project('valatest', 'c', default_options : 'werror=true') if find_program('valac', required : false).found() add_languages('vala') valadeps = [dependency('glib-2.0'), dependency('gobject-2.0')] # Must fail due to -Werror and unused variable in C file executable('valaprog', 'prog.vala', 'unused-var.c', dependencies : valadeps) else executable('failprog', 'unused-var.c') endif