Fix lib/llvm to support MacOS

[winksaville]

lib/llvm/Makefile: OSX does not support LLVM_USE_LINKER so do not specify
a LLVM_LINKER and instead use the default system linker.

• Default LLVM_LINKER to empty value
• Only set LLVM_USE_LINKER if LLVM_LINKER is not empty

lib/llvm/llvm-base.rules: OSX does not support the -T parameter so just
use the position parameters. The first parameter is the target
and the second parameter is the name of the symlink, so removing
the -T fixes this incompatibility.

[winksaville]

Testing only DO NOT MERGE.

@SeanTAllen, please test this on Mac OSX

[SeanTAllen]

This is awesome @winksaville. Thanks. I'll give this a trial run sometime this weekend.

[SeanTAllen]

Testing this now.

I've identified one small additional issue:

MacOS find readlink as the readlink binary used for LLVM_READ_LINK.
When that is used on line 91 of the lib/llvm/Makefile, it uses the -f option that isn't supported on MacOS.

[SeanTAllen]

@winksaville this worked fine, there is that one readlink issue.

[winksaville]

@SeanTAllen could you past the readlink --help I want to see if there is -e, --canonicalize-existing options. Here is what I have on my Arch Linux system:

$ readlink --help
Usage: readlink [OPTION]... FILE...
Print value of a symbolic link or canonical file name

  -f, --canonicalize            canonicalize by following every symlink in
                                every component of the given name recursively;
                                all but the last component must exist
  -e, --canonicalize-existing   canonicalize by following every symlink in
                                every component of the given name recursively,
                                all components must exist
  -m, --canonicalize-missing    canonicalize by following every symlink in
                                every component of the given name recursively,
                                without requirements on components existence
  -n, --no-newline              do not output the trailing delimiter
  -q, --quiet
  -s, --silent                  suppress most error messages (on by default)
  -v, --verbose                 report error messages
  -z, --zero                    end each output line with NUL, not newline
      --help     display this help and exit
      --version  output version information and exit

GNU coreutils online help: <https://www.gnu.org/software/coreutils/>
Full documentation <https://www.gnu.org/software/coreutils/readlink>
or available locally via: info '(coreutils) readlink invocation'

[SeanTAllen]

@winksaville it doesn't even support --help

I tried -e and got:

readlink: illegal option -- e
usage: readlink [-n] [file ...]

It appears from the manpage that it only support -n

This FreeBSD manpage is the same as what I get on MacOS:

https://man.openbsd.org/FreeBSD-11.1/stat.1

[winksaville]

Would it be reasonable to coreutils it should be available via brew or macports, see this? If you can install coreutils try printing help and lets see what it supports.

[SeanTAllen]

coreutils installs greadlink which is in /usr/local/bin.

Usage: /usr/local/bin/greadlink [OPTION]... FILE...
Print value of a symbolic link or canonical file name

  -f, --canonicalize            canonicalize by following every symlink in
                                every component of the given name recursively;
                                all but the last component must exist
  -e, --canonicalize-existing   canonicalize by following every symlink in
                                every component of the given name recursively,
                                all components must exist
  -m, --canonicalize-missing    canonicalize by following every symlink in
                                every component of the given name recursively,
                                without requirements on components existence
  -n, --no-newline              do not output the trailing delimiter
  -q, --quiet,
  -s, --silent                  suppress most error messages (on by default)
  -v, --verbose                 report error messages
  -z, --zero                    end each output line with NUL, not newline
      --help     display this help and exit
      --version  output version information and exit

GNU coreutils online help: <http://www.gnu.org/software/coreutils/>
Full documentation at: <http://www.gnu.org/software/coreutils/readlink>
or available locally via: info '(coreutils) readlink invocation'

Seems like checking for greadlink before readlink would be a good idea?

[winksaville]

@SeanTAllen,

Tweaks to prefer greadlink and if OSTYPE is osx and report an error if greadlink is not available as the readlink that might exist isn't going to work.

[SeanTAllen]

@winksaville sounds good.

[SeanTAllen]

@winksaville tested again. looking good. you happy with now and ready for a merge?

[winksaville]

LGTM, this last change just removed the debug I'd enabled. So lets run the tests one last time and you do one last test before merging.

[SeanTAllen]

@winksaville I left one comment re: ld-gold. Not sure if the line I noted is intentionally or left over from debugging.

[winksaville]

@winksaville I left one comment re: ld-gold. Not sure if the line I noted is intentionally or left over from debugging.

I'd missed that comment, I've now commented on it and marked it as resolved.

[SeanTAllen]

Failure is unrelated. Merging. Thanks @winksaville.

[winksaville]

@SeanTAllen, you're most welcome!