Mostly generated by Gemini; TODO annotations added for cases where we
should support a better way of doing various parts of this.
Assisted-by: Gemini 3 Pro
---------
Co-authored-by: Carbon Infra Bot <carbon-external-infra@google.com>
This enables on-demand building of runtimes by default, and enables
their header files for all of the Clang invocations. This also switches
the default flags to use the LLVM-provided runtimes (compiler-rt,
libunwind, and libcxx).
This also switches even `llvm_symlinks_test` to use the Bazel prebuilt
runtimes, which requires having a way to pass a Carbon flag even when
invoking the busybox as `clang` or `clang++`. This uses the pattern that
has worked for other Clang wrappers of spelling flags:
`-X<tool-name>=--flag=value`
Last but not least, this updates the Carbon Bazel rules to use our
installed and the Bazel prebuilt runtimes. With that, we make the C++
interop hello-world be enabled by default as this should pass reliably
on both Linux and macOS now.
Based on #5920.
Added commented out better examples and clarified what is missing to
support them.
Added `tags` support to `carbon_binary` (based on #5967) to set the
`BUILD` rule to manual until we can find `cstdio` in macos.
```shell
$ bazel run examples/interop/cpp:hello_world
...
Hello world!
```
Richard SmithandCarbon Infra Bot
Chandler Carruth
Boaz Brickner