Different classes of users have different needs from a toolchain. This is originally from an email on the scons dev list by Michael Haubenwallner, with some additions by Gary Oberbrunner.

• The upstream package source maintainer

  • Specify which language-tools are to be initialized: C89, C99, C++, C++11, JavaC, ...
    • or let SCons auto-detect used languages along the list of source-files
  • Avoid the need to take care of platform- and tool-details:
    • Let the language-tool delegate to (or know about): cl.exe/gcc/xlc/hp-cc/...
    • Make additional resource-tools a no-op on platforms not using them
  • Specify package-default (used during development) language-/tool-options
    • warnings (as errors), debugging, optimization, ...
    • the language tool implementation filters unsupported flags
  • Don't care about a library to be static or shared - just define a Library:
    • fex, AIX traditionally used just one file target for both the static and the shared library (yes, shared objects can be linked statically).
  • (maybe more)

• The downstream (distro) package build/integration maintainer

  • Define the language-tool implementation to use: cl.exe/gcc/xlc/hp-cc/...
  • Define the actual tool-executable to use (PATH, ...)
  • Set the final language-/tool-options:
    • warnings (as errors), debugging, optimization, additional QA flags
    • override the package-default values
  • Define to build the Library as static and/or shared.
  • Define the search path for package dependencies.
  • (maybe more)

• The downstream (distro) package build/integration maintainer for SCons:

  • Define default language-tool implementation to use: cl.exe/gcc/xlc/hp-cc/...
    • To be used by upstream package source maintainer
  • Define the default tool-executable to use (PATH, ...)
  • Define the default search path for package dependencies.
  • (maybe more)

• Commercial software developers (in-house)

  • Define exactly which language/tool implementation to use, including version (optionally)
    • Possibly overridable by individual developers or external config files
  • Give good error messages when tools are missing or misconfigured For each design decision, IMHO it is important to think of /who/:

• defines the defaults,

• overrides the defaults,

• prepends/appends to the defaults.