Make sure we don't deny macro vars w keyword names

compiler/rustc_lint/src/builtin.rs

@@ -40,6 +40,7 @@ use crate::{
     },
     EarlyContext, EarlyLintPass, LateContext, LateLintPass, Level, LintContext,
 };
+use ast::token::TokenKind;
 use rustc_ast::tokenstream::{TokenStream, TokenTree};
 use rustc_ast::visit::{FnCtxt, FnKind};
 use rustc_ast::{self as ast, *};
@@ -1869,16 +1870,24 @@ struct UnderMacro(bool);
 
 impl KeywordIdents {
     fn check_tokens(&mut self, cx: &EarlyContext<'_>, tokens: &TokenStream) {
+        // Check if the preceding token is `$`, because we want to allow `$async`, etc.
+        let mut prev_dollar = false;
         for tt in tokens.trees() {
             match tt {
                 // Only report non-raw idents.
                 TokenTree::Token(token, _) => {
                     if let Some((ident, token::IdentIsRaw::No)) = token.ident() {
-                        self.check_ident_token(cx, UnderMacro(true), ident);
+                        if !prev_dollar {
+                            self.check_ident_token(cx, UnderMacro(true), ident);
+                        }
+                    } else if token.kind == TokenKind::Dollar {
+                        prev_dollar = true;
+                        continue;
                     }
                 }
                 TokenTree::Delimited(.., tts) => self.check_tokens(cx, tts),
             }
+            prev_dollar = false;
         }
     }
 

tests/ui/rust-2018/async-ident.fixed

@@ -9,16 +9,14 @@ fn r#async() {} //~ ERROR async
 
 macro_rules! foo {
     ($foo:ident) => {};
-    ($r#async:expr, r#async) => {};
+    ($async:expr, r#async) => {};
     //~^ ERROR async
-    //~| ERROR async
-    //~| WARN this is accepted in the current edition
     //~| WARN this is accepted in the current edition
 }
 
 foo!(r#async);
-    //~^ ERROR async
-    //~| WARN this is accepted in the current edition
+//~^ ERROR async
+//~| WARN this is accepted in the current edition
 
 mod dont_lint_raw {
     fn r#async() {}

tests/ui/rust-2018/async-ident.rs

@@ -11,14 +11,12 @@ macro_rules! foo {
     ($foo:ident) => {};
     ($async:expr, async) => {};
     //~^ ERROR async
-    //~| ERROR async
-    //~| WARN this is accepted in the current edition
     //~| WARN this is accepted in the current edition
 }
 
 foo!(async);
-    //~^ ERROR async
-    //~| WARN this is accepted in the current edition
+//~^ ERROR async
+//~| WARN this is accepted in the current edition
 
 mod dont_lint_raw {
     fn r#async() {}

tests/ui/rust-2018/async-ident.stderr

@@ -13,15 +13,6 @@ LL | #![deny(keyword_idents)]
    |         ^^^^^^^^^^^^^^
    = note: `#[deny(keyword_idents_2018)]` implied by `#[deny(keyword_idents)]`
 
-error: `async` is a keyword in the 2018 edition
-  --> $DIR/async-ident.rs:12:7
-   |
-LL |     ($async:expr, async) => {};
-   |       ^^^^^ help: you can use a raw identifier to stay compatible: `r#async`
-   |
-   = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2018!
-   = note: for more information, see issue #49716 <https://github.com/rust-lang/rust/issues/49716>
-
 error: `async` is a keyword in the 2018 edition
   --> $DIR/async-ident.rs:12:19
    |
@@ -32,7 +23,7 @@ LL |     ($async:expr, async) => {};
    = 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:19:6
+  --> $DIR/async-ident.rs:17:6
    |
 LL | foo!(async);
    |      ^^^^^ help: you can use a raw identifier to stay compatible: `r#async`
@@ -41,7 +32,7 @@ LL | foo!(async);
    = 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:28:11
+  --> $DIR/async-ident.rs:26:11
    |
 LL |     trait async {}
    |           ^^^^^ help: you can use a raw identifier to stay compatible: `r#async`
@@ -50,7 +41,7 @@ LL |     trait async {}
    = 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:32:10
+  --> $DIR/async-ident.rs:30:10
    |
 LL |     impl async for MyStruct {}
    |          ^^^^^ help: you can use a raw identifier to stay compatible: `r#async`
@@ -59,7 +50,7 @@ LL |     impl async for MyStruct {}
    = 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:38:12
+  --> $DIR/async-ident.rs:36:12
    |
 LL |     static async: u32 = 0;
    |            ^^^^^ help: you can use a raw identifier to stay compatible: `r#async`
@@ -68,7 +59,7 @@ LL |     static async: u32 = 0;
    = 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:44:11
+  --> $DIR/async-ident.rs:42:11
    |
 LL |     const async: u32 = 0;
    |           ^^^^^ help: you can use a raw identifier to stay compatible: `r#async`
@@ -77,7 +68,7 @@ LL |     const async: u32 = 0;
    = 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:50:15
+  --> $DIR/async-ident.rs:48:15
    |
 LL | impl Foo { fn async() {} }
    |               ^^^^^ help: you can use a raw identifier to stay compatible: `r#async`
@@ -86,7 +77,7 @@ LL | impl Foo { fn async() {} }
    = 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:55:12
+  --> $DIR/async-ident.rs:53:12
    |
 LL |     struct async {}
    |            ^^^^^ help: you can use a raw identifier to stay compatible: `r#async`
@@ -95,7 +86,7 @@ LL |     struct async {}
    = 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:58:9
+  --> $DIR/async-ident.rs:56:9
    |
 LL |     let async: async = async {};
    |         ^^^^^ help: you can use a raw identifier to stay compatible: `r#async`
@@ -104,7 +95,7 @@ LL |     let async: async = async {};
    = 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:58:16
+  --> $DIR/async-ident.rs:56:16
    |
 LL |     let async: async = async {};
    |                ^^^^^ help: you can use a raw identifier to stay compatible: `r#async`
@@ -113,7 +104,7 @@ LL |     let async: async = async {};
    = 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:58:24
+  --> $DIR/async-ident.rs:56:24
    |
 LL |     let async: async = async {};
    |                        ^^^^^ help: you can use a raw identifier to stay compatible: `r#async`
@@ -122,7 +113,7 @@ LL |     let async: async = async {};
    = 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:69:19
+  --> $DIR/async-ident.rs:67:19
    |
 LL |     () => (pub fn async() {})
    |                   ^^^^^ help: you can use a raw identifier to stay compatible: `r#async`
@@ -131,13 +122,13 @@ LL |     () => (pub fn async() {})
    = 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:76:6
+  --> $DIR/async-ident.rs:74:6
    |
 LL |     (async) => (1)
    |      ^^^^^ help: you can use a raw identifier to stay compatible: `r#async`
    |
    = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2018!
    = note: for more information, see issue #49716 <https://github.com/rust-lang/rust/issues/49716>
 
-error: aborting due to 15 previous errors
+error: aborting due to 14 previous errors
 

tests/ui/rust-2024/gen-kw-in-macro.rs

@@ -0,0 +1,13 @@
+//@ check-pass
+
+#![deny(keyword_idents_2024)]
+
+macro_rules! foo {
+    ($gen:expr) => {
+        $gen
+    };
+}
+
+fn main() {
+    foo!(println!("hello, world"));
+}

tests/ui/rust-2024/gen-kw.e2015.stderr

@@ -22,5 +22,14 @@ LL |     let gen = r#gen;
    = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2024!
    = note: for more information, see issue #49716 <https://github.com/rust-lang/rust/issues/49716>
 
-error: aborting due to 2 previous errors
+error: `gen` is a keyword in the 2024 edition
+  --> $DIR/gen-kw.rs:19:27
+   |
+LL |     () => { mod test { fn gen() {} } }
+   |                           ^^^ help: you can use a raw identifier to stay compatible: `r#gen`
+   |
+   = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2024!
+   = note: for more information, see issue #49716 <https://github.com/rust-lang/rust/issues/49716>
+
+error: aborting due to 3 previous errors
 

tests/ui/rust-2024/gen-kw.e2018.stderr

@@ -22,5 +22,14 @@ LL |     let gen = r#gen;
    = warning: this is accepted in the current edition (Rust 2018) but is a hard error in Rust 2024!
    = note: for more information, see issue #49716 <https://github.com/rust-lang/rust/issues/49716>
 
-error: aborting due to 2 previous errors
+error: `gen` is a keyword in the 2024 edition
+  --> $DIR/gen-kw.rs:19:27
+   |
+LL |     () => { mod test { fn gen() {} } }
+   |                           ^^^ help: you can use a raw identifier to stay compatible: `r#gen`
+   |
+   = warning: this is accepted in the current edition (Rust 2018) but is a hard error in Rust 2024!
+   = note: for more information, see issue #49716 <https://github.com/rust-lang/rust/issues/49716>
+
+error: aborting due to 3 previous errors
 

tests/ui/rust-2024/gen-kw.rs

@@ -14,3 +14,12 @@ fn main() {
     //[e2015]~| WARNING this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2024!
     //[e2018]~| WARNING this is accepted in the current edition (Rust 2018) but is a hard error in Rust 2024!
 }
+
+macro_rules! t {
+    () => { mod test { fn gen() {} } }
+    //~^ ERROR `gen` is a keyword in the 2024 edition
+    //[e2015]~| WARNING this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2024!
+    //[e2018]~| WARNING this is accepted in the current edition (Rust 2018) but is a hard error in Rust 2024!
+}
+
+t!();