[vlc-devel] [PATCH 1/2] configure: allow toggling of -Wl, -z, defs and -no-undefined

[Hugo Beauzée-Luyssen]

On Mon, Jun 19, 2017, at 02:31 PM, Marvin Scholz wrote:
> On 15 Mar 2017, at 19:31, Marvin Scholz wrote:
> 
> > On 15 Mar 2017, at 15:46, Rémi Denis-Courmont wrote:
> >
> >> On March 15, 2017 4:42:34 PM GMT+02:00, "Filip Roséen" 
> >> <filip at atch.se> wrote:
> >>> Hi Rémi,
> >>>
> >>> On 2017-03-15 16:28, Rémi Denis-Courmont wrote:
> >>>
> >>>> On mercredi 15 mars 2017 15:24:06 EET Filip Roséen wrote:
> >>>>> A developer should know his/her platform well enough to be able to
> >>>>> manually specify the sanitizer flags, which
> >>> `--disable-no-undefined`
> >>>>> allows.
> >>>>
> >>>> A developer should know his/her platform well enough to handle
> >>> sanitizers with
> >>>> the --no-undefined option.
> >>>
> >>> So you are saying that those who wants to use the sanitizer with a
> >>> shall manually patch `configure.ac` and the relevant `Makefile.am` 
> >>> in
> >>> order to remove the usage of `-Wl,-z,defs` and `-no-undefined` in
> >>> order to achieve satisfying sanitizer usage?
> >>>
> >>> Or specify complicated flags just to circumvent the fact that we now
> >>> unconditionally add flags on platform where they apply, but silently
> >>> ignore them on platforms that says they do not.
> >>>
> >>> If we want to have developers to really fight in order
> >>> to use a sanitizer, or prevent `-Wl,-z,defs` and `-no-undefined` 
> >>> from
> >>> being able to easily test functions from out-of-tree objects (which
> >>> greatly simplies things such as benchmarks of individual functions, 
> >>> at
> >>> least in my opinion), I guess one also **could** replace the linker
> >>> with a wrapper that pretends that it does not understand the 
> >>> relevant
> >>> flags, and have a "clean" build without `-Wl,-z,defs`.
> >>>
> >>>> I agree that an option for sanitizers is not very useful insofar as
> >>> it will be
> >>>> disabled by default. Afterall, those who know about it, would also
> >>> know how to
> >>>> do it manually. Well then there are no needs to change anything at
> >>> all. Easy.
> >>>
> >>> I did not say that the option for sanitizer would not be very 
> >>> useful.
> >>> My fear is that it will be more complex to implement than to allow
> >>> developers to specify `--disable-no-undefined` and setting the
> >>> *simple* flags themselves.
> >>>
> >>> Also, as mentioned, if `--enable-sanitizer=...` is allowed to 
> >>> disable
> >>> the usage of `-Wl,-z,defs` and `-no-undefined` I cannot understand 
> >>> why
> >>> such would be allowed, but not this patch.
> >>>
> >>> Best Regards,\
> >>> Filip
> >>
> >> To be clear, I have no problems using all 3 sanitizers with both GCC 
> >> and clang and without patching the build system. So I am unable to 
> >> answer your question.
> >
> > I am not sure about other operating systems, but at least on macOS I 
> > am not aware of an easy way of using the address
> > sanitizer without the flag introduced by this patch.
> >
> 
> This patch is still relevant, could I please get a reply? If there is 
> another way to build with asan on macOS, please let me know.
> 
> The asan documentation states:
> 
> > When linking shared libraries, the AddressSanitizer run-time is not 
> > linked, so -Wl,-z,defs may cause link errors (don’t use it with 
> > AddressSanitizer)
> 
> and I currently know of no way to do this, without these patches.
> 
> Regards,
> Marvin Scholz

I'm having a similar issue with thread sanitizer, and would really like
to know how to build correctly without the mentioned flags.

Regards,

-- 
  Hugo Beauzée-Luyssen
  hugo at beauzee.fr