On 8 June 2018 at 16:11, Joseph Myers wrote: > On Fri, 8 Jun 2018, Jonathan Wakely wrote: > >> > The root cause is PR66203 which I reported quite some time ago, which >> > points to a newlib problem: on aarch64 there is no default rom >> > monitor, one has to explicitly use a --specs flag for the link to >> > succeed. >> >> I have no idea why this causes the libstdc++ configuration problem >> though, I don't understand the issue. > > Generically libstdc++ should not be doing link tests for bare-metal > targets; rather, there is a hardcoded set of defines in configure.ac for > functions present on such targets.
Thanks, I thought that might be how we need to fix this. > (For most other targets, link tests > *should* be run even when cross-compiling, there have been plenty of bugs > in the past where something tested in the $GLIBCXX_IS_NATIVE case wasn't > also tested in crossconfig.m4 for targets such as GNU/Linux where a target > libc is guaranteed to be linkable against for building libstdc++.) Yes, this requirement is very fragile and introduces differences (sometimes serious ones) between native and cross builds (e.g. r260678, r258468, r244169 ...)
