[Bug c++/70590] [6 Regression] r234810 causes error: location references block not in block tree

[trippels at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70590

--- Comment #4 from Markus Trippelsdorf <trippels at gcc dot gnu.org> ---
(In reply to Patrick Palka from comment #3)
> (In reply to Jakub Jelinek from comment #2)
> > location references block not in block tree generally means insufficient
> > unsharing, where some function that got through gimple-low.c where
> > TREE_SET_BLOCK has been used on some of the trees is sharing trees with a
> > different function.
> 
> That makes sense.  So in cxx_eval_call_expression we should unconditionally
> unshare the result of the call because the two caches (fundef_copies_table
> and constexpr_call_table) may cause us to share the same trees in different
> functions.  Alternatively we can just call unshare_expr once in the
> top-level cxx_eval_outermost_constant_expression, I think.  Markus, does
> this patch fix the build for you?

No. It now ICEs: in maybe_constant_value_1, at cp/constexpr.c:4328