fenv() support broken with GCC 10 on ARM

[Sebastian Huber]

On 08/07/2020 15:00, Sebastian Huber wrote:

> Hello,
>
> I get the following linker errors with GCC and the latest Newlib on ARM:
>
> /build/rtems/6/lib/gcc/arm-rtems6/10.1.1/../../../../arm-rtems6/bin/ld: 
> /build/rtems/6/lib/gcc/arm-rtems6/10.1.1/../../../../arm-rtems6/lib/thumb/cortex-m3/libm.a(lib_a-fenv-vfp.o):/scratch/git-rtems-source-builder/rtems/build/arm-rtems6-gcc-50666d2-newlib-f095752-x86_64-linux-gnu-1/build/arm-rtems6/thumb/cortex-m3/newlib/targ-include/machine/fenv-softfloat.h:61: 
> multiple definition of `__softfloat_float_rounding_mode'; 
> /build/rtems/6/lib/gcc/arm-rtems6/10.1.1/../../../../arm-rtems6/lib/thumb/cortex-m3/libm.a(lib_a-fenv-softfp.o):/scratch/git-rtems-source-builder/rtems/build/arm-rtems6-gcc-50666d2-newlib-f095752-x86_64-linux-gnu-1/build/arm-rtems6/thumb/cortex-m3/newlib/targ-include/machine/fenv-softfloat.h:61: 
> first defined here
> /build/rtems/6/lib/gcc/arm-rtems6/10.1.1/../../../../arm-rtems6/bin/ld: 
> /build/rtems/6/lib/gcc/arm-rtems6/10.1.1/../../../../arm-rtems6/lib/thumb/cortex-m3/libm.a(lib_a-fenv-vfp.o):/scratch/git-rtems-source-builder/rtems/build/arm-rtems6-gcc-50666d2-newlib-f095752-x86_64-linux-gnu-1/build/arm-rtems6/thumb/cortex-m3/newlib/targ-include/machine/fenv-softfloat.h:60: 
> multiple definition of `__softfloat_float_exception_mask'; 
> /build/rtems/6/lib/gcc/arm-rtems6/10.1.1/../../../../arm-rtems6/lib/thumb/cortex-m3/libm.a(lib_a-fenv-softfp.o):/scratch/git-rtems-source-builder/rtems/build/arm-rtems6-gcc-50666d2-newlib-f095752-x86_64-linux-gnu-1/build/arm-rtems6/thumb/cortex-m3/newlib/targ-include/machine/fenv-softfloat.h:60: 
> first defined here
> /build/rtems/6/lib/gcc/arm-rtems6/10.1.1/../../../../arm-rtems6/bin/ld: 
> /build/rtems/6/lib/gcc/arm-rtems6/10.1.1/../../../../arm-rtems6/lib/thumb/cortex-m3/libm.a(lib_a-fenv-vfp.o):/scratch/git-rtems-source-builder/rtems/build/arm-rtems6-gcc-50666d2-newlib-f095752-x86_64-linux-gnu-1/build/arm-rtems6/thumb/cortex-m3/newlib/targ-include/machine/fenv-softfloat.h:59: 
> multiple definition of `__softfloat_float_exception_flags'; 
> /build/rtems/6/lib/gcc/arm-rtems6/10.1.1/../../../../arm-rtems6/lib/thumb/cortex-m3/libm.a(lib_a-fenv-softfp.o):/scratch/git-rtems-source-builder/rtems/build/arm-rtems6-gcc-50666d2-newlib-f095752-x86_64-linux-gnu-1/build/arm-rtems6/thumb/cortex-m3/newlib/targ-include/machine/fenv-softfloat.h:59: 
> first defined here

Affected are ARM and MIPS:

grep -r 'int __softfloat_float_' .
newlib/libc/machine/arm/machine/fenv-softfloat.h:int 
__softfloat_float_exception_flags;
newlib/libc/machine/arm/machine/fenv-softfloat.h:int 
__softfloat_float_exception_mask;
newlib/libc/machine/arm/machine/fenv-softfloat.h:int 
__softfloat_float_rounding_mode;
newlib/libc/machine/mips/machine/fenv-softfloat.h:int 
__softfloat_float_exception_flags;
newlib/libc/machine/mips/machine/fenv-softfloat.h:int 
__softfloat_float_exception_mask;
newlib/libc/machine/mips/machine/fenv-softfloat.h:int 
__softfloat_float_rounding_mode;

There needs to be a declaration only in the header file and a definition 
somewhere else.