Add ui tests for slice::from_{ptr_range,raw_parts}

Author: WaffleLapkin

src/test/ui/const-ptr/allowed_slices.rs

@@ -0,0 +1,106 @@
+// run-pass
+#![feature(
+    const_slice_from_raw_parts,
+    slice_from_ptr_range,
+    slice_from_ptr_range_const,
+    pointer_byte_offsets,
+    const_pointer_byte_offsets
+)]
+use std::{
+    mem::MaybeUninit,
+    ptr,
+    slice::{from_ptr_range, from_raw_parts},
+};
+
+// Dangling is ok, as long as it's either for ZST reads or for no reads
+pub static S0: &[u32] = unsafe { from_raw_parts(dangling(), 0) };
+pub static S1: &[()] = unsafe { from_raw_parts(dangling(), 3) };
+
+// References are always valid of reads of a single element (basically `slice::from_ref`)
+pub static S2: &[u32] = unsafe { from_raw_parts(&D0, 1) };
+pub static S3: &[MaybeUninit<&u32>] = unsafe { from_raw_parts(&D1, 1) };
+
+// Reinterpreting data is fine, as long as layouts match
+pub static S4: &[u8] = unsafe { from_raw_parts((&D0) as *const _ as _, 3) };
+// This is only valid because D1 has uninitialized bytes, if it was an initialized pointer,
+// that would reinterpret pointers as integers which is UB in CTFE.
+pub static S5: &[MaybeUninit<u8>] = unsafe { from_raw_parts((&D1) as *const _ as _, 2) };
+// Even though u32 and [bool; 4] have different layouts, D0 has a value that
+// is valid as [bool; 4], so this is not UB (it's basically a transmute)
+pub static S6: &[bool] = unsafe { from_raw_parts((&D0) as *const _ as _, 4) };
+
+// Structs are considered single allocated objects,
+// as long as you don't reinterpret padding as initialized
+// data everything is ok.
+pub static S7: &[u16] = unsafe {
+    let ptr = (&D2 as *const Struct as *const u16).byte_add(4);
+
+    from_raw_parts(ptr, 3)
+};
+pub static S8: &[MaybeUninit<u16>] = unsafe {
+    let ptr = &D2 as *const Struct as *const MaybeUninit<u16>;
+
+    from_raw_parts(ptr, 6)
+};
+
+pub static R0: &[u32] = unsafe { from_ptr_range(dangling()..dangling()) };
+// from_ptr_range panics on zst
+//pub static R1: &[()] = unsafe { from_ptr_range(dangling(), dangling().byte_add(3)) };
+pub static R2: &[u32] = unsafe {
+    let ptr = &D0 as *const u32;
+    from_ptr_range(ptr..ptr.add(1))
+};
+pub static R3: &[MaybeUninit<&u32>] = unsafe {
+    let ptr = &D1 as *const MaybeUninit<&u32>;
+    from_ptr_range(ptr..ptr.add(1))
+};
+pub static R4: &[u8] = unsafe {
+    let ptr = &D0 as *const u32 as *const u8;
+    from_ptr_range(ptr..ptr.add(3))
+};
+pub static R5: &[MaybeUninit<u8>] = unsafe {
+    let ptr = &D1 as *const MaybeUninit<&u32> as *const MaybeUninit<u8>;
+    from_ptr_range(ptr..ptr.add(2))
+};
+pub static R6: &[bool] = unsafe {
+    let ptr = &D0 as *const u32 as *const bool;
+    from_ptr_range(ptr..ptr.add(4))
+};
+pub static R7: &[u16] = unsafe {
+    let d2 = &D2;
+    let l = &d2.b as *const u32 as *const u16;
+    let r = &d2.d as *const u8 as *const u16;
+
+    from_ptr_range(l..r)
+};
+pub static R8: &[MaybeUninit<u16>] = unsafe {
+    let d2 = &D2;
+    let l = d2 as *const Struct as *const MaybeUninit<u16>;
+    let r = &d2.d as *const u8 as *const MaybeUninit<u16>;
+
+    from_ptr_range(l..r)
+};
+
+// Using valid slice is always valid
+pub static R9: &[u32] = unsafe { from_ptr_range(R0.as_ptr_range()) };
+pub static R10: &[u32] = unsafe { from_ptr_range(R2.as_ptr_range()) };
+
+const D0: u32 = (1 << 16) | 1;
+const D1: MaybeUninit<&u32> = MaybeUninit::uninit();
+const D2: Struct = Struct { a: 1, b: 2, c: 3, d: 4 };
+
+const fn dangling<T>() -> *const T {
+    ptr::NonNull::dangling().as_ptr() as _
+}
+
+#[repr(C)]
+struct Struct {
+    a: u8,
+    // _pad: [MaybeUninit<u8>; 3]
+    b: u32,
+    c: u16,
+    d: u8,
+    // _pad: [MaybeUninit<u8>; 1]
+}
+
+fn main() {}

src/test/ui/const-ptr/forbidden_slices.rs

@@ -0,0 +1,95 @@
+#![feature(
+    const_slice_from_raw_parts,
+    slice_from_ptr_range,
+    slice_from_ptr_range_const,
+    pointer_byte_offsets,
+    const_pointer_byte_offsets
+)]
+use std::{
+    mem::{size_of, MaybeUninit},
+    ptr,
+    slice::{from_ptr_range, from_raw_parts},
+};
+
+// Null is never valid for reads
+pub static S0: &[u32] = unsafe { from_raw_parts(ptr::null(), 0) };
+pub static S1: &[()] = unsafe { from_raw_parts(ptr::null(), 0) };
+
+// Out of bounds
+pub static S2: &[u32] = unsafe { from_raw_parts(&D0, 2) };
+
+// Reading uninitialized  data
+pub static S4: &[u8] = unsafe { from_raw_parts((&D1) as *const _ as _, 1) }; //~ ERROR: it is undefined behavior to use this value
+// Reinterpret pointers as integers (UB in CTFE.)
+pub static S5: &[u8] = unsafe { from_raw_parts((&D3) as *const _ as _, size_of::<&u32>()) }; //~ ERROR: it is undefined behavior to use this value
+// Layout mismatch
+pub static S6: &[bool] = unsafe { from_raw_parts((&D0) as *const _ as _, 4) }; //~ ERROR: it is undefined behavior to use this value
+
+// Reading padding is not ok
+pub static S7: &[u16] = unsafe {
+    //~^ ERROR: it is undefined behavior to use this value
+    let ptr = (&D2 as *const Struct as *const u16).byte_add(1);
+
+    from_raw_parts(ptr, 4)
+};
+
+// Unaligned read
+pub static S8: &[u64] = unsafe {
+    let ptr = (&D4 as *const [u32; 2] as *const u32).byte_add(1).cast::<u64>();
+
+    from_raw_parts(ptr, 1)
+};
+
+pub static R0: &[u32] = unsafe { from_ptr_range(ptr::null()..ptr::null()) };
+pub static R1: &[()] = unsafe { from_ptr_range(ptr::null()..ptr::null()) };
+pub static R2: &[u32] = unsafe {
+    let ptr = &D0 as *const u32;
+    from_ptr_range(ptr..ptr.add(2))
+};
+pub static R4: &[u8] = unsafe {
+    //~^ ERROR: it is undefined behavior to use this value
+    let ptr = (&D1) as *const MaybeUninit<&u32> as *const u8;
+    from_ptr_range(ptr..ptr.add(1))
+};
+pub static R5: &[u8] = unsafe {
+    //~^ ERROR: it is undefined behavior to use this value
+    let ptr = &D3 as *const &u32;
+    from_ptr_range(ptr.cast()..ptr.add(1).cast())
+};
+pub static R6: &[bool] = unsafe {
+    //~^ ERROR: it is undefined behavior to use this value
+    let ptr = &D0 as *const u32 as *const bool;
+    from_ptr_range(ptr..ptr.add(4))
+};
+pub static R7: &[u16] = unsafe {
+    //~^ ERROR: it is undefined behavior to use this value
+    let ptr = (&D2 as *const Struct as *const u16).byte_add(1);
+    from_ptr_range(ptr..ptr.add(4))
+};
+pub static R8: &[u64] = unsafe {
+    let ptr = (&D4 as *const [u32; 2] as *const u32).byte_add(1).cast::<u64>();
+    from_ptr_range(ptr..ptr.add(1))
+};
+
+// This is sneaky: &D0 and &D0 point to different objects
+// (even if at runtime they have the same address)
+pub static R9: &[u32] = unsafe { from_ptr_range(&D0..(&D0 as *const u32).add(1)) };
+pub static R10: &[u32] = unsafe { from_ptr_range(&D0..&D0) };
+
+const D0: u32 = 0x11;
+const D1: MaybeUninit<&u32> = MaybeUninit::uninit();
+const D2: Struct = Struct { a: 1, b: 2, c: 3, d: 4 };
+const D3: &u32 = &42;
+const D4: [u32; 2] = [17, 42];
+
+#[repr(C)]
+struct Struct {
+    a: u8,
+    // _pad: [MaybeUninit<u8>; 3]
+    b: u32,
+    c: u16,
+    d: u8,
+    // _pad: [MaybeUninit<u8>; 1]
+}
+
+fn main() {}