cmake: accept versioned libatomic.so.1 in find_library - #176
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got3nks merged 1 commit intoJun 16, 2026
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openSUSE's `libatomic1` package ships only `libatomic.so.1` — there's no separate -devel package, and therefore no unversioned `libatomic.so` symlink, so the previous `find_library(NAMES atomic)` failed even though the library was installed. Accept `libatomic.so.1` as a fallback name. The canonical unversioned name is kept first so distros that do ship the symlink (Debian / Fedora / Arch) still resolve to it. Also tag the STATUS line with the resolved path so the chosen variant is visible in the configure summary.
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Summary
Closes #171.
The 32-bit
find_library (NAMES atomic)call only looks for the unversionedlibatomic.sosymlink, which on Debian / Fedora / Arch lives in the-dev/-develpackage alongside the runtime library. openSUSE shipslibatomic1with only the versionedlibatomic.so.1; there's no separate-develpackage, so the symlink is absent andfind_libraryhard-fails the configure even when the linker would happily resolve-latomicagainst the versioned library at link time.@gcomes reported this on #171 (openSUSE Tumbleweed packman maintainer, i586 32-bit build); his workaround was to manually create the missing
libatomic.sosymlink. @mrjimenez confirmed the openSUSE package names withzypper search --provides 'libatomic.so'output.Changes
Widen
find_libraryNAMES to accept both forms:Unversioned stays the preferred path; the versioned
.so.1is the fallback for distros that don't ship the symlink. The STATUS line also logs the resolved path so the build log captures which form matched.Test plan
libatomic.sosymlink, pulling this branch, and runningcmake -B buildon your openSUSE Tumbleweed i586 environment? The configure should now succeed without the symlink trick, and the STATUS line should print something like32-bit target: linking libatomic for std::atomic<int64_t> (/usr/lib/libatomic.so.1). Please paste the configure output in code fences either way (success or failure).Background
The binary's runtime libatomic dependency stays empty regardless — GNU ld's
--as-neededdefault drops theDT_NEEDEDentry when the compiler inlines the lock-free expansion (CMPXCHG8B on i586+). That's why @gcomes observedlddshowing no libatomic dependency in the linked binary. The-latomicflag is link-time scaffolding for cross-TU__atomic_*_8references that the compiler can't inline, kept as a safety net per the rationale in CMakeLists.txt:282-292 (see also 22ba4f2 / closes #643).