[Issue 6949] no warning or error if unsigned variable is compared to 0

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http://d.puremagic.com/issues/show_bug.cgi?id=6949



--- Comment #16 from bearophile_hugs at eml.cc 2012-11-30 09:36:58 PST ---
(In reply to comment #15)

> BTW std.bigint has a lot of examples of valid comparisons of  unsigned < 0 .

The comparisons in std.bigint are like this, all of them are inside templated
functions:

    BigInt opAssign(T: long)(T x)
    {
        data = cast(ulong)((x < 0) ? -x : x);
        sign = (x < 0);
        return this;
    }

    BigInt opOpAssign(string op, T)(T y)
        if ((op=="+" || op=="-" || op=="*" || op=="/" || op=="%"
          || op==">>" || op=="<<" || op=="^^") && is (T: long))
    {
        ulong u = cast(ulong)(y < 0 ? -y : y);
...




> It's easy.
> DSymbol.inTemplateInstance()  returns non-NULL if you are inside a template.
> You just need to call it on the function you're in.

Thank you Don.
If it's not hard to do then I suggest to add that in this line to exclude
templates from this test, and take a look at what the Phobos autotester says:

// Error when unsigned type is compared less-than to zero, but not in enum
declarations or in static if
if ((!(sc->flags & SCOPEstaticif)) && sc->parent &&
!sc->parent->isEnumDeclaration())

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