[Rd] Windows gcc toolchain for R 3.2.0

[Duncan Murdoch]

I have updated and moved the notes on the new toolchain.  Their URL is

https://rawgit.com/kevinushey/RToolsToolchainUpdate/master/mingwnotes.html

Thanks to Kevin for setting this up.  Anyone who can solve the problems
on that page, or who finds a new problem, please get in contact with us
by email or on Github.

Duncan Murdoch

On 18/03/2015 9:27 AM, Duncan Murdoch wrote:
> To anyone following the Windows toolchain saga:
> 
> The gcc 4.9.2 toolchain that is currently in Rtools33 has too many 
> incompatibilities with existing code, so we won't be using it in the R 
> 3.2.0 build.  I will soon be uploading to CRAN a new version of Rtools33 
> that is very similar to Rtools32, containing gcc 4.6.3.
> 
> We are continuing to work on the new toolchain, and hope to have it 
> ready before R 3.2.1 is released.
> 
> The known problems are as follows:
> 
>    - C++ code should not call Rf_error(), as it uses longjmp, and the 
> behaviour of longjmp is undefined in C++ when destructors need to be 
> called.  However, a number of packages do call Rf_error, and in gcc 
> 4.6.3, they get away with it.  In our candidate 4.9.2 build, they 
> crashed.  If we can't work around this, I'll suggest that we test for 
> the presence of Rf_error in C++ code, and start issuing warnings or 
> errors when it is seen.  But before we do that, we need a solid replacement.
> 
>   - There are some other crashes that appear to be unrelated, also with 
> C++ code.
> 
>   - There are some subtle differences in arithmetic that result in tests 
> failing.  These may be due to bugs in MinGW-w64 code,
> or may be unavoidable.
> 
> Duncan Murdoch
>