Rollup merge of #143210 - Kivooeo:tf19, r=tgross35

`tests/ui`: A New Order [19/N]

> [!NOTE]
>
> Intermediate commits are intended to help review, but will be squashed prior to merge.

Some `tests/ui/` housekeeping, to trim down number of tests directly under `tests/ui/`. Part of #133895.

r? `@tgross35`

Author: GuillaumeGomez

tests/ui/closures/basic-closure-syntax.rs

@@ -0,0 +1,35 @@
+//! Test basic closure syntax and usage with generic functions.
+//!
+//! This test checks that closure syntax works correctly for:
+//! - Closures with parameters and return values
+//! - Closures without parameters (both expression and block forms)
+//! - Integration with generic functions and FnOnce trait bounds
+
+//@ run-pass
+
+fn f<F>(i: isize, f: F) -> isize
+where
+    F: FnOnce(isize) -> isize,
+{
+    f(i)
+}
+
+fn g<G>(_g: G)
+where
+    G: FnOnce(),
+{
+}
+
+pub fn main() {
+    // Closure with parameter that returns the same value
+    assert_eq!(f(10, |a| a), 10);
+
+    // Closure without parameters - expression form
+    g(|| ());
+
+    // Test closure reuse in generic context
+    assert_eq!(f(10, |a| a), 10);
+
+    // Closure without parameters - block form
+    g(|| {});
+}

tests/ui/generics/newtype-with-generics.rs

@@ -0,0 +1,32 @@
+//! Test newtype pattern with generic parameters.
+
+//@ run-pass
+
+#[derive(Clone)]
+struct MyVec<T>(Vec<T>);
+
+fn extract_inner_vec<T: Clone>(wrapper: MyVec<T>) -> Vec<T> {
+    let MyVec(inner_vec) = wrapper;
+    inner_vec.clone()
+}
+
+fn get_first_element<T>(wrapper: MyVec<T>) -> T {
+    let MyVec(inner_vec) = wrapper;
+    inner_vec.into_iter().next().unwrap()
+}
+
+pub fn main() {
+    let my_vec = MyVec(vec![1, 2, 3]);
+    let cloned_vec = my_vec.clone();
+
+    // Test extracting inner vector
+    let extracted = extract_inner_vec(cloned_vec);
+    assert_eq!(extracted[1], 2);
+
+    // Test getting first element
+    assert_eq!(get_first_element(my_vec.clone()), 1);
+
+    // Test direct destructuring
+    let MyVec(inner) = my_vec;
+    assert_eq!(inner[2], 3);
+}

tests/ui/new-impl-syntax.rs renamed to tests/ui/impl-trait/basic-trait-impl.rs

@@ -1,10 +1,12 @@
+//! Test basic trait implementation syntax for both simple and generic types.
+
 //@ run-pass
 
 use std::fmt;
 
 struct Thingy {
     x: isize,
-    y: isize
+    y: isize,
 }
 
 impl fmt::Debug for Thingy {
@@ -14,10 +16,10 @@ impl fmt::Debug for Thingy {
 }
 
 struct PolymorphicThingy<T> {
-    x: T
+    x: T,
 }
 
-impl<T:fmt::Debug> fmt::Debug for PolymorphicThingy<T> {
+impl<T: fmt::Debug> fmt::Debug for PolymorphicThingy<T> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         write!(f, "{:?}", self.x)
     }

tests/ui/new-import-syntax.rs

@@ -1,6 +1,12 @@
+//! Test ES6-style Unicode escape sequences in string literals.
+//!
+//! Regression test for RFC 446 implementation.
+//! See <https://github.com/rust-lang/rust/pull/19480>.
+
 //@ run-pass
 
 pub fn main() {
+    // Basic Unicode escape - snowman character
     let s = "\u{2603}";
     assert_eq!(s, "☃");
 

tests/ui/new-style-constants.rs

@@ -0,0 +1,25 @@
+//! Test basic newtype pattern functionality.
+
+//@ run-pass
+
+#[derive(Copy, Clone)]
+struct Counter(CounterData);
+
+#[derive(Copy, Clone)]
+struct CounterData {
+    compute: fn(Counter) -> isize,
+    val: isize,
+}
+
+fn compute_value(counter: Counter) -> isize {
+    let Counter(data) = counter;
+    data.val + 20
+}
+
+pub fn main() {
+    let my_counter = Counter(CounterData { compute: compute_value, val: 30 });
+
+    // Test destructuring and function pointer call
+    let Counter(data) = my_counter;
+    assert_eq!((data.compute)(my_counter), 50);
+}

tests/ui/newlambdas.rs

@@ -0,0 +1,22 @@
+//! Test that enums inherit Send/!Send properties from their variants.
+//!
+//! Uses the unstable `negative_impls` feature to explicitly opt-out of Send.
+
+#![feature(negative_impls)]
+
+use std::marker::Send;
+
+struct NoSend;
+impl !Send for NoSend {}
+
+enum Container {
+    WithNoSend(NoSend),
+}
+
+fn requires_send<T: Send>(_: T) {}
+
+fn main() {
+    let container = Container::WithNoSend(NoSend);
+    requires_send(container);
+    //~^ ERROR `NoSend` cannot be sent between threads safely
+}