add tests for niches in pointers

tests/ui/enum-discriminant/ptr_niche.rs

@@ -0,0 +1,38 @@
+//@ run-pass
+//! Check that we can codegen setting and getting discriminants, including non-null niches,
+//! for enums with a pointer-like ABI. This used to crash llvm.
+
+#![feature(rustc_attrs)]
+use std::{ptr, mem};
+
+
+#[rustc_layout_scalar_valid_range_start(1)]
+#[rustc_layout_scalar_valid_range_end(100)]
+#[derive(Copy, Clone)]
+struct PointerWithRange(#[allow(dead_code)] *const u8);
+
+
+fn main() {
+    let val = unsafe { PointerWithRange(ptr::without_provenance(90)) };
+
+    let ptr = Some(val);
+    assert!(ptr.is_some());
+    let raw = unsafe { mem::transmute::<_, usize>(ptr) };
+    assert_eq!(raw, 90);
+
+    let ptr = Some(Some(val));
+    assert!(ptr.is_some());
+    assert!(ptr.unwrap().is_some());
+    let raw = unsafe { mem::transmute::<_, usize>(ptr) };
+    assert_eq!(raw, 90);
+
+    let ptr: Option<PointerWithRange> = None;
+    assert!(ptr.is_none());
+    let raw = unsafe { mem::transmute::<_, usize>(ptr) };
+    assert!(!(1..=100).contains(&raw));
+
+    let ptr: Option<Option<PointerWithRange>> = None;
+    assert!(ptr.is_none());
+    let raw = unsafe { mem::transmute::<_, usize>(ptr) };
+    assert!(!(1..=100).contains(&raw));
+}

tests/ui/structs-enums/type-sizes.rs

@@ -5,6 +5,7 @@
 #![allow(dead_code)]
 #![feature(never_type)]
 #![feature(pointer_is_aligned_to)]
+#![feature(rustc_attrs)]
 
 use std::mem::size_of;
 use std::num::NonZero;
@@ -237,6 +238,10 @@ struct VecDummy {
     len: usize,
 }
 
+#[rustc_layout_scalar_valid_range_start(1)]
+#[rustc_layout_scalar_valid_range_end(100)]
+struct PointerWithRange(#[allow(dead_code)] *const u8);
+
 pub fn main() {
     assert_eq!(size_of::<u8>(), 1 as usize);
     assert_eq!(size_of::<u32>(), 4 as usize);
@@ -354,4 +359,6 @@ pub fn main() {
     assert!(ptr::from_ref(&v.a).addr() > ptr::from_ref(&v.b).addr());
 
 
+    assert_eq!(size_of::<Option<PointerWithRange>>(), size_of::<PointerWithRange>());
+    assert_eq!(size_of::<Option<Option<PointerWithRange>>>(), size_of::<PointerWithRange>());
 }