Re: [PATCH] Add --with-system-libbacktrace

On Thu, 13 Aug 2026, John Ericson wrote:

> We have other --with-system-* flags for using pre-installed libraries,
> but not for libbacktrace. It might not be *prudent* to use a
> libbacktrace other than the in-tree one, but that doesn't mean we should
> make it impossible to *try*.

A new configure option should be documented in install.texi.

> For most consumers this just swaps a relative path for -lbacktrace.
> libstdc++, however, normally compiles the sources itself with every
> symbol renamed. Using a pre-built libbacktrace for it is therefore a
> larger change, as it entails exposing those symbols downstream, where
> they may conflict with a libbacktrace the program links for itself.
> 
> The libstdc++ renaming, now being optional, is simply implemented by
> using the normal identifiers in libstdc++'s own source files, and then
> applying the same renaming trick that was previously used only on the
> vendored libbacktrace to libstdc++ itself.

I'd expect such a configure option to be either for the host, or for the 
target, but not both, as availability of a pre-installed library for one 
of host and target doesn't say anything about whether it's available for 
the other; if you want to cover both cases because this library can be 
used both for the host and the target, they should be separate options.

-- 
Joseph S. Myers
[email protected]