also lint diverging methods

Author: oli-obk

clippy_lints/src/eval_order_dependence.rs

@@ -133,7 +133,15 @@ impl<'a, 'tcx, 'v> Visitor<'v> for DivergenceVisitor<'a, 'tcx> {
                 },
                 _ => {},
             },
-            ExprMethodCall(..) => { /* TODO */ },
+            ExprMethodCall(..) => {
+                let method_call = ty::MethodCall::expr(e.id);
+                let borrowed_table = self.0.tcx.tables.borrow();
+                let method_type = borrowed_table.method_map.get(&method_call).expect("This should never happen.");
+                let result_ty = method_type.ty.fn_ret();
+                if let ty::TyNever = self.0.tcx.erase_late_bound_regions(&result_ty).sty {
+                    self.report_diverging_sub_expr(e);
+                }
+            },
             _ => {
                 // do not lint expressions referencing objects of type `!`, as that required a diverging expression to begin with
             },

tests/compile-fail/diverging_sub_expression.rs

@@ -5,10 +5,17 @@
 #[allow(empty_loop)]
 fn diverge() -> ! { loop {} }
 
+struct A;
+
+impl A {
+    fn foo(&self) -> ! { diverge() }
+}
+
 #[allow(unused_variables, unnecessary_operation)]
 fn main() {
     let b = true;
     b || diverge(); //~ ERROR sub-expression diverges
+    b || A.foo(); //~ ERROR sub-expression diverges
     let y = (5, diverge(), 6); //~ ERROR sub-expression diverges
     println!("{}", y.1);
 }