Build with --disable-elf-tls doesn't disable tls

[rillian]

Sorry for not testing this earlier, but the no-tls builds we were doing for gecko seem to be broken in 1.7.0.

If I set MACOSX_DEPLOYMENT_TARGET=10.7 and configure --disable-elf-tls as before, the resulting build uses thread-local storage:

 15:57:48 INFO - ld: targeted OS version does not support use of thread local variables in __ZN10sys_common11thread_info14current_thread20h4ec593d7ee7ff5477SsE for architecture x86_64

So it seems like --disable-elf-tls is broken. The target_thread_local changes in #30417 added MACOSX_DEPLOYMENT_TARGET-based detection. However, it seems building against a 10.6 target also doesn't work:

$ MACOSX_DEPLOYMENT_TARGET=10.6 ./configure --prefix=_dist/rustc --target=x86_64-apple-darwin,i686-apple-darwin --disable-docs
[...]
$ MACOSX_DEPLOYMENT_TARGET=10.6 make -j8
[...]
clang: error: invalid deployment target for -stdlib=libc++ (requires OS X 10.7 or later)

Is there an sdk I'm missing or has llvm dropped 10.6 support?

[rillian]

Building with MACOSX_DEPLOYMENT_TARGET=10.6 doesn't work in rust 1.6 either, so the issue is just that --disable-elf-tls doesn't work any more.

[alexcrichton]

Yeah with #30417 the --disable-elf-tls option was basically obsoleted as the environment variable is the way to control it now. We may need to change how we compile/link LLVM to work with 10.6, however.

[rillian]

There's another proposal to stop supporting MacOS X 10.6 is Firefox this year, with a timeframe which should let us stay on rustc 1.6 for supporting those builds, so we may not need to address this.

https://groups.google.com/forum/#!topic/mozilla.dev.platform/gXZj0rQWEfI

Is anyone besides gecko supporting this target?

[alexcrichton]

I don't believe so, no

[Mark-Simulacrum]

configure still accepts this, but I don't think it's read anywhere else within Rust, since ripgrep doesn't return any results... I'm going to close this, but please do reopen if this is still a problem.