how to compile some specific files in gcc package?

[Andy]

Hello, everyone,

I want to sperate part of the gcc out and compile it as a library.
But I run into problems related to config.h.  To compile a file,
we need the config.h file generated automatically by gcc build
script. For example, the following is the command gcc is used
to compile   gcc/cp/cp-lang.o.

gcc -c   -g -O2 -DIN_GCC   -W -Wall -Wwrite-strings -Wstrict-prototypes
-Wmissing-prototypes -Wold-style-definition -Wmissing-format-attribute
  -DHAVE_CONFIG_H -I. -Icp -I../../gcc-4.1.1/gcc
-I../../gcc-4.1.1/gcc/cp -I../../gcc-4.1.1/gcc/../include
-I../../gcc-4.1.1/gcc/../libcpp/include
../../gcc-4.1.1/gcc/cp/cp-lang.c -o cp/cp-lang.o

Is there another way that I can generate config.h  files?

Thanks a lot!

-Andy