bug#30788: 27.0.50; Getting 'char-displayable-p: Invalid hash table rehash size: 1.0' when starting emacs -Q

[Eli Zaretskii]

> From: Peter Dyballa <Peter_Dyballa@Web.DE>
> Date: Tue, 15 May 2018 16:02:28 +0200
> Cc: 30788@debbugs.gnu.org
> 
> I started a new attempt. On 
> http://git.savannah.gnu.org/cgit/emacs.git/commit/?id=15fa8de1ae3228413fde95e583008d9b9f19e7c7
>  I found this number. I patched a MacPorts control file and so port used the 
> command '/usr/bin/git checkout -q 15fa8de1ae3228413fde95e583008d9b9f19e7c7' 
> to fetch the sources. GNU Emacs 27.0.50 could be build, and it shows here on 
> my Mac still the same error with the "Invalid hash table rehash size."
> 
> I also have two X servers installed (actually three). The one is XQuartz 
> 2.7.11, which comes inside an Apple installer package, the other is X11, 
> built from source by port from the sources of the packages xorg-server 1.18.4 
> or xorg-server-devel 1.19.99.1. What I can observe is that GNU Emacsen 26.x 
> or 27.0.50 built in one X server do *not* run in that X server ("Invalid hash 
> table rehash size"), but they *do* in the other.

Based on previous similar problems, it's some snafu with locale
definitions and some software on your system that resets the locale's
LC_NUMERIC setting, which disrupts the Lisp reader's reading of X.Y
float values.  Does the workaround in

  https://debbugs.gnu.org/cgi/bugreport.cgi?bug=30788#26

succeed to solve the problem in your case?