mixed_entries.dart:33:32: Error: Both Iterable and Map spread elements encountered in ambiguous literal.
+// var error4 = {if (b) 0: 1 else for (var a in list) a};
+//                                ^
+//
+// pkg/front_end/testcases/unified_collections/mixed_entries.dart:34:22: Error: Both Iterable and Map spread elements encountered in ambiguous literal.
+// var error5 = {if (b) for (var a in list) a else 0: 1};
+//                      ^
+//
+// pkg/front_end/testcases/unified_collections/mixed_entries.dart:41:32: Error: Both Iterable and Map spread elements encountered in ambiguous literal.
+// var error8 = {if (b) 0: 1 else for (var i = 0; i < list.length; i++) list[i]};
+//                                ^
+//
+// pkg/front_end/testcases/unified_collections/mixed_entries.dart:42:22: Error: Both Iterable and Map spread elements encountered in ambiguous literal.
+// var error9 = {if (b) for (var i = 0; i < list.length; i++) list[i] else 0: 1};
+//                      ^
+//
+import self as self;
+import "dart:core" as core;
+
+static field core::bool* b;
+static field core::List<dynamic>* list;
+static field core::Map<dynamic, dynamic>* map0;
+static field core::Map<dynamic, dynamic>* map1;
+static field core::Map<dynamic, dynamic>* map2;
+static field core::Map<dynamic, dynamic>* map3;
+static field core::Map<dynamic, core::int*>* map4;
+static field core::Map<dynamic, core::int*>* map5;
+static field core::Map<dynamic, core::int*>* map6;
+static field core::Map<dynamic, core::int*>* map7;
+static field core::Map<dynamic, core::int*>* map8;
+static field core::Map<dynamic, core::int*>* map9;
+static field core::Map<dynamic, core::int*>* map10;
+static field core::Map<dynamic, core::int*>* map11;
+static field core::Map<core::int*, core::int*>* map12;
+static field core::Map<dynamic, core::Null?>* error4;
+static field core::Map<dynamic, core::Null?>* error5;
+static field dynamic error6;
+static field dynamic error7;
+static field core::Map<dynamic, core::Null?>* error8;
+static field core::Map<dynamic, core::Null?>* error9;
+static field dynamic error10;
+static field dynamic error11;
+static field dynamic error12;
+static method main() → dynamic
+  ;