Re: eassert always aborts in eval.c in an optimized build

[Paul Eggert]

On 2024-10-27 01:50, Eli Zaretskii wrote:
> Something is wrong with our definition/use of eassert in eval.c when
> Emacs is compiled with optimizations and with --enable-checking: all
> the functions in eval.c that assert pdl->kind's value are compiled
> into code that always aborts.

A quick look suggests that although the actual code is fine, GDB is 
confused and its "disassemble" and other commands think that the symbol 
"backtrace_function" stands for the address of just part of the 
backtrace_function code, not the address of the function's first 
instruction.

If my guess is right, if you try to debug Emacs with GDB and use 
xbacktrace or similar commands, things will go haywire. You'll see 
symptoms like this:

(gdb) p backtrace_function
$1 = {Lisp_Object (union specbinding *)} 0x6ed5c <backtrace_function>

... whereas the shell command "nm emacs | grep backtrace_function" 
outputs this:

0000000000293cd0 T backtrace_function
000000000006ee78 t backtrace_function.cold
000000000006ed5c t backtrace_function.part.0

... and we can see that GDB has the wrong "backtrace_function".

Does this match the symptoms you're observing?

If my guess is right, GDB should be fixed, and also we should look into 
patching Emacs to work around the GDB bug.