Re: performing updates from gcc cvs and building

[Ian Lance Taylor <ian at airs dot com>]

Mathieu Lacage <Mathieu.Lacage@sophia.inria.fr> writes:

> I did a gcc check from cvs HEAD, then, a few days later, I updated with
> contrib/gcc_update, rm -rf objdir/*, configure again with c and c++
> only, make, touch gcc/tree-optimize.c, make and I get the following
> error:
> gcc -c   -g -O2 -DIN_GCC   -W -Wall -Wwrite-strings -Wstrict-prototypes
> -Wmissing-prototypes -pedantic -Wno-long-long -Wno-variadic-macros -
> Wold-style-definition -fno-common   -DHAVE_CONFIG_H    -I. -I. -
> I../../gcc -I../../gcc/. -I../../gcc/../include -
> I../../gcc/../libcpp/include  ../../gcc/tree-optimize.c -o tree-
> optimize.o
> cc1: error: unrecognized command line option "-Wno-variadic-macros"
> 
> Would someone be kind enough to tell me what I do wrong ? I failed to
> find any kind of information on how to repeatedly build gcc in the same
> objdir directory without doing a complete rm -rf objdir/* between each
> build which I find annoying...

Impossible to tell precisely what happened without the precise
commands which you ran.  Your original configure decided that the
compiler you were using supported the -Wno-variadic-macros option (it
wa added in February, and is not in 3.4).  Then you tried to rebuild
with a compiler which did not support the -Wno-variadic-macros option.
So somehow you are using a different compiler from the one which you
ran configure for.  Note that most of the values computed by configure
are saved across runs of configure in the config.cache file.

Basically, if you ever change the compiler you are using, which
generally means the first gcc found in PATH, then you need to remove
the config.cache file and run configure again.

Ian