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Bug 863038 - sci-libs/vtk-9.1.0-r2 fails to compile (lto): vtkAMRFlashReaderInternal.h:77:16: error: type struct tagBlock violates the C++ One Definition Rule [-Werror=odr]
Summary: sci-libs/vtk-9.1.0-r2 fails to compile (lto): vtkAMRFlashReaderInternal.h:77:...
Status: RESOLVED FIXED
Alias: None
Product: Gentoo Linux
Classification: Unclassified
Component: Current packages (show other bugs)
Hardware: All Linux
: Normal normal
Assignee: Gentoo Science Related Packages
URL:
Whiteboard:
Keywords: PullRequest
Depends on:
Blocks: lto
  Show dependency tree
 
Reported: 2022-08-02 14:07 UTC by Agostino Sarubbo
Modified: 2022-09-01 02:24 UTC (History)
2 users (show)

See Also:
Package list:
Runtime testing required: ---


Attachments
build.log.xz (build.log.xz,126.30 KB, application/x-xz)
2022-08-02 14:07 UTC, Agostino Sarubbo
Details

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Description Agostino Sarubbo gentoo-dev 2022-08-02 14:07:49 UTC
https://blogs.gentoo.org/ago/2020/07/04/gentoo-tinderbox/

Issue: sci-libs/vtk-9.1.0-r2 fails to compile (lto).
Discovered on: amd64 (internal ref: lto_tinderbox)

NOTE:
This machine uses lto with CFLAGS=-flto -Werror=odr -Werror=lto-type-mismatch -Werror=strict-aliasing

Here is a bit of explanation:

-Werror=lto-type-mismatch:
User to find possible runtime issues in packages. It likely means the package is unsafe to build & use with LTO.
For projects using the same identifier but with different types across different files, they must be fixed to be consistent across the codebase.

-Werror=odr:
Used to find possible runtime issues in packages. These bugs are a problem anyway but may be even worse when combined with LTO. C++ code must comply with the One Definition Rule (ODR) - see https://en.cppreference.com/w/cpp/language/definition#One_Definition_Rule.

-Werror=strict-aliasing:
Used to find possible runtime issues in packages. These bugs are a problem anyway but may be even worse when combined with LTO.

Workarounds:
- If upstream is friendly and still active, file a bug upstream. For emulators, codecs, games, or multimedia packages, it may be worth just applying a workaround instead, as upstreams sometimes aren't receptive to these bugs (VALID FOR ALL).
- Use the new 'filter-lto' from flag-o-matic.eclass as it's likely to be unsafe with LTO (VALID FOR lto-type-mismatch - odr).
- Fix it yourself if interested, of course (VALID FOR ALL).
- Append-flags -fno-strict-aliasing (VALID FOR strict-aliasing).
- Use memcpy() but a union is sometimes suitable too (VALID FOR strict-aliasing).
- -fstrict-aliasing is implied by -O2, so this must be addressed in some form (VALID FOR strict-aliasing).

See also: https://marc.info/?l=gentoo-dev&m=165639574126280&w=2
Comment 1 Agostino Sarubbo gentoo-dev 2022-08-02 14:07:53 UTC
Created attachment 796885 [details]
build.log.xz

build log and emerge --info (compressed because it exceeds attachment limit, use 'xzless' to read it)
Comment 2 Agostino Sarubbo gentoo-dev 2022-08-02 14:07:55 UTC
Error(s) that match a know pattern in addition to what has been reported in the summary:


FAILED: lib64/libvtkParallel-9.1.so.9.1.0 
/var/tmp/portage/sci-libs/vtk-9.1.0-r2/work/VTK-9.1.0/IO/AMR/vtkAMRFlashReaderInternal.h:77:16: error: type ‘struct tagBlock’ violates the C++ One Definition Rule [-Werror=odr]
Comment 3 Larry the Git Cow gentoo-dev 2022-09-01 02:24:47 UTC
The bug has been closed via the following commit(s):

https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=2e02cfbf0edd45b41747e2707fc56b7512c6aef6

commit 2e02cfbf0edd45b41747e2707fc56b7512c6aef6
Author:     Bernd Waibel <waebbl-gentoo@posteo.net>
AuthorDate: 2022-08-23 16:54:15 +0000
Commit:     Sam James <sam@gentoo.org>
CommitDate: 2022-09-01 02:23:53 +0000

    sci-libs/vtk: build with LTO enabled
    
    Closes: https://bugs.gentoo.org/863038
    Signed-off-by: Bernd Waibel <waebbl-gentoo@posteo.net>
    Closes: https://github.com/gentoo/gentoo/pull/27010
    Signed-off-by: Sam James <sam@gentoo.org>

 ...-or-scope-struct-names-to-avoid-conflicts.patch | 126 +++++++++++++++++++++
 sci-libs/vtk/vtk-9.1.0-r2.ebuild                   |   1 +
 2 files changed, 127 insertions(+)