Re: infer GCC_REQD from USE_LANGUAGES

[Jonathan Perkin <jperkin%joyent.com@localhost>]

* On 2019-01-09 at 08:51 GMT, maya%netbsd.org@localhost wrote:

> mk/compiler/gcc.mk has,
> 
> #  Special case packages which are themselves a dependency of gcc runtime.
> .  if empty(PKGPATH:Mdevel/libtool-base) && empty(PKGPATH:Mdevel/binutils) && \
>       empty(PKGPATH:Mlang/gcc4?) && empty(PKGPATH:Mlang/gcc[5-9])
> 
> Seems like a good place ot expand upon that, but I haven't understood
> how pkgsrc-from-GCC works out for the Joyent case.

It's complicated, which is why I've never advocated that we attempt to
make it work out of the box.  It will also differ across operating
systems depending on whether they require libgcc and thus a gcc-libs
dependency for everything or not.

We have two lists, one for PKGSRC_USE_SSP which doubles as a way to
enable _USE_GCC_SHLIB and avoid all the missing USE_GCC_RUNTIMEs:

  https://github.com/joyent/pkgbuild/blob/master/include/gcc-libs.mk

and the list of packages that GCC depends on to avoid circular
dependencies:

  https://github.com/joyent/pkgbuild/blob/master/include/pkgsrc-gcc.mk

However, we also have a few additional settings to use external tools
when building GCC.  This is required when the dependency itself
requires GCC runtime:

  https://github.com/joyent/pkgbuild/blob/master/include/exttools.mk

If you don't have the latter, then you end up shipping packages that
depend upon an external GCC, which in our case is untenable.

-- 
Jonathan Perkin  -  Joyent, Inc.  -  www.joyent.com