Bug 28076 - float and double - GetHashCode is inconsistent with .NET
Summary: float and double - GetHashCode is inconsistent with .NET
Alias: None
Product: Class Libraries
Classification: Mono
Component: mscorlib ()
Version: unspecified
Hardware: PC Windows
: --- normal
Target Milestone: Untriaged
Assignee: Bugzilla
Depends on:
Reported: 2015-03-16 14:27 UTC by athibodeau
Modified: 2015-05-14 11:02 UTC (History)
2 users (show)

Is this bug a regression?: ---
Last known good build:

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Description athibodeau 2015-03-16 14:27:07 UTC
For negative and positive zero, the result of GetHashCode differs between Mono and .NET.

The following code allows to demonstrate the inconsistency:
// Test for float.
float f1 = 1.0f * 0.0f;
float f2 = -1.0f * 0.0f;
Console.WriteLine(f1 == f2);
Console.WriteLine(f1.GetHashCode() == f2.GetHashCode()); // Mono returns false but .NET returns true
Console.WriteLine(BitConverter.ToInt32(BitConverter.GetBytes(f1), 0));
Console.WriteLine(BitConverter.ToInt32(BitConverter.GetBytes(f2), 0));

// Test for double.
double d1 = 1.0 * 0.0;
double d2 = -1.0 * 0.0;
Console.WriteLine(d1 == d2);
Console.WriteLine(d1.GetHashCode() == d2.GetHashCode()); // Mono returns false but .NET returns true
Comment 1 Marek Safar 2015-05-14 11:02:42 UTC
Fixed in master