test/ui/consts: Add tests for const ptr offsets

Signed-off-by: Joe Richey <[email protected]>

src/test/ui/consts/offset.rs

@@ -0,0 +1,115 @@
+// run-pass
+#![feature(const_ptr_offset)]
+#![feature(const_ptr_offset_from)]
+#![feature(ptr_offset_from)]
+use std::ptr;
+
+#[repr(C)]
+struct Struct {
+    a: u32,
+    b: u32,
+    c: u32,
+}
+static S: Struct = Struct { a: 0, b: 0, c: 0 };
+
+// For these tests we use offset_from to check that two pointers are equal.
+// Rust doesn't currently support comparing pointers in const fn.
+
+static OFFSET_NO_CHANGE: bool = unsafe {
+    let p1 = &S.b as *const u32;
+    let p2 = p1.offset(2).offset(-2);
+    p1.offset_from(p2) == 0
+};
+static OFFSET_MIDDLE: bool = unsafe {
+    let p1 = (&S.a as *const u32).offset(1);
+    let p2 = (&S.c as *const u32).offset(-1);
+    p1.offset_from(p2) == 0
+};
+// Pointing to the end of the allocation is OK
+static OFFSET_END: bool = unsafe {
+    let p1 = (&S.a as *const u32).offset(3);
+    let p2 = (&S.c as *const u32).offset(1);
+    p1.offset_from(p2) == 0
+};
+// Casting though a differently sized type is OK
+static OFFSET_U8_PTR: bool = unsafe {
+    let p1 = (&S.a as *const u32 as *const u8).offset(5);
+    let p2 = (&S.c as *const u32 as *const u8).offset(-3);
+    p1.offset_from(p2) == 0
+};
+// Any offset with a ZST does nothing
+const OFFSET_ZST: bool = unsafe {
+    let pz = &() as *const ();
+    // offset_from can't work with ZSTs, so cast to u8 ptr
+    let p1 = pz.offset(5) as *const u8;
+    let p2 = pz.offset(isize::MIN) as *const u8;
+    p1.offset_from(p2) == 0
+};
+const OFFSET_ZERO: bool = unsafe {
+    let p = [0u8; 0].as_ptr();
+    p.offset(0).offset_from(p) == 0
+};
+const OFFSET_ONE: bool = unsafe {
+    let p = &42u32 as *const u32;
+    p.offset(1).offset_from(p) == 1
+};
+const OFFSET_DANGLING: bool = unsafe {
+    let p = ptr::NonNull::<u8>::dangling().as_ptr();
+    p.offset(0).offset_from(p) == 0
+};
+const OFFSET_UNALIGNED: bool = unsafe {
+    let arr = [0u8; 32];
+    let p1 = arr.as_ptr();
+    let p2 = (p1.offset(2) as *const u32).offset(1);
+    (p2 as *const u8).offset_from(p1) == 6
+};
+
+const WRAP_OFFSET_NO_CHANGE: bool = unsafe {
+    let p1 = &42u32 as *const u32;
+    let p2 = p1.wrapping_offset(1000).wrapping_offset(-1000);
+    let p3 = p1.wrapping_offset(-1000).wrapping_offset(1000);
+    (p1.offset_from(p2) == 0) & (p1.offset_from(p3) == 0)
+};
+const WRAP_ADDRESS_SPACE: bool = unsafe {
+    let p1 = &42u8 as *const u8;
+    let p2 = p1.wrapping_offset(isize::MIN).wrapping_offset(isize::MIN);
+    p1.offset_from(p2) == 0
+};
+// Wrap on the count*size_of::<T>() calculation.
+const WRAP_SIZE_OF: bool = unsafe {
+    // Make sure that if p1 moves backwards, we are still in range
+    let arr = [0u32; 2];
+    let p = &arr[1] as *const u32;
+    // With wrapping arithmetic, isize::MAX * 4 == -4
+    let wrapped = p.wrapping_offset(isize::MAX);
+    let backward = p.wrapping_offset(-1);
+    wrapped.offset_from(backward) == 0
+};
+const WRAP_INTEGER_POINTER: bool = unsafe {
+    let p1 = (0x42 as *const u32).wrapping_offset(4);
+    let p2 = 0x52 as *const u32;
+    p1.offset_from(p2) == 0
+};
+const WRAP_NULL: bool = unsafe {
+    let p1 = ptr::null::<u32>().wrapping_offset(1);
+    let p2 = 0x4 as *const u32;
+    p1.offset_from(p2) == 0
+};
+
+fn main() {
+    assert!(OFFSET_NO_CHANGE);
+    assert!(OFFSET_MIDDLE);
+    assert!(OFFSET_END);
+    assert!(OFFSET_U8_PTR);
+    assert!(OFFSET_ZST);
+    assert!(OFFSET_ZERO);
+    assert!(OFFSET_ONE);
+    assert!(OFFSET_DANGLING);
+    assert!(OFFSET_UNALIGNED);
+
+    assert!(WRAP_OFFSET_NO_CHANGE);
+    assert!(WRAP_ADDRESS_SPACE);
+    assert!(WRAP_SIZE_OF);
+    assert!(WRAP_INTEGER_POINTER);
+    assert!(WRAP_NULL);
+}

src/test/ui/consts/offset_ub.rs

@@ -0,0 +1,22 @@
+// ignore-tidy-linelength
+#![feature(const_ptr_offset)]
+use std::ptr;
+
+// normalize-stderr-test "alloc\d+" -> "allocN"
+
+pub const BEFORE_START: *const u8 = unsafe { (&0u8 as *const u8).offset(-1) }; //~NOTE
+pub const AFTER_END: *const u8 = unsafe { (&0u8 as *const u8).offset(2) }; //~NOTE
+pub const AFTER_ARRAY: *const u8 = unsafe { [0u8; 100].as_ptr().offset(101) }; //~NOTE
+
+pub const OVERFLOW: *const u16 = unsafe { [0u16; 1].as_ptr().offset(isize::MAX) }; //~NOTE
+pub const UNDERFLOW: *const u16 = unsafe { [0u16; 1].as_ptr().offset(isize::MIN) }; //~NOTE
+pub const OVERFLOW_ADDRESS_SPACE: *const u8 = unsafe { (usize::MAX as *const u8).offset(2) }; //~NOTE
+pub const UNDERFLOW_ADDRESS_SPACE: *const u8 = unsafe { (1 as *const u8).offset(-2) }; //~NOTE
+
+pub const ZERO_SIZED_ALLOC: *const u8 = unsafe { [0u8; 0].as_ptr().offset(1) }; //~NOTE
+pub const DANGLING: *const u8 = unsafe { ptr::NonNull::<u8>::dangling().as_ptr().offset(4) }; //~NOTE
+
+// Right now, a zero offset from null is UB
+pub const NULL_OFFSET_ZERO: *const u8 = unsafe { ptr::null::<u8>().offset(0) }; //~NOTE
+
+fn main() {}

src/test/ui/consts/offset_ub.stderr

@@ -0,0 +1,154 @@
+error: any use of this value will cause an error
+  --> $SRC_DIR/libcore/ptr/const_ptr.rs:LL:COL
+   |
+LL |         intrinsics::offset(self, count)
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |         |
+   |         overflowing in-bounds pointer arithmetic
+   |         inside `std::ptr::const_ptr::<impl *const u8>::offset` at $SRC_DIR/libcore/ptr/const_ptr.rs:LL:COL
+   |         inside `BEFORE_START` at $DIR/offset_ub.rs:7:46
+   | 
+  ::: $DIR/offset_ub.rs:7:1
+   |
+LL | pub const BEFORE_START: *const u8 = unsafe { (&0u8 as *const u8).offset(-1) };
+   | ------------------------------------------------------------------------------
+   |
+   = note: `#[deny(const_err)]` on by default
+
+error: any use of this value will cause an error
+  --> $SRC_DIR/libcore/ptr/const_ptr.rs:LL:COL
+   |
+LL |         intrinsics::offset(self, count)
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |         |
+   |         inbounds test failed: pointer must be in-bounds at offset 2, but is outside bounds of allocN which has size 1
+   |         inside `std::ptr::const_ptr::<impl *const u8>::offset` at $SRC_DIR/libcore/ptr/const_ptr.rs:LL:COL
+   |         inside `AFTER_END` at $DIR/offset_ub.rs:8:43
+   | 
+  ::: $DIR/offset_ub.rs:8:1
+   |
+LL | pub const AFTER_END: *const u8 = unsafe { (&0u8 as *const u8).offset(2) };
+   | --------------------------------------------------------------------------
+
+error: any use of this value will cause an error
+  --> $SRC_DIR/libcore/ptr/const_ptr.rs:LL:COL
+   |
+LL |         intrinsics::offset(self, count)
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |         |
+   |         inbounds test failed: pointer must be in-bounds at offset 101, but is outside bounds of allocN which has size 100
+   |         inside `std::ptr::const_ptr::<impl *const u8>::offset` at $SRC_DIR/libcore/ptr/const_ptr.rs:LL:COL
+   |         inside `AFTER_ARRAY` at $DIR/offset_ub.rs:9:45
+   | 
+  ::: $DIR/offset_ub.rs:9:1
+   |
+LL | pub const AFTER_ARRAY: *const u8 = unsafe { [0u8; 100].as_ptr().offset(101) };
+   | ------------------------------------------------------------------------------
+
+error: any use of this value will cause an error
+  --> $SRC_DIR/libcore/ptr/const_ptr.rs:LL:COL
+   |
+LL |         intrinsics::offset(self, count)
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |         |
+   |         inbounds pointer arithmetic: overflow computing offset
+   |         inside `std::ptr::const_ptr::<impl *const u16>::offset` at $SRC_DIR/libcore/ptr/const_ptr.rs:LL:COL
+   |         inside `OVERFLOW` at $DIR/offset_ub.rs:11:43
+   | 
+  ::: $DIR/offset_ub.rs:11:1
+   |
+LL | pub const OVERFLOW: *const u16 = unsafe { [0u16; 1].as_ptr().offset(isize::MAX) };
+   | ----------------------------------------------------------------------------------
+
+error: any use of this value will cause an error
+  --> $SRC_DIR/libcore/ptr/const_ptr.rs:LL:COL
+   |
+LL |         intrinsics::offset(self, count)
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |         |
+   |         inbounds pointer arithmetic: overflow computing offset
+   |         inside `std::ptr::const_ptr::<impl *const u16>::offset` at $SRC_DIR/libcore/ptr/const_ptr.rs:LL:COL
+   |         inside `UNDERFLOW` at $DIR/offset_ub.rs:12:44
+   | 
+  ::: $DIR/offset_ub.rs:12:1
+   |
+LL | pub const UNDERFLOW: *const u16 = unsafe { [0u16; 1].as_ptr().offset(isize::MIN) };
+   | -----------------------------------------------------------------------------------
+
+error: any use of this value will cause an error
+  --> $SRC_DIR/libcore/ptr/const_ptr.rs:LL:COL
+   |
+LL |         intrinsics::offset(self, count)
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |         |
+   |         overflowing in-bounds pointer arithmetic
+   |         inside `std::ptr::const_ptr::<impl *const u8>::offset` at $SRC_DIR/libcore/ptr/const_ptr.rs:LL:COL
+   |         inside `OVERFLOW_ADDRESS_SPACE` at $DIR/offset_ub.rs:13:56
+   | 
+  ::: $DIR/offset_ub.rs:13:1
+   |
+LL | pub const OVERFLOW_ADDRESS_SPACE: *const u8 = unsafe { (usize::MAX as *const u8).offset(2) };
+   | ---------------------------------------------------------------------------------------------
+
+error: any use of this value will cause an error
+  --> $SRC_DIR/libcore/ptr/const_ptr.rs:LL:COL
+   |
+LL |         intrinsics::offset(self, count)
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |         |
+   |         overflowing in-bounds pointer arithmetic
+   |         inside `std::ptr::const_ptr::<impl *const u8>::offset` at $SRC_DIR/libcore/ptr/const_ptr.rs:LL:COL
+   |         inside `UNDERFLOW_ADDRESS_SPACE` at $DIR/offset_ub.rs:14:57
+   | 
+  ::: $DIR/offset_ub.rs:14:1
+   |
+LL | pub const UNDERFLOW_ADDRESS_SPACE: *const u8 = unsafe { (1 as *const u8).offset(-2) };
+   | --------------------------------------------------------------------------------------
+
+error: any use of this value will cause an error
+  --> $SRC_DIR/libcore/ptr/const_ptr.rs:LL:COL
+   |
+LL |         intrinsics::offset(self, count)
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |         |
+   |         inbounds test failed: pointer must be in-bounds at offset 1, but is outside bounds of allocN which has size 0
+   |         inside `std::ptr::const_ptr::<impl *const u8>::offset` at $SRC_DIR/libcore/ptr/const_ptr.rs:LL:COL
+   |         inside `ZERO_SIZED_ALLOC` at $DIR/offset_ub.rs:16:50
+   | 
+  ::: $DIR/offset_ub.rs:16:1
+   |
+LL | pub const ZERO_SIZED_ALLOC: *const u8 = unsafe { [0u8; 0].as_ptr().offset(1) };
+   | -------------------------------------------------------------------------------
+
+error: any use of this value will cause an error
+  --> $SRC_DIR/libcore/ptr/mut_ptr.rs:LL:COL
+   |
+LL |         intrinsics::offset(self, count) as *mut T
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |         |
+   |         unable to turn bytes into a pointer
+   |         inside `std::ptr::mut_ptr::<impl *mut u8>::offset` at $SRC_DIR/libcore/ptr/mut_ptr.rs:LL:COL
+   |         inside `DANGLING` at $DIR/offset_ub.rs:17:42
+   | 
+  ::: $DIR/offset_ub.rs:17:1
+   |
+LL | pub const DANGLING: *const u8 = unsafe { ptr::NonNull::<u8>::dangling().as_ptr().offset(4) };
+   | ---------------------------------------------------------------------------------------------
+
+error: any use of this value will cause an error
+  --> $SRC_DIR/libcore/ptr/const_ptr.rs:LL:COL
+   |
+LL |         intrinsics::offset(self, count)
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |         |
+   |         inbounds test failed: 0x0 is not a valid pointer
+   |         inside `std::ptr::const_ptr::<impl *const u8>::offset` at $SRC_DIR/libcore/ptr/const_ptr.rs:LL:COL
+   |         inside `NULL_OFFSET_ZERO` at $DIR/offset_ub.rs:20:50
+   | 
+  ::: $DIR/offset_ub.rs:20:1
+   |
+LL | pub const NULL_OFFSET_ZERO: *const u8 = unsafe { ptr::null::<u8>().offset(0) };
+   | -------------------------------------------------------------------------------
+
+error: aborting due to 10 previous errors
+