Re: Emacs 28.1 doesn't compile on Mac OS 10.7.5

[Jeffrey Walton]

On Sun, Apr 17, 2022 at 10:33 AM Ryan Schmidt <gnulib@ryandesign.com> wrote:
>
> On Apr 17, 2022, at 02:54, Paul Eggert wrote:
>
> > On 4/16/22 20:28, Jeffrey Walton wrote:
> >> maybe you should define a couple of macros
> >> like GNULIB_LLVM_CLANG_VER and GNULIB_APPLE_CLANG_VER
> >
> > I hope we don't need to do that. This is software archaeology (Mac OS X 
> > 10.7.5 is so old that neither the Subject: line nor my patch got its name 
> > right, and nobody mentioned the mistake :-) and these macros would clutter 
> > the code for little benefit. Most Clang-specific code nowadays shouldn't 
> > use Clang version numbers; it should use __has_builtin etc.
>
> I agree you should detect features if you can. If you can't, and you need to 
> look at the compiler version, you need to first establish whether you're 
> using Apple Clang or open source clang, since the two use different version 
> numbering schemes. If __clang__ is defined and __apple_build_version__ is 
> defined, you're using Apple Clang and you could inspect that constant 
> directly or you could look at __clang_major__, __clang_minor__, and/or 
> __clang_patchlevel__ interpreted as Apple Clang version numbers. If __clang__ 
> is defined and __apple_build_version__ is not defined, you're using open 
> source clang and can look at the __clang_*__ defines interpreted as open 
> source clang version numbers.
>
>
> Some sample output from my system:
>
> $ clang -dM -E - < /dev/null | egrep '__(clang|apple)'
> #define __apple_build_version__ 4250028
> #define __clang__ 1
> #define __clang_major__ 4
> #define __clang_minor__ 2
> #define __clang_patchlevel__ 0
> #define __clang_version__ "4.2 (clang-425.0.28)"
>
> $ clang -v
> Apple LLVM version 4.2 (clang-425.0.28) (based on LLVM 3.2svn)
> Target: x86_64-apple-darwin11.4.2
> Thread model: posix
>
> $ xcodebuild -version
> Xcode 4.6.3
> Build version 4H1503
>
> $ sw_vers
> ProductName:    Mac OS X
> ProductVersion: 10.7.5
> BuildVersion:   11G63

One other thing that is helpful is this cross reference for version
numbers: https://gist.github.com/yamaya/2924292

If you cut a feature in for LLVM Clang, then you can lookup the Apple
Clang version if you don't have an Apple machine with the compiler
handy.

Jeff