Make async_idents an edition incompat lint

src/librustc_lint/builtin.rs

@@ -1788,7 +1788,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnnameableTestFunctions {
 
 declare_lint! {
     pub ASYNC_IDENTS,
-    Allow,
+    Deny,
     "detects `async` being used as an identifier"
 }
 
@@ -1798,7 +1798,7 @@ pub struct Async2018;
 
 impl LintPass for Async2018 {
     fn get_lints(&self) -> LintArray {
-        lint_array!()
+        lint_array!(ASYNC_IDENTS)
     }
 }
 

src/librustc_lint/lib.rs

@@ -189,7 +189,6 @@ pub fn register_builtins(store: &mut lint::LintStore, sess: Option<&Session>) {
     add_lint_group!(sess,
                     "rust_2018_idioms",
                     BARE_TRAIT_OBJECTS,
-                    ASYNC_IDENTS,
                     UNREACHABLE_PUB,
                     UNUSED_EXTERN_CRATES,
                     ELLIPSIS_INCLUSIVE_RANGE_PATTERNS);
@@ -224,6 +223,11 @@ pub fn register_builtins(store: &mut lint::LintStore, sess: Option<&Session>) {
             reference: "issue #35896 <https://github.com/rust-lang/rust/issues/35896>",
             edition: Some(Edition::Edition2018),
         },
+        FutureIncompatibleInfo {
+            id: LintId::of(ASYNC_IDENTS),
+            reference: "issue #49716 <https://github.com/rust-lang/rust/issues/49716>",
+            edition: Some(Edition::Edition2018),
+        },
         FutureIncompatibleInfo {
             id: LintId::of(SAFE_EXTERN_STATICS),
             reference: "issue #36247 <https://github.com/rust-lang/rust/issues/36247>",

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

@@ -11,6 +11,7 @@
 // edition:2015
 
 #![feature(raw_identifiers)]
+#![allow(async_idents)]
 
 #[macro_export]
 macro_rules! produces_async {

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

@@ -11,6 +11,7 @@
 // edition:2018
 
 #![feature(raw_identifiers)]
+#![allow(async_idents)]
 
 #[macro_export]
 macro_rules! produces_async {

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

@@ -13,6 +13,7 @@
 // compile-pass
 
 #![feature(raw_identifiers)]
+#![allow(async_idents)]
 
 #[macro_use]
 extern crate edition_kw_macro_2015;

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

@@ -13,6 +13,7 @@
 // compile-pass
 
 #![feature(raw_identifiers)]
+#![allow(async_idents)]
 
 #[macro_use]
 extern crate edition_kw_macro_2015;

src/test/ui/rust-2018/async-ident.fixed

@@ -9,18 +9,21 @@
 // except according to those terms.
 
 #![feature(raw_identifiers)]
-#![deny(rust_2018_idioms)]
+#![allow(dead_code, unused_variables, non_camel_case_types, non_upper_case_globals)]
-#![allow(dead_code)]
 
+// edition:2015
 // run-rustfix
 
 fn r#async() {} //~ ERROR async
+//~^ WARN hard error in the 2018 edition
 
 macro_rules! foo {
     ($foo:ident) => {};
     ($r#async:expr, r#async) => {};
     //~^ ERROR async
     //~| ERROR async
+    //~| WARN hard error in the 2018 edition
+    //~| WARN hard error in the 2018 edition
 }
 
 foo!(async);
@@ -29,4 +32,56 @@ mod dont_lint_raw {
     fn r#async() {}
 }
 
-fn main() {}
+mod async_trait {
+    trait r#async {}
+    //~^ ERROR async
+    //~| WARN hard error in the 2018 edition
+    struct MyStruct;
+    impl r#async for MyStruct {}
+    //~^ ERROR async
+    //~| WARN hard error in the 2018 edition
+}
+
+mod async_static {
+    static r#async: u32 = 0;
+    //~^ ERROR async
+    //~| WARN hard error in the 2018 edition
+}
+
+mod async_const {
+    const r#async: u32 = 0;
+    //~^ ERROR async
+    //~| WARN hard error in the 2018 edition
+}
+
+struct Foo;
+impl Foo { fn r#async() {} }
+    //~^ ERROR async
+    //~| WARN hard error in the 2018 edition
+
+fn main() {
+    struct r#async {}
+    //~^ ERROR async
+    //~| WARN hard error in the 2018 edition
+    let r#async: r#async = r#async {};
+    //~^ ERROR async
+    //~| WARN hard error in the 2018 edition
+    //~| ERROR async
+    //~| WARN hard error in the 2018 edition
+    //~| ERROR async
+    //~| WARN hard error in the 2018 edition
+}
+
+#[macro_export]
+macro_rules! produces_async {
+    () => (pub fn r#async() {})
+    //~^ ERROR async
+    //~| WARN hard error in the 2018 edition
+}
+
+#[macro_export]
+macro_rules! consumes_async {
+    (r#async) => (1)
+    //~^ ERROR async
+    //~| WARN hard error in the 2018 edition
+}

src/test/ui/rust-2018/async-ident.rs

@@ -9,18 +9,21 @@
 // except according to those terms.
 
 #![feature(raw_identifiers)]
-#![deny(rust_2018_idioms)]
+#![allow(dead_code, unused_variables, non_camel_case_types, non_upper_case_globals)]
-#![allow(dead_code)]
 
+// edition:2015
 // run-rustfix
 
 fn async() {} //~ ERROR async
+//~^ WARN hard error in the 2018 edition
 
 macro_rules! foo {
     ($foo:ident) => {};
     ($async:expr, async) => {};
     //~^ ERROR async
     //~| ERROR async
+    //~| WARN hard error in the 2018 edition
+    //~| WARN hard error in the 2018 edition
 }
 
 foo!(async);
@@ -29,4 +32,56 @@ mod dont_lint_raw {
     fn r#async() {}
 }
 
-fn main() {}
+mod async_trait {
+    trait async {}
+    //~^ ERROR async
+    //~| WARN hard error in the 2018 edition
+    struct MyStruct;
+    impl async for MyStruct {}
+    //~^ ERROR async
+    //~| WARN hard error in the 2018 edition
+}
+
+mod async_static {
+    static async: u32 = 0;
+    //~^ ERROR async
+    //~| WARN hard error in the 2018 edition
+}
+
+mod async_const {
+    const async: u32 = 0;
+    //~^ ERROR async
+    //~| WARN hard error in the 2018 edition
+}
+
+struct Foo;
+impl Foo { fn async() {} }
+    //~^ ERROR async
+    //~| WARN hard error in the 2018 edition
+
+fn main() {
+    struct async {}
+    //~^ ERROR async
+    //~| WARN hard error in the 2018 edition
+    let async: async = async {};
+    //~^ ERROR async
+    //~| WARN hard error in the 2018 edition
+    //~| ERROR async
+    //~| WARN hard error in the 2018 edition
+    //~| ERROR async
+    //~| WARN hard error in the 2018 edition
+}
+
+#[macro_export]
+macro_rules! produces_async {
+    () => (pub fn async() {})
+    //~^ ERROR async
+    //~| WARN hard error in the 2018 edition
+}
+
+#[macro_export]
+macro_rules! consumes_async {
+    (async) => (1)
+    //~^ ERROR async
+    //~| WARN hard error in the 2018 edition
+}

src/test/ui/rust-2018/async-ident.stderr

@@ -4,24 +4,126 @@ error: `async` is a keyword in the 2018 edition
 LL | fn async() {} //~ ERROR async
    |    ^^^^^ help: you can use a raw identifier to stay compatible: `r#async`
    |
-note: lint level defined here
+   = note: #[deny(async_idents)] on by default
-  --> $DIR/async-ident.rs:12:9
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in the 2018 edition!
-   |
+   = note: for more information, see issue #49716 <https://github.com/rust-lang/rust/issues/49716>
-LL | #![deny(rust_2018_idioms)]
-   |         ^^^^^^^^^^^^^^^^
-   = note: #[deny(async_idents)] implied by #[deny(rust_2018_idioms)]
 
 error: `async` is a keyword in the 2018 edition
-  --> $DIR/async-ident.rs:21:7
+  --> $DIR/async-ident.rs:22:7
    |
 LL |     ($async:expr, async) => {};
    |       ^^^^^ help: you can use a raw identifier to stay compatible: `r#async`
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in the 2018 edition!
+   = note: for more information, see issue #49716 <https://github.com/rust-lang/rust/issues/49716>
 
 error: `async` is a keyword in the 2018 edition
-  --> $DIR/async-ident.rs:21:19
+  --> $DIR/async-ident.rs:22:19
    |
 LL |     ($async:expr, async) => {};
    |                   ^^^^^ help: you can use a raw identifier to stay compatible: `r#async`
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in the 2018 edition!
+   = note: for more information, see issue #49716 <https://github.com/rust-lang/rust/issues/49716>
 
-error: aborting due to 3 previous errors
+error: `async` is a keyword in the 2018 edition
+  --> $DIR/async-ident.rs:36:11
+   |
+LL |     trait async {}
+   |           ^^^^^ help: you can use a raw identifier to stay compatible: `r#async`
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in the 2018 edition!
+   = note: for more information, see issue #49716 <https://github.com/rust-lang/rust/issues/49716>
+
+error: `async` is a keyword in the 2018 edition
+  --> $DIR/async-ident.rs:40:10
+   |
+LL |     impl async for MyStruct {}
+   |          ^^^^^ help: you can use a raw identifier to stay compatible: `r#async`
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in the 2018 edition!
+   = note: for more information, see issue #49716 <https://github.com/rust-lang/rust/issues/49716>
+
+error: `async` is a keyword in the 2018 edition
+  --> $DIR/async-ident.rs:46:12
+   |
+LL |     static async: u32 = 0;
+   |            ^^^^^ help: you can use a raw identifier to stay compatible: `r#async`
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in the 2018 edition!
+   = note: for more information, see issue #49716 <https://github.com/rust-lang/rust/issues/49716>
+
+error: `async` is a keyword in the 2018 edition
+  --> $DIR/async-ident.rs:52:11
+   |
+LL |     const async: u32 = 0;
+   |           ^^^^^ help: you can use a raw identifier to stay compatible: `r#async`
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in the 2018 edition!
+   = note: for more information, see issue #49716 <https://github.com/rust-lang/rust/issues/49716>
+
+error: `async` is a keyword in the 2018 edition
+  --> $DIR/async-ident.rs:58:15
+   |
+LL | impl Foo { fn async() {} }
+   |               ^^^^^ help: you can use a raw identifier to stay compatible: `r#async`
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in the 2018 edition!
+   = note: for more information, see issue #49716 <https://github.com/rust-lang/rust/issues/49716>
+
+error: `async` is a keyword in the 2018 edition
+  --> $DIR/async-ident.rs:63:12
+   |
+LL |     struct async {}
+   |            ^^^^^ help: you can use a raw identifier to stay compatible: `r#async`
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in the 2018 edition!
+   = note: for more information, see issue #49716 <https://github.com/rust-lang/rust/issues/49716>
+
+error: `async` is a keyword in the 2018 edition
+  --> $DIR/async-ident.rs:66:9
+   |
+LL |     let async: async = async {};
+   |         ^^^^^ help: you can use a raw identifier to stay compatible: `r#async`
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in the 2018 edition!
+   = note: for more information, see issue #49716 <https://github.com/rust-lang/rust/issues/49716>
+
+error: `async` is a keyword in the 2018 edition
+  --> $DIR/async-ident.rs:66:16
+   |
+LL |     let async: async = async {};
+   |                ^^^^^ help: you can use a raw identifier to stay compatible: `r#async`
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in the 2018 edition!
+   = note: for more information, see issue #49716 <https://github.com/rust-lang/rust/issues/49716>
+
+error: `async` is a keyword in the 2018 edition
+  --> $DIR/async-ident.rs:66:24
+   |
+LL |     let async: async = async {};
+   |                        ^^^^^ help: you can use a raw identifier to stay compatible: `r#async`
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in the 2018 edition!
+   = note: for more information, see issue #49716 <https://github.com/rust-lang/rust/issues/49716>
+
+error: `async` is a keyword in the 2018 edition
+  --> $DIR/async-ident.rs:77:19
+   |
+LL |     () => (pub fn async() {})
+   |                   ^^^^^ help: you can use a raw identifier to stay compatible: `r#async`
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in the 2018 edition!
+   = note: for more information, see issue #49716 <https://github.com/rust-lang/rust/issues/49716>
+
+error: `async` is a keyword in the 2018 edition
+  --> $DIR/async-ident.rs:84:6
+   |
+LL |     (async) => (1)
+   |      ^^^^^ help: you can use a raw identifier to stay compatible: `r#async`
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in the 2018 edition!
+   = note: for more information, see issue #49716 <https://github.com/rust-lang/rust/issues/49716>
+
+error: aborting due to 14 previous errors