On Sat, Aug 07 2021, Jeff King wrote:

On Sat, Aug 07, 2021 at 04:26:33PM +0200, Ævar Arnfjörð Bjarmason wrote:

quoted

quoted

That would probably be better. I would be curious to hear from somebody
with a mac if this technique gives more sensible version numbers for the
Apple-clang compiler.

It does, on the gcc304 box on the gccfarm (recent apple M1 Mac Mini):

    avar@minimac ~ % uname -a
    Darwin minimac.moose.housegordon.com 20.4.0 Darwin Kernel
Version 20.4.0: Thu Apr 22 21:46:41 PDT 2021;
root:xnu-7195.101.2~1/RELEASE_ARM64_T8101 arm64
    avar@minimac ~ % clang --version
    Apple clang version 12.0.5 (clang-1205.0.22.9)
    Target: arm64-apple-darwin20.4.0
    Thread model: posix
    InstalledDir: /Library/Developer/CommandLineTools/usr/bin

    avar@minimac ~ % cat >f  
    GNUC=__GNUC__
    GNUC_MINOR=__GNUC_MINOR__
    GNUC_PATCHLEVEL=__GNUC_PATCHLEVEL__
    clang=__clang__
    clang_major=__clang_major__
    clang_minor=__clang_minor__
    clang_patchlevel=__clang_patchlevel__
    
    ^C

    avar@minimac ~ % clang -E - <f
    # 1 "<stdin>"
    # 1 "<built-in>" 1
    # 1 "<built-in>" 3
    # 384 "<built-in>" 3
    # 1 "<command line>" 1
    # 1 "<built-in>" 2
    # 1 "<stdin>" 2
    GNUC=4
    GNUC_MINOR=2
    GNUC_PATCHLEVEL=1
    clang=1
    clang_major=12
    clang_minor=0
    clang_patchlevel=5

Hmm, now I'm really confused, though. Is that really clang 12 (for which
there is no 12.0.5; 12.0.1 is the latest version, shipped in July)? Or
is it XCode 12, shipping with LLVM 11, according to the table in:

  https://en.wikipedia.org/wiki/Xcode#Xcode_11.x_-_13.x_(since_SwiftUI_framework)

(sorry, there are actually _two_ tables with that same anchor on the
page; the one you want is the second one, under "Toolchain versions").

The distinction does not matter for our script (where we only care about
"clang4" and up). I guess the most relevant test would be to get XCode
8.x and see what it says. I expect it to claim "clang 8.1.0" or similar,
but actually be clang-3. And therefore not support
-Wtautological-constant-out-of-range-compare.

If we can't get easily get hold of such a platform, then maybe that is a
good indication that this conversation is too academic for now, and we
should wait until somebody wants to add a more recent version-specifier
to config.mak.dev. ;)

I think it's clang 12.0.5, and Apple just takes upstream versions and
increments them, e.g. I found this:
https://gist.github.com/yamaya/2924292

So you can presumably rely on it for having clang 12 features, and we'd
only ever care about the clang_major...