Bug 5800 – Wrong NAN bit pattern during array initialization

Environment: dmd 2.052, 64-bit Ubuntu. The following program passes the two asserts, showing that the array elements are not initialized as NANs. The dumpBytes() function shows that the bit pattern is different than a local variable's: import std.stdio; void main() { double[1] a; auto myNaN = double.nan; assert (a[0] != myNaN); // <-- passes; BUG assert (a[0] != double.nan); // <-- passes; BUG dumpBytes(a[0]); dumpBytes(myNaN); } void dumpBytes(T)(ref T var) { const ubyte * beg = cast(ubyte*)&var; foreach (bayt; beg .. beg + T.sizeof) { writef("%02x ", *bayt); } writeln(); } The bug manifests itself for float and real as well and the bit pattern changes depending on whether -m32 or -m64 is used. Here is one output of the program with -m64: 00 00 00 00 00 00 fc 7f 00 00 00 00 00 00 f8 7f Ali

Isn't it expected that 'nan' does not equate to itself?

My mistake: "Equality Expressions" at http://digitalmars.com/d/2.0/expression.html says "If either or both operands are NAN, then both the == returns false and != returns true." [sic]