Auto merge of #88316 - est31:remove_box_tests, r=Mark-Simulacrum

Remove most box syntax uses from the testsuite except for src/test/ui/issues

Removes most box syntax uses from the testsuite outside of the src/test/ui/issues directory. The goal was to only change tests where box syntax is an implementation detail instead of the actual feature being tested. So some tests were left out, like the regression test for #87935, or tests where the obtained error message changed significantly.

Mostly this replaces box syntax with `Box::new`, but there are some minor drive by improvements, like formatting improvements or `assert_eq` instead of `assert!( == )`.

Prior PR that removed box syntax from the compiler and tools: #87781

Author: bors

src/test/debuginfo/borrowed-struct.rs

@@ -63,7 +63,6 @@
 // lldbr-check:(f64) *unique_val_interior_ref_2 = 26.5
 
 #![allow(unused_variables)]
-#![feature(box_syntax)]
 #![feature(omit_gdb_pretty_printer_section)]
 #![omit_gdb_pretty_printer_section]
 
@@ -79,7 +78,7 @@ fn main() {
     let stack_val_interior_ref_2: &f64 = &stack_val.y;
     let ref_to_unnamed: &SomeStruct = &SomeStruct { x: 11, y: 24.5 };
 
-    let unique_val: Box<_> = box SomeStruct { x: 13, y: 26.5 };
+    let unique_val: Box<_> = Box::new(SomeStruct { x: 13, y: 26.5 });
     let unique_val_ref: &SomeStruct = &*unique_val;
     let unique_val_interior_ref_1: &isize = &unique_val.x;
     let unique_val_interior_ref_2: &f64 = &unique_val.y;

src/test/debuginfo/borrowed-tuple.rs

@@ -37,7 +37,6 @@
 
 
 #![allow(unused_variables)]
-#![feature(box_syntax)]
 #![feature(omit_gdb_pretty_printer_section)]
 #![omit_gdb_pretty_printer_section]
 
@@ -46,7 +45,7 @@ fn main() {
     let stack_val_ref: &(i16, f32) = &stack_val;
     let ref_to_unnamed: &(i16, f32) = &(-15, -20f32);
 
-    let unique_val: Box<(i16, f32)> = box (-17, -22f32);
+    let unique_val: Box<(i16, f32)> = Box::new((-17, -22f32));
     let unique_val_ref: &(i16, f32) = &*unique_val;
 
     zzz(); // #break