Re: [Qemu-devel] [RFC PATCH 2/4] configure: introduce --extra-libs

["Alex Bennée" <alex.bennee@linaro.org>]

Paolo Bonzini <pbonzini@redhat.com> writes:

> On 25/01/2016 19:15, Alex Bennée wrote:
>>
>> Paolo Bonzini <pbonzini@redhat.com> writes:
>>
>>> On 25/01/2016 17:49, Alex Bennée wrote:
>>>> If for example you want to use the thread sanitizer you want to ensure all
>>>> binaries are linked with the library:
>>>>
>>>>   ./configure ${TARGETS} --cc=gcc-5 --cxx=g++-5 \
>>>>     --extra-cflags="-fsanitize=thread" --extra-libs="-ltsan"
>>>
>>> Shouldn't -fsanitize=thread work as a linker command line flag too?
>>
>> No, the sanitizers are compile time options as they instrument the
>> generated code. It's just in the case of the ThreadSanitizer you also
>> need the support library.
>
> That's certainly not the case.  My system has at least a libubsan,
> libasan and liblsan (in addition to libtsan), and "gcc -dumpspecs"
> suggests that the -fsanitize options are also valid at link time:
>
>    %{%:sanitize(address):%{!shared:libasan_preinit%O%s} %{static-libasan:%{!shared:-Bstatic --whole-archive -lasan --no-whole-archive -Bdynamic}}%{!static-libasan:-lasan}}
>    %{%:sanitize(thread):%{static-libtsan:%{!shared:-Bstatic --whole-archive -ltsan --no-whole-archive -Bdynamic}}%{!static-libtsan:-ltsan}}
>    %{%:sanitize(leak):%{static-liblsan:%{!shared:-Bstatic --whole-archive -llsan --no-whole-archive -Bdynamic}}%{!static-liblsan:-llsan}}
>
> (GCC specs are what they are, but you get the idea).

Hmm odd. I ran the undefined and address sanitizers without having to
mess with the ldflags. I'll have a deeper dive into the docs to see
whats going on.

>
> Paolo


--
Alex Bennée