[PATCH] Deprecate -frepo option.

[Nathan Sidwell]

On 7/9/19 6:39 AM, Richard Biener wrote:
> On Mon, Jul 8, 2019 at 2:04 PM Martin Liška <mliska@suse.cz> wrote:
>>

>>
>> Same happens also for GCC7. It does 17 iteration (#define MAX_ITERATIONS 17) and
>> apparently 17 is not enough to resolve all symbols. And it's really slow.
> 
> Ouch.

hm, 17 is a magic number.  in C++98 it was the maximum depth of template 
instantiations that implementations needed to support.  Portable code 
could not expect more.  So the worst case -frepo behaviour would be 17 
iterations.

That's not true any more, it's been 1024 since C++11.

Has a bug been filed about this frepo problem?  If not, it suggest those 
using frepo are not compiling modern C++.

>> That said, I would recommend to remove it :)
> 
> In the end it's up to the C++ FE maintainers but the above clearly
> doesn't look promising
> (not sure if it keeps re-compiling _all_ repo-triggered templates or
> just incrementally adds
> them to new object files).

> I'm not opposed to removing -frepo from GCC 10 but then I would start
> noting it is obsolete
> on the GCC 9 branch at least.

I concur.  frepo's serial reinvocation of the compiler is not compatible 
with modern C++ code bases.

nathan

-- 
Nathan Sidwell