Re: [Buildroot] [PATCH 1/2] package/exim: fix build with libexecinfo

["Yann E. MORIN" <yann.morin.1998@free.fr>]

Bernd, Luca, All,

On 2023-12-28 09:51 +0100, Luca Ceresoli via buildroot spake thusly:
> On Wed, 27 Dec 2023 19:17:55 +0100
> Bernd Kuhls <bernd@kuhls.net> wrote:
> > Upstream added optional support for execinfo
[--SNIP--]
> > @@ -126,6 +127,15 @@ ifeq ($(BR2_STATIC_LIBS),y)
> >  EXIM_STATIC_FLAGS = LFLAGS="-pthread --static"
> >  endif
> >  
> > +ifeq ($(BR2_PACKAGE_LIBEXECINFO),y)
> > +EXIM_DEPENDENCIES += libexecinfo
> > +define EXIM_EXTRALIBS
> > +$(call exim-config-add,EXTRALIBS,-lexecinfo)
> > +endef
> > +else
> > +EXIM_C_FLAGS = -DNO_EXECINFO
> > +endif
> 
> I think this logic is not entirely correct. As I read it:
> 
>  * on non-glibc systems it automatically enables the new exim
>    stack dump feature if libexecinfo is enabled
>  * on glibc systems, which always have the backtrace() and related
>    functions without additional libraries, we never enable this feature
> 
> For consistency, the else branch should just be removed to avoid
> setting NO_EXECINFO, thus enabling the stack dump feature whenever it
> is possible.

If I understand correctly, your proposal would not work either: for a
non-glibc config that does not have libexecinfo eabled, we do want to
define NO_EXECINFO.

Instead, the logic should be somthong like:

    if glibc:
        do nothing, execinfo is available
    elif libexecinfo enabled:
        add dependency and extra-lib
    else:
        define NO_EXECINFO

Since libexecinfo embedds the fact that it is also non-glibc, we can
rewrite the condition as:

    if libexecinfo:
        add dependency and extra-lib
    elif non-glibc;
        define NO_EXECINFO

So, the 'else' clause only needs to be changed into:
    else ifneq ($(BR2_TOOLCHAIN_USES_GLIBC),y)

Unless I missed something less obvious...

Regards,
Yann E. MORIN.

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