Rollup merge of #142214 - Kivooeo:tf9, r=jieyouxu

`tests/ui`: A New Order [9/N]

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

Author: GuillaumeGomez

tests/ui/empty-allocation-non-null.rs renamed to tests/ui/allocator/empty-alloc-nonnull-guarantee.rs

@@ -1,3 +1,7 @@
+//! Check that the default global Rust allocator produces non-null Box allocations for ZSTs.
+//!
+//! See https://github.com/rust-lang/rust/issues/11998
+
 //@ run-pass
 
 pub fn main() {

tests/ui/diverging-fn-tail-35849.rs

@@ -0,0 +1,19 @@
+//! Test early return within binary operation expressions
+
+//@ run-pass
+
+#![allow(dead_code)]
+#![allow(unreachable_code)]
+
+use std::ops::Add;
+
+/// Function that performs addition with an early return in the right operand
+fn add_with_early_return<T: Add<Output = T> + Copy>(n: T) -> T {
+    n + { return n }
+}
+
+pub fn main() {
+    // Test with different numeric types to ensure generic behavior works
+    let _result1 = add_with_early_return(42i32);
+    let _result2 = add_with_early_return(3.14f64);
+}

tests/ui/early-ret-binop-add.rs

@@ -1,3 +1,5 @@
+//! Test that duplicate use bindings in same namespace produce error
+
 mod foo {
     pub use self::bar::X;
     use self::bar::X;

tests/ui/elide-errors-on-mismatched-tuple.rs

@@ -1,5 +1,5 @@
 error[E0252]: the name `X` is defined multiple times
-  --> $DIR/double-type-import.rs:3:9
+  --> $DIR/duplicate-use-bindings.rs:5:9
    |
 LL |     pub use self::bar::X;
    |             ------------ previous import of the type `X` here

tests/ui/elided-test.rs

@@ -0,0 +1,25 @@
+//! Regression test for issue #50333: elide irrelevant E0277 errors on tuple mismatch
+
+// Hide irrelevant E0277 errors (#50333)
+
+trait T {}
+
+struct A;
+
+impl T for A {}
+
+impl A {
+    fn new() -> Self {
+        Self {}
+    }
+}
+
+fn main() {
+    // This creates a tuple type mismatch: 2-element tuple destructured into 3 variables
+    let (a, b, c) = (A::new(), A::new());
+    //~^ ERROR mismatched types
+
+    // This line should NOT produce an E0277 error about `Sized` trait bounds,
+    // because `a`, `b`, and `c` are `TyErr` due to the mismatch above
+    let _ts: Vec<&dyn T> = vec![&a, &b, &c];
+}

tests/ui/elided-test.stderr

@@ -1,7 +1,7 @@
 error[E0308]: mismatched types
-  --> $DIR/elide-errors-on-mismatched-tuple.rs:14:9
+  --> $DIR/elide-on-tuple-mismatch.rs:19:9
    |
-LL |     let (a, b, c) = (A::new(), A::new()); // This tuple is 2 elements, should be three
+LL |     let (a, b, c) = (A::new(), A::new());
    |         ^^^^^^^^^   -------------------- this expression has type `(A, A)`
    |         |
    |         expected a tuple with 2 elements, found one with 3 elements

tests/ui/else-if.rs

@@ -1,3 +1,5 @@
+//! Test parsing of multiple references with various whitespace arrangements
+
 //@ run-pass
 
 #![allow(dead_code)]

tests/ui/expr/early-return-in-binop.rs

@@ -0,0 +1,8 @@
+//! Test that #[test] functions are elided when not running tests, causing missing main error
+
+#[test]
+fn main() {
+    // This function would normally serve as main, but since it's marked with #[test],
+    // it gets elided when not running tests
+}
+//~^ ERROR `main` function not found in crate `test_function_elided_no_main`

tests/ui/double-type-import.rs renamed to tests/ui/imports/duplicate-use-bindings.rs

@@ -0,0 +1,9 @@
+error[E0601]: `main` function not found in crate `test_function_elided_no_main`
+  --> $DIR/test-function-elided-no-main.rs:7:2
+   |
+LL | }
+   |  ^ consider adding a `main` function to `$DIR/test-function-elided-no-main.rs`
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0601`.

tests/ui/double-type-import.stderr renamed to tests/ui/imports/duplicate-use-bindings.stderr

@@ -0,0 +1,10 @@
+//! Regression test for issue #35849: transmute with panic in diverging function
+
+fn assert_sizeof() -> ! {
+    unsafe {
+        ::std::mem::transmute::<f64, [u8; 8]>(panic!())
+        //~^ ERROR mismatched types
+    }
+}
+
+fn main() {}

tests/ui/mismatched_types/elide-on-tuple-mismatch.rs

@@ -1,5 +1,5 @@
 error[E0308]: mismatched types
-  --> $DIR/diverging-fn-tail-35849.rs:3:9
+  --> $DIR/diverging-fn-transmute.rs:5:9
    |
 LL | fn assert_sizeof() -> ! {
    |                       - expected `!` because of return type