[RFC] Adding a default file location to config file support

Clang Frontend
41

I think the best way to provide such flexibility is to have a single configuration file that can consult available data (e.g., driver name used, host platform, target, etc…) and alter configuration accordingly (frequently via some form of conditional inclusion). Something like:

!if $driver_name ~ *clang
!include clang.cfg
!elif $driver_name ~ *clang-cl
!include clang-cl.cfg
!endif

!if exists($target.cfg)
!include $target.cfg
!endif

!if $host_platform ~ zos* and $target ~ zos*
-L'//SYS1.SCEELIB'
!endif

The benefits of such an approach are:

  1. Less guessing about which config file(s) are being consulted.
  2. Support for distribution specific conventions.
  3. Support for composition (e.g., dropping new .cfg files into the configuration directory.
  4. Support for future extensions.