Re: [PULL 00/12] Misc, mostly meson patches for 2021-06-23

[Peter Maydell]

On Thu, 24 Jun 2021 at 22:05, Paolo Bonzini <pbonzini@redhat.com> wrote:
>
> On 24/06/21 21:09, Peter Maydell wrote:
> > This generates a new warning on one of my boxes:
> >
> > [...]
> > Has header "sasl/sasl.h" : YES (cached)
> > Library sasl2 found: YES
> > Has header "security/pam_appl.h" : YES
> > Library pam found: YES
> > ../meson.build:926: WARNING: could not link libpam, disabling
>
> This is probably too old a libpam, or something like that.  What distro
> is it, and could you please attach the resulting meson-logs/meson-log.txt?

I saw this on Ubuntu 18.04.5 LTS and also on Debian bullseye; I've uploaded
the full meson-log.txt for the Ubuntu box to
https://people.linaro.org/~peter.maydell/meson-log.txt
but the important part seems to be:

Running compile:
Working directory:
/home/peter.maydell/qemu-netbsd/build/meson-private/tmp97iric39
Command line:  cc
/home/peter.maydell/qemu-netbsd/build/meson-private/tmp97iric39/testfile.c
-o /home/peter.maydell/qemu-netbsd/build/
meson-private/tmp97iric39/output.exe -pipe -D_FILE_OFFSET_BITS=64 -O0
-std=gnu99 -Wl,--start-group -lpam -Wl,--end-group

Code:

   #include <security/pam_appl.h>
   int main(void) {
     const char *service_name = "qemu";
     const char *user = "frank";
     const struct pam_conv pam_conv = { 0 };
     pam_handle_t *pamh = NULL;
     pam_start(service_name, user, &pam_conv, &pamh);
     return 0;
   }
Compiler stdout:

Compiler stderr:
 /home/peter.maydell/qemu-netbsd/build/meson-private/tmp97iric39/testfile.c:
In function 'main':
/home/peter.maydell/qemu-netbsd/build/meson-private/tmp97iric39/testfile.c:7:27:
error: 'NULL' undeclared (first use in this function)
      pam_handle_t *pamh = NULL;
                           ^~~~
/home/peter.maydell/qemu-netbsd/build/meson-private/tmp97iric39/testfile.c:7:27:
note: each undeclared identifier is reported only onc
e for each function it appears in

../meson.build:926: WARNING: could not link libpam, disabling


Looks like a missing #include <stddef.h> in the test code, rather
than anything specifically libpam related.


More generally, I think if meson probes for some library
and can't find it, the correct response is that it should
just print "Library libpam found: NO", not a "WARNING".
"You don't have an optional library, we'll skip that optional
feature" is a normal situation.

thanks
-- PMM