Re: more bogus meson warnings

[Paolo Bonzini <pbonzini@redhat.com>]

On 11/4/21 12:02, Peter Maydell wrote:
> The link of the test program against libsnappy.a fails because
> it is being linked with cc and nothing is putting the C++ stdlib
> that libsnappy needs on the link line, so you get errors like:
> 
>   /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/libsnappy.a(snappy.cc.o):
> In function `snappy::internal::WorkingMemory::GetHashTable(unsigned
> long, int*)':
> (.text+0x15b): undefined reference to `operator new[](unsigned long)'

That's interesting.  So there was also a bug before moving the test
to meson; statically-linked binaries would not use snappy even if
linking would be done by a C++ compiler.  This should fix it:

diff --git a/meson.build b/meson.build
index e330438270..cbc5c7a868 100644
--- a/meson.build
+++ b/meson.build
@@ -197,6 +197,9 @@ add_project_arguments('-iquote', '.',
  link_language = meson.get_external_property('link_language', 'cpp')
  if link_language == 'cpp'
    add_languages('cpp', required: true, native: false)
+  linker = cxx = meson.get_compiler('cpp')
+else
+  linker = cc
  endif
  if host_machine.system() == 'darwin'
    add_languages('objc', required: false, native: false)
@@ -1111,7 +1114,7 @@ if not get_option('snappy').auto() or have_system
                             required: get_option('snappy'),
                             kwargs: static_kwargs)
  endif
-if snappy.found() and not cc.links('''
+if snappy.found() and not linker.links('''
     #include <snappy-c.h>
     int main(void) { snappy_max_compressed_length(4096); return 0; }''', dependencies: snappy)
    snappy = not_found


> There's generally
> nothing much the user can do about this, beyond file a bug report with
> the distro if they're feeling enthusiastic.

It could be filed in snappy as well, but yeah I'm not feeling
enthusiastic about that.  Besides in this case we're not even using the
.pc file, but rather looking for -lsnappy by hand.

Paolo