src/test/ui/linkage1.rs

   1 // run-pass
   2 // ignore-windows
   3 // ignore-macos
   4 // ignore-emscripten doesn't support this linkage
   5 // ignore-sgx weak linkage not permitted
   6 // aux-build:linkage1.rs
   7
   8 #![feature(linkage)]
   9
  10 extern crate linkage1 as other;
  11
  12 extern {
  13     #[linkage = "extern_weak"]
  14     static foo: *const isize;
  15     #[linkage = "extern_weak"]
  16     static something_that_should_never_exist: *mut isize;
  17 }
  18
  19 fn main() {
  20     // It appears that the --as-needed flag to linkers will not pull in a dynamic
  21     // library unless it satisfies a non weak undefined symbol. The 'other' crate
  22     // is compiled as a dynamic library where it would only be used for a
  23     // weak-symbol as part of an executable, so the dynamic library would be
  24     // discarded. By adding and calling `other::bar`, we get around this problem.
  25     other::bar();
  26
  27     unsafe {
  28         assert!(!foo.is_null());
  29         assert_eq!(*foo, 3);
  30         assert!(something_that_should_never_exist.is_null());
  31     }
  32 }