[Issue 11493] New: dlang.org/type.html incorrectly says that you can't cast from -1 to unsigned types

[d-bugmail at puremagic.com]

https://d.puremagic.com/issues/show_bug.cgi?id=11493

           Summary: dlang.org/type.html incorrectly says that you can't
                    cast from -1 to unsigned types
           Product: D
           Version: D2
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: normal
          Priority: P2
         Component: websites
        AssignedTo: nobody at puremagic.com
        ReportedBy: jmdavisProg at gmx.com


--- Comment #0 from Jonathan M Davis <jmdavisProg at gmx.com> 2013-11-10 13:22:54 PST ---
dlang.org/type.html gives this example

    ubyte  u1 = cast(byte)-1;  // error, -1 cannot be represented in a ubyte
    ushort u2 = cast(short)-1; // error, -1 cannot be represented in a ushort
    uint   u3 = cast(int)-1;   // ok, -1 can be represented in a uint
    ulong  u4 = cast(long)-1; // ok, -1 can be represented in a ulong

However, all 4 compile, which makes sense, because casts are blunt and don't
care about what does and doesn't fit. This won't compile

    ubyte  u1 = -1;
    ushort u2 = -1;

which is a bit interesting given that this compiles just fine

    byte i1 = -1;
    short i2 = -1;
    ubyte  u1 = i1;
    ushort u2 = i2;

But regardless of whether

    ubyte  u1 = -1;
    ushort u2 = -1;

should compile, the example in documentation definitely should, and the
documentation claims that it shouldn't, so the documentation is wrong and needs
to be updated.

And honestly, I don't understand the logic of how -1 can be represented in a
uint but not a ushort like the docs claim, since it can't be represented in
either, since they're unsigned, so I don't understand how the example in the
docs ever would have made sense.

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