FTBFS (tests/examples/benchmarks) on Arch Linux since 48b8aeb217734b459d4d9170e602a65af9080f39

scnlib's tests/examples/benchmarks fail to build from source on Arch (both with GCC 15.1.1 and Clang 20.1.8) since commit 48b8aeb217734b459d4d9170e602a65af9080f39.

### Error

```console
$ cmake --build build --target all -j1
[1/18] Linking CXX executable benchmark/runtime/basic/scn_basic_bench
FAILED: benchmark/runtime/basic/scn_basic_bench
: && /usr/lib/ccache/bin/c++ -O3 -DNDEBUG -Wl,--dependency-file=benchmark/runtime/basic/CMakeFiles/scn_basic_bench.dir/link.d benchmark/runtime/basic/CMakeFiles/scn_basic_bench.dir/basic_bench.cpp.o -o benchmark/runtime/basic/scn_basic_bench  -Wl,-rpath,/srv/build/work/scnlib-git/src/build/_deps/google-benchmark-build/src:/srv/build/work/scnlib-git/src/build  _deps/google-benchmark-build/src/libbenchmark_main.so.1.9.4  libscn.so.4.0.1  _deps/google-benchmark-build/src/libbenchmark.so.1.9.4 && :
/usr/bin/ld: benchmark/runtime/basic/CMakeFiles/scn_basic_bench.dir/basic_bench.cpp.o: in function `bench_basic_scn_value(benchmark::State&)':
basic_bench.cpp:(.text+0x27f): undefined reference to `scn::v4::detail::vscan_value_impl(std::basic_string_view<char, std::char_traits<char> >, scn::v4::basic_scan_arg<scn::v4::basic_scan_context<scn::v4::detail::buffer_range_tag, char> >)'
/usr/bin/ld: benchmark/runtime/basic/CMakeFiles/scn_basic_bench.dir/basic_bench.cpp.o: in function `bench_basic_scn(benchmark::State&)':
basic_bench.cpp:(.text+0x597): undefined reference to `scn::v4::detail::vscan_impl(std::basic_string_view<char, std::char_traits<char> >, std::basic_string_view<char, std::char_traits<char> >, scn::v4::basic_scan_args<scn::v4::basic_scan_context<scn::v4::detail::buffer_range_tag, char> >)'
/usr/bin/ld: benchmark/runtime/basic/CMakeFiles/scn_basic_bench.dir/basic_bench.cpp.o: in function `bench_basic_scn_withoptions(benchmark::State&)':
basic_bench.cpp:(.text+0x757): undefined reference to `scn::v4::detail::vscan_impl(std::basic_string_view<char, std::char_traits<char> >, std::basic_string_view<char, std::char_traits<char> >, scn::v4::basic_scan_args<scn::v4::basic_scan_context<scn::v4::detail::buffer_range_tag, char> >)'
/usr/bin/ld: benchmark/runtime/basic/CMakeFiles/scn_basic_bench.dir/basic_bench.cpp.o: in function `bench_basic_scn_withlocale(benchmark::State&)':
basic_bench.cpp:(.text+0x94a): undefined reference to `scn::v4::scan_expected<long> scn::v4::detail::vscan_localized_impl<std::locale>(std::locale const&, std::basic_string_view<char, std::char_traits<char> >, std::basic_string_view<char, std::char_traits<char> >, scn::v4::basic_scan_args<scn::v4::basic_scan_context<scn::v4::detail::buffer_range_tag, char> >)'
/usr/bin/ld: benchmark/runtime/basic/CMakeFiles/scn_basic_bench.dir/basic_bench.cpp.o: in function `bench_basic_scn_localized(benchmark::State&)':
basic_bench.cpp:(.text+0xb2a): undefined reference to `scn::v4::scan_expected<long> scn::v4::detail::vscan_localized_impl<std::locale>(std::locale const&, std::basic_string_view<char, std::char_traits<char> >, std::basic_string_view<char, std::char_traits<char> >, scn::v4::basic_scan_args<scn::v4::basic_scan_context<scn::v4::detail::buffer_range_tag, char> >)'
collect2: error: ld returned 1 exit status
ninja: build stopped: subcommand failed.
```

(other tests/benchmarks/examples fail similarly, run `ninja -k0` or `make -k`)

### Build configuration

```sh
cmake -S scnlib -B build \
        -DCMAKE_BUILD_TYPE=Release \
        -DBUILD_SHARED_LIBS=ON \
&& cmake --build build --target all
```

### Bisect

```console
$ git bisect start master v4.0.1
Bisecting: 20 revisions left to test after this (roughly 4 steps)
[8b8f3052b62976dc6cdc0b664a0df46b155ed1b3] Fix other-archs build job

$ git bisect run bash -ex -c "rm -rf build; cmake -S . -B build -DCMAKE_BUILD_TYPE=Release -DBUILD_SHARED_LIBS=ON; cmake --build build --target all; cmake --build build --target test"
<...>
48b8aeb217734b459d4d9170e602a65af9080f39 is the first bad commit
commit 48b8aeb217734b459d4d9170e602a65af9080f39
Author: Elias Kosunen <elias.kosunen@gmail.com>
Date:   Wed Jun 4 01:58:26 2025 +0300

    Initial support for modules

 .github/workflows/linux.yml                        |    4 +-
 .github/workflows/modules.yml                      |  126 +++
 CMakeLists.txt                                     |   66 +-
 README.md                                          |    2 +-
 cmake/icm_build_failure_parse_and_run.cmake        |    7 +-
 cmake/icm_build_failure_testing.cmake              |   15 +-
 cmake/install.cmake                                |   10 +
 cmake/options.cmake                                |    2 +
 include/scn/chrono.h                               |   10 +-
 include/scn/fwd.h                                  | 1093 +-------------------
 include/scn/istream.h                              |    4 +
 include/scn/macros.h                               | 1091 +++++++++++++++++++
 include/scn/regex.h                                |    4 +
 include/scn/scan.h                                 |   33 +-
 src/modules/CMakeLists.txt                         |   30 -
 src/modules/chrono.cppm                            |   58 --
 src/modules/istream.cppm                           |   27 -
 src/modules/ranges.cppm                            |   29 -
 src/modules/scan.cppm                              |  138 ---
 src/modules/scn.cppm                               |   24 -
 src/scn/impl.cpp                                   |    2 +-
 src/scn/scn.cppm                                   |  204 ++++
 tests/consumer-test/CMakeLists.txt                 |    8 -
 tests/consumer-test/library/CMakeLists.txt         |    8 +
 tests/consumer-test/{ => library}/main.cpp         |    0
 tests/consumer-test/module/CMakeLists.txt          |    9 +
 tests/consumer-test/module/main.cpp                |   12 +
 tests/unittests/CMakeLists.txt                     |   12 +-
 .../regex.cppm => tests/unittests/module_test.cpp  |   21 +-
 29 files changed, 1589 insertions(+), 1460 deletions(-)
 create mode 100644 .github/workflows/modules.yml
 create mode 100644 include/scn/macros.h
 delete mode 100644 src/modules/CMakeLists.txt
 delete mode 100644 src/modules/chrono.cppm
 delete mode 100644 src/modules/istream.cppm
 delete mode 100644 src/modules/ranges.cppm
 delete mode 100644 src/modules/scan.cppm
 delete mode 100644 src/modules/scn.cppm
 create mode 100644 src/scn/scn.cppm
 delete mode 100644 tests/consumer-test/CMakeLists.txt
 create mode 100644 tests/consumer-test/library/CMakeLists.txt
 rename tests/consumer-test/{ => library}/main.cpp (100%)
 create mode 100644 tests/consumer-test/module/CMakeLists.txt
 create mode 100644 tests/consumer-test/module/main.cpp
 rename src/modules/regex.cppm => tests/unittests/module_test.cpp (61%)
bisect found first bad commit

$ git bisect log
# bad: [aeaee06538611a142cf273ff2537841cdc8b15fc] Fix issue found by fuzzing
# good: [e937be1a52588621b406d58ce8614f96bb5de747] Prepare v4.0.1
git bisect start 'master' 'v4.0.1'
# good: [8b8f3052b62976dc6cdc0b664a0df46b155ed1b3] Fix other-archs build job
git bisect good 8b8f3052b62976dc6cdc0b664a0df46b155ed1b3
# good: [646fcd7586b8726c2472118048aa97e832e16eba] Replace use of ubuntu-20.04 in CI with containers
git bisect good 646fcd7586b8726c2472118048aa97e832e16eba
# good: [aca4cf20a38bbd8ba0be58608ddc7ee859c539d0] int128 and ext-float fixes
git bisect good aca4cf20a38bbd8ba0be58608ddc7ee859c539d0
# bad: [c7f05757c41e397ceaa80cfe54bf47a080842a38] Warning fixes
git bisect bad c7f05757c41e397ceaa80cfe54bf47a080842a38
# bad: [48b8aeb217734b459d4d9170e602a65af9080f39] Initial support for modules
git bisect bad 48b8aeb217734b459d4d9170e602a65af9080f39
# good: [e42892687f751df67032b27f035422924036ad35] Add C++20 modules support
git bisect good e42892687f751df67032b27f035422924036ad35
# first bad commit: [48b8aeb217734b459d4d9170e602a65af9080f39] Initial support for modules
```

### How to reproduce

```console
$ podman run -it --rm archlinux:latest

[root@container /]$ pacman -Sy base-devel git cmake ninja
[root@container /]$ git clone https://github.com/eliaskosunen/scnlib --revision 48b8aeb217734b459d4d9170e602a65af9080f39
[root@container /]$ cmake -G Ninja -S scnlib -B build -DCMAKE_BUILD_TYPE=Release -DBUILD_SHARED_LIBS=ON
[root@container /]$ cmake --build build --target all -- -k0
```

### Analysis

The issue seems to be the newly-changed visibility flags, making visibility default to "hidden" for all symbols:

https://github.com/eliaskosunen/scnlib/blob/48b8aeb217734b459d4d9170e602a65af9080f39/CMakeLists.txt#L30-L39

Overriding the `-fvisibility=hidden` flag, reverting to "default" visibility for non-inlines, is enough to fix the FTBFS and have the tests pass:

```sh
cmake -S scnlib -B build \
        -DCMAKE_BUILD_TYPE=Release \
        -DBUILD_SHARED_LIBS=ON \
        -DCMAKE_CXX_VISIBILITY_PRESET=default \
&& cmake --build build --target all \
&& cmake --build build --target tests
```

Overriding `-fvisibility-inlines-hidden` is not necessary to fix FTBFS (though I can't comment on semantic correctness).

	if (NOT DEFINED CMAKE_CXX_VISIBILITY_PRESET)
	message(STATUS "No CMAKE_CXX_VISIBILITY_PRESET set, defaulting to hidden")
	set(CMAKE_CXX_VISIBILITY_PRESET hidden CACHE STRING "Preset for the export of private symbols")
	set_property(CACHE CMAKE_CXX_VISIBILITY_PRESET PROPERTY STRINGS hidden default)
	endif ()
	if (NOT DEFINED CMAKE_VISIBILITY_INLINES_HIDDEN)
	message(STATUS "No CMAKE_VISIBILITY_INLINES_HIDDEN set, defaulting to ON")
	set(CMAKE_VISIBILITY_INLINES_HIDDEN ON CACHE BOOL
	"Whether to add a compiler flag to hide symbols of inline functions")
	endif ()

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FTBFS (tests/examples/benchmarks) on Arch Linux since 48b8aeb217734b459d4d9170e602a65af9080f39 #152

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FTBFS (tests/examples/benchmarks) on Arch Linux since 48b8aeb217734b459d4d9170e602a65af9080f39 #152

Description

Error

Build configuration

Bisect

How to reproduce

Analysis

Metadata

Metadata

Assignees

Labels

Projects

Milestone

Relationships

Development

Issue actions