do not use 'let _', it is strange

Author: RalfJung

tests/compile-fail-fullmir/ptr_offset_overflow.rs

@@ -2,5 +2,5 @@
 fn main() {
     let v = [1i8, 2];
     let x = &v[1] as *const i8;
-    let _ = unsafe { x.offset(isize::min_value()) };
+    let _val = unsafe { x.offset(isize::min_value()) };
 }

tests/compile-fail/invalid_enum_discriminant.rs

@@ -12,5 +12,5 @@ pub enum Foo {
 
 fn main() {
     let f = unsafe { std::mem::transmute::<i32, Foo>(42) };
-    let _ = mem::discriminant(&f);
+    let _val = mem::discriminant(&f);
 }

tests/compile-fail/pointer_byte_read_1.rs

@@ -3,5 +3,5 @@ fn main() {
     let y = &x;
     let z = &y as *const &i32 as *const usize;
     let ptr_bytes = unsafe { *z }; // the actual deref is fine, because we read the entire pointer at once
-    let _ = ptr_bytes / 432; //~ ERROR invalid arithmetic on pointers that would leak base addresses
+    let _val = ptr_bytes / 432; //~ ERROR invalid arithmetic on pointers that would leak base addresses
 }

tests/compile-fail/pointer_byte_read_2.rs

@@ -3,5 +3,5 @@ fn main() {
     let y = &x;
     let z = &y as *const &i32 as *const u8;
     // the deref fails, because we are reading only a part of the pointer
-    let _ = unsafe { *z }; //~ ERROR tried to access part of a pointer value as raw bytes
+    let _val = unsafe { *z }; //~ ERROR tried to access part of a pointer value as raw bytes
 }

tests/compile-fail/ptr_bitops2.rs

@@ -1,5 +1,5 @@
 fn main() {
     let val = 13usize;
     let addr = &val as *const _ as usize;
-    let _ = addr & 13; //~ ERROR access part of a pointer value as raw bytes
+    let _val = addr & 13; //~ ERROR access part of a pointer value as raw bytes
 }

tests/compile-fail/ptr_int_cast.rs

@@ -4,5 +4,5 @@ fn main() {
     let x = x as *const i32;
     let x = x as u8; //~ ERROR a raw memory access tried to access part of a pointer value as raw bytes
     let x = x as *const i32;
-    let _ = unsafe { *x };
+    let _val = unsafe { *x };
 }

tests/compile-fail/ptr_offset_int_plus_int.rs

@@ -3,6 +3,6 @@
 fn main() {
     // Can't offset an integer pointer by non-zero offset.
     unsafe {
-        let _ = (1 as *mut u8).offset(1);
+        let _val = (1 as *mut u8).offset(1);
     }
 }

tests/compile-fail/ptr_offset_int_plus_ptr.rs

@@ -4,6 +4,6 @@ fn main() {
     let ptr = Box::into_raw(Box::new(0u32));
     // Can't start with an integer pointer and get to something usable
     unsafe {
-        let _ = (1 as *mut u8).offset(ptr as isize);
+        let _val = (1 as *mut u8).offset(ptr as isize);
     }
 }

tests/compile-fail/ptr_rem.rs

@@ -1,5 +1,5 @@
 fn main() {
     let val = 13usize;
     let addr = &val as *const _ as usize;
-    let _ = addr % 16; //~ ERROR access part of a pointer value as raw bytes
+    let _val = addr % 16; //~ ERROR access part of a pointer value as raw bytes
 }

tests/compile-fail/ptr_wrapping_offset_int_plus_ptr.rs

@@ -4,5 +4,5 @@ fn main() {
     let ptr = Box::into_raw(Box::new(0u32));
     // Can't start with an integer pointer and get to something usable
     let ptr = (1 as *mut u8).wrapping_offset(ptr as isize);
-    let _ = unsafe { *ptr };
+    let _val = unsafe { *ptr };
 }