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[dart2js] Remove tests/dart2js/boolean_conversion_test.

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The dart2js_2 version still exists.

Prior to null safety, it was legal to assign `null` to a `bool`, so
things like boolean operators and control flow constructs required
null checks on their inputs. `--omit-implicit-checks` removed these null
checks, so we had to specify what the behavior would be in these cases.
(In general, `null` was just treated as a falsey value, since that's
what happens in JS.)

With null safety, it is no longer legal to assign `null` to a
(non-nullable) `bool`, so the backend freely optimizes boolean
expressions under this assumption. It's possible to smuggle `null` in
via a cast to `dynamic` and an implicit downcast to `bool`. The downcast
ordinarily fails at runtime but can be removed with
`--omit-implicit-checks`. We do not want to specify the behavior in this
case. We do not guarantee the behavior under `--omit-implicit-checks` of
code which would have failed with checks enabled.

Maintaining the old behavior would likely require us to be pessimistic
about nullability and miss optimization opportunities.

Fixes: https://github.com/dart-lang/sdk/issues/43471
Change-Id: I7e8e7c66f777ef631ef4054a8dfe211e3e2bef55
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/169820
Reviewed-by: Stephen Adams <sra@google.com>
Commit-Queue: Mayank Patke <fishythefish@google.com>
This commit is contained in:
Mayank Patke 2020-10-30 15:21:20 +00:00 committed by commit-bot@chromium.org
parent 04105ec124
commit a5afc3e974
1 changed files with 0 additions and 103 deletions
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103
tests/dart2js/boolean_conversion_test.dart
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@ -1,103 +0,0 @@
// 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.
// dart2jsOptions=--omit-implicit-checks
// Note: --omit-implicit-checks causes Expect.isNull to misbehave, so we use
// Expect.equals(null, ...) instead.
import 'package:expect/expect.dart';
void main() {
conditionalTest();
orTest();
andTest();
ifTest();
forTest();
whileTest();
doTest();
notTest();
ifElementTest();
forElementTest();
}
void conditionalTest() {
bool x = null as dynamic;
Expect.isFalse(x ? true : false);
}
void orTest() {
bool x = null as dynamic;
Expect.equals(null, x || x);
Expect.isFalse(x || false);
Expect.isTrue(x || true);
Expect.equals(null, false || x);
Expect.isTrue(true || x);
}
void andTest() {
bool x = null as dynamic;
Expect.isFalse(x && x);
Expect.isFalse(x && false);
Expect.isFalse(x && true);
Expect.isFalse(false && x);
Expect.equals(null, true && x);
}
void ifTest() {
bool x = null as dynamic;
Expect.isFalse(() {
if (x) {
return true;
} else {
return false;
}
}());
}
void forTest() {
bool x = null as dynamic;
Expect.isFalse(() {
for (; x;) {
return true;
}
return false;
}());
}
void whileTest() {
bool x = null as dynamic;
Expect.isFalse(() {
while (x) {
return true;
}
return false;
}());
}
void doTest() {
bool x = null as dynamic;
Expect.equals(1, () {
int n = 0;
do {
n++;
} while (x);
return n;
}());
}
void notTest() {
bool x = null as dynamic;
Expect.isTrue(!x);
}
void ifElementTest() {
bool x = null as dynamic;
Expect.listEquals([], [if (x) 1]);
}
void forElementTest() {
bool x = null as dynamic;
Expect.listEquals([], [for (var i = 0; x; i++) i]);
}