librustc: Implement a lint mode for default methods

src/librustc/middle/lint.rs

@@ -65,6 +65,7 @@ enum lint {
  non_camel_case_types,
  structural_records,
  type_limits,
+ default_methods,
 
  managed_heap_memory,
  owned_heap_memory,
@@ -200,7 +201,12 @@ fn get_lint_dict() -> lint_dict {
  (~"type_limits",
  @{lint: type_limits,
  desc: ~"comparisons made useless by limits of the types involved",
- default: warn})
+ default: warn}),
+
+ (~"default_methods",
+ @{lint: default_methods,
+ desc: ~"allow default methods",
+ default: forbid}),
 
  /* FIXME(#3266)--make liveness warnings lintable
  (~"unused_variable",
@@ -414,6 +420,7 @@ fn check_item(i: @ast::item, cx: ty::ctxt) {
  check_item_structural_records(cx, i);
  check_item_deprecated_modes(cx, i);
  check_item_type_limits(cx, i);
+ check_item_default_methods(cx, i);
 }
 
 // Take a visitor, and modify it so that it will not proceed past subitems.
@@ -563,6 +570,27 @@ fn check_item_type_limits(cx: ty::ctxt, it: @ast::item) {
  visit::visit_item(it, (), visit);
 }
 
+fn check_item_default_methods(cx: ty::ctxt, item: @ast::item) {
+ match item.node {
+ ast::item_trait(_, _, methods) => {
+ for methods.each |method| {
+ match *method {
+ ast::required(*) => {}
+ ast::provided(*) => {
+ cx.sess.span_lint(
+ default_methods,
+ item.id,
+ item.id,
+ item.span,
+ ~"default methods are experimental");
+ }
+ }
+ }
+ }
+ _ => {}
+ }
+}
+
 fn check_item_structural_records(cx: ty::ctxt, it: @ast::item) {
  let visit = item_stopping_visitor(visit::mk_simple_visitor(@{
  visit_expr: fn@(e: @ast::expr) {

src/test/compile-fail/lint-default-methods.rs

@@ -0,0 +1,8 @@
+#[forbid(default_methods)];
+
+trait Foo {
+ fn bar() { io::println("hi"); } //~ ERROR default methods are experimental
+}
+
+fn main() {}
+