RcppParallel 6.1.1: `tbbLibraryPath()` broken on Windows - looks in build-time RTools not runtime

[andrjohns]

The use of RcppParallel::tbbLibraryPath("tbb") on Windows returns nothing when called from the CRAN pre-built binary, and tbbRoot() returns a filepath on a D:/ drive:

utils::packageVersion("RcppParallel")
#> [1] '6.1.1'
RcppParallel::tbbLibraryPath("tbb")
RcppParallel:::tbbRoot()
#> [1] "D:/rtools45/x86_64-w64-mingw32.static.posix/lib"

All works as expected when RcppParallel is built from source:

install.packages("RcppParallel", type = "source")
#> Installing package into 'C:/Users/andrew/AppData/Local/R/win-library/4.6'
#> (as 'lib' is unspecified)
RcppParallel::tbbLibraryPath("tbb")
#> [1] "C:/rtools45/x86_64-w64-mingw32.static.posix/lib/libtbb12.a"
RcppParallel:::tbbRoot()
#> [1] "C:/rtools45/x86_64-w64-mingw32.static.posix/lib"

This appears to be due to RcppParallel looking in the dir specified by the internal TBB_LIB variable set by the configure run at package build time, rather than the location at runtime

[kevinushey]

Argh. Thanks for the bug report; I'll take a look.

[kevinushey]

Beyond this, what actual issue(s) are you seeing with using RcppParallel right now? A more concrete example would be helpful.

[andrjohns]

I've got a package that I've updated to link directly to the tbb libraries instead of RcppParallel, and it uses RcppParallel::tbbLibraryPath() to lookup the right location and library name.

Unfortunately, this results in a build failure on Windows when the library path returns nothing:

 Error in basename(RcppParallel::tbbLibraryPath("tbb")) : 
   a character vector argument expected
 Calls: cat -> basename
 Execution halted
 g++ -std=gnu++20 -shared -s -static-libgcc -o StanEstimators.dll tmp.def StanEstimators.o init.o -LC:/Rtools/x86_64-w64-mingw32.static.posix/lib -l -LC:/rtools45/x86_64-w64-mingw32.static.posix/lib/x64 -LC:/rtools45/x86_64-w64-mingw32.static.posix/lib -LC:/R/bin/x64 -lR
 C:\rtools45\x86_64-w64-mingw32.static.posix\bin/ld.exe: cannot find -l-LC:/rtools45/x86_64-w64-mingw32.static.posix/lib/x64: Invalid argument

[kevinushey]

Thanks; that's exactly the example I needed. One thought, though -- why not use RcppParallelLibs() instead of deriving the TBB library paths + compiler invocation by hand?

EDIT: But that also appears to be similarly broken ...

[andrjohns]

Thanks; that's exactly the example I needed. One thought, though -- why not use RcppParallelLibs() instead of deriving the TBB library paths + compiler invocation by hand?

EDIT: But that also appears to be similarly broken ...

That change was spawned from this issue where the recommendation was to link against TBB directly since the symbols weren't exported through RcppParallel anymore - but it looks like that might have changed?