Migrate some tests away from concat-idents

`concat_idents!` is in the process of being removed, but a few things it
is used to test will still be relevant. Migrate these tests to something
other than `concat_idents`.

Author: tgross35

tests/rustdoc-js/big-result.rs

@@ -1,4 +1,3 @@
-#![feature(concat_idents)]
 #![allow(nonstandard_style)]
 /// Generate 250 items that all match the query, starting with the longest.
 /// Those long items should be dropped from the result set, and the short ones

tests/ui/issues/issue-32950.rs

@@ -1,10 +1,12 @@
-#![feature(concat_idents)]
-#![expect(deprecated)] // concat_idents is deprecated
+// Issue: #32950
+// Ensure that using macros rather than a type doesn't break `derive`.
 
 #[derive(Debug)]
-struct Baz<T>(
-    concat_idents!(Foo, Bar) //~ ERROR `derive` cannot be used on items with type macros
-                             //~^ ERROR cannot find type `FooBar` in this scope
-);
+struct Nonsense<T> {
+    //~^ ERROR type parameter `T` is never used
+    should_be_vec_t: vec![T],
+    //~^ ERROR `derive` cannot be used on items with type macros
+    //~| ERROR expected type, found `expr` metavariable
+}
 
 fn main() {}

tests/ui/issues/issue-32950.stderr

@@ -1,15 +1,30 @@
 error: `derive` cannot be used on items with type macros
-  --> $DIR/issue-32950.rs:6:5
+  --> $DIR/nonsense-input-to-debug.rs:7:22
    |
-LL |     concat_idents!(Foo, Bar)
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^
+LL |     should_be_vec_t: vec![T],
+   |                      ^^^^^^^
 
-error[E0412]: cannot find type `FooBar` in this scope
-  --> $DIR/issue-32950.rs:6:5
+error: expected type, found `expr` metavariable
+  --> $DIR/nonsense-input-to-debug.rs:7:22
    |
-LL |     concat_idents!(Foo, Bar)
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^ not found in this scope
+LL |     should_be_vec_t: vec![T],
+   |                      ^^^^^^^
+   |                      |
+   |                      expected type
+   |                      in this macro invocation
+   |                      this macro call doesn't expand to a type
+   |
+   = note: this error originates in the macro `vec` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error[E0392]: type parameter `T` is never used
+  --> $DIR/nonsense-input-to-debug.rs:5:17
+   |
+LL | struct Nonsense<T> {
+   |                 ^ unused type parameter
+   |
+   = help: consider removing `T`, referring to it in a field, or using a marker such as `PhantomData`
+   = help: if you intended `T` to be a const parameter, use `const T: /* Type */` instead
 
-error: aborting due to 2 previous errors
+error: aborting due to 3 previous errors
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0392`.

tests/ui/issues/issue-50403.rs

@@ -1,6 +1,12 @@
-#![feature(concat_idents)]
-#![expect(deprecated)] // concat_idents is deprecated
+// Issue 50403
+// Ensure that `concat` can't create empty identifiers
+// FIXME(macro_metavar_expr_concat): this error message could be improved
+
+macro_rules! empty {
+    () => { ${concat()} } //~ ERROR expected identifier or string literal
+                          //~^ERROR expected expression
+}
 
 fn main() {
-    let x = concat_idents!(); //~ ERROR `concat_idents!()` takes 1 or more arguments
+    let x = empty!();
 }

tests/ui/issues/issue-50403.stderr

@@ -1,8 +1,19 @@
-error: `concat_idents!()` takes 1 or more arguments
-  --> $DIR/issue-50403.rs:5:13
+error: expected identifier or string literal
+  --> $DIR/empty-input.rs:6:14
    |
-LL |     let x = concat_idents!();
-   |             ^^^^^^^^^^^^^^^^
+LL |     () => { ${concat()} }
+   |              ^^^^^^^^^^
 
-error: aborting due to 1 previous error
+error: expected expression, found `$`
+  --> $DIR/empty-input.rs:6:13
+   |
+LL |     () => { ${concat()} }
+   |             ^ expected expression
+...
+LL |     let x = empty!();
+   |             -------- in this macro invocation
+   |
+   = note: this error originates in the macro `empty` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: aborting due to 2 previous errors
 

tests/ui/unpretty/exhaustive.expanded.stdout

@@ -12,7 +12,6 @@
 #![feature(auto_traits)]
 #![feature(box_patterns)]
 #![feature(builtin_syntax)]
-#![feature(concat_idents)]
 #![feature(const_trait_impl)]
 #![feature(decl_macro)]
 #![feature(deref_patterns)]
@@ -309,7 +308,6 @@ mod expressions {
 
 
 
-        // concat_idents is deprecated
 
 
 
@@ -622,8 +620,12 @@ mod types {
         /*! there is no syntax for this */
     }
     /// TyKind::MacCall
-    #[expect(deprecated)]
-    fn ty_mac_call() { let _: T; let _: T; let _: T; }
+    fn ty_mac_call() {
+        macro_rules! ty { ($ty:ty) => { $ty } }
+        let _: T;
+        let _: T;
+        let _: T;
+    }
     /// TyKind::CVarArgs
     fn ty_c_var_args() {
         /*! FIXME: todo */

tests/ui/unpretty/exhaustive.hir.stderr

@@ -1,17 +1,17 @@
 error[E0697]: closures cannot be static
-  --> $DIR/exhaustive.rs:211:9
+  --> $DIR/exhaustive.rs:210:9
    |
 LL |         static || value;
    |         ^^^^^^^^^
 
 error[E0697]: closures cannot be static
-  --> $DIR/exhaustive.rs:212:9
+  --> $DIR/exhaustive.rs:211:9
    |
 LL |         static move || value;
    |         ^^^^^^^^^^^^^^
 
 error[E0728]: `await` is only allowed inside `async` functions and blocks
-  --> $DIR/exhaustive.rs:241:13
+  --> $DIR/exhaustive.rs:240:13
    |
 LL |     fn expr_await() {
    |     --------------- this is not `async`
@@ -20,19 +20,19 @@ LL |         fut.await;
    |             ^^^^^ only allowed inside `async` functions and blocks
 
 error: in expressions, `_` can only be used on the left-hand side of an assignment
-  --> $DIR/exhaustive.rs:290:9
+  --> $DIR/exhaustive.rs:289:9
    |
 LL |         _;
    |         ^ `_` not allowed here
 
 error[E0214]: parenthesized type parameters may only be used with a `Fn` trait
-  --> $DIR/exhaustive.rs:300:9
+  --> $DIR/exhaustive.rs:299:9
    |
 LL |         x::();
    |         ^^^^^ only `Fn` traits may use parentheses
 
 error[E0214]: parenthesized type parameters may only be used with a `Fn` trait
-  --> $DIR/exhaustive.rs:301:9
+  --> $DIR/exhaustive.rs:300:9
    |
 LL |         x::(T, T) -> T;
    |         ^^^^^^^^^^^^^^ only `Fn` traits may use parentheses
@@ -44,31 +44,31 @@ LL +         x::<T, T> -> T;
    |
 
 error[E0214]: parenthesized type parameters may only be used with a `Fn` trait
-  --> $DIR/exhaustive.rs:302:9
+  --> $DIR/exhaustive.rs:301:9
    |
 LL |         crate::() -> ()::expressions::() -> ()::expr_path;
    |         ^^^^^^^^^^^^^^^ only `Fn` traits may use parentheses
 
 error[E0214]: parenthesized type parameters may only be used with a `Fn` trait
-  --> $DIR/exhaustive.rs:302:26
+  --> $DIR/exhaustive.rs:301:26
    |
 LL |         crate::() -> ()::expressions::() -> ()::expr_path;
    |                          ^^^^^^^^^^^^^^^^^^^^^ only `Fn` traits may use parentheses
 
 error[E0214]: parenthesized type parameters may only be used with a `Fn` trait
-  --> $DIR/exhaustive.rs:305:9
+  --> $DIR/exhaustive.rs:304:9
    |
 LL |         core::()::marker::()::PhantomData;
    |         ^^^^^^^^ only `Fn` traits may use parentheses
 
 error[E0214]: parenthesized type parameters may only be used with a `Fn` trait
-  --> $DIR/exhaustive.rs:305:19
+  --> $DIR/exhaustive.rs:304:19
    |
 LL |         core::()::marker::()::PhantomData;
    |                   ^^^^^^^^^^ only `Fn` traits may use parentheses
 
 error: `yield` can only be used in `#[coroutine]` closures, or `gen` blocks
-  --> $DIR/exhaustive.rs:392:9
+  --> $DIR/exhaustive.rs:391:9
    |
 LL |         yield;
    |         ^^^^^
@@ -79,29 +79,29 @@ LL |     #[coroutine] fn expr_yield() {
    |     ++++++++++++
 
 error[E0703]: invalid ABI: found `C++`
-  --> $DIR/exhaustive.rs:472:23
+  --> $DIR/exhaustive.rs:471:23
    |
 LL |         unsafe extern "C++" {}
    |                       ^^^^^ invalid ABI
    |
    = note: invoke `rustc --print=calling-conventions` for a full list of supported calling conventions
 
 error: `..` patterns are not allowed here
-  --> $DIR/exhaustive.rs:679:13
+  --> $DIR/exhaustive.rs:678:13
    |
 LL |         let ..;
    |             ^^
    |
    = note: only allowed in tuple, tuple struct, and slice patterns
 
 error[E0214]: parenthesized type parameters may only be used with a `Fn` trait
-  --> $DIR/exhaustive.rs:794:16
+  --> $DIR/exhaustive.rs:793:16
    |
 LL |         let _: T() -> !;
    |                ^^^^^^^^ only `Fn` traits may use parentheses
 
 error[E0562]: `impl Trait` is not allowed in the type of variable bindings
-  --> $DIR/exhaustive.rs:809:16
+  --> $DIR/exhaustive.rs:808:16
    |
 LL |         let _: impl Send;
    |                ^^^^^^^^^
@@ -112,7 +112,7 @@ LL |         let _: impl Send;
    = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
 
 error[E0562]: `impl Trait` is not allowed in the type of variable bindings
-  --> $DIR/exhaustive.rs:810:16
+  --> $DIR/exhaustive.rs:809:16
    |
 LL |         let _: impl Send + 'static;
    |                ^^^^^^^^^^^^^^^^^^^
@@ -123,7 +123,7 @@ LL |         let _: impl Send + 'static;
    = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
 
 error[E0562]: `impl Trait` is not allowed in the type of variable bindings
-  --> $DIR/exhaustive.rs:811:16
+  --> $DIR/exhaustive.rs:810:16
    |
 LL |         let _: impl 'static + Send;
    |                ^^^^^^^^^^^^^^^^^^^
@@ -134,7 +134,7 @@ LL |         let _: impl 'static + Send;
    = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
 
 error[E0562]: `impl Trait` is not allowed in the type of variable bindings
-  --> $DIR/exhaustive.rs:812:16
+  --> $DIR/exhaustive.rs:811:16
    |
 LL |         let _: impl ?Sized;
    |                ^^^^^^^^^^^
@@ -145,7 +145,7 @@ LL |         let _: impl ?Sized;
    = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
 
 error[E0562]: `impl Trait` is not allowed in the type of variable bindings
-  --> $DIR/exhaustive.rs:813:16
+  --> $DIR/exhaustive.rs:812:16
    |
 LL |         let _: impl ~const Clone;
    |                ^^^^^^^^^^^^^^^^^
@@ -156,7 +156,7 @@ LL |         let _: impl ~const Clone;
    = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
 
 error[E0562]: `impl Trait` is not allowed in the type of variable bindings
-  --> $DIR/exhaustive.rs:814:16
+  --> $DIR/exhaustive.rs:813:16
    |
 LL |         let _: impl for<'a> Send;
    |                ^^^^^^^^^^^^^^^^^

tests/ui/unpretty/exhaustive.hir.stdout

@@ -11,7 +11,6 @@
 #![feature(auto_traits)]
 #![feature(box_patterns)]
 #![feature(builtin_syntax)]
-#![feature(concat_idents)]
 #![feature(const_trait_impl)]
 #![feature(decl_macro)]
 #![feature(deref_patterns)]
@@ -349,7 +348,6 @@ mod expressions {
 
 
 
-        // concat_idents is deprecated
 
 
 
@@ -696,8 +694,12 @@ mod types {
     /*! there is no syntax for this */
     fn ty_implicit_self() { }
     /// TyKind::MacCall
-    #[expect(deprecated)]
-    fn ty_mac_call() { let _: T; let _: T; let _: T; }
+    fn ty_mac_call() {
+        macro_rules! ty { ($ty:ty) => { $ty } }
+        let _: T;
+        let _: T;
+        let _: T;
+    }
     /// TyKind::CVarArgs
     /*! FIXME: todo */
     fn ty_c_var_args() { }

tests/ui/unpretty/exhaustive.rs

@@ -11,7 +11,6 @@
 #![feature(auto_traits)]
 #![feature(box_patterns)]
 #![feature(builtin_syntax)]
-#![feature(concat_idents)]
 #![feature(const_trait_impl)]
 #![feature(decl_macro)]
 #![feature(deref_patterns)]
@@ -835,11 +834,13 @@ mod types {
     }
 
     /// TyKind::MacCall
-    #[expect(deprecated)] // concat_idents is deprecated
     fn ty_mac_call() {
-        let _: concat_idents!(T);
-        let _: concat_idents![T];
-        let _: concat_idents! { T };
+        macro_rules! ty {
+            ($ty:ty) => { $ty }
+        }
+        let _: ty!(T);
+        let _: ty![T];
+        let _: ty! { T };
     }
 
     /// TyKind::CVarArgs