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Bug 1937698

Summary:	gcc: Remove libstdc++ symbols which are not going to be part of the GCC 11 upstream release
Product:	[Fedora] Fedora	Reporter:	Florian Weimer <fweimer>
Component:	gcc	Assignee:	Jonathan Wakely <jwakely>
Status:	ASSIGNED ---	QA Contact:	Fedora Extras Quality Assurance <extras-qa>
Severity:	high	Docs Contact:
Priority:	unspecified
Version:	34	CC:	aoliva, dmalcolm, fweimer, jakub, jwakely, kwizart, law, mpolacek, msebor, nickc, sipoyare
Target Milestone:	---
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	If docs needed, set a value
Doc Text:		Story Points:	---
Clone Of:
Clones:	1937700 (view as bug list)		Environment:
Last Closed:		Type:	Bug
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:	1959316, 1959320, 1926594, 1959307, 1959310, 1959312, 1959319, 1959323
Bug Blocks:	1937700

Description Florian Weimer 2021-03-11 11:17:36 UTC

The following symbols will be removed from libstdc++.so.6 before the GCC 11 upstream release:

_ZNSt9once_flag11_M_activateEv
_ZNSt9once_flag9_M_finishEb

We need to make this change in Fedora as well (in stages; first avoid creating symbol references from new builds, rebuild packages, and then remove the symbol for real).

Comment 1 Nicolas Chauvet (kwizart) 2021-04-02 16:28:06 UTC

What is the best way to detect the usage of theses symbols in any (non-fedora) package ? rpm2cpio + readelf ?
Eventually, having the range of the affected gcc compiler would help (or the first known good compiler) ?


Thanks in advance.

Comment 2 Jonathan Wakely 2021-04-03 14:46:42 UTC

(In reply to Nicolas Chauvet (kwizart) from comment #1)
> What is the best way to detect the usage of theses symbols in any
> (non-fedora) package ? rpm2cpio + readelf ?

Yes, that works.

> Eventually, having the range of the affected gcc compiler would help (or the
> first known good compiler) ?

The broken std::call_once was committed upstream Nov 3 2020. Rawhide switched to gcc-11.0.0 in late November, so all versions of gcc-11.0.0 will create references to the broken symbols. The fixed gcc that doesn't create references to those symbols (but still has them in libstdc++.so for now) is gcc-11.0.1-0.2.fc34 / gcc-11.0.1-0.2.fc35 (but the earlier build, gcc-11.0.1-0.1, is still bad).