fix lookup path for tbb stub library on windows#250
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The stub loader added in #249 resolved tbb.dll via tbbRoot(), which prefers TBB_LIB when set -- and on Windows, configure always sets TBB_LIB to the Rtools library directory, which contains only static TBB libraries. As a result, the lookup silently failed and the stub was never loaded. Resolve against the package's own lib directory instead, which is where install.libs.R places the stub.
This was referenced Jul 23, 2026
kevinushey
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Jul 23, 2026
Stale or unexpected TBB libraries swept into the installed package have been a subtle source of downstream load failures, and were invisible in installation logs. Report which headers and libraries are installed and from where, and note when the tbb stub build is skipped because a tbb.dll is already present. Additionally, when the VERBOSE environment variable is set (as already used by the bundled TBB build), report how TBB libraries are resolved and loaded at package load time; this would have surfaced the lookup bug fixed in #250 immediately.
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Follow-up to #249: the stub loader resolved
tbb.dllviatbbRoot(), which prefersTBB_LIBwhen set. On Windows, configure always setsTBB_LIBto the Rtools library directory (the source of the static TBB link), which contains no DLLs -- so the lookup silently failed and the stub was never loaded. Confirmed on a real Windows machine: after loading a patched RcppParallel,getLoadedDLLs()showed notbbentry.Resolve against the package's own
lib/x64directory instead, which is whereinstall.libs.Rplaces the stub.