Bad option: -march=native on gcc 4.2.1?

[Matt Fago <fago@xxxxxxxxxxxxx>]

I've built and installed gcc 4.2.1 on a MacBook Pro.

This works:
/usr/local/bin/gcc -O3 -mtune=native -c Weapon.c

This does not:
/usr/local/bin/gcc -march=native Weapon.c -c -O3
Weapon.c:1: error: bad value (native) for -march= switch
Weapon.c:1: error: bad value (native) for -mtune= switch


gcc -v yields:
Using built-in specs.
Target: i386-apple-darwin8.10.1
Configured with: ../gcc-4.2.1/configure --disable-checking --enable- 
languages=c,c++,fortran --with-arch=nocona
Thread model: posix
gcc version 4.2.1

Have I misunderstood something here, or is this some wierd bug?


Thanks,
Matt