Bug 906040

Summary:	sys-devel/gcc-config-2.10 on llvm profile: unmerging leaves /etc/clang/gentoo-gcc-install.cfg with stale --gcc-install-dir
Product:	Gentoo Linux	Reporter:	Ilja ”Zucca” Sara <zuccavondille>
Component:	Current packages	Assignee:	Gentoo Toolchain Maintainers <toolchain>
Status:	CONFIRMED ---
Severity:	minor	CC:	sam
Priority:	Normal
Version:	unspecified
Hardware:	All
OS:	Linux
URL:	https://forums.gentoo.org/viewtopic-t-1163243.html
Whiteboard:
Package list:		Runtime testing required:	---

Description Ilja ”Zucca” Sara 2023-05-09 18:47:37 UTC

gcc-config leaves traces of gcc installation inside /etc/clang even when gcc and gcc-config are removed from the system.
The main culprit is /etc/clang/gentoo-gcc-install.cfg, which is included from /etc/clang/gentoo-common.cfg.

Reproducible: Always

Steps to Reproduce:
1. Have a llvm profile enabled
2. run: emerge --oneshot gcc
3. run: emerge --depclean
4. Try emerge any package which needs c and/or c++ code compiling
Actual Results:  
Portage can't use any compiler. Tries to run clang, but clang complains about missing gcc installation

Expected Results:  
A Working Portage which can compile c and c++ -based software.

We had some conversation already at forums. Please see the URL.

I don't see this as a very critical bug as one can either clean /etc/clang from gcc-config leftovers or just refraing from using (emerging) gcc in llvm based system.
A quickest fix would be to add package.mask for gcc and gcc-config in llvm profiles.

I accidentaly stumbled upon this because refind doesn't compile using clang at the moment. So masking gcc and gcc-config could potentially also block some other packages on llvm profiles.

Comment 1 Sam James archtester

2023-05-10 00:53:37 UTC

1. gcc becomes depcleanable
2. gcc (and then gcc-config) are unmerged
3. /etc/clang/gentoo-gcc-install.cfg's --gcc-install-dir points to a now-non-existent path

We should either clean it up in toolchain.eclass in pre/postrm or in pre/postrm in gcc-config.

(prerm sounds better because we narrow the race then.)

gcc-config might be able to do it by itself as well.

Comment 2 Ilja ”Zucca” Sara 2023-05-28 18:14:16 UTC

Also this gets printed when doing 'emerge --info'

!!! No gcc found. You probably need to 'source /etc/profile'
!!! to update the environment of this terminal and possibly 
!!! other terminals also. 

I'm not sure if this happens because gcc-config did leave something else hanging under /etc or if portage/emerge always expects gcc to be founf from the system even when using llvm based profile.