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turns out that dangling pointer branch is dead code; remove it and improve the error that actually gets shown a bit

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This commit is contained in:
Ralf Jung 2019-07-01 19:11:32 +02:00
parent 317c6ac129
commit d9d6b3bb28
5 changed files with 97 additions and 49 deletions
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21
src/librustc_mir/interpret/validity.rs
View File

@ -11,7 +11,7 @@ use std::hash::Hash;
use super::{
GlobalAlloc, InterpResult, InterpError,
OpTy, Machine, InterpCx, ValueVisitor, MPlaceTy, AllocCheck,
OpTy, Machine, InterpCx, ValueVisitor, MPlaceTy,
};
macro_rules! validation_failure {
@ -502,17 +502,14 @@ impl<'rt, 'mir, 'tcx, M: Machine<'mir, 'tcx>> ValueVisitor<'mir, 'tcx, M>
if lo == 1 && hi == max_hi {
// Only NULL is the niche. So make sure the ptr is NOT NULL.
if self.ecx.memory.ptr_may_be_null(ptr) {
// These conditions are just here to improve the diagnostics so we can
// differentiate between null pointers and dangling pointers.
if self.ref_tracking_for_consts.is_some() &&
self.ecx.memory.get_size_and_align(ptr.alloc_id, AllocCheck::Live)
.is_err()
{
return validation_failure!(
"a dangling pointer", self.path
);
}
return validation_failure!("a potentially NULL pointer", self.path);
return validation_failure!(
"a potentially NULL pointer",
self.path,
format!(
"something that cannot possibly fail to be {}",
wrapping_range_format(&layout.valid_range, max_hi)
)
);
}
return Ok(());
} else {

32
src/test/ui/consts/const-eval/ub-enum.rs
View File

@ -1,5 +1,10 @@
#![allow(const_err)] // make sure we cannot allow away the errors tested here
#[repr(transparent)]
#[derive(Copy, Clone)]
struct Wrap<T>(T);
#[repr(usize)]
#[derive(Copy, Clone)]
enum Enum {
@ -7,11 +12,20 @@ enum Enum {
}
union TransmuteEnum {
in1: &'static u8,
in2: usize,
out1: Enum,
out2: Wrap<Enum>,
}
// A pointer is guaranteed non-null
const BAD_ENUM: Enum = unsafe { TransmuteEnum { in1: &1 }.out1 };
const GOOD_ENUM: Enum = unsafe { TransmuteEnum { in2: 0 }.out1 };
const BAD_ENUM: Enum = unsafe { TransmuteEnum { in2: 1 }.out1 };
//~^ ERROR is undefined behavior
const BAD_ENUM_PTR: Enum = unsafe { TransmuteEnum { in1: &1 }.out1 };
//~^ ERROR is undefined behavior
const BAD_ENUM_WRAPPED: Wrap<Enum> = unsafe { TransmuteEnum { in1: &1 }.out2 };
//~^ ERROR is undefined behavior
// (Potentially) invalid enum discriminant
@ -20,9 +34,7 @@ const BAD_ENUM: Enum = unsafe { TransmuteEnum { in1: &1 }.out1 };
enum Enum2 {
A = 2,
}
#[repr(transparent)]
#[derive(Copy, Clone)]
struct Wrap<T>(T);
union TransmuteEnum2 {
in1: usize,
in2: &'static u8,
@ -33,17 +45,17 @@ union TransmuteEnum2 {
}
const BAD_ENUM2: Enum2 = unsafe { TransmuteEnum2 { in1: 0 }.out1 };
//~^ ERROR is undefined behavior
const BAD_ENUM3: Enum2 = unsafe { TransmuteEnum2 { in2: &0 }.out1 };
const BAD_ENUM2_PTR: Enum2 = unsafe { TransmuteEnum2 { in2: &0 }.out1 };
//~^ ERROR is undefined behavior
const BAD_ENUM4: Wrap<Enum2> = unsafe { TransmuteEnum2 { in2: &0 }.out2 };
const BAD_ENUM2_WRAPPED: Wrap<Enum2> = unsafe { TransmuteEnum2 { in2: &0 }.out2 };
//~^ ERROR is undefined behavior
// Undef enum discriminant.
const BAD_ENUM_UNDEF : Enum2 = unsafe { TransmuteEnum2 { in3: () }.out1 };
const BAD_ENUM2_UNDEF : Enum2 = unsafe { TransmuteEnum2 { in3: () }.out1 };
//~^ ERROR is undefined behavior
// Pointer value in an enum with a niche that is not just 0.
const BAD_ENUM_PTR: Option<Enum2> = unsafe { TransmuteEnum2 { in2: &0 }.out3 };
const BAD_ENUM2_OPTION_PTR: Option<Enum2> = unsafe { TransmuteEnum2 { in2: &0 }.out3 };
//~^ ERROR is undefined behavior
// Invalid enum field content (mostly to test printing of paths for enum tuple
@ -53,7 +65,7 @@ union TransmuteChar {
b: char,
}
// Need to create something which does not clash with enum layout optimizations.
const BAD_ENUM_CHAR: Option<(char, char)> = Some(('x', unsafe { TransmuteChar { a: !0 }.b }));
const BAD_OPTION_CHAR: Option<(char, char)> = Some(('x', unsafe { TransmuteChar { a: !0 }.b }));
//~^ ERROR is undefined behavior
fn main() {

56
src/test/ui/consts/const-eval/ub-enum.stderr
View File

@ -1,13 +1,29 @@
error[E0080]: it is undefined behavior to use this value
--> $DIR/ub-enum.rs:14:1
--> $DIR/ub-enum.rs:22:1
|
LL | const BAD_ENUM: Enum = unsafe { TransmuteEnum { in1: &1 }.out1 };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ type validation failed: encountered a pointer, but expected a valid enum discriminant
LL | const BAD_ENUM: Enum = unsafe { TransmuteEnum { in2: 1 }.out1 };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ type validation failed: encountered 1, but expected a valid enum discriminant
|
= note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rust compiler repository if you believe it should not be considered undefined behavior
error[E0080]: it is undefined behavior to use this value
--> $DIR/ub-enum.rs:34:1
--> $DIR/ub-enum.rs:25:1
|
LL | const BAD_ENUM_PTR: Enum = unsafe { TransmuteEnum { in1: &1 }.out1 };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ type validation failed: encountered a pointer, but expected a valid enum discriminant
|
= note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rust compiler repository if you believe it should not be considered undefined behavior
error[E0080]: it is undefined behavior to use this value
--> $DIR/ub-enum.rs:28:1
|
LL | const BAD_ENUM_WRAPPED: Wrap<Enum> = unsafe { TransmuteEnum { in1: &1 }.out2 };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ type validation failed: encountered a pointer, but expected something that cannot possibly fail to be less or equal to 0
|
= note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rust compiler repository if you believe it should not be considered undefined behavior
error[E0080]: it is undefined behavior to use this value
--> $DIR/ub-enum.rs:46:1
|
LL | const BAD_ENUM2: Enum2 = unsafe { TransmuteEnum2 { in1: 0 }.out1 };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ type validation failed: encountered 0, but expected a valid enum discriminant
@ -15,45 +31,45 @@ LL | const BAD_ENUM2: Enum2 = unsafe { TransmuteEnum2 { in1: 0 }.out1 };
= note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rust compiler repository if you believe it should not be considered undefined behavior
error[E0080]: it is undefined behavior to use this value
--> $DIR/ub-enum.rs:36:1
--> $DIR/ub-enum.rs:48:1
|
LL | const BAD_ENUM3: Enum2 = unsafe { TransmuteEnum2 { in2: &0 }.out1 };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ type validation failed: encountered a pointer, but expected a valid enum discriminant
LL | const BAD_ENUM2_PTR: Enum2 = unsafe { TransmuteEnum2 { in2: &0 }.out1 };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ type validation failed: encountered a pointer, but expected a valid enum discriminant
|
= note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rust compiler repository if you believe it should not be considered undefined behavior
error[E0080]: it is undefined behavior to use this value
--> $DIR/ub-enum.rs:38:1
--> $DIR/ub-enum.rs:50:1
|
LL | const BAD_ENUM4: Wrap<Enum2> = unsafe { TransmuteEnum2 { in2: &0 }.out2 };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ type validation failed: encountered a pointer, but expected something that cannot possibly fail to be in the range 2..=2
LL | const BAD_ENUM2_WRAPPED: Wrap<Enum2> = unsafe { TransmuteEnum2 { in2: &0 }.out2 };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ type validation failed: encountered a pointer, but expected something that cannot possibly fail to be in the range 2..=2
|
= note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rust compiler repository if you believe it should not be considered undefined behavior
error[E0080]: it is undefined behavior to use this value
--> $DIR/ub-enum.rs:42:1
--> $DIR/ub-enum.rs:54:1
|
LL | const BAD_ENUM_UNDEF : Enum2 = unsafe { TransmuteEnum2 { in3: () }.out1 };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ type validation failed: encountered uninitialized bytes, but expected a valid enum discriminant
LL | const BAD_ENUM2_UNDEF : Enum2 = unsafe { TransmuteEnum2 { in3: () }.out1 };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ type validation failed: encountered uninitialized bytes, but expected a valid enum discriminant
|
= note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rust compiler repository if you believe it should not be considered undefined behavior
error[E0080]: it is undefined behavior to use this value
--> $DIR/ub-enum.rs:46:1
--> $DIR/ub-enum.rs:58:1
|
LL | const BAD_ENUM_PTR: Option<Enum2> = unsafe { TransmuteEnum2 { in2: &0 }.out3 };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ type validation failed: encountered a pointer, but expected a valid enum discriminant
LL | const BAD_ENUM2_OPTION_PTR: Option<Enum2> = unsafe { TransmuteEnum2 { in2: &0 }.out3 };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ type validation failed: encountered a pointer, but expected a valid enum discriminant
|
= note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rust compiler repository if you believe it should not be considered undefined behavior
error[E0080]: it is undefined behavior to use this value
--> $DIR/ub-enum.rs:56:1
--> $DIR/ub-enum.rs:68:1
|
LL | const BAD_ENUM_CHAR: Option<(char, char)> = Some(('x', unsafe { TransmuteChar { a: !0 }.b }));
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ type validation failed: encountered 4294967295 at .<downcast-variant(Some)>.0.1, but expected something less or equal to 1114111
LL | const BAD_OPTION_CHAR: Option<(char, char)> = Some(('x', unsafe { TransmuteChar { a: !0 }.b }));
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ type validation failed: encountered 4294967295 at .<downcast-variant(Some)>.0.1, but expected something less or equal to 1114111
|
= note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rust compiler repository if you believe it should not be considered undefined behavior
error: aborting due to 7 previous errors
error: aborting due to 9 previous errors
For more information about this error, try `rustc --explain E0080`.

10
src/test/ui/consts/const-eval/ub-nonnull.rs
View File

@ -5,9 +5,19 @@ use std::mem;
use std::ptr::NonNull;
use std::num::{NonZeroU8, NonZeroUsize};
const NON_NULL: NonNull<u8> = unsafe { mem::transmute(1usize) };
const NON_NULL_PTR: NonNull<u8> = unsafe { mem::transmute(&1) };
const NULL_PTR: NonNull<u8> = unsafe { mem::transmute(0usize) };
//~^ ERROR it is undefined behavior to use this value
const OUT_OF_BOUNDS_PTR: NonNull<u8> = { unsafe {
//~^ ERROR it is undefined behavior to use this value
let ptr: &(u8, u8, u8) = mem::transmute(&0u8); // &0 gets promoted so it does not dangle
let out_of_bounds_ptr = &ptr.2; // use address-of-field for pointer arithmetic
mem::transmute(out_of_bounds_ptr)
} };
const NULL_U8: NonZeroU8 = unsafe { mem::transmute(0u8) };
//~^ ERROR it is undefined behavior to use this value
const NULL_USIZE: NonZeroUsize = unsafe { mem::transmute(0usize) };

27
src/test/ui/consts/const-eval/ub-nonnull.stderr
View File

@ -1,5 +1,5 @@
error[E0080]: it is undefined behavior to use this value
--> $DIR/ub-nonnull.rs:8:1
--> $DIR/ub-nonnull.rs:11:1
|
LL | const NULL_PTR: NonNull<u8> = unsafe { mem::transmute(0usize) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ type validation failed: encountered 0, but expected something greater or equal to 1
@ -7,7 +7,20 @@ LL | const NULL_PTR: NonNull<u8> = unsafe { mem::transmute(0usize) };
= note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rust compiler repository if you believe it should not be considered undefined behavior
error[E0080]: it is undefined behavior to use this value
--> $DIR/ub-nonnull.rs:11:1
--> $DIR/ub-nonnull.rs:14:1
|
LL | / const OUT_OF_BOUNDS_PTR: NonNull<u8> = { unsafe {
LL | |
LL | | let ptr: &(u8, u8, u8) = mem::transmute(&0u8); // &0 gets promoted so it does not dangle
LL | | let out_of_bounds_ptr = &ptr.2; // use address-of-field for pointer arithmetic
LL | | mem::transmute(out_of_bounds_ptr)
LL | | } };
| |____^ type validation failed: encountered a potentially NULL pointer, but expected something that cannot possibly fail to be greater or equal to 1
|
= note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rust compiler repository if you believe it should not be considered undefined behavior
error[E0080]: it is undefined behavior to use this value
--> $DIR/ub-nonnull.rs:21:1
|
LL | const NULL_U8: NonZeroU8 = unsafe { mem::transmute(0u8) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ type validation failed: encountered 0, but expected something greater or equal to 1
@ -15,7 +28,7 @@ LL | const NULL_U8: NonZeroU8 = unsafe { mem::transmute(0u8) };
= note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rust compiler repository if you believe it should not be considered undefined behavior
error[E0080]: it is undefined behavior to use this value
--> $DIR/ub-nonnull.rs:13:1
--> $DIR/ub-nonnull.rs:23:1
|
LL | const NULL_USIZE: NonZeroUsize = unsafe { mem::transmute(0usize) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ type validation failed: encountered 0, but expected something greater or equal to 1
@ -23,7 +36,7 @@ LL | const NULL_USIZE: NonZeroUsize = unsafe { mem::transmute(0usize) };
= note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rust compiler repository if you believe it should not be considered undefined behavior
error[E0080]: it is undefined behavior to use this value
--> $DIR/ub-nonnull.rs:20:1
--> $DIR/ub-nonnull.rs:30:1
|
LL | const UNINIT: NonZeroU8 = unsafe { Transmute { uninit: () }.out };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ type validation failed: encountered uninitialized bytes, but expected something greater or equal to 1
@ -31,7 +44,7 @@ LL | const UNINIT: NonZeroU8 = unsafe { Transmute { uninit: () }.out };
= note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rust compiler repository if you believe it should not be considered undefined behavior
error[E0080]: it is undefined behavior to use this value
--> $DIR/ub-nonnull.rs:28:1
--> $DIR/ub-nonnull.rs:38:1
|
LL | const BAD_RANGE1: RestrictedRange1 = unsafe { RestrictedRange1(42) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ type validation failed: encountered 42, but expected something in the range 10..=30
@ -39,13 +52,13 @@ LL | const BAD_RANGE1: RestrictedRange1 = unsafe { RestrictedRange1(42) };
= note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rust compiler repository if you believe it should not be considered undefined behavior
error[E0080]: it is undefined behavior to use this value
--> $DIR/ub-nonnull.rs:34:1
--> $DIR/ub-nonnull.rs:44:1
|
LL | const BAD_RANGE2: RestrictedRange2 = unsafe { RestrictedRange2(20) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ type validation failed: encountered 20, but expected something less or equal to 10, or greater or equal to 30
|
= note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rust compiler repository if you believe it should not be considered undefined behavior
error: aborting due to 6 previous errors
error: aborting due to 7 previous errors
For more information about this error, try `rustc --explain E0080`.