Re: [PATCH] GDB: maint: Fix build on FreeBSD

[Simon Marchi <simark@simark.ca>]

On 6/27/25 12:45 AM, Thiago Jung Bauermann wrote:
> While trying to build current trunk of GDB on FreeBSD 14.3 on aarch64,
> I hit this warning converted to an error:
> 
> In file included from /home/bauermann/src/binutils-gdb/gdb/maint.c:37:
> /home/bauermann/src/binutils-gdb/gdb/maint.h:64:8: error: private field 'm_start_space' is not used [-Werror,-Wunused-private-field]
>    64 |   long m_start_space;
>       |        ^
> 1 error generated.
> gmake[2]: *** [Makefile:1973: maint.o] Error 1
> 
> I used the default compiler on this system:
> 
> $ c++ --version
> FreeBSD clang version 19.1.7 (https://github.com/llvm/llvm-project.git llvmorg-19.1.7-0-gcd708029e0b2)
> Target: aarch64-unknown-freebsd14.3
> Thread model: posix
> InstalledDir: /usr/bin
> 
> The problem is that the only two places that use m_start_space are
> guarded by HAVE_USEFUL_SBRK, so also guard the member declaration with
> it.
> 
> Build-tested on aarch64-unknown-freebsd14.3.

I think there is nothing wrong with fixing the build, so:

Approved-By: Simon Marchi <simon.marchi@efficios.com>

But then, is this feature useful at all nowadays?  I don't have a deep
knowledge of memory allocators work, but my understanding is that modern
allocators use mmap to obtain more memory from the system (or they use
both).  So the memory usage computed using sbrk would not be very
accurate.  All of this to say that, if there is a metric we know is not
accurate, it might be better to remove it.

Simon