I downloaded gcc-2.95.3 from gnu.I want to use it in my PC with SCO UNIX 3.2v5.0.4. On my PC , I have installed SCO development system . It uses cc/CC to compile c/c++ program. After running ./configure , I run make . While compiling bad.c , cc reports  that "-W-Wall" option is error. So I delete "-W -Wall" option in Makefile . And then proty.h(Maybe a other name like it) compiles error, Compile programm reports the Line :#ERROR: "..." --- error, And there is another program error in the Line : typedef long long something . I think that there is something not supported by SCO UNIX compiler,and I also think there only have two ways to solve the problem: 1.change the program 2.get a old version gcc binary to install , and use it to compile the program again   And so can anyone help me ?