[R-SIG-Mac] compilation with newer compilers on macos sierra

[Kostas Savvidis]

Good morning,

Compiling R-3.3.2 on macOS sierra produced a series of difficulties. Some of them are surely self-inflicted but
in my estimation all will have to be dealt with sooner or later. I used gcc6 from macports to compile it.


1) In R-3.3.2/src/modules/lapack need the flag:
-flax-vector-conversions

2) libz.h version checking in configure is broken, i.e. version 1.2.10 that i have from macports is flagged as too old.
  Culprit is in line 35513 of configure:
   strncmp(ZLIB_VERSION, "1.2.5", 5) 
  workaround: in libz.h replace the 1.2.10 string with 1.2.910 

3) Flags for libintl are not picked up at configure stage: needed to manually add it later
 LDFLAGS="-L/opt/local/lib" ./configure ...
	Note: somewhere along the compilation I spot "/opt/local/lib/libintl.dylib" on the command line compiling tools.so
       - who or what put it there?


4) --with-lapack option resulted eventually in:

byte-compiling package 'grDevices'
Warning in solve.default(rgb) :
 unable to load shared object '/Users/kosta/Downloads/R-3.3.2/modules//lapack.so':
 dlopen(/Users/kosta/Downloads/R-3.3.2/modules//lapack.so, 6): image not found
Error in solve.default(rgb) : LAPACK routines cannot be loaded
Error: unable to load R code in package 'grDevices'


5) The compilation with native clang compiler did not work for some reason so i confifured with gcc-mp-6 as obtained from macports. This compiler cannot compile the code in grdevices, the files devQuartz.c, qdBitmap.c and qdPDF.c
had to be compiled manually with apple's gcc.

Many thanks,
Kostas