Support the #[expect] attribute on fn parameters (RFC-2383)

compiler/rustc_ast_passes/src/ast_validation.rs

@@ -420,7 +420,15 @@ impl<'a> AstValidator<'a> {
             .iter()
             .flat_map(|i| i.attrs.as_ref())
             .filter(|attr| {
-                let arr = [sym::allow, sym::cfg, sym::cfg_attr, sym::deny, sym::forbid, sym::warn];
+                let arr = [
+                    sym::allow,
+                    sym::cfg,
+                    sym::cfg_attr,
+                    sym::deny,
+                    sym::expect,
+                    sym::forbid,
+                    sym::warn,
+                ];
                 !arr.contains(&attr.name_or_empty()) && rustc_attr::is_builtin_attr(attr)
             })
             .for_each(|attr| {
@@ -435,7 +443,7 @@ impl<'a> AstValidator<'a> {
                 } else {
                     self.err_handler().span_err(
                         attr.span,
-                        "allow, cfg, cfg_attr, deny, \
+                        "allow, cfg, cfg_attr, deny, expect, \
                 forbid, and warn are the only allowed built-in attributes in function parameters",
                     );
                 }

src/test/ui/attributes/attrs-on-params.rs

@@ -2,7 +2,7 @@
 
 fn function(#[inline] param: u32) {
     //~^ ERROR attribute should be applied to function or closure
-    //~| ERROR allow, cfg, cfg_attr, deny, forbid, and warn are the only allowed built-in attributes
+    //~| ERROR allow, cfg, cfg_attr, deny, expect, forbid, and warn are the only allowed built-in attributes
 }
 
 fn main() {}

src/test/ui/attributes/attrs-on-params.stderr

@@ -1,4 +1,4 @@
-error: allow, cfg, cfg_attr, deny, forbid, and warn are the only allowed built-in attributes in function parameters
+error: allow, cfg, cfg_attr, deny, expect, forbid, and warn are the only allowed built-in attributes in function parameters
   --> $DIR/attrs-on-params.rs:3:13
    |
 LL | fn function(#[inline] param: u32) {

src/test/ui/lint/rfc-2383-lint-reason/expect_on_fn_params.rs

@@ -0,0 +1,15 @@
+// check-pass
+#![feature(lint_reasons)]
+
+#[warn(unused_variables)]
+
+/// This should catch the unused_variables lint and not emit anything
+fn check_fulfilled_expectation(#[expect(unused_variables)] unused_value: u32) {}
+
+fn check_unfulfilled_expectation(#[expect(unused_variables)] used_value: u32) {
+    //~^ WARNING this lint expectation is unfulfilled [unfulfilled_lint_expectations]
+    //~| NOTE `#[warn(unfulfilled_lint_expectations)]` on by default
+    println!("I use the value {used_value}");
+}
+
+fn main() {}

src/test/ui/lint/rfc-2383-lint-reason/expect_on_fn_params.stderr

@@ -0,0 +1,10 @@
+warning: this lint expectation is unfulfilled
+  --> $DIR/expect_on_fn_params.rs:9:43
+   |
+LL | fn check_unfulfilled_expectation(#[expect(unused_variables)] used_value: u32) {
+   |                                           ^^^^^^^^^^^^^^^^
+   |
+   = note: `#[warn(unfulfilled_lint_expectations)]` on by default
+
+warning: 1 warning emitted
+

src/test/ui/rfc-2565-param-attrs/param-attrs-builtin-attrs.rs

@@ -7,11 +7,11 @@ extern "C" {
         /// Bar
         //~^ ERROR documentation comments cannot be applied to function
         #[must_use]
-        //~^ ERROR allow, cfg, cfg_attr, deny, forbid, and warn are the only allowed built-in
+        //~^ ERROR allow, cfg, cfg_attr, deny, expect, forbid, and warn are the only allowed built-in attributes in function parameters
         /// Baz
         //~^ ERROR documentation comments cannot be applied to function
         #[no_mangle] b: i32,
-        //~^ ERROR allow, cfg, cfg_attr, deny, forbid, and warn are the only allowed built-in
+        //~^ ERROR allow, cfg, cfg_attr, deny, expect, forbid, and warn are the only allowed built-in attributes in function parameters
     );
 }
 
@@ -23,11 +23,11 @@ type FnType = fn(
     /// Bar
     //~^ ERROR documentation comments cannot be applied to function
     #[must_use]
-    //~^ ERROR allow, cfg, cfg_attr, deny, forbid, and warn are the only allowed built-in
+    //~^ ERROR allow, cfg, cfg_attr, deny, expect, forbid, and warn are the only allowed built-in attributes in function parameters
     /// Baz
     //~^ ERROR documentation comments cannot be applied to function
     #[no_mangle] b: i32,
-    //~^ ERROR allow, cfg, cfg_attr, deny, forbid, and warn are the only allowed built-in
+    //~^ ERROR allow, cfg, cfg_attr, deny, expect, forbid, and warn are the only allowed built-in attributes in function parameters
 );
 
 pub fn foo(
@@ -38,11 +38,11 @@ pub fn foo(
     /// Bar
     //~^ ERROR documentation comments cannot be applied to function
     #[must_use]
-    //~^ ERROR allow, cfg, cfg_attr, deny, forbid, and warn are the only allowed built-in
+    //~^ ERROR allow, cfg, cfg_attr, deny, expect, forbid, and warn are the only allowed built-in attributes in function parameters
     /// Baz
     //~^ ERROR documentation comments cannot be applied to function
     #[no_mangle] b: i32,
-    //~^ ERROR allow, cfg, cfg_attr, deny, forbid, and warn are the only allowed built-in
+    //~^ ERROR allow, cfg, cfg_attr, deny, expect, forbid, and warn are the only allowed built-in attributes in function parameters
 ) {}
 
 struct SelfStruct {}
@@ -58,11 +58,11 @@ impl SelfStruct {
         /// Baz
         //~^ ERROR documentation comments cannot be applied to function
         #[must_use]
-        //~^ ERROR allow, cfg, cfg_attr, deny, forbid, and warn are the only allowed built-in
+        //~^ ERROR allow, cfg, cfg_attr, deny, expect, forbid, and warn are the only allowed built-in attributes in function parameters
         /// Qux
         //~^ ERROR documentation comments cannot be applied to function
         #[no_mangle] b: i32,
-        //~^ ERROR allow, cfg, cfg_attr, deny, forbid, and warn are the only allowed built-in
+        //~^ ERROR allow, cfg, cfg_attr, deny, expect, forbid, and warn are the only allowed built-in attributes in function parameters
     ) {}
 
     fn issue_64682_associated_fn(
@@ -73,11 +73,11 @@ impl SelfStruct {
         /// Baz
         //~^ ERROR documentation comments cannot be applied to function
         #[must_use]
-        //~^ ERROR allow, cfg, cfg_attr, deny, forbid, and warn are the only allowed built-in
+        //~^ ERROR allow, cfg, cfg_attr, deny, expect, forbid, and warn are the only allowed built-in attributes in function parameters
         /// Qux
         //~^ ERROR documentation comments cannot be applied to function
         #[no_mangle] b: i32,
-        //~^ ERROR allow, cfg, cfg_attr, deny, forbid, and warn are the only allowed built-in
+        //~^ ERROR allow, cfg, cfg_attr, deny, expect, forbid, and warn are the only allowed built-in attributes in function parameters
     ) {}
 }
 
@@ -94,11 +94,11 @@ impl RefStruct {
         /// Baz
         //~^ ERROR documentation comments cannot be applied to function
         #[must_use]
-        //~^ ERROR allow, cfg, cfg_attr, deny, forbid, and warn are the only allowed built-in
+        //~^ ERROR allow, cfg, cfg_attr, deny, expect, forbid, and warn are the only allowed built-in attributes in function parameters
         /// Qux
         //~^ ERROR documentation comments cannot be applied to function
         #[no_mangle] b: i32,
-        //~^ ERROR allow, cfg, cfg_attr, deny, forbid, and warn are the only allowed built-in
+        //~^ ERROR allow, cfg, cfg_attr, deny, expect, forbid, and warn are the only allowed built-in attributes in function parameters
     ) {}
 }
 trait RefTrait {
@@ -113,11 +113,11 @@ trait RefTrait {
         /// Baz
         //~^ ERROR documentation comments cannot be applied to function
         #[must_use]
-        //~^ ERROR allow, cfg, cfg_attr, deny, forbid, and warn are the only allowed built-in
+        //~^ ERROR allow, cfg, cfg_attr, deny, expect, forbid, and warn are the only allowed built-in attributes in function parameters
         /// Qux
         //~^ ERROR documentation comments cannot be applied to function
         #[no_mangle] b: i32,
-        //~^ ERROR allow, cfg, cfg_attr, deny, forbid, and warn are the only allowed built-in
+        //~^ ERROR allow, cfg, cfg_attr, deny, expect, forbid, and warn are the only allowed built-in attributes in function parameters
     ) {}
 
     fn issue_64682_associated_fn(
@@ -128,11 +128,11 @@ trait RefTrait {
         /// Baz
         //~^ ERROR documentation comments cannot be applied to function
         #[must_use]
-        //~^ ERROR allow, cfg, cfg_attr, deny, forbid, and warn are the only allowed built-in
+        //~^ ERROR allow, cfg, cfg_attr, deny, expect, forbid, and warn are the only allowed built-in attributes in function parameters
         /// Qux
         //~^ ERROR documentation comments cannot be applied to function
         #[no_mangle] b: i32,
-        //~^ ERROR allow, cfg, cfg_attr, deny, forbid, and warn are the only allowed built-in
+        //~^ ERROR allow, cfg, cfg_attr, deny, expect, forbid, and warn are the only allowed built-in attributes in function parameters
     ) {}
 }
 
@@ -148,11 +148,11 @@ impl RefTrait for RefStruct {
         /// Baz
         //~^ ERROR documentation comments cannot be applied to function
         #[must_use]
-        //~^ ERROR allow, cfg, cfg_attr, deny, forbid, and warn are the only allowed built-in
+        //~^ ERROR allow, cfg, cfg_attr, deny, expect, forbid, and warn are the only allowed built-in attributes in function parameters
         /// Qux
         //~^ ERROR documentation comments cannot be applied to function
         #[no_mangle] b: i32,
-        //~^ ERROR allow, cfg, cfg_attr, deny, forbid, and warn are the only allowed built-in
+        //~^ ERROR allow, cfg, cfg_attr, deny, expect, forbid, and warn are the only allowed built-in attributes in function parameters
     ) {}
 }
 
@@ -165,10 +165,10 @@ fn main() {
         /// Bar
         //~^ ERROR documentation comments cannot be applied to function
         #[must_use]
-        //~^ ERROR allow, cfg, cfg_attr, deny, forbid, and warn are the only allowed built-in
+        //~^ ERROR allow, cfg, cfg_attr, deny, expect, forbid, and warn are the only allowed built-in attributes in function parameters
         /// Baz
         //~^ ERROR documentation comments cannot be applied to function
         #[no_mangle] b: i32
-        //~^ ERROR allow, cfg, cfg_attr, deny, forbid, and warn are the only allowed built-in
+        //~^ ERROR allow, cfg, cfg_attr, deny, expect, forbid, and warn are the only allowed built-in attributes in function parameters
     | {};
 }

src/test/ui/rfc-2565-param-attrs/param-attrs-builtin-attrs.stderr

@@ -70,7 +70,7 @@ error: documentation comments cannot be applied to function parameters
 LL |         /// Bar
    |         ^^^^^^^ doc comments are not allowed here
 
-error: allow, cfg, cfg_attr, deny, forbid, and warn are the only allowed built-in attributes in function parameters
+error: allow, cfg, cfg_attr, deny, expect, forbid, and warn are the only allowed built-in attributes in function parameters
   --> $DIR/param-attrs-builtin-attrs.rs:9:9
    |
 LL |         #[must_use]
@@ -82,7 +82,7 @@ error: documentation comments cannot be applied to function parameters
 LL |         /// Baz
    |         ^^^^^^^ doc comments are not allowed here
 
-error: allow, cfg, cfg_attr, deny, forbid, and warn are the only allowed built-in attributes in function parameters
+error: allow, cfg, cfg_attr, deny, expect, forbid, and warn are the only allowed built-in attributes in function parameters
   --> $DIR/param-attrs-builtin-attrs.rs:13:9
    |
 LL |         #[no_mangle] b: i32,
@@ -100,7 +100,7 @@ error: documentation comments cannot be applied to function parameters
 LL |     /// Bar
    |     ^^^^^^^ doc comments are not allowed here
 
-error: allow, cfg, cfg_attr, deny, forbid, and warn are the only allowed built-in attributes in function parameters
+error: allow, cfg, cfg_attr, deny, expect, forbid, and warn are the only allowed built-in attributes in function parameters
   --> $DIR/param-attrs-builtin-attrs.rs:25:5
    |
 LL |     #[must_use]
@@ -112,7 +112,7 @@ error: documentation comments cannot be applied to function parameters
 LL |     /// Baz
    |     ^^^^^^^ doc comments are not allowed here
 
-error: allow, cfg, cfg_attr, deny, forbid, and warn are the only allowed built-in attributes in function parameters
+error: allow, cfg, cfg_attr, deny, expect, forbid, and warn are the only allowed built-in attributes in function parameters
   --> $DIR/param-attrs-builtin-attrs.rs:29:5
    |
 LL |     #[no_mangle] b: i32,
@@ -130,7 +130,7 @@ error: documentation comments cannot be applied to function parameters
 LL |     /// Bar
    |     ^^^^^^^ doc comments are not allowed here
 
-error: allow, cfg, cfg_attr, deny, forbid, and warn are the only allowed built-in attributes in function parameters
+error: allow, cfg, cfg_attr, deny, expect, forbid, and warn are the only allowed built-in attributes in function parameters
   --> $DIR/param-attrs-builtin-attrs.rs:40:5
    |
 LL |     #[must_use]
@@ -142,7 +142,7 @@ error: documentation comments cannot be applied to function parameters
 LL |     /// Baz
    |     ^^^^^^^ doc comments are not allowed here
 
-error: allow, cfg, cfg_attr, deny, forbid, and warn are the only allowed built-in attributes in function parameters
+error: allow, cfg, cfg_attr, deny, expect, forbid, and warn are the only allowed built-in attributes in function parameters
   --> $DIR/param-attrs-builtin-attrs.rs:44:5
    |
 LL |     #[no_mangle] b: i32,
@@ -166,7 +166,7 @@ error: documentation comments cannot be applied to function parameters
 LL |         /// Baz
    |         ^^^^^^^ doc comments are not allowed here
 
-error: allow, cfg, cfg_attr, deny, forbid, and warn are the only allowed built-in attributes in function parameters
+error: allow, cfg, cfg_attr, deny, expect, forbid, and warn are the only allowed built-in attributes in function parameters
   --> $DIR/param-attrs-builtin-attrs.rs:60:9
    |
 LL |         #[must_use]
@@ -178,7 +178,7 @@ error: documentation comments cannot be applied to function parameters
 LL |         /// Qux
    |         ^^^^^^^ doc comments are not allowed here
 
-error: allow, cfg, cfg_attr, deny, forbid, and warn are the only allowed built-in attributes in function parameters
+error: allow, cfg, cfg_attr, deny, expect, forbid, and warn are the only allowed built-in attributes in function parameters
   --> $DIR/param-attrs-builtin-attrs.rs:64:9
    |
 LL |         #[no_mangle] b: i32,
@@ -196,7 +196,7 @@ error: documentation comments cannot be applied to function parameters
 LL |         /// Baz
    |         ^^^^^^^ doc comments are not allowed here
 
-error: allow, cfg, cfg_attr, deny, forbid, and warn are the only allowed built-in attributes in function parameters
+error: allow, cfg, cfg_attr, deny, expect, forbid, and warn are the only allowed built-in attributes in function parameters
   --> $DIR/param-attrs-builtin-attrs.rs:75:9
    |
 LL |         #[must_use]
@@ -208,7 +208,7 @@ error: documentation comments cannot be applied to function parameters
 LL |         /// Qux
    |         ^^^^^^^ doc comments are not allowed here
 
-error: allow, cfg, cfg_attr, deny, forbid, and warn are the only allowed built-in attributes in function parameters
+error: allow, cfg, cfg_attr, deny, expect, forbid, and warn are the only allowed built-in attributes in function parameters
   --> $DIR/param-attrs-builtin-attrs.rs:79:9
    |
 LL |         #[no_mangle] b: i32,
@@ -232,7 +232,7 @@ error: documentation comments cannot be applied to function parameters
 LL |         /// Baz
    |         ^^^^^^^ doc comments are not allowed here
 
-error: allow, cfg, cfg_attr, deny, forbid, and warn are the only allowed built-in attributes in function parameters
+error: allow, cfg, cfg_attr, deny, expect, forbid, and warn are the only allowed built-in attributes in function parameters
   --> $DIR/param-attrs-builtin-attrs.rs:96:9
    |
 LL |         #[must_use]
@@ -244,7 +244,7 @@ error: documentation comments cannot be applied to function parameters
 LL |         /// Qux
    |         ^^^^^^^ doc comments are not allowed here
 
-error: allow, cfg, cfg_attr, deny, forbid, and warn are the only allowed built-in attributes in function parameters
+error: allow, cfg, cfg_attr, deny, expect, forbid, and warn are the only allowed built-in attributes in function parameters
   --> $DIR/param-attrs-builtin-attrs.rs:100:9
    |
 LL |         #[no_mangle] b: i32,
@@ -268,7 +268,7 @@ error: documentation comments cannot be applied to function parameters
 LL |         /// Baz
    |         ^^^^^^^ doc comments are not allowed here
 
-error: allow, cfg, cfg_attr, deny, forbid, and warn are the only allowed built-in attributes in function parameters
+error: allow, cfg, cfg_attr, deny, expect, forbid, and warn are the only allowed built-in attributes in function parameters
   --> $DIR/param-attrs-builtin-attrs.rs:115:9
    |
 LL |         #[must_use]
@@ -280,7 +280,7 @@ error: documentation comments cannot be applied to function parameters
 LL |         /// Qux
    |         ^^^^^^^ doc comments are not allowed here
 
-error: allow, cfg, cfg_attr, deny, forbid, and warn are the only allowed built-in attributes in function parameters
+error: allow, cfg, cfg_attr, deny, expect, forbid, and warn are the only allowed built-in attributes in function parameters
   --> $DIR/param-attrs-builtin-attrs.rs:119:9
    |
 LL |         #[no_mangle] b: i32,
@@ -298,7 +298,7 @@ error: documentation comments cannot be applied to function parameters
 LL |         /// Baz
    |         ^^^^^^^ doc comments are not allowed here
 
-error: allow, cfg, cfg_attr, deny, forbid, and warn are the only allowed built-in attributes in function parameters
+error: allow, cfg, cfg_attr, deny, expect, forbid, and warn are the only allowed built-in attributes in function parameters
   --> $DIR/param-attrs-builtin-attrs.rs:130:9
    |
 LL |         #[must_use]
@@ -310,7 +310,7 @@ error: documentation comments cannot be applied to function parameters
 LL |         /// Qux
    |         ^^^^^^^ doc comments are not allowed here
 
-error: allow, cfg, cfg_attr, deny, forbid, and warn are the only allowed built-in attributes in function parameters
+error: allow, cfg, cfg_attr, deny, expect, forbid, and warn are the only allowed built-in attributes in function parameters
   --> $DIR/param-attrs-builtin-attrs.rs:134:9
    |
 LL |         #[no_mangle] b: i32,
@@ -334,7 +334,7 @@ error: documentation comments cannot be applied to function parameters
 LL |         /// Baz
    |         ^^^^^^^ doc comments are not allowed here
 
-error: allow, cfg, cfg_attr, deny, forbid, and warn are the only allowed built-in attributes in function parameters
+error: allow, cfg, cfg_attr, deny, expect, forbid, and warn are the only allowed built-in attributes in function parameters
   --> $DIR/param-attrs-builtin-attrs.rs:150:9
    |
 LL |         #[must_use]
@@ -346,7 +346,7 @@ error: documentation comments cannot be applied to function parameters
 LL |         /// Qux
    |         ^^^^^^^ doc comments are not allowed here
 
-error: allow, cfg, cfg_attr, deny, forbid, and warn are the only allowed built-in attributes in function parameters
+error: allow, cfg, cfg_attr, deny, expect, forbid, and warn are the only allowed built-in attributes in function parameters
   --> $DIR/param-attrs-builtin-attrs.rs:154:9
    |
 LL |         #[no_mangle] b: i32,
@@ -364,7 +364,7 @@ error: documentation comments cannot be applied to function parameters
 LL |         /// Bar
    |         ^^^^^^^ doc comments are not allowed here
 
-error: allow, cfg, cfg_attr, deny, forbid, and warn are the only allowed built-in attributes in function parameters
+error: allow, cfg, cfg_attr, deny, expect, forbid, and warn are the only allowed built-in attributes in function parameters
   --> $DIR/param-attrs-builtin-attrs.rs:167:9
    |
 LL |         #[must_use]
@@ -376,7 +376,7 @@ error: documentation comments cannot be applied to function parameters
 LL |         /// Baz
    |         ^^^^^^^ doc comments are not allowed here
 
-error: allow, cfg, cfg_attr, deny, forbid, and warn are the only allowed built-in attributes in function parameters
+error: allow, cfg, cfg_attr, deny, expect, forbid, and warn are the only allowed built-in attributes in function parameters
   --> $DIR/param-attrs-builtin-attrs.rs:171:9
    |
 LL |         #[no_mangle] b: i32

src/test/ui/rustdoc/check-doc-alias-attr-location.stderr

@@ -1,4 +1,4 @@
-error: allow, cfg, cfg_attr, deny, forbid, and warn are the only allowed built-in attributes in function parameters
+error: allow, cfg, cfg_attr, deny, expect, forbid, and warn are the only allowed built-in attributes in function parameters
   --> $DIR/check-doc-alias-attr-location.rs:22:12
    |
 LL |     fn foo(#[doc(alias = "qux")] _x: u32) -> Self::X {