build: fix when knot-dns headers are on non-standard location

daemon/lua/meson.build

@@ -59,24 +59,32 @@ run_target(  # run manually to re-generate kres-gen.lua
 # but this basic sanity check could be ran always, except for cross compilation,
 # as we *run* luajit to find out the real sizes.
 if get_option('kres_gen_test') and not meson.is_cross_build()
-  types_to_check = {
-    'time_t' : '#include <sys/time.h>',
-    'struct timeval' : '#include <sys/time.h>',
-    'zs_scanner_t' : '#include <libzscanner/scanner.h>',
-    'knot_pkt_t' : '#include <libknot/packet/pkt.h>',
-  }
+  types_to_check = [
+    { 'tname': 'time_t', 'incl': '#include <sys/time.h>' },
+    { 'tname': 'struct timeval', 'incl' : '#include <sys/time.h>' },
+    { 'tname': 'zs_scanner_t', 'incl': '#include <libzscanner/scanner.h>', 'dep': libzscanner },
+    { 'tname': 'knot_pkt_t', 'incl' : '#include <libknot/packet/pkt.h>', 'dep': libknot },
+  ]
   # Construct the lua tester as a meson string.
   kres_gen_test_luastr = '''
     dofile('@0@')
     local ffi = require('ffi')
   '''.format(meson.current_source_dir() / kres_gen_fname)
-  foreach tname, tinclude: types_to_check
+  foreach ttc: types_to_check
+    # We're careful with adding just includes; otherwise it's more fragile (e.g. linking flags).
+    if 'dep' in ttc
+      dep = ttc.get('dep').partial_dependency(includes: true, compile_args: true)
+    else
+      dep = []
+    endif
+    tsize = meson.get_compiler('c').sizeof(ttc.get('tname'), prefix: ttc.get('incl'),
+                                           dependencies: dep)
     kres_gen_test_luastr += '''
       assert(ffi.sizeof(ffi.typeof('@0@')) == @1@,
         'Lua binding for C type ' .. '@0@' .. ' has incorrect size: '
         .. ffi.sizeof(ffi.typeof('@0@'))
       )
-    '''.format(tname, meson.get_compiler('c').sizeof(tname, prefix : tinclude))
+    '''.format(ttc.get('tname'), tsize)
   endforeach
   # Now feed it directly into luajit.
   kres_gen_test = run_command(find_program('luajit'), '-e', kres_gen_test_luastr)