[llvm-dev] Expanding response file's base directory

[Jack Andersen via llvm-dev]

A preliminary patch is available at
<https://reviews.llvm.org/D115604>. `<cfgdir>` has been replaced with
`<@>` to reflect the relationship with `@` expansions.

On Sat, 11 Dec 2021 at 18:48, Jack Andersen <jackoalan at gmail.com> wrote:
>
> I am looking for thoughts on how feasible it would be to have
> CommandLine.cpp's ExpandResponseFiles generate paths relative to the
> response file itself. Essentially, this involves transforming a
> reserved character sequence into the base path of the response file.
> Of course this would be trivial to implement, but the main
> consideration here is to avoid breakage for existing users. The
> reserved character sequence could contain shell operator characters,
> thereby eliminating the vast majority of accidental transformations. A
> reserved word would reduce this probability even further.
>
> I would like to propose "<cfgdir>" as a possibility.
>
> This would be a valuable feature for deploying portable, non-installed
> directories containing clang .cfg files and items for the toolchain to
> use without further search path arguments from the user.
>
> Use case:
>
> ```sample_target_sdk.cfg
> --target=sample_target
> -isystem <cfgdir>/include
> -L <cfgdir>/lib
> ```