Bug 722992

Summary:	"llvm-libunwind" USE flag for usage of llvm-runtimes/libunwind
Product:	Gentoo Linux	Reporter:	Arfrever Frehtes Taifersar Arahesis <arfrever.fta>
Component:	Current packages	Assignee:	LLVM support project <llvm>
Status:	CONFIRMED ---
Severity:	normal	CC:	gentoo, paolo.pedroni, sam
Priority:	Normal	Keywords:	PATCH
Version:	unspecified
Hardware:	All
OS:	All
Whiteboard:
Package list:		Runtime testing required:	---
Attachments:	Patch for sys-libs/libcxxabi Patch for sys-libs/libcxxabi Patch for sys-libs/libcxxabi

Description Arfrever Frehtes Taifersar Arahesis 2020-05-14 10:36:15 UTC

sys-libs/libcxxabi currently has this dependency:
>   libunwind? (
>     || (
>       >=sys-libs/libunwind-1.0.1-r1[static-libs?,${MULTILIB_USEDEP}]
>       >=sys-libs/llvm-libunwind-3.9.0-r1[static-libs?,${MULTILIB_USEDEP}]
>     )
>   )

sys-libs/libunwind and sys-libs/llvm-libunwind are ABI-incompatible, at least due to different sonames of libraries:
  sys-libs/libunwind provides libunwind.so.8
  sys-libs/llvm-libunwind provides libunwind.so.1

This means that switching between sys-libs/libunwind and sys-libs/llvm-libunwind requires rebuilding of all reverse dependencies.

I suggest introduction of global "llvm-libunwind" USE, which would indicate using sys-libs/llvm-libunwind instead of sys-libs/libunwind (similarly to "graphicsmagick" and "libressl" USE flags).

Above dependency would be rewritten to:
>   libunwind? (
>     llvm-libunwind? ( >=sys-libs/llvm-libunwind-3.9.0-r1[static-libs?,${MULTILIB_USEDEP}] )
>     !llvm-libunwind? ( >=sys-libs/libunwind-1.0.1-r1[static-libs?,${MULTILIB_USEDEP}] )
>   )

Comment 1 Larry the Git Cow gentoo-dev

2021-04-09 22:32:35 UTC

The bug has been referenced in the following commit(s):

https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=218a5ccc68d1eefeafebcccb831ec9c2034cfaee

commit 218a5ccc68d1eefeafebcccb831ec9c2034cfaee
Author:     Arfrever Frehtes Taifersar Arahesis <Arfrever@Apache.Org>
AuthorDate: 2021-04-01 00:00:00 +0000
Commit:     Mike Gilbert <floppym@gentoo.org>
CommitDate: 2021-04-09 22:32:17 +0000

    profiles/use.desc: Add "llvm-libunwind" USE flag.
    
    Bug: https://bugs.gentoo.org/722992
    Signed-off-by: Arfrever Frehtes Taifersar Arahesis <Arfrever@Apache.Org>
    Signed-off-by: Mike Gilbert <floppym@gentoo.org>

 profiles/use.desc | 1 +
 1 file changed, 1 insertion(+)

Comment 2 Arfrever Frehtes Taifersar Arahesis 2021-04-10 03:14:46 UTC

Created attachment 698862 [details, diff]
Patch for sys-libs/libcxxabi

Comment 3 Arfrever Frehtes Taifersar Arahesis 2021-06-16 13:12:17 UTC

Created attachment 716454 [details, diff]
Patch for sys-libs/libcxxabi

Comment 4 Arfrever Frehtes Taifersar Arahesis 2021-06-17 10:59:54 UTC

Created attachment 716586 [details, diff]
Patch for sys-libs/libcxxabi