Phil Prentice wrote:
Hi
I have some basic questions around compiler definitions. I am porting some
code which contains a mixture of BSD & SVR4 from Solaris to Linux.
Forgive me if some of these questions are rather basic.
1) I have been using the -ansi flag definition, because that seemed the
right thing to do? I seem to remember that -ansi will (where possible) check
prototyping and will define the __STDC__ definition.
Am I correct to be trying to use this -ansi flag????
2) The sad thing is that if I use the -ansi flag it stops many of the 'C'
files from compiling. For example MAXNAMLEN will be undefined or things like
u_long or S_IFDIR will not be defined. I presume that this is related to
compiler definitions like __USE_BSD or __USE_POSIX or __USE_XOPEN etc
Presumably -ansi is automatically turning some of these compiler
definitions off??
these are not compiler definitions. They come from include files. Presumably
they are being disabled when STDC is defined. You probably want something like
#define _POSIX somevalueorother
#define _XOPEN_SOURCE somevalueorother
before #including sytem files. You'll need to consult your system
documentation (or grep /usr/include/**/*.h for their uses.
/usr/include/features.h might be a good one to look in.)
Should I be defining these definitions (as required) when I'm building
the 'C' files using -ansi????
Do not define the __USE_BSD type things, use the higher level switches
I just mentioned.
Any other suggestions?
Currently in many cases I am simply defining these defn's as part of
the C source.....not the most ideal solution.
3) Can I get the compiler to somehow list out the compiler definitions
that it is using?
Perhaps -E -dD will help you here.
nathan
--
Nathan Sidwell :: http://www.codesourcery.com :: CodeSourcery LLC
nathan@xxxxxxxxxxxxxxxx :: http://www.planetfall.pwp.blueyonder.co.uk
