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LibJS: Correctly handle mixing +0 and -0 in Math.{min,max}()

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The native C++ < and > operators won't handle this correctly, so the
result was different depending on the order of arguments. This is now
fixed by explicitly checking for positive and negative zero values.

Fixes #6589.
This commit is contained in:
Linus Groh 2021-04-23 20:47:53 +02:00
parent 883e8683b2
commit 0053816e9d
3 changed files with 8 additions and 2 deletions
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6
Userland/Libraries/LibJS/Runtime/MathObject.cpp
View file

@ -157,7 +157,8 @@ JS_DEFINE_NATIVE_FUNCTION(MathObject::max)
auto cur = vm.argument(i).to_number(global_object); auto cur = vm.argument(i).to_number(global_object);
if (vm.exception()) if (vm.exception())
return {}; return {};
max = Value(cur.as_double() > max.as_double() ? cur : max); if ((max.is_negative_zero() && cur.is_positive_zero()) || cur.as_double() > max.as_double())
max = cur;
} }
return max; return max;
} }
@ -174,7 +175,8 @@ JS_DEFINE_NATIVE_FUNCTION(MathObject::min)
auto cur = vm.argument(i).to_number(global_object); auto cur = vm.argument(i).to_number(global_object);
if (vm.exception()) if (vm.exception())
return {}; return {};
min = Value(cur.as_double() < min.as_double() ? cur : min); if ((min.is_positive_zero() && cur.is_negative_zero()) || cur.as_double() < min.as_double())
min = cur;
} }
return min; return min;
} }

2
Userland/Libraries/LibJS/Tests/builtins/Math/Math.max.js
View file

@ -5,6 +5,8 @@ test("basic functionality", () => {
expect(Math.max(1)).toBe(1); expect(Math.max(1)).toBe(1);
expect(Math.max(2, 1)).toBe(2); expect(Math.max(2, 1)).toBe(2);
expect(Math.max(1, 2, 3)).toBe(3); expect(Math.max(1, 2, 3)).toBe(3);
expect(Math.max(-0, 0)).toBe(0);
expect(Math.max(0, -0)).toBe(0);
expect(Math.max(NaN)).toBeNaN(); expect(Math.max(NaN)).toBeNaN();
expect(Math.max("String", 1)).toBeNaN(); expect(Math.max("String", 1)).toBeNaN();
}); });

2
Userland/Libraries/LibJS/Tests/builtins/Math/Math.min.js vendored
View file

@ -4,6 +4,8 @@ test("basic functionality", () => {
expect(Math.min(1)).toBe(1); expect(Math.min(1)).toBe(1);
expect(Math.min(2, 1)).toBe(1); expect(Math.min(2, 1)).toBe(1);
expect(Math.min(1, 2, 3)).toBe(1); expect(Math.min(1, 2, 3)).toBe(1);
expect(Math.min(-0, 0)).toBe(-0);
expect(Math.min(0, -0)).toBe(-0);
expect(Math.min(NaN)).toBeNaN(); expect(Math.min(NaN)).toBeNaN();
expect(Math.min("String", 1)).toBeNaN(); expect(Math.min("String", 1)).toBeNaN();
}); });