Auto merge of #50307 - petrochenkov:keyhyg2, r=nikomatsakis

Implement edition hygiene for keywords

Determine "keywordness" of an identifier in its hygienic context.
cc https://github.com/rust-lang/rust/pull/49611

I've resurrected `proc` as an Edition-2015-only keyword for testing purposes, but it should probably be buried again. EDIT: `proc` is removed again.

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

@@ -20,6 +20,7 @@ extern crate rustc_plugin;
 
 use std::borrow::ToOwned;
 use syntax::ast;
+use syntax::ext::hygiene;
 use syntax::ext::build::AstBuilder;
 use syntax::ext::base::{TTMacroExpander, ExtCtxt, MacResult, MacEager, NormalTT};
 use syntax::print::pprust;
@@ -54,5 +55,6 @@ pub fn plugin_registrar(reg: &mut Registry) {
             allow_internal_unstable: false,
             allow_internal_unsafe: false,
             unstable_feature: None,
+            edition: hygiene::default_edition(),
         });
 }

src/test/run-pass/auxiliary/edition-kw-macro-2015.rs

@@ -0,0 +1,38 @@
+// Copyright 2018 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.
+
+// compile-flags: --edition=2015
+
+#![feature(raw_identifiers)]
+
+#[macro_export]
+macro_rules! produces_async {
+    () => (pub fn async() {})
+}
+
+#[macro_export]
+macro_rules! produces_async_raw {
+    () => (pub fn r#async() {})
+}
+
+#[macro_export]
+macro_rules! consumes_async {
+    (async) => (1)
+}
+
+#[macro_export]
+macro_rules! consumes_async_raw {
+    (r#async) => (1)
+}
+
+#[macro_export]
+macro_rules! passes_ident {
+    ($i: ident) => ($i)
+}

src/test/run-pass/auxiliary/edition-kw-macro-2018.rs

@@ -0,0 +1,38 @@
+// Copyright 2018 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.
+
+// compile-flags: --edition=2018
+
+#![feature(raw_identifiers)]
+
+#[macro_export]
+macro_rules! produces_async {
+    () => (pub fn async() {})
+}
+
+#[macro_export]
+macro_rules! produces_async_raw {
+    () => (pub fn r#async() {})
+}
+
+#[macro_export]
+macro_rules! consumes_async {
+    (async) => (1)
+}
+
+#[macro_export]
+macro_rules! consumes_async_raw {
+    (r#async) => (1)
+}
+
+#[macro_export]
+macro_rules! passes_ident {
+    ($i: ident) => ($i)
+}

src/test/run-pass/edition-keywords-2015-2015.rs

@@ -0,0 +1,43 @@
+// Copyright 2018 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.
+
+// compile-flags: --edition=2015
+// aux-build:edition-kw-macro-2015.rs
+
+#![feature(raw_identifiers)]
+
+#[macro_use]
+extern crate edition_kw_macro_2015;
+
+pub fn check_async() {
+    let mut async = 1; // OK
+    let mut r#async = 1; // OK
+
+    r#async = consumes_async!(async); // OK
+    // r#async = consumes_async!(r#async); // ERROR, not a match
+    // r#async = consumes_async_raw!(async); // ERROR, not a match
+    r#async = consumes_async_raw!(r#async); // OK
+
+    if passes_ident!(async) == 1 {} // OK
+    if passes_ident!(r#async) == 1 {} // OK
+    one_async::async(); // OK
+    one_async::r#async(); // OK
+    two_async::async(); // OK
+    two_async::r#async(); // OK
+}
+
+mod one_async {
+    produces_async! {} // OK
+}
+mod two_async {
+    produces_async_raw! {} // OK
+}
+
+fn main() {}

src/test/run-pass/edition-keywords-2015-2018.rs

@@ -0,0 +1,43 @@
+// Copyright 2018 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.
+
+// compile-flags: --edition=2015
+// aux-build:edition-kw-macro-2018.rs
+
+#![feature(raw_identifiers)]
+
+#[macro_use]
+extern crate edition_kw_macro_2018;
+
+pub fn check_async() {
+    let mut async = 1; // OK
+    let mut r#async = 1; // OK
+
+    r#async = consumes_async!(async); // OK
+    // r#async = consumes_async!(r#async); // ERROR, not a match
+    // r#async = consumes_async_raw!(async); // ERROR, not a match
+    r#async = consumes_async_raw!(r#async); // OK
+
+    if passes_ident!(async) == 1 {} // OK
+    if passes_ident!(r#async) == 1 {} // OK
+    // one_async::async(); // ERROR, unresolved name
+    // one_async::r#async(); // ERROR, unresolved name
+    two_async::async(); // OK
+    two_async::r#async(); // OK
+}
+
+mod one_async {
+    // produces_async! {} // ERROR, reserved
+}
+mod two_async {
+    produces_async_raw! {} // OK
+}
+
+fn main() {}

src/test/run-pass/edition-keywords-2018-2015.rs

@@ -0,0 +1,43 @@
+// Copyright 2018 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.
+
+// compile-flags: --edition=2018
+// aux-build:edition-kw-macro-2015.rs
+
+#![feature(raw_identifiers)]
+
+#[macro_use]
+extern crate edition_kw_macro_2015;
+
+pub fn check_async() {
+    // let mut async = 1; // ERROR, reserved
+    let mut r#async = 1; // OK
+
+    r#async = consumes_async!(async); // OK
+    // r#async = consumes_async!(r#async); // ERROR, not a match
+    // r#async = consumes_async_raw!(async); // ERROR, not a match
+    r#async = consumes_async_raw!(r#async); // OK
+
+    // if passes_ident!(async) == 1 {} // ERROR, reserved
+    if passes_ident!(r#async) == 1 {} // OK
+    // one_async::async(); // ERROR, reserved
+    one_async::r#async(); // OK
+    // two_async::async(); // ERROR, reserved
+    two_async::r#async(); // OK
+}
+
+mod one_async {
+    produces_async! {} // OK
+}
+mod two_async {
+    produces_async_raw! {} // OK
+}
+
+fn main() {}

src/test/run-pass/edition-keywords-2018-2018.rs

@@ -0,0 +1,43 @@
+// Copyright 2018 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.
+
+// compile-flags: --edition=2018
+// aux-build:edition-kw-macro-2018.rs
+
+#![feature(raw_identifiers)]
+
+#[macro_use]
+extern crate edition_kw_macro_2018;
+
+pub fn check_async() {
+    // let mut async = 1; // ERROR, reserved
+    let mut r#async = 1; // OK
+
+    r#async = consumes_async!(async); // OK
+    // r#async = consumes_async!(r#async); // ERROR, not a match
+    // r#async = consumes_async_raw!(async); // ERROR, not a match
+    r#async = consumes_async_raw!(r#async); // OK
+
+    // if passes_ident!(async) == 1 {} // ERROR, reserved
+    if passes_ident!(r#async) == 1 {} // OK
+    // one_async::async(); // ERROR, reserved
+    // one_async::r#async(); // ERROR, unresolved name
+    // two_async::async(); // ERROR, reserved
+    two_async::r#async(); // OK
+}
+
+mod one_async {
+    // produces_async! {} // ERROR, reserved
+}
+mod two_async {
+    produces_async_raw! {} // OK
+}
+
+fn main() {}

src/test/ui/auxiliary/edition-kw-macro-2015.rs

@@ -0,0 +1,38 @@
+// Copyright 2018 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.
+
+// compile-flags: --edition=2015
+
+#![feature(raw_identifiers)]
+
+#[macro_export]
+macro_rules! produces_async {
+    () => (pub fn async() {})
+}
+
+#[macro_export]
+macro_rules! produces_async_raw {
+    () => (pub fn r#async() {})
+}
+
+#[macro_export]
+macro_rules! consumes_async {
+    (async) => (1)
+}
+
+#[macro_export]
+macro_rules! consumes_async_raw {
+    (r#async) => (1)
+}
+
+#[macro_export]
+macro_rules! passes_ident {
+    ($i: ident) => ($i)
+}

src/test/ui/auxiliary/edition-kw-macro-2018.rs

@@ -0,0 +1,38 @@
+// Copyright 2018 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.
+
+// compile-flags: --edition=2018
+
+#![feature(raw_identifiers)]
+
+#[macro_export]
+macro_rules! produces_async {
+    () => (pub fn async() {})
+}
+
+#[macro_export]
+macro_rules! produces_async_raw {
+    () => (pub fn r#async() {})
+}
+
+#[macro_export]
+macro_rules! consumes_async {
+    (async) => (1)
+}
+
+#[macro_export]
+macro_rules! consumes_async_raw {
+    (r#async) => (1)
+}
+
+#[macro_export]
+macro_rules! passes_ident {
+    ($i: ident) => ($i)
+}

src/test/ui/edition-keywords-2015-2015-expansion.rs

@@ -0,0 +1,27 @@
+// Copyright 2018 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.
+
+// compile-flags: --edition=2015
+// aux-build:edition-kw-macro-2015.rs
+// compile-pass
+
+#![feature(raw_identifiers)]
+
+#[macro_use]
+extern crate edition_kw_macro_2015;
+
+mod one_async {
+    produces_async! {} // OK
+}
+mod two_async {
+    produces_async_raw! {} // OK
+}
+
+fn main() {}

src/test/ui/edition-keywords-2015-2015-parsing.rs

@@ -0,0 +1,32 @@
+// Copyright 2018 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.
+
+// compile-flags: --edition=2015
+// aux-build:edition-kw-macro-2015.rs
+
+#![feature(raw_identifiers)]
+
+#[macro_use]
+extern crate edition_kw_macro_2015;
+
+pub fn check_async() {
+    let mut async = 1; // OK
+    let mut r#async = 1; // OK
+
+    r#async = consumes_async!(async); // OK
+    r#async = consumes_async!(r#async); //~ ERROR no rules expected the token `r#async`
+    r#async = consumes_async_raw!(async); //~ ERROR no rules expected the token `async`
+    r#async = consumes_async_raw!(r#async); // OK
+
+    if passes_ident!(async) == 1 {} // OK
+    if passes_ident!(r#async) == 1 {} // OK
+    module::async(); // OK
+    module::r#async(); // OK
+}

src/test/ui/edition-keywords-2015-2015-parsing.stderr

@@ -0,0 +1,14 @@
+error: no rules expected the token `r#async`
+  --> $DIR/edition-keywords-2015-2015-parsing.rs:24:31
+   |
+LL |     r#async = consumes_async!(r#async); //~ ERROR no rules expected the token `r#async`
+   |                               ^^^^^^^
+
+error: no rules expected the token `async`
+  --> $DIR/edition-keywords-2015-2015-parsing.rs:25:35
+   |
+LL |     r#async = consumes_async_raw!(async); //~ ERROR no rules expected the token `async`
+   |                                   ^^^^^
+
+error: aborting due to 2 previous errors
+

src/test/ui/edition-keywords-2015-2018-expansion.rs

@@ -0,0 +1,24 @@
+// Copyright 2018 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.
+
+// compile-flags: --edition=2015
+// aux-build:edition-kw-macro-2018.rs
+
+#![feature(raw_identifiers)]
+
+#[macro_use]
+extern crate edition_kw_macro_2018;
+
+mod one_async {
+    produces_async! {} // ERROR expected identifier, found reserved keyword
+}
+mod two_async {
+    produces_async_raw! {} // OK
+}

src/test/ui/edition-keywords-2015-2018-expansion.stderr

@@ -0,0 +1,10 @@
+error: expected identifier, found reserved keyword `async`
+  --> $DIR/edition-keywords-2015-2018-expansion.rs:20:5
+   |
+LL |     produces_async! {} // ERROR expected identifier, found reserved keyword
+   |     ^^^^^^^^^^^^^^^^^^ expected identifier, found reserved keyword
+   |
+   = note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
+
+error: aborting due to previous error
+

src/test/ui/edition-keywords-2015-2018-parsing.rs

@@ -0,0 +1,32 @@
+// Copyright 2018 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.
+
+// compile-flags: --edition=2015
+// aux-build:edition-kw-macro-2018.rs
+
+#![feature(raw_identifiers)]
+
+#[macro_use]
+extern crate edition_kw_macro_2018;
+
+pub fn check_async() {
+    let mut async = 1; // OK
+    let mut r#async = 1; // OK
+
+    r#async = consumes_async!(async); // OK
+    r#async = consumes_async!(r#async); //~ ERROR no rules expected the token `r#async`
+    r#async = consumes_async_raw!(async); //~ ERROR no rules expected the token `async`
+    r#async = consumes_async_raw!(r#async); // OK
+
+    if passes_ident!(async) == 1 {} // OK
+    if passes_ident!(r#async) == 1 {} // OK
+    module::async(); // OK
+    module::r#async(); // OK
+}

src/test/ui/edition-keywords-2015-2018-parsing.stderr

@@ -0,0 +1,14 @@
+error: no rules expected the token `r#async`
+  --> $DIR/edition-keywords-2015-2018-parsing.rs:24:31
+   |
+LL |     r#async = consumes_async!(r#async); //~ ERROR no rules expected the token `r#async`
+   |                               ^^^^^^^
+
+error: no rules expected the token `async`
+  --> $DIR/edition-keywords-2015-2018-parsing.rs:25:35
+   |
+LL |     r#async = consumes_async_raw!(async); //~ ERROR no rules expected the token `async`
+   |                                   ^^^^^
+
+error: aborting due to 2 previous errors
+

src/test/ui/edition-keywords-2018-2015-expansion.rs

@@ -0,0 +1,27 @@
+// Copyright 2018 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.
+
+// compile-flags: --edition=2018
+// aux-build:edition-kw-macro-2015.rs
+// compile-pass
+
+#![feature(raw_identifiers)]
+
+#[macro_use]
+extern crate edition_kw_macro_2015;
+
+mod one_async {
+    produces_async! {} // OK
+}
+mod two_async {
+    produces_async_raw! {} // OK
+}
+
+fn main() {}

src/test/ui/edition-keywords-2018-2015-parsing.rs

@@ -0,0 +1,32 @@
+// Copyright 2018 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.
+
+// compile-flags: --edition=2018
+// aux-build:edition-kw-macro-2015.rs
+
+#![feature(raw_identifiers)]
+
+#[macro_use]
+extern crate edition_kw_macro_2015;
+
+pub fn check_async() {
+    let mut async = 1; //~ ERROR expected identifier, found reserved keyword `async`
+    let mut r#async = 1; // OK
+
+    r#async = consumes_async!(async); // OK
+    r#async = consumes_async!(r#async); //~ ERROR no rules expected the token `r#async`
+    r#async = consumes_async_raw!(async); //~ ERROR no rules expected the token `async`
+    r#async = consumes_async_raw!(r#async); // OK
+
+    if passes_ident!(async) == 1 {} //~ ERROR expected expression, found reserved keyword `async`
+    if passes_ident!(r#async) == 1 {} // OK
+    module::async(); //~ ERROR expected identifier, found reserved keyword `async`
+    module::r#async(); // OK
+}

src/test/ui/edition-keywords-2018-2015-parsing.stderr

@@ -0,0 +1,32 @@
+error: expected identifier, found reserved keyword `async`
+  --> $DIR/edition-keywords-2018-2015-parsing.rs:20:13
+   |
+LL |     let mut async = 1; //~ ERROR expected identifier, found reserved keyword `async`
+   |             ^^^^^ expected identifier, found reserved keyword
+
+error: expected identifier, found reserved keyword `async`
+  --> $DIR/edition-keywords-2018-2015-parsing.rs:30:13
+   |
+LL |     module::async(); //~ ERROR expected identifier, found reserved keyword `async`
+   |             ^^^^^ expected identifier, found reserved keyword
+
+error: no rules expected the token `r#async`
+  --> $DIR/edition-keywords-2018-2015-parsing.rs:24:31
+   |
+LL |     r#async = consumes_async!(r#async); //~ ERROR no rules expected the token `r#async`
+   |                               ^^^^^^^
+
+error: no rules expected the token `async`
+  --> $DIR/edition-keywords-2018-2015-parsing.rs:25:35
+   |
+LL |     r#async = consumes_async_raw!(async); //~ ERROR no rules expected the token `async`
+   |                                   ^^^^^
+
+error: expected expression, found reserved keyword `async`
+  --> $DIR/edition-keywords-2018-2015-parsing.rs:28:22
+   |
+LL |     if passes_ident!(async) == 1 {} //~ ERROR expected expression, found reserved keyword `async`
+   |                      ^^^^^ expected expression
+
+error: aborting due to 5 previous errors
+

src/test/ui/edition-keywords-2018-2018-expansion.rs

@@ -0,0 +1,24 @@
+// Copyright 2018 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.
+
+// compile-flags: --edition=2018
+// aux-build:edition-kw-macro-2018.rs
+
+#![feature(raw_identifiers)]
+
+#[macro_use]
+extern crate edition_kw_macro_2018;
+
+mod one_async {
+    produces_async! {} // ERROR expected identifier, found reserved keyword `async`
+}
+mod two_async {
+    produces_async_raw! {} // OK
+}

src/test/ui/edition-keywords-2018-2018-expansion.stderr

@@ -0,0 +1,10 @@
+error: expected identifier, found reserved keyword `async`
+  --> $DIR/edition-keywords-2018-2018-expansion.rs:20:5
+   |
+LL |     produces_async! {} // ERROR expected identifier, found reserved keyword `async`
+   |     ^^^^^^^^^^^^^^^^^^ expected identifier, found reserved keyword
+   |
+   = note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
+
+error: aborting due to previous error
+

src/test/ui/edition-keywords-2018-2018-parsing.rs

@@ -0,0 +1,32 @@
+// Copyright 2018 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.
+
+// compile-flags: --edition=2018
+// aux-build:edition-kw-macro-2018.rs
+
+#![feature(raw_identifiers)]
+
+#[macro_use]
+extern crate edition_kw_macro_2018;
+
+pub fn check_async() {
+    let mut async = 1; //~ ERROR expected identifier, found reserved keyword `async`
+    let mut r#async = 1; // OK
+
+    r#async = consumes_async!(async); // OK
+    r#async = consumes_async!(r#async); //~ ERROR no rules expected the token `r#async`
+    r#async = consumes_async_raw!(async); //~ ERROR no rules expected the token `async`
+    r#async = consumes_async_raw!(r#async); // OK
+
+    if passes_ident!(async) == 1 {} //~ ERROR expected expression, found reserved keyword `async`
+    if passes_ident!(r#async) == 1 {} // OK
+    module::async(); //~ ERROR expected identifier, found reserved keyword `async`
+    module::r#async(); // OK
+}

src/test/ui/edition-keywords-2018-2018-parsing.stderr

@@ -0,0 +1,32 @@
+error: expected identifier, found reserved keyword `async`
+  --> $DIR/edition-keywords-2018-2018-parsing.rs:20:13
+   |
+LL |     let mut async = 1; //~ ERROR expected identifier, found reserved keyword `async`
+   |             ^^^^^ expected identifier, found reserved keyword
+
+error: expected identifier, found reserved keyword `async`
+  --> $DIR/edition-keywords-2018-2018-parsing.rs:30:13
+   |
+LL |     module::async(); //~ ERROR expected identifier, found reserved keyword `async`
+   |             ^^^^^ expected identifier, found reserved keyword
+
+error: no rules expected the token `r#async`
+  --> $DIR/edition-keywords-2018-2018-parsing.rs:24:31
+   |
+LL |     r#async = consumes_async!(r#async); //~ ERROR no rules expected the token `r#async`
+   |                               ^^^^^^^
+
+error: no rules expected the token `async`
+  --> $DIR/edition-keywords-2018-2018-parsing.rs:25:35
+   |
+LL |     r#async = consumes_async_raw!(async); //~ ERROR no rules expected the token `async`
+   |                                   ^^^^^
+
+error: expected expression, found reserved keyword `async`
+  --> $DIR/edition-keywords-2018-2018-parsing.rs:28:22
+   |
+LL |     if passes_ident!(async) == 1 {} //~ ERROR expected expression, found reserved keyword `async`
+   |                      ^^^^^ expected expression
+
+error: aborting due to 5 previous errors
+