https://blogs.gentoo.org/ago/2020/07/04/gentoo-tinderbox/ Issue: dev-cpp/abseil-cpp-20211102.0-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
Created attachment 800692 [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: FAILED: bin/absl_flags_flag_test /var/tmp/portage/dev-cpp/abseil-cpp-20211102.0-r2/work/abseil-cpp-20211102.0/absl/flags/flag_test.cc:45:1: error: ‘FLAGS_mistyped_string_flag’ violates the C++ One Definition Rule [-Werror=odr]
// This file is used to test the mismatch of the flag type between definition // and declaration. These are definitions. flag_test.cc contains declarations. #include <string> #include "absl/flags/flag.h" ABSL_FLAG(int, mistyped_int_flag, 0, ""); ABSL_FLAG(std::string, mistyped_string_flag, "", ""); ABSL_FLAG(bool, flag_on_separate_file, false, ""); ABSL_RETIRED_FLAG(bool, retired_flag_on_separate_file, false, ""); And in another file: ABSL_DECLARE_FLAG(int64_t, mistyped_int_flag); ABSL_DECLARE_FLAG(std::vector<std::string>, mistyped_string_flag); This, erm, looks very deliberate. Testsuite checks out. :D
