Auto merge of #48309 - mark-i-m:anon_param_lint, r=nikomatsakis

Make anon params lint warn-by-default

This is intended as a followup on anonymous parameters deprecation.

Cross-posting from #41686:

> After having read a bit more of the discussion that I can find, I propose a more aggressive deprecation strategy:
> - We make the lint warn-by-default as soon as possible
> - We make anon parameters a hard error at the epoch boundary

cc @matklad @est31 @aturon

src/test/compile-fail-fulldeps/auxiliary/lint_for_crate.rs

@@ -13,6 +13,7 @@
 #![feature(plugin_registrar, rustc_private)]
 #![feature(box_syntax)]
 #![feature(macro_vis_matcher)]
+#![feature(macro_at_most_once_rep)]
 
 #[macro_use] extern crate rustc;
 extern crate rustc_plugin;

src/test/compile-fail-fulldeps/auxiliary/lint_group_plugin_test.rs

@@ -13,6 +13,7 @@
 #![feature(plugin_registrar)]
 #![feature(box_syntax, rustc_private)]
 #![feature(macro_vis_matcher)]
+#![feature(macro_at_most_once_rep)]
 
 // Load rustc as a plugin to get macros
 #[macro_use]

src/test/compile-fail-fulldeps/auxiliary/lint_plugin_test.rs

@@ -13,6 +13,7 @@
 #![feature(plugin_registrar)]
 #![feature(box_syntax, rustc_private)]
 #![feature(macro_vis_matcher)]
+#![feature(macro_at_most_once_rep)]
 
 extern crate syntax;
 

src/test/compile-fail/anon-params-deprecated.rs

@@ -12,13 +12,13 @@
 // Test for the anonymous_parameters deprecation lint (RFC 1685)
 
 trait T {
-    fn foo(i32); //~ ERROR use of deprecated anonymous parameter
+    fn foo(i32); //~ ERROR anonymous parameters are deprecated
                  //~| WARNING hard error
 
     fn bar_with_default_impl(String, String) {}
-    //~^ ERROR use of deprecated anonymous parameter
+    //~^ ERROR anonymous parameters are deprecated
     //~| WARNING hard error
-    //~| ERROR use of deprecated anonymous parameter
+    //~| ERROR anonymous parameters are deprecated
     //~| WARNING hard error
 }
 

src/test/compile-fail/future-incompatible-lint-group.rs

@@ -11,7 +11,7 @@
 #![deny(future_incompatible)]
 
 trait Tr {
-    fn f(u8) {} //~ ERROR use of deprecated anonymous parameter
+    fn f(u8) {} //~ ERROR anonymous parameters are deprecated
                 //~^ WARN this was previously accepted
 }
 

src/test/run-pass-fulldeps/auxiliary/lint_for_crate.rs

@@ -13,6 +13,7 @@
 #![feature(plugin_registrar, rustc_private)]
 #![feature(box_syntax)]
 #![feature(macro_vis_matcher)]
+#![feature(macro_at_most_once_rep)]
 
 #[macro_use] extern crate rustc;
 extern crate rustc_plugin;

src/test/run-pass-fulldeps/proc-macro/auxiliary/issue-40001-plugin.rs

@@ -9,6 +9,7 @@
 // except according to those terms.
 #![feature(box_syntax, plugin, plugin_registrar, rustc_private)]
 #![feature(macro_vis_matcher)]
+#![feature(macro_at_most_once_rep)]
 #![crate_type = "dylib"]
 
 #[macro_use]

src/test/ui-fulldeps/auxiliary/lint_group_plugin_test.rs

@@ -13,6 +13,7 @@
 #![feature(plugin_registrar)]
 #![feature(box_syntax, rustc_private)]
 #![feature(macro_vis_matcher)]
+#![feature(macro_at_most_once_rep)]
 
 // Load rustc as a plugin to get macros
 #[macro_use]

src/test/ui-fulldeps/auxiliary/lint_plugin_test.rs

@@ -13,6 +13,7 @@
 #![feature(plugin_registrar)]
 #![feature(box_syntax, rustc_private)]
 #![feature(macro_vis_matcher)]
+#![feature(macro_at_most_once_rep)]
 
 extern crate syntax;
 

src/test/ui/lint-anon-param-edition.fixed

@@ -0,0 +1,23 @@
+// Copyright 2016 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// tests that the anonymous_parameters lint is warn-by-default on the 2018 edition
+
+// compile-pass
+// compile-flags: --edition=2018
+// run-rustfix
+
+trait Foo {
+    fn foo(_: u8);
+    //^ WARN anonymous parameters are deprecated
+    //| WARN this was previously accepted
+}
+
+fn main() {}

src/test/ui/lint-anon-param-edition.rs

@@ -0,0 +1,23 @@
+// Copyright 2016 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// tests that the anonymous_parameters lint is warn-by-default on the 2018 edition
+
+// compile-pass
+// compile-flags: --edition=2018
+// run-rustfix
+
+trait Foo {
+    fn foo(u8);
+    //^ WARN anonymous parameters are deprecated
+    //| WARN this was previously accepted
+}
+
+fn main() {}

src/test/ui/lint-anon-param-edition.stderr

@@ -0,0 +1,10 @@
+warning: anonymous parameters are deprecated and will be removed in the next edition.
+  --> $DIR/lint-anon-param-edition.rs:18:12
+   |
+LL |     fn foo(u8);
+   |            ^^ help: Try naming the parameter or explicitly ignoring it: `_: u8`
+   |
+   = note: #[warn(anonymous_parameters)] on by default
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #41686 <https://github.com/rust-lang/rust/issues/41686>
+