[Bug target/69471] "-march=native" unintentionally breaks further -march/-mtune flags

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69471

--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Some discussion at https://gcc.gnu.org/ml/gcc/2016-01/msg00000.html

However ...

(In reply to wavexx from comment #0)
> Since I generally override the default flags in makefiles by appending
> exceptions where needed, I expect the regular behavior where the last flags
> overrides previous ones and thus found the current behavior unexpected.

Why would either you or the makefile add something like -march=opteron on a
haswell host?

Surely the makefile should only add option that make sense, and you should only
override them with options that make sense.