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

[wavexx at thregr dot org]

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

--- Comment #2 from wavexx at thregr dot org ---
On 25/01/16 18:38, redi at gcc dot gnu.org wrote:
> 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.

I generally use -march=native for most of my in-house projects.

However, on very few binaries part of a larger project I actually target
some older ISAs so I simply append -march=[x] as an exception with the
usual CFLAGS += ....

I could also (as I'm currently doing) splice -march out of CFLAGS and/or
override CFLAGS in the required rules, so it's not a huge deal (as
outlined in the original discussion), but even if documented, I would
find the current behavior unexpected.

I would have expected -march=native to simply expand to -march=haswell
so that I could override it normally as I do for almost everything else.