GCC: sorry, unimplemented: 64-bit mode not compiled in

Question

I have built GCC 4.7 on my x86 32-bit linux system. When I try to cross-compile with the -m64 flag I get the following:

sorry, unimplemented: 64-bit m

Answer 1

Had the same issues. My solution:

Update everything (R, Rstudio, R packages) and close Rstudio.
Uninstall Rtools and install the latest version.
Add only 2 entries under Enviroment Variables/System variables/Path:
- C:\Rtools\bin
- C:\Rtools\mingw_64\bin (!not the 32bit version)
Path entries have to be in this order and above %SystemRoot\System32
I did NOT install in the strongly recommended default location on C:

After that open Rstudio and re-install Rcpp via console:
install.packages("Rcpp")

Test if it's working with:
Rcpp::evalCpp("2+2")

After that just switch to the Terminal in Rstudio, go into the cmdstan source folder and type 'make build'.
--- CmdStan v2.19.1 built ---
Done!

Details:

*> sessionInfo()
R version 3.6.0 (2019-04-26)
Platform: x86_64-w64-mingw32/x64 (64-bit)
Running under: Windows 10 x64 (build 17763)
Matrix products: default
locale:
[1] LC_COLLATE=Slovenian_Slovenia.1250  LC_CTYPE=Slovenian_Slovenia.1250    LC_MONETARY=Slovenian_Slovenia.1250 LC_NUMERIC=C                       
[5] LC_TIME=Slovenian_Slovenia.1250    
attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base     
loaded via a namespace (and not attached):
[1] compiler_3.6.0 tools_3.6.0*