fix (un)likely intrinsics

src/intrinsic.rs

@@ -245,7 +245,13 @@ pub trait EvalContextExt<'a, 'mir, 'tcx: 'a+'mir>: crate::MiriEvalContextExt<'a,
                 this.binop_ignore_overflow(mir::BinOp::Div, a, b, dest)?;
             },
 
-            "likely" | "unlikely" | "forget" => {}
+            "forget" => {}
+
+            "likely" | "unlikely" => {
+                // These just return their argument
+                let b = this.read_immediate(args[0])?;
+                this.write_immediate(*b, dest)?;
+            }
 
             "init" => {
                 // Check fast path: we don't want to force an allocation in case the destination is a simple value,

tests/run-pass/iter.rs

@@ -0,0 +1,40 @@
+fn iter_empty_and_zst() {
+    for _ in Vec::<u32>::new().iter() { // this iterates over a Unique::empty()
+        panic!("We should never be here.");
+    }
+
+    // Iterate over a ZST (uses arith_offset internally)
+    let mut count = 0;
+    for _ in &[(), (), ()] {
+        count += 1;
+    }
+    assert_eq!(count, 3);
+}
+
+fn test_iterator_step_by_nth() {
+    let mut it = (0..16).step_by(5);
+    assert_eq!(it.nth(0), Some(0));
+    assert_eq!(it.nth(0), Some(5));
+    assert_eq!(it.nth(0), Some(10));
+    assert_eq!(it.nth(0), Some(15));
+    assert_eq!(it.nth(0), None);
+}
+
+fn iter_any() {
+    let f = |x: &u8| { 10u8 == *x };
+    f(&1u8);
+
+    let g = |(), x: &u8| { 10u8 == *x };
+    g((), &1u8);
+
+    let h = |(), (), x: &u8| { 10u8 == *x };
+    h((), (), &1u8);
+
+    [1, 2, 3u8].into_iter().any(|elt| 10 == *elt);
+}
+
+fn main() {
+    test_iterator_step_by_nth();
+    iter_any();
+    iter_empty_and_zst();
+}

tests/run-pass/iter_any.rs

@@ -1,12 +0,0 @@
-pub fn main() {
-    let f = |x: &u8| { 10u8 == *x };
-    f(&1u8);
-
-    let g = |(), x: &u8| { 10u8 == *x };
-    g((), &1u8);
-
-    let h = |(), (), x: &u8| { 10u8 == *x };
-    h((), (), &1u8);
-
-    [1, 2, 3u8].into_iter().any(|elt| 10 == *elt);
-}

tests/run-pass/iter_slice.rs

@@ -1,12 +0,0 @@
-fn main() {
-    for _ in Vec::<u32>::new().iter() { // this iterates over a Unique::empty()
-        panic!("We should never be here.");
-    }
-
-    // Iterate over a ZST (uses arith_offset internally)
-    let mut count = 0;
-    for _ in &[(), (), ()] {
-        count += 1;
-    }
-    assert_eq!(count, 3);
-}