Typeinfo inconsistencies

[H. S. Teoh]

On Tue, Aug 13, 2013 at 09:48:10PM +0200, Maxim Fomin wrote:
> On Tuesday, 13 August 2013 at 17:42:31 UTC, H. S. Teoh wrote:
> >So, I got some free time today and decided to look into issue 6210,
> >and found out that the problem was caused by this:
> >
> >	char[]        a = "h".dup;
> >	const(char)[] b = "h";
> >	string        c = "h";
> >
> >	writeln(typeid(a).getHash(&a)); // prints 104
> >	writeln(typeid(b).getHash(&b)); // prints 703014434222502
> >	writeln(typeid(c).getHash(&c)); // prints 104
> >
> >This is completely b0rken, because it causes the following code to
> >fail:
> >
> >	int[char[]] aa;
> >	aa["h"] = 1;
> >
> >	assert(aa.dup == aa);	// fails
> >
> >The reason for this inconsistency is that char[] and
> >immutable(char)[] (aka string) have their getHash functions
> >overridden in druntime's src/rt/typeinfo/ti_Ag.d, but there is no
> >such override for const(char)[].
> >
> >I tried adding another subclass for const(char)[]'s typeid that
> >inherits the correct version of getHash, but it didn't work because
> >presumably this stuff is hardcoded into the compiler somewhere.
> >
> >So my question is, where in the compiler decides to use the specific
> >typeinfos for char[] and immutable(char)[], but not const(char)[]?
> >
> >
> >T
> 
> OK
> 
> --- a/src/typinf.c
> +++ b/src/typinf.c
> @@ -790,7 +790,8 @@ int TypeDArray::builtinTypeInfo()
>  #if DMDV2
>      return !mod && (next->isTypeBasic() != NULL && !next->mod ||
>          // strings are so common, make them builtin
> -        next->ty == Tchar && next->mod == MODimmutable);
> +        next->ty == Tchar && next->mod == MODimmutable ||
> +        next->ty == Tchar && next->mod == MODconst);
>  #else
>      return next->isTypeBasic() != NULL;
>  #endif
> 
> --- a/src/rt/typeinfo/ti_Ag.d
> +++ b/src/rt/typeinfo/ti_Ag.d
> @@ -186,3 +186,15 @@ class TypeInfo_Aya : TypeInfo_Aa
>      }
>  }
> 
> +// const(char)[]
> +
> +class TypeInfo_Axa : TypeInfo_Aa
> +{
> +    override string toString() const { return "const(char)[]"; }
> +
> +    override @property inout(TypeInfo) next() inout
> +    {
> +        return cast(inout)typeid(const(char));
> +    }
> +}
> +

Thanks!! Will you submit a pull request? You can reference bug 6210. I'm
guessing that this will probably also fix one or two other AA-related
bugs that have been around for a while.


T

-- 
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