Compiler Depenedent Error with typedef

Compiler Depenedent Error with typedef

I am trying to compile my project with different compilers. i have a
stable compiled version of the project compiling without any error with
the ARM 4.41 compiler. I want to compiler the exactly same source code
with the ARM 5 compiler and the Win64 compiler. How ever without any
change in the source code, just by switching the compiler from ARM 4.41 to
ARM 5 && ARM 4.41 to Win64 i am getting the following error with the
typedef's.
I am not able to figure it out, why does it behaves so..?
Header file with typedef's - a_stdtypes.h
#define _STD_TYPE_H
typedef unsigned char bool; // Error #84: invalid combination of type
specifiers
typedef unsigned char bit8;
typedef unsigned short bit16;
typedef unsigned long bit32;