Properly check arguments of #[rustc_must_implement_one_of]

Author: JonathanBrouwer

compiler/rustc_attr_parsing/src/attributes/rustc_internal.rs

@@ -49,7 +49,7 @@ impl<S: Stage> SingleAttributeParser<S> for RustcMustImplementOneOfParser {
 
         let mut errored = false;
         for argument in inputs {
-            let Some(meta) = argument.meta_item() else {
+            let Some(meta) = argument.meta_item_no_args() else {
                 cx.adcx().expected_identifier(argument.span());
                 return None;
             };

tests/ui/attributes/args-checked.rs

@@ -43,4 +43,12 @@ const fn g() {}
 //~^ ERROR malformed
 #[used(always(x, y, z))]
 //~^ ERROR malformed
-static H: u64 = 5;
+static H: u64 = 5;
+
+#[rustc_must_implement_one_of(eq = 5, neq)]
+//~^ ERROR malformed
+#[rustc_must_implement_one_of(eq(x, y, z), neq)]
+//~^ ERROR malformed
+trait T {
+
+}

tests/ui/attributes/args-checked.stderr

@@ -188,6 +188,24 @@ LL - #[used(always(x, y, z))]
 LL + #[used]
    |
 
+error[E0539]: malformed `rustc_must_implement_one_of` attribute input
+  --> $DIR/args-checked.rs:48:1
+   |
+LL | #[rustc_must_implement_one_of(eq = 5, neq)]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^------^^^^^^^
+   | |                             |
+   | |                             expected a valid identifier here
+   | help: must be of the form: `#[rustc_must_implement_one_of(function1, function2, ...)]`
+
+error[E0539]: malformed `rustc_must_implement_one_of` attribute input
+  --> $DIR/args-checked.rs:50:1
+   |
+LL | #[rustc_must_implement_one_of(eq(x, y, z), neq)]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^-----------^^^^^^^
+   | |                             |
+   | |                             expected a valid identifier here
+   | help: must be of the form: `#[rustc_must_implement_one_of(function1, function2, ...)]`
+
 error: valid forms for the attribute are `#[macro_export(local_inner_macros)]` and `#[macro_export]`
   --> $DIR/args-checked.rs:26:1
    |
@@ -207,7 +225,7 @@ LL | #[macro_export(local_inner_macros(x, y, z))]
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
    = note: for more information, see issue #57571 <https://github.com/rust-lang/rust/issues/57571>
 
-error: aborting due to 14 previous errors
+error: aborting due to 16 previous errors
 
 For more information about this error, try `rustc --explain E0539`.
 Future incompatibility report: Future breakage diagnostic: