[Rd] building windows packages under wine/linux and cross-compiling.

[Hin-Tak Leung]

Prof Brian Ripley wrote:
> On Mon, 31 Jul 2006, Hin-Tak Leung wrote:
> 
>> Had some fun today, and thought it might be a good idea to share
>> and possibly for inclusion to R/src/gnuwin32/README.packages .
> 
> [...]
> 
>> Cross-compiling: The instruction in R/src/gnuwin32/README.packages 
>> essentially works, with one missing detail: "R_EXE=/usr/bin/R" is also 
>> needed. Thus it should be:
>>
>>      make R_EXE=/usr/bin/R PKGDIR=/mysources RLIB=/R/win/library \
>>              pkg-mypkg
>>      make P_EXE=/usr/bin/R KGDIR=/mysources RLIB=/R/win/library \
>>              pkgcheck-mypkg
> 
> The instructions do work for those who actually follow them! That file 
> says
> 
>   Edit MkRules to set BUILD=CROSS and the appropriate paths (including
>   HEADER) as needed.

Apologies... but in fact I did *not* edit HEADER, and essentially did 
not understand the 2nd part of the above sentence, either.

Would it be better phrased as '...BUILD=CROSS near the top, and HEADER, 
R_EXE, etc in the "cross-compilation settings" section in the middle
of the file' ? Better still, have it in MkRules itself:

   # Alternatives MINGW (mingw), CROSS (Linux)
   #  - if you change BUILD, remember to edit and adjust the relevant
   #    native/cross cofiguration section further down
   BUILD=MINGW

This is all about user-friendliness/useability...


> ## =================== cross-compilation settings  =================
> 
> ifeq ($(strip $(BUILD)),CROSS)
> # Next might be mingw32- or i386-mingw32msvc- or i586-
> # depending on the cross-compiler.
> BINPREF=i586-mingw32-
> # Set this to where the mingw32 include files are. It must be accurate.
> HEADER=/users/ripley/R/cross-tools5/i586-mingw32/include
> endif
> # path (possibly full path) to same version of R on the host system
> # R_EXE=R
> 
> and please do note the last two lines.

I did not modify the HEADER line - and it wasn't necessary -
I guess mingw32 either knows the header files is right next to the
compiler, picked up enough from linux glibc's headers, or what not.

On a different note, I am rather uncomfortable doing *both*
makefile editing and setting options on the comand lines
"make option1=value1 option2=vaule2 ...". Surely it is possible
to do it entirely one way, e.g.

  make CROSS_ON_LINUX=1 <rest_of_options>

or have the switching inside the makefile itself? e.g. (probably
wrong syntax - and depends on cygwin uname which isn't in Rtools)

     ifeq ($(uname -a),Linux)
     BUILD=CROSS
     else
     BUILD=MINGW
     endif

Hin-Tak Leung