Link cephes-gtsam against libm#2590
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cephes/gamma.c, igam.c, and the other remaining cephes sources call libm functions (e.g. sin) directly, but cephes-gtsam was never linked against libm itself, leaving the symbol to be resolved transitively through whatever else the final binary happens to link against. That can crash the dynamic linker while relinking an IFUNC-resolved symbol (glibc printing "Relink `libcephes-gtsam.so' with `libm.so' for IFUNC symbol `sin'" before segfaulting in _dl_relocate_object) depending on link order in the consuming binary. Same failure mode as https://bugzilla.redhat.com/show_bug.cgi?id=1883501 in an unrelated project. Reproduced consistently when linking a downstream consumer that pulls in enough of libgtsam's symbol surface to shift link order, and confirmed fixed by this change (readelf -d shows a proper NEEDED entry for libm.so.6 afterward). Uses find_library(MATH_LIBRARY m) rather than an explicit -lm so this naturally no-ops on platforms without a separate libm (Windows, and effectively macOS where it's already part of libSystem).
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Summary
cephes-gtsamcalls libm functions directly (e.g.sinincephes/gamma.c)but was never linked against libm itself. It happened to keep working
because the symbol got resolved transitively through whatever else ends up
in the final process, but that's fragile: depending on link order in a
downstream consumer, glibc's dynamic linker can crash while relinking the
IFUNC-resolved
sinsymbol (printsRelinklibcephes-gtsam.so' withlibm.so' for IFUNC symbolsin'right before segfaulting inside_dl_relocate_object`). Same failure mode asRHBZ#1883501 in an
unrelated project (cp2k/libxc).
I hit this building a downstream Rust FFI binding against GTSAM: a build
that pulled in more of libgtsam's symbol surface shifted link order enough
to trigger the crash reliably. Confirmed the missing dependency directly
(
readelf -d libcephes-gtsam.sohad noNEEDEDentry forlibm.so), andconfirmed this fix resolves it.
Fix
find_library(MATH_LIBRARY m)+ conditionaltarget_link_libraries,rather than a bare
-lm, so it naturally no-ops on platforms without aseparate libm (Windows, and effectively macOS where it's already part of
libSystem).Not a duplicate of #2273 (fixed a different issue: duplicate declarations of
libm functions in
cephes.hconflicting under static linking) or #2371(trimmed which cephes source files are built); neither touched linking
cephes-gtsam against libm itself.
Test plan
cmakeconfigure +make cephes-gtsamsucceedsreadelf -don the resultinglibcephes-gtsam.soshows aNEEDEDentry for
libm.so.6(previously absent)runs cleanly, repeated across multiple rebuilds