[R] SOLVED (was Re: using MAKEFLAGS in compiling C code as a shared library using R CMD SHLIB)

[Faheem Mitha]

Dear R People,

I'm replying to my own question here. The maintainer of GNU
Make, Paul Smith, kindly replied to a message I posted to the GNU Make
help list, help-make at gnu.org.

I suggest that an example be added to the appropriate section of the FAQ
to reflect this issue, or perhaps the current example could be expanded.
Granted, this is just a shell quoting issue, but it might save someone,
sometime, from some head scratching.

                                          Sincerely, Faheem Mitha.

*******************************************************************

%% Faheem Mitha <faheem at email.unc.edu> writes:

  fm> MAKEFLAGS="CC=gcc-3.0 PKG_CFLAGS= -Wall -pedantic" R CMD SHLIB rc.c
-o rc.so

  fm> does not work fine. Make throws a fit and spews forth gibberish.

Make is interpreting the -Wall and -pedantic as lists of make options,
rather than as the value of PKG_CFLAGS, which is entirely correct given
that command string.

  fm> My understanding of MAKEFLAGS is that it is for passing flags to
some
  fm> submake process, in this case R CMD SHLIB. The documentation (make
  fm> manual) says that

  fm> "Words in the value of `MAKEFLAGS' that contain `=', `make' treats
as
  fm> variable definitions just as if they appeared on the command line."

  fm> However, there seems to be a problem when the variable definition
  fm> contains blanks, as PKG_CFLAGS does above.

That's because the ''PKG_CFLAGS= -Wall -pedantic'' above is not _one_
word containing an =, it's three words, only the first of which contains
an =.  So only the first word is considered to be a variable definition.

  fm> Can anyone advise on what is the correct syntax for this?

The simplest solution is to use backslashes to quote the spaces:

 MAKEFLAGS='CC=gcc-3.0 PKG_CFLAGS=\ -Wall\ -pedantic' R CMD SHLIB rc.c -o
rc.so

will work (note the change to single quotes: if you must use double
quotes you'll have to type two backslashes to get one--see the
documentation for your shell).

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