Add more JS subtyping semantics to CFE constant evaluator.

fishythefish · commit-bot@chromium.org · commit ab66a3808b28 · 2019-04-10T21:09:03.000Z
If we're targeting a JS backend, `isSubtype` considers every int to be a double. We need to additionally allow any integer-valued double to be an int. This mainly allows us to handle signed zeroes correctly. Fixes dart-lang/sdk#36562. Change-Id: I00d1e693bb3f1268ac100a76c9bec8fcc612b182 Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/99101 Commit-Queue: Mayank Patke <fishythefish@google.com> Reviewed-by: Sigmund Cherem <sigmund@google.com>
diff --git a/pkg/front_end/lib/src/fasta/kernel/constant_evaluator.dart b/pkg/front_end/lib/src/fasta/kernel/constant_evaluator.dart
@@ -2193,6 +2193,14 @@ class ConstantEvaluator extends RecursiveVisitor<Constant> {
         // With JS semantics, an integer is also a double.
         return true;
       }
+
+      if (constantType == typeEnvironment.doubleType &&
+          type == typeEnvironment.intType) {
+        double value = (constant as DoubleConstant).value;
+        if (value.isFinite && value == value.truncateToDouble()) {
+          return true;
+        }
+      }
     }
     return typeEnvironment.isSubtypeOf(constantType, type);
   }
diff --git a/tests/compiler/dart2js_extra/issue36562_test.dart b/tests/compiler/dart2js_extra/issue36562_test.dart
@@ -0,0 +1,12 @@
+// 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.
+
+const int x = 0;
+
+const List<int> l = const [
+  1,
+  -x,
+];
+
+main() => print(l);

Original file line number	Diff line number	Diff line change
`@@ -2193,6 +2193,14 @@ class ConstantEvaluator extends RecursiveVisitor<Constant> {`
`2193`	`2193`	`// With JS semantics, an integer is also a double.`
`2194`	`2194`	`return true;`
`2195`	`2195`	`}`
	`2196`	`+`
	`2197`	`+ if (constantType == typeEnvironment.doubleType &&`
	`2198`	`+ type == typeEnvironment.intType) {`
	`2199`	`+ double value = (constant as DoubleConstant).value;`
	`2200`	`+ if (value.isFinite && value == value.truncateToDouble()) {`
	`2201`	`+ return true;`
	`2202`	`+ }`
	`2203`	`+ }`
`2196`	`2204`	`}`
`2197`	`2205`	`return typeEnvironment.isSubtypeOf(constantType, type);`
`2198`	`2206`	`}`