Auto merge of #15268 - HKalbasi:mir, r=HKalbasi

Add write_bytes and ctlz intrinsics

crates/hir-ty/src/consteval/tests.rs

@@ -1725,6 +1725,18 @@ fn function_pointer() {
         "#,
         5,
     );
+    check_number(
+        r#"
+    fn add2(x: u8) -> u8 {
+        x + 2
+    }
+    const GOAL: u8 = {
+        let plus2 = add2 as fn(u8) -> u8;
+        plus2(3)
+    };
+        "#,
+        5,
+    );
     check_number(
         r#"
     //- minicore: coerce_unsized, index, slice

crates/hir-ty/src/consteval/tests/intrinsics.rs

@@ -510,6 +510,24 @@ fn copy_nonoverlapping() {
     );
 }
 
+#[test]
+fn write_bytes() {
+    check_number(
+        r#"
+        extern "rust-intrinsic" {
+            fn write_bytes<T>(dst: *mut T, val: u8, count: usize);
+        }
+
+        const GOAL: i32 = unsafe {
+            let mut x = 2;
+            write_bytes(&mut x, 5, 1);
+            x
+        };
+        "#,
+        0x05050505,
+    );
+}
+
 #[test]
 fn copy() {
     check_number(
@@ -545,6 +563,20 @@ fn ctpop() {
     );
 }
 
+#[test]
+fn ctlz() {
+    check_number(
+        r#"
+        extern "rust-intrinsic" {
+            pub fn ctlz<T: Copy>(x: T) -> T;
+        }
+
+        const GOAL: u8 = ctlz(0b0001_1100_u8);
+        "#,
+        3,
+    );
+}
+
 #[test]
 fn cttz() {
     check_number(