Re: C++ runtime library selection via -stdlib=libstdc++/libc++ (WIP)

[René J.V. Bertin <rjvbertin at gmail dot com>]

On Thursday November 09 2017 17:41:39 Joseph Myers wrote:

>Your __APPLE__ conditional would appear to condition something on whether 
>the *host* is an Apple system.  If you wish to change the default for 

Evidently. As I said, there are a number of settings that will (probably) need to be determined at the configure stage.
I must admit I hadn't thought about cross-compiling (or cross-building) at all. My first concern has been to get the feature working so I can test it.
(I, and potentially other Mac users; my patch is currently set up to integrate with the MacPorts package for gcc7; a bit of wide-spread testing in the wild cannot be a bad thing before incorporating this, right? :))

I wouldn't particularly mind in fact if making libc++ the default runtime library were made through an explicit configure option. That might even be better for users of libc++-based systems who have integrated g++ and its incompatible runtime into their workflows. I expect the powers that be on here will have a better educated opinion on this.

>All options should be accessible by names starting with "--", meaning the 
>new options should have such aliases added as well.

Ok, I'll have a look how that would work, I was expecting that the check for "this option with an extra dash" would be done in code.

I hope I'm not violating any rules in processing the same options in 2 locations (once to know where to look for C++ headers, once to know which runtime lib to link)?

R.