Re: [PATCH 2/2] build: overhaul wrapper script system for multiple wrapper support

[Rich Felker <dalias@libc.org>]

On Mon, Jun 01, 2015 at 05:39:46PM +0200, Shiz wrote:
> > On 01 Jun 2015, at 16:47, Rich Felker <dalias@libc.org> wrote:
> > 
> > There are two reasons I prefer the approach I described:
> > 
> > 1. It's better not to auto-enable wrappers unless we're pretty
> > confident they work. The wrappers are not magically universal; they're
> > a way to use musl with a preexisting non-musl-targeted toolchain that
> > meets a fairly large set of internal assumptions, and they won't
> > necessarily work with arbitrary toolchains. In particular I'm pretty
> > sure musl-gcc does not work with Rob's toolchains from Aboriginal
> > Linux that are using their own wrapper (named gcc) around an internal
> > gcc elsewhere, and presumably (being uclibc based) these would even be
> > detected as "ok for wrapper”.
> 
> I’d like to note that a __GLIBC__ check would not help here either
> presumably, as uclibc defines __GLIBC__ as well. :)

Yes, that's what I was trying to say.

> So I see your use case for testing in C code itself as opposed to testing
> compiler features. That being said, I’m still not at all a fan of __GLIBC__,
> for reasons mentioned in the previous post. While a false-positive is worse
> than a false-negative, I feel just solely testing for this provides a large
> opportunity for false-negatives, and even some false positives as you yourself
> mentioned in point one.

I'm not aware of any real-world false-negatives. A Bionic-based system
would probably be one, if any such system with a compiler toolchain
exists, but depending on the properties of the toolchain that might
even be a proper negative rather than a false-negative, so I'd
actually prefer to research whether the wrappers work for such
Bionic-based toolchains and then enable them explicitly if they do,
rather than just assuming they work.

> It’s a tough thing to check thoroughly and accurately, but I do not think
> checking __GLIBC__ is at all the solution either.

Still open to more options.

Rich