[Issue 4835] New: DMD should warn about integer overflow in computed constant

[d-bugmail at puremagic.com]

http://d.puremagic.com/issues/show_bug.cgi?id=4835

           Summary: DMD should warn about integer overflow in computed
                    constant
           Product: D
           Version: D2
          Platform: x86_64
        OS/Version: Linux
            Status: NEW
          Severity: enhancement
          Priority: P2
         Component: DMD
        AssignedTo: nobody at puremagic.com
        ReportedBy: lars.holowko at gmail.com


--- Comment #0 from Lars Holowko <lars.holowko at gmail.com> 2010-09-07 10:09:23 PDT ---
I got bitten by this when I wanted to create a 6GB large file to test 64 bit
support in std.stdio with dmd 2.048.


The output of:


import std.stdio;

void main(string args[])
{
    long l_dangerous = 1024 * 1024 * 1024 * 6;
    writefln("l_dangerous = 0x%x", l_dangerous);
    writefln("l_dangerous = %s", l_dangerous);

    long l_ok = 1024 * 1024 * 1024 * 6L;
    writefln("l_ok = 0x%x", l_ok);
    writefln("l_ok = %s", l_ok);
    return;    
}

is

l_dangerous = 0xffffffff80000000
l_dangerous = -2147483648
l_ok = 0x180000000
l_ok = 6442450944


dmd 2.048 did not issue a warning about the integer overflow (neither with or
without -w)

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