Static strings in templates

Steven Schveighoffer schveiguy at yahoo.com
Fri May 2 13:54:26 PDT 2008


"Janice Caron" wrote
>I don't know if this is a bug or not. Someone please help me out.
> Here's the deal. Suppose I declare:
>
>    int foo(T)(T s, T t)
>
> with the expectation that the template will be passed a couple of
> strings, wstrings or dstring. All works fine if I do
>
>    string s;
>    string t;
>    int n = foo(s,t);
>
> However, the template can't be instantiated with
>
>    int n = foo("abcde","fg");
>
> because the type of the first argument is invariant(char)[5u], and the
> type of the second argument is invariant(char)[2u], and the compiler
> can't figure out that both can (and should) be implicitly cast to
> invariant(char)[].
>
> It occurs to me that even with only a single parameter, passing string
> literals to templated string function will lead to a lot of template
> bloat, if the template always considers the argument type to be
> invariant(char)[N] (for some N), as opposed to simply
> invariant(char)[].
>
> Is this a bug? Can anything be done about this? Is there a workaround?

I think the workaround is to do foo("abcde"[], "fg");

But I have logged a bug for something similar:

http://d.puremagic.com/issues/show_bug.cgi?id=1817

I think if the compiler template generation always generated template code 
for X[] instead of X[5], it would fix both our problems.

-Steve 





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