Embed absolute path to bash in cc_wrapper template

[aaliddell]

Alternate to #448 that allows still using bash, with the absolute path resolved at templating time, see bazelbuild/rules_rust#3535. Opened as draft for visibility but there may be other scripts that need similar patch and there should also be an error check for repository_ctx.which("bash") returning None if somehow bash is unavailable.

[keith]

probably not great to go this route because folks could easily invalidate the build by this file being different

[fmeum]

If we want to embed a path, it should be the one from rules_shell's sh_toolchain. Since this is a repo rule, we would need to add a way to obtain it.

[UebelAndre]

Is there any opposition to the wrappers being converted to pure shell from bash?

If we want to embed a path, it should be the one from rules_shell's sh_toolchain. Since this is a repo rule, we would need to add a way to obtain it.

There's an example of this here https://github.com/bazelbuild/rules_rust/blob/c7f09c03b158a08dcefb22a56da3c41b10acd3c4/util/process_wrapper/private/bootstrap_process_wrapper.bzl#L9-L20

[fmeum]

+1 to pure posix sh

[aaliddell]

Yep suits me fine 👍

[UebelAndre]

#466 it's not quite pure posix shell since there's still uses of dirname, readlink, etc but I think something like this would work and be an improvement.

[aaliddell]

Superseded by #466