Dmitry Antipov wrote:
 > Why not use #pragma in the way similar to bytecode.c?

I'd rather not head down that direction, as it is ugly in a different way: seven 
lines' worth of preprocessor directives to silence one bogus diagnostic?!

 > '--enable-gcc-warnings --with-x-toolkit=no' build should have the
 > Fnext_read_file_uses_dialog_p-like issue with Fx_uses_old_gtk_dialog.
 > But I don't see it, and don't understand why

I don't know why either.  Apparently GCC does not do a perfect job of suggesting 
the attribute.

Stefan Monnier wrote:

> Easy, then: either you live with this warning, or you don't
> enable -Wsuggest-attribute=const.

Let's do the latter.  A couple of things.  First, I checked, and the attribute 
doesn't significantly help Emacs's performance, so it appears to be more trouble 
than it's worth for us.  Second, I audited the code and found five instances 
where we blindly followed GCC's advice and added ATTRIBUTE_CONST even though 
this was incorrect on some platforms; these mistakes suggest that we need to be 
more skeptical of GCC's diagnostics in this area on the rare occasions when we 
do use -Wsuggest-attribute=const.

I installed the attached patch to try to fix all this.