Don't gate methods Fn(Mut,Once)::call(mut,once) with feature unboxed_closures

They are already gated with feature `fn_traits`

Author: petrochenkov

src/libcollections/lib.rs

@@ -49,7 +49,6 @@
 #![feature(specialization)]
 #![feature(staged_api)]
 #![feature(step_by)]
-#![feature(unboxed_closures)]
 #![feature(unicode)]
 #![feature(unique)]
 #![feature(unsafe_no_drop_flag)]

src/libcoretest/lib.rs

@@ -31,7 +31,6 @@
 #![feature(step_by)]
 #![feature(test)]
 #![feature(try_from)]
-#![feature(unboxed_closures)]
 #![feature(unicode)]
 #![feature(unique)]
 

src/librustc_driver/lib.rs

@@ -31,7 +31,6 @@
 #![feature(set_stdio)]
 #![feature(staged_api)]
 #![feature(question_mark)]
-#![feature(unboxed_closures)]
 
 extern crate arena;
 extern crate flate;

src/librustc_typeck/check/callee.rs

@@ -27,33 +27,8 @@ use rustc::hir;
 /// to `trait_id` (this only cares about the trait, not the specific
 /// method that is called)
 pub fn check_legal_trait_for_method_call(ccx: &CrateCtxt, span: Span, trait_id: DefId) {
-    let tcx = ccx.tcx;
-    let did = Some(trait_id);
-    let li = &tcx.lang_items;
-
-    if did == li.drop_trait() {
-        span_err!(tcx.sess, span, E0040, "explicit use of destructor method");
-    } else if !tcx.sess.features.borrow().unboxed_closures {
-        // the #[feature(unboxed_closures)] feature isn't
-        // activated so we need to enforce the closure
-        // restrictions.
-
-        let method = if did == li.fn_trait() {
-            "call"
-        } else if did == li.fn_mut_trait() {
-            "call_mut"
-        } else if did == li.fn_once_trait() {
-            "call_once"
-        } else {
-            return // not a closure method, everything is OK.
-        };
-
-        struct_span_err!(tcx.sess, span, E0174,
-                         "explicit use of unboxed closure method `{}` is experimental",
-                         method)
-            .help("add `#![feature(unboxed_closures)]` to the crate \
-                  attributes to enable")
-            .emit();
+    if ccx.tcx.lang_items.drop_trait() == Some(trait_id) {
+        span_err!(ccx.tcx.sess, span, E0040, "explicit use of destructor method");
     }
 }
 

src/librustc_typeck/diagnostics.rs

@@ -1944,89 +1944,6 @@ To learn more about traits, take a look at the Book:
 https://doc.rust-lang.org/book/traits.html
 "##,
 
-E0174: r##"
-This error occurs because of the explicit use of unboxed closure methods
-that are an experimental feature in current Rust version.
-
-Example of erroneous code:
-
-```compile_fail
-fn foo<F: Fn(&str)>(mut f: F) {
-    f.call(("call",));
-    // error: explicit use of unboxed closure method `call`
-    f.call_mut(("call_mut",));
-    // error: explicit use of unboxed closure method `call_mut`
-    f.call_once(("call_once",));
-    // error: explicit use of unboxed closure method `call_once`
-}
-
-fn bar(text: &str) {
-    println!("Calling {} it works!", text);
-}
-
-fn main() {
-    foo(bar);
-}
-```
-
-Rust's implementation of closures is a bit different than other languages.
-They are effectively syntax sugar for traits `Fn`, `FnMut` and `FnOnce`.
-To understand better how the closures are implemented see here:
-https://doc.rust-lang.org/book/closures.html#closure-implementation
-
-To fix this you can call them using parenthesis, like this: `foo()`.
-When you execute the closure with parenthesis, under the hood you are executing
-the method `call`, `call_mut` or `call_once`. However, using them explicitly is
-currently an experimental feature.
-
-Example of an implicit call:
-
-```
-fn foo<F: Fn(&str)>(f: F) {
-    f("using ()"); // Calling using () it works!
-}
-
-fn bar(text: &str) {
-    println!("Calling {} it works!", text);
-}
-
-fn main() {
-    foo(bar);
-}
-```
-
-To enable the explicit calls you need to add `#![feature(unboxed_closures)]`.
-
-This feature is still unstable so you will also need to add
-`#![feature(fn_traits)]`.
-More details about this issue here:
-https://github.com/rust-lang/rust/issues/29625
-
-Example of use:
-
-```
-#![feature(fn_traits)]
-#![feature(unboxed_closures)]
-
-fn foo<F: Fn(&str)>(mut f: F) {
-    f.call(("call",)); // Calling 'call' it works!
-    f.call_mut(("call_mut",)); // Calling 'call_mut' it works!
-    f.call_once(("call_once",)); // Calling 'call_once' it works!
-}
-
-fn bar(text: &str) {
-    println!("Calling '{}' it works!", text);
-}
-
-fn main() {
-    foo(bar);
-}
-```
-
-To see more about closures take a look here:
-https://doc.rust-lang.org/book/closures.html`
-"##,
-
 E0178: r##"
 In types, the `+` type operator has low precedence, so it is often necessary
 to use parentheses.
@@ -4049,6 +3966,7 @@ register_diagnostics! {
     E0167,
 //  E0168,
 //  E0173, // manual implementations of unboxed closure traits are experimental
+//  E0174,
     E0182,
     E0183,
 //  E0187, // can't infer the kind of the closure

src/test/compile-fail/associated-types/bound-lifetime-constrained.rs

@@ -12,7 +12,6 @@
 
 #![allow(dead_code)]
 #![feature(rustc_attrs)]
-#![feature(unboxed_closures)]
 #![deny(hr_lifetime_in_assoc_type)]
 
 trait Foo<'a> {

src/test/compile-fail/associated-types/cache/wasm-issue-32330.rs

@@ -13,7 +13,6 @@
 
 #![allow(dead_code, unused_variables)]
 #![deny(hr_lifetime_in_assoc_type)]
-#![feature(unboxed_closures)]
 
 use std::str::Chars;
 

src/test/compile-fail/borrowck/borrowck-call-is-borrow-issue-12224.rs

@@ -10,8 +10,6 @@
 
 // Ensure that invoking a closure counts as a unique immutable borrow
 
-#![feature(unboxed_closures)]
-
 type Fn<'a> = Box<FnMut() + 'a>;
 
 struct Test<'a> {

src/test/compile-fail/borrowck/borrowck-unboxed-closures.rs

@@ -8,8 +8,6 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-#![feature(overloaded_calls, unboxed_closures)]
-
 fn a<F:Fn(isize, isize) -> isize>(mut f: F) {
     let g = &mut f;
     f(1, 2);    //~ ERROR cannot borrow `f` as immutable

src/test/compile-fail/feature-gate-unboxed-closures-method-calls.rs

@@ -11,9 +11,9 @@
 #![allow(dead_code)]
 
 fn foo<F: Fn()>(mut f: F) {
-    f.call(()); //~ ERROR explicit use of unboxed closure method `call`
-    f.call_mut(()); //~ ERROR explicit use of unboxed closure method `call_mut`
-    f.call_once(()); //~ ERROR explicit use of unboxed closure method `call_once`
+    f.call(()); //~ ERROR use of unstable library feature 'fn_traits'
+    f.call_mut(()); //~ ERROR use of unstable library feature 'fn_traits'
+    f.call_once(()); //~ ERROR use of unstable library feature 'fn_traits'
 }
 
 fn main() {}