Bug 877447 – net-libs/libmicrohttpd-0.9.75 fails tests (lto): test_tls_options.c:39:5: error: type of curl_check_version does not match original declaration [-Werror=lto-type-mismatch]

• Status: RESOLVED FIXED
• Product: Gentoo Linux

[Description Agostino Sarubbo 2022-10-17 13:39:21 UTC]

https://blogs.gentoo.org/ago/2020/07/04/gentoo-tinderbox/

Issue: net-libs/libmicrohttpd-0.9.75 fails tests (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 2022-10-17 13:39:23 UTC]

Created attachment 824595 [details]
build.log

build log and emerge --info

[Comment 2 Karlson2k 2022-10-17 14:22:57 UTC]

The error is generated for the old part of the test-suite.
It was already fixed in the git master, but has not been released yet.

The problematic part:
----------------------------------
/var/tmp/portage/net-libs/libmicrohttpd-0.9.75/work/libmicrohttpd-0.9.75/src/testcurl/https/test_tls_options.c:39:5: error: type of 'curl_check_version' does not match original declaration [-Werror=lto-type-mismatch]
   39 | int curl_check_version (const char *req_version, ...);
      |     ^
/var/tmp/portage/net-libs/libmicrohttpd-0.9.75/work/libmicrohttpd-0.9.75/src/testcurl/https/curl_version_check.c:78:1: note: types have different parameter counts
   78 | curl_check_version (const char *req_version)
      | ^
/var/tmp/portage/net-libs/libmicrohttpd-0.9.75/work/libmicrohttpd-0.9.75/src/testcurl/https/curl_version_check.c:78:1: note: 'curl_check_version' was previously declared here
----------------------------------

There is no problem in the library code itself. The only problematic part is testcase code.

[Comment 3 Larry the Git Cow 2022-10-20 23:34:28 UTC]

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

https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=2f2316ccd5516c31dd42a90ffde9ff9ab89d9b88

commit 2f2316ccd5516c31dd42a90ffde9ff9ab89d9b88
Author:     Karlson2k (Evgeny Grin) <[e-mail]>
AuthorDate: 2022-10-17 17:49:04 +0000
Commit:     Sam James <[e-mail]>
CommitDate: 2022-10-20 23:34:16 +0000

    net-libs/libmicrohttpd: fixed tests with LTO
    
    Bug: https://bugs.gentoo.org/877447
    Signed-off-by: Karlson2k (Evgeny Grin) <[e-mail]>
    Closes: https://github.com/gentoo/gentoo/pull/27823
    Signed-off-by: Sam James <[e-mail]>

 ...bmicrohttpd-0.9.75-fix-testsuite-with-lto.patch | 60 ++++++++++++++++++++++
 net-libs/libmicrohttpd/libmicrohttpd-0.9.72.ebuild |  3 +-
 net-libs/libmicrohttpd/libmicrohttpd-0.9.73.ebuild |  3 +-
 net-libs/libmicrohttpd/libmicrohttpd-0.9.74.ebuild |  2 +
 net-libs/libmicrohttpd/libmicrohttpd-0.9.75.ebuild |  2 +
 5 files changed, 68 insertions(+), 2 deletions(-)