Re: How to choose (pkgsrc) gcc version for build ?

[Greg Troxel <gdt%lexort.com@localhost>]

vom513 <vom513%gmail.com@localhost> writes:

> I looked over:
>
> https://www.netbsd.org/docs/pkgsrc/configuring.html
>
> https://wiki.netbsd.org/pkgsrc/gcc/
>
> And I’m afraid I still can’t tell if this is possible.  I’d like to use a pkgsrc (i.e. newer) gcc for building one specific package.
>
> Is there a way to do this ?

Set GCC_REQD for that package only.  Something like (edited from
something else, not tested) in mk.conf

  .if "${PKGPATH}" == "foo/bar"
  GCC_REQD+=              14
  .endif

This won't force that version, because there might be GCC_REQD+=17
someplace else.

Or just add the line into your copy of pkgsrc, or

  make GCC_REQD=14 package-install

> And of course if what I’m asking is “bad mojo” please tell me that as
> well… It’s just I have something I need to build that supposedly will
> work with gcc14 - but I don’t necessarily want to build everything
> afterwards with it (unless this is actually recommended?)

Well, the entire situation is messy, as in theory there are ABI
differences among gcc versions and mixing libstdc++ versions in one
binary because one lib was build with N and one lib with M is messy.

However, we do it all the time, and pkgsrc has lots of USE_CXX_FEATURES
to specify a language variant for conditional upgdrade.

Many people believe, and a few insist on it, that the best thing is to
use one compiler for everything, period.  But that's not typical
practice.

> Obviously to even build gcc14 I had to bootstrap with the system gcc
> (12.5.0 I think) - so there are a handful of packages built with that
> already (chicken vs. egg).

Yes, you can just cd /usr/pkgsrc/lang/gcc14 and build the package.

There are three paths from that:

  1. Set GCC_REQD+=14 for packages that need it.  If so, you are
     probably finding a bug and perhaps the package uses the unreleased
     C++27 :-)   But seriously, it's a good question if it's something
     about you or your system, or if everybody else would have the same
     issue.

  2. After building gcc14, set GCC_REQD+=14 in mk.conf, so everything
     else uses 14.  For extra points, use conditionals to omit gcc14 and
     dependencies.  sysutils/auto-admin may be useful.

  3. After building gcc14, "pkg_admin set rebuild=yes \*" and run
     pkg_rolling-replace, so that you have even gcc14 and deps built
     with gcc14.

There's a fourth path, which is to bootstrap pkgsrc to eg
/usr/pkg-compiler and build gcc14, and then set up pkgsrc to use that as
an external compiler and build everything.
  
Generally option 1 is ok.