Now I'm wondering how much of this behavior should be "string"-specific. If we're paying attention to conversion operators from non-POD types, why not check for all possible conversion operators? I think this is a better solution than checking to see if there's a conversion operator from the return type of a c_str() function.
Not depending on std::string was the plan, and in fact how I implemented it :) On Mon, Jun 4, 2012 at 1:44 PM, Chandler Carruth <[email protected]>wrote: > On Mon, Jun 4, 2012 at 1:37 PM, Sam Panzer <[email protected]> wrote: > >> Here is one other question: With this patch, incorrectly passing an >> std::string to printf generates an error (can't pass non-POD member), a >> warning (printf format doesn't match), and a note (the c_str() suggestion). >> Is this the behavior we want? > > > I don't think so... Ideally: > > 1) If we are about to issue a an error (non-POD object passed through > printf), check whether the non-POD object has a 'c_str()' method that > returns a type which matches the format specifier. If so, use a specific > diagnostic message for the error, attach a fixit-hint suggesting > '.c_str()', and continue parsing as-if the user had done that. > > 2) If there is no error (passing a std::string* perhaps), then in the > warning message, give a more precise message than 'cannot convert > std::string* to const char*' or whatever by checking if there is a c_str() > method that matches the type of the printf. > > > One thing I would encourage you to do: don't base this on 'std::string'. I > actually think the error/warning should fire for any class type with a > c_str method that returns a viable type. That way non-standard string > libraries will get the same benefit if they conform the the same conceptual > interface as the standard string library. >
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