Consume the pipes before waiting for pid (#411)

In general one shouldn't call waitpid until the child closed its end of
the pipe. This works fine with libtool invocations that do not produce
more than `_PC_PIPE_BUF` bytes of output but deadlocks when the pipe
fills up.

Revert "Fix oso_prefix paths (#347)" (#405)

This linker bug was fixed in Xcode 16.3. It would be a bit of a pain to
support both so this just reverts the fix and users on the older
versions should stay on older apple_supports until they upgrade Xcode.

Fixes #401
Fixes #404

This reverts commit 8ee7a2d.

Use absolute path to dirname (#400)

Fixes #399

Remove relative path to wrapped_clang from osx_cc_wrapper.sh (#395)

Otherwise path mapping does not work with these files since the path to
wrapped clang contained the transition hash. Now we fetch the relative
path to wrapped_clang dynamically.

Move toolchain tool setup out of repo rule (#393)

Now that we're building the tools used in the toolchain as normal rules,
there's really no need for them to be part of the toolchain setup. This
is more understandable in general since it removes a layer of
indirection.

Fix when `libtool` is called from a location other than Bazel’s execu…

…tion root (#375)

Fixes #374.

Signed-off-by: Brentley Jones <github@brentleyjones.com>

Revert "Enable link time -Os in opt builds (#348)" (#372)

Sidestep #371 until
it's fixed in Xcode. Users who still want this vs can pass
`--linkopt=-Os`

This reverts commit 27df79d.

Always create toolchain (#365)

Because we use the toolchain API, this should be a no-op on non-macOS
builds. This allows for cross-platform RBE.

Signed-off-by: Brentley Jones <github@brentleyjones.com>

Fix oso_prefix paths (#347)

When bazel executions actions in the sandbox, pwd is a path like this:

```
/private/var/tmp/_bazel_ksmiley/92410d0e3373f265902564b48493ac12/sandbox/darwin-sandbox/8/execroot/_main
```

Inside this directory are the inputs, which are symlinks to outside of
this pwd:

```
/private/var/tmp/_bazel_ksmiley/92410d0e3373f265902564b48493ac12/sandbox/darwin-sandbox/1/execroot/_main/bazel-out/darwin_arm64-dbg/bin/_objs/main/main.o -> /private/var/tmp/_bazel_ksmiley/92410d0e3373f265902564b48493ac12/execroot/_main/bazel-out/darwin_arm64-dbg/bin/_objs/main/main.o
```

ld64 resolves the absolute path to this object file, including resolving
symlinks, _before_ it strips the -oso_prefix argument. Because of this
the previous `__BAZEL_EXECUTION_ROOT__` replacement, which was the
sandbox pwd, isn't actually a prefix of the canonicalized object file
path, leading to -oso_prefix being a no-op, and absolute paths ending up
in the binary.

I think many folks didn't see this locally because it's common for Apple
projects to disable sandboxing for local development for perf reasons,
and that's when you're likely to have this debug info in the binary in
the first place.

With this change we add a new substitution that calculates the
sandbox-independent prefix and passes that along instead.

Use `-Xlinker` for `-install_name` (#343)

This supports `,` in `runtime_solib_name`.