add tests

Author: bend-n

tests/ui/consts/const-eval/raw-bytes.rs

@@ -2,7 +2,7 @@
 //@ ignore-endian-big
 // ignore-tidy-linelength
 //@ normalize-stderr: "╾─*ALLOC[0-9]+(\+[a-z0-9]+)?(<imm>)?─*╼" -> "╾ALLOC_ID$1╼"
-#![allow(invalid_value)]
+#![allow(invalid_value, redundant_transmutation)]
 #![feature(never_type, rustc_attrs, ptr_metadata, slice_from_ptr_range, const_slice_from_ptr_range)]
 
 use std::mem;

tests/ui/consts/const-eval/ub-enum.rs

@@ -3,7 +3,7 @@
 //@ normalize-stderr: "([0-9a-f][0-9a-f] |╾─*ALLOC[0-9]+(\+[a-z0-9]+)?(<imm>)?─*╼ )+ *│.*" -> "HEX_DUMP"
 //@ normalize-stderr: "0x0+" -> "0x0"
 #![feature(never_type)]
-#![allow(invalid_value)]
+#![allow(invalid_value, redundant_transmutation)]
 
 use std::mem;
 

tests/ui/issues/issue-25746-bool-transmute.rs

@@ -1,4 +1,5 @@
 //@ run-pass
+#![allow(redundant_transmutation)]
 use std::mem::transmute;
 
 fn main() {

tests/ui/transmute/redundant-transmutation.fixed

@@ -0,0 +1,27 @@
+//@ run-rustfix
+#![deny(redundant_transmutation)]
+#![feature(integer_sign_cast)]
+#![allow(unused_unsafe, unused_imports)]
+use std::mem::transmute;
+
+pub fn bytes_at_home(x: u32) -> [u8; 4] {
+    unsafe { u32::to_ne_bytes(x) }
+    //~^ ERROR
+}
+
+pub fn from_ne_bytes(x: [u8; 2]) -> u16 {
+    unsafe { u16::from_ne_bytes(x) }
+    //~^ ERROR
+}
+
+pub fn cast_unsigned(x: i16) -> u16 {
+    unsafe { i16::cast_unsigned(x) }
+    //~^ ERROR
+}
+
+pub fn to_u32(x: char) -> u32 {
+    unsafe { (x) as u32 }
+    //~^ ERROR
+}
+
+fn main() {}

tests/ui/transmute/redundant-transmutation.rs

@@ -0,0 +1,27 @@
+//@ run-rustfix
+#![deny(redundant_transmutation)]
+#![feature(integer_sign_cast)]
+#![allow(unused_unsafe, unused_imports)]
+use std::mem::transmute;
+
+pub fn bytes_at_home(x: u32) -> [u8; 4] {
+    unsafe { transmute(x) }
+    //~^ ERROR
+}
+
+pub fn from_ne_bytes(x: [u8; 2]) -> u16 {
+    unsafe { transmute(x) }
+    //~^ ERROR
+}
+
+pub fn cast_unsigned(x: i16) -> u16 {
+    unsafe { transmute(x) }
+    //~^ ERROR
+}
+
+pub fn to_u32(x: char) -> u32 {
+    unsafe { transmute(x) }
+    //~^ ERROR
+}
+
+fn main() {}

tests/ui/transmute/redundant-transmutation.stderr

@@ -0,0 +1,35 @@
+error: this transmute could be performed safely
+  --> $DIR/redundant-transmutation.rs:8:14
+   |
+LL |     unsafe { transmute(x) }
+   |              ^^^^^^^^^^^^ help: replace `transmute`: `u32::to_ne_bytes(x)`
+   |
+   = help: there's also `to_le_bytes` and `to_ne_bytes` if you expect a particular byte order
+note: the lint level is defined here
+  --> $DIR/redundant-transmutation.rs:2:9
+   |
+LL | #![deny(redundant_transmutation)]
+   |         ^^^^^^^^^^^^^^^^^^^^^^^
+
+error: this transmute could be performed safely
+  --> $DIR/redundant-transmutation.rs:13:14
+   |
+LL |     unsafe { transmute(x) }
+   |              ^^^^^^^^^^^^ help: replace `transmute`: `u16::from_ne_bytes(x)`
+   |
+   = help: there's also `from_le_bytes` and `from_ne_bytes` if you expect a particular byte order
+
+error: this transmute could be performed safely
+  --> $DIR/redundant-transmutation.rs:18:14
+   |
+LL |     unsafe { transmute(x) }
+   |              ^^^^^^^^^^^^ help: replace `transmute`: `i16::cast_unsigned(x)`
+
+error: this transmute could be performed safely
+  --> $DIR/redundant-transmutation.rs:23:14
+   |
+LL |     unsafe { transmute(x) }
+   |              ^^^^^^^^^^^^ help: replace `transmute`: `(x) as u32`
+
+error: aborting due to 4 previous errors
+