https://blogs.gentoo.org/ago/2020/07/04/gentoo-tinderbox/ Issue: net-vpn/openvpn-2.5.7 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
Created attachment 824843 [details] build.log build log and emerge --info
Error(s) that match a know pattern in addition to what has been reported in the summary: <artificial>:(.text+0x1316): undefined reference to `__wrap_parse_line' collect2: error: ld returned 1 exit status
Still in openvpn-2.6.8
OpenVPN upstream here. This is cmocka based unit test code, with gcc being called with `-Wl,--wrap=parse_line` to, well, create a link-time wrapper for `parse_line()` (which would then be __wrap_parse_line(), provided by test_argv.c). As far as I can see, the C signatures match, so there is no reason why `-flto` should be complaining here. OTOH, -Wl,-wrap is documented as "only undefined references are replaced by the linker" and maybe this fails if the linker considers all .o files as "one" (but then I'd expect a complaint about `parse_line()` which would indeed be not present). In other words: I think the compiler upsets itself here, and I do not see anything we could do about it (except not use -Wl,-wrap= and rewrite our unit test code).
