Fix anon param + make it allow-by-def

Author: mark-i-m

src/librustc_lint/builtin.rs

@@ -627,7 +627,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for MissingDebugImplementations {
 
 declare_lint! {
     pub ANONYMOUS_PARAMETERS,
-    Warn,
+    Allow,
     "detects anonymous parameters"
 }
 

src/librustc_lint/lib.rs

@@ -276,7 +276,7 @@ pub fn register_builtins(store: &mut lint::LintStore, sess: Option<&Session>) {
         FutureIncompatibleInfo {
             id: LintId::of(ANONYMOUS_PARAMETERS),
             reference: "issue #41686 <https://github.com/rust-lang/rust/issues/41686>",
-            edition: None,
+            edition: Some(Edition::Edition2018),
         },
         FutureIncompatibleInfo {
             id: LintId::of(PARENTHESIZED_PARAMS_IN_TYPES_AND_MODULES),

src/libstd/sys/windows/backtrace/mod.rs

@@ -152,7 +152,14 @@ type StackWalk64Fn = unsafe extern "system" fn(
 trait StackWalker {
     type Item: StackFrame;
 
-    fn walk(&self, c::DWORD, c::HANDLE, c::HANDLE, &mut Self::Item, &mut c::CONTEXT) -> c::BOOL;
+    fn walk(
+        &self,
+        _: c::DWORD,
+        _: c::HANDLE,
+        _: c::HANDLE,
+        _: &mut Self::Item,
+        _: &mut c::CONTEXT
+    ) -> c::BOOL;
 }
 
 impl StackWalker for StackWalkExFn {