On Fri, Feb 04, 2022 at 02:10:03PM -0600, Peter Bergner wrote: > On 2/4/22 12:03 PM, Segher Boessenkool wrote: > > On Fri, Feb 04, 2022 at 04:43:53PM +0100, Andreas Schwab wrote: > >> On Feb 04 2022, Michael Meissner via Gcc-patches wrote: > >>> If the user did not specify a default long double format when configuring > >>> GCC, use the long double default from the host compiler. > >> > >> That doesn't make any sense. The host compiler can be any random > >> compiler completely unrelated to the target. > > > > Yes, see <https://gcc.gnu.org/onlinedocs/gccint/Portability.html>. > [snip] > > I already NAKed this patch for weeks, and I do it again now. > > Did you NAK the patch due to its specific implementation or are you > even against the aim of the patch, namely that gcc configure tries > to determine the long double default of the underlying system and > matches that?
As I said before, I didn't even read the patch, just the one line summary was enough for a NAK. If the patch in fact does something else, then it is still incorrect, and needs a very different subject and summary. I hope you see how "using the default of the underlying system" is questionable in itself, but is something completely different from using the default of the build compiler, which makes even less sense. You want a configure flag to set the default long double format to be IEEE QP. This cannot be enabled by default until a (big) majority of systems "in the wild" will work with that (only on powerpc64le-linux or some *big* thing like that is fine, only default it to enabled there then). At that point in time, configure shouls complain, and the user would have to explicitly *disable* it to build without that support. Anything else is pretend progress and costs us too much. Yes, this is a "flag day", but only for the default. We will still support the double-double format for a loooooong time, if only because there are no concrete plans for moving most of its users (or no plans at all is more truthful actually)! Segher
