ronin2@bellatlantic.net wrote:
On Tue, 18 Mar 2003 02:35:52 +1100 Rob Weir <rweir@ertius.org> wrote:If setting CFLAGS is the answer, do you need to set all of them, oronly> the one you want to change?Hm, I don't think I quite got what you meant there...You just set whatever flags you'd set on the command line, anyway...Suppose: 1. I set CFLAGS to <something> 2. In a program I want to compile (or its Makefile or wherever) CFLAGS is set to <a bunch of things> Does CFLAGS end up as <something> or as <something plus a bunch of things>? Does my setting add to or replace what would otherwise be set?
Let me take a shot at this. "CFLAGS" is just a popular name for a makefile variable to hold the flags to be sent to the compiler. Whether or how it gets used is entirely up to the Makefile or configure script being used. GCC and other compilers do NOT look for or use CFLAGS, its not "special" to them. So you'll need to look at the Makefile[.in] and maybe the configure.[in,ac], if present, to to see how CFLAGS is being used, if at all.
If your package is using a configure script, i.e. it uses autoconf to build the Makefile for you, CFLAGS is normally used, and you can usually set CFLAGS first before running configure. On a bash shell you do something like this:
CFLAGS=-O2 ./configureBy convention, configure will use a CFLAGS variable if it exists at the moment configure is run. Otherwise the script uses its own defaults. Most configure scripts (by convention) will also *add* to the CFLAGS variable anything they need, instead of overwriting or replacing it. After running configure, you can look in the Makefile just produced and see your flags being assigned to the CFLAGS variable.
If you aren't using a configure script, just a Makefile, you'll need to look at the Makefile to see if it uses a CFLAGS variable, since there aren't the same kind of conventions involved in hand-written Makefiles like there are with using autoconf. In fact, there may not be a CFLAGS variable at all, or even one like it but using a different name. In this case you'll have to edit the Makefile yourself to set the flags you want passed to the compiler.