lint: Warn about no-mangled statics that are not exported

src/librustc/lint/builtin.rs

@@ -2065,6 +2065,12 @@ declare_lint! {
     "functions marked #[no_mangle] should be exported"
 }
 
+declare_lint! {
+    PRIVATE_NO_MANGLE_STATICS,
+    Warn,
+    "statics marked #[no_mangle] should be exported"
+}
+
 declare_lint! {
     NO_MANGLE_CONST_ITEMS,
     Deny,
@@ -2077,6 +2083,7 @@ pub struct InvalidNoMangleItems;
 impl LintPass for InvalidNoMangleItems {
     fn get_lints(&self) -> LintArray {
         lint_array!(PRIVATE_NO_MANGLE_FNS,
+                    PRIVATE_NO_MANGLE_STATICS,
                     NO_MANGLE_CONST_ITEMS)
     }
 
@@ -2090,6 +2097,14 @@ impl LintPass for InvalidNoMangleItems {
                     cx.span_lint(PRIVATE_NO_MANGLE_FNS, it.span, msg.as_slice());
                 }
             },
+            ast::ItemStatic(..) => {
+                if attr::contains_name(it.attrs.as_slice(), "no_mangle") &&
+                       !cx.exported_items.contains(&it.id) {
+                    let msg = format!("static {} is marked #[no_mangle], but not exported",
+                                      it.ident);
+                    cx.span_lint(PRIVATE_NO_MANGLE_STATICS, it.span, msg.as_slice());
+                }
+            },
             ast::ItemConst(..) => {
                 if attr::contains_name(it.attrs.as_slice(), "no_mangle") {
                     let msg = "const items should never be #[no_mangle]";

src/test/compile-fail/lint-unexported-no-mangle.rs

@@ -8,7 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-// compile-flags:-F private_no_mangle_fns -F no_mangle_const_items
+// compile-flags:-F private_no_mangle_fns -F no_mangle_const_items -F private_no_mangle_statics
 
 // FIXME(#19495) no_mangle'ing main ICE's.
 #[no_mangle]
@@ -26,6 +26,14 @@ pub const PUB_FOO: u64 = 1; //~ ERROR const items should never be #[no_mangle]
 pub fn bar()  {
 }
 
+#[no_mangle]
+pub static BAR: u64 = 1;
+
+#[allow(dead_code)]
+#[no_mangle]
+static PRIVATE_BAR: u64 = 1; //~ ERROR static PRIVATE_BAR is marked #[no_mangle], but not exported
+
+
 fn main() {
     foo();
     bar();