Make liveness analysis respect privacy

Author: varkor

src/librustc/middle/liveness.rs

@@ -1197,7 +1197,8 @@ impl<'a, 'tcx> Liveness<'a, 'tcx> {
             }
 
             hir::ExprKind::Call(ref f, ref args) => {
-                let succ = if self.tables.expr_ty(expr).conservative_is_uninhabited(self.ir.tcx) {
+                let m = self.ir.tcx.hir.get_module_parent(expr.id);
+                let succ = if self.ir.tcx.is_ty_uninhabited_from(m, self.tables.expr_ty(expr)) {
                     self.s.exit_ln
                 } else {
                     succ
@@ -1207,7 +1208,8 @@ impl<'a, 'tcx> Liveness<'a, 'tcx> {
             }
 
             hir::ExprKind::MethodCall(.., ref args) => {
-                let succ = if self.tables.expr_ty(expr).conservative_is_uninhabited(self.ir.tcx) {
+                let m = self.ir.tcx.hir.get_module_parent(expr.id);
+                let succ = if self.ir.tcx.is_ty_uninhabited_from(m, self.tables.expr_ty(expr)) {
                     self.s.exit_ln
                 } else {
                     succ

src/test/ui/uninhabited/privately-uninhabited-dead-code.rs

@@ -1,6 +1,6 @@
 // compile-pass
 
-#![deny(unreachable_code)]
+#![deny(unused_variables)]
 
 mod foo {
     enum Bar {}
@@ -14,6 +14,7 @@ mod foo {
 }
 
 fn main() {
+    let a = 42;
     foo::give_foo();
-    println!("Hello, world!"); // ok: we can't tell that this code is dead
+    println!("Hello, {}", a); // ok: we can't tell that this code is dead
 }