SUMMARY: strange "cc -E" behaviour
2007-12-25 5:00:00
my problem:
I tried to understand the different behaviour of several C preprocessors
while parsing a small test file on my Solaris 10 x86
----------------------------------------
#define SWITCH -g
SWITCH
----------------------------------------
- /usr/ccs/lib/cpp
- /usr/sfw/bin/cpp
- /usr/sfw/bin/gcc -E
creates '-g'
- /opt/SUNWspro/bin/cc -E
creates '- g'. Note the extra whitespace.
The "solution"
This behaviour of all preprocessors is correct, because C preprocessors
has to create standard compliant C code, and '-g' is equal to '- g' in C.
We can get the output without whitespace with Suns C compiler too by using
"cc -E -Xs".
Thanks again to Casper Dik for his full description of the behaviour.
Wesley W. Garland asked what I really tried to do.
I tried to compile emacs 21.4 on my Solaris 10 x86 system using Suns C
compiler. The configure script uses /usr/ccs/lib/cpp as preprocessor
and this is not able to parse for example /usr/include/sys/isa_defs.h
without an error.
Setting CPP to 'cc -E' creates:
What compiler should emacs be built with? cc - g - O
The configure script creates a small file with several defines and than
calls eval with the output of the preprocessed file:
eval `${CPP} -Isrc ${tempcname} \
| sed -n -e 's/^configure___ \([^=]*=\)\(.*\)$/\1"\2"/p'`
The maintainer of emacs should better go with M4 for this.
I'm now calling configure with
CC="cc -xc99=%none"
CPP=""cc -E -Xs"
Thanks again to all for this great list
Willi
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