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Auto merge of #85332 - RalfJung:ptr-in-str, r=oli-obk
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CTFE validation: handle pointers in str

I also finally learned how I can match *some* NOTEs in a ui test without matching all of them, and applied that to some const tests in the 2nd commit where I added NOTE because I did not know what I was doing. I can separate this into its own PR if you prefer.

Fixes #83182
r? `@oli-obk`
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bors committed May 16, 2021
2 parents 94ecdfd + 70c1cf1 commit 3f46b82
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Showing 15 changed files with 111 additions and 119 deletions.
1 change: 1 addition & 0 deletions compiler/rustc_mir/src/interpret/validity.rs
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Expand Up @@ -833,6 +833,7 @@ impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValueVisitor<'mir, 'tcx, M>
self.ecx.memory.read_bytes(mplace.ptr, Size::from_bytes(len)),
self.path,
err_ub!(InvalidUninitBytes(..)) => { "uninitialized data in `str`" },
err_unsup!(ReadPointerAsBytes) => { "a pointer in `str`" },
);
}
ty::Array(tys, ..) | ty::Slice(tys)
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6 changes: 2 additions & 4 deletions src/test/ui/consts/const-eval/dangling.rs
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Expand Up @@ -3,13 +3,11 @@
use std::mem;

// Make sure we error with the right kind of error on a too large slice.
const TEST: () = { unsafe { //~ NOTE
const TEST: () = { unsafe {
let slice: *const [u8] = mem::transmute((1usize, usize::MAX));
let _val = &*slice; //~ ERROR: any use of this value will cause an error
//~| NOTE: slice is bigger than largest supported object
//~| on by default
//~| slice is bigger than largest supported object
//~| WARN this was previously accepted by the compiler but is being phased out
//~| NOTE
} };

fn main() {}
1 change: 0 additions & 1 deletion src/test/ui/consts/const-eval/dangling.stderr
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Expand Up @@ -6,7 +6,6 @@ LL | | let slice: *const [u8] = mem::transmute((1usize, usize::MAX));
LL | | let _val = &*slice;
| | ^^^^^^^ invalid metadata in wide pointer: slice is bigger than largest supported object
LL | |
... |
LL | |
LL | | } };
| |____-
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4 changes: 1 addition & 3 deletions src/test/ui/consts/const-points-to-static.rs
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Expand Up @@ -5,9 +5,7 @@

const TEST: &u8 = &MY_STATIC;
//~^ ERROR it is undefined behavior to use this value
//~| NOTE encountered a reference pointing to a static variable
//~| NOTE undefined behavior
//~| NOTE the raw bytes of the constant
//~| encountered a reference pointing to a static variable

static MY_STATIC: u8 = 4;

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14 changes: 14 additions & 0 deletions src/test/ui/consts/issue-83182.32bit.stderr
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@@ -0,0 +1,14 @@
error[E0080]: it is undefined behavior to use this value
--> $DIR/issue-83182.rs:5:1
|
LL | const MYSTR_NO_INIT: &MyStr = unsafe { mem::transmute::<&[_], _>(&[&()]) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ type validation failed: encountered a pointer in `str` at .<deref>.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 rustc repository if you believe it should not be considered undefined behavior.
= note: the raw bytes of the constant (size: 8, align: 4) {
╾─alloc3──╼ 01 00 00 00 │ ╾──╼....
}

error: aborting due to previous error

For more information about this error, try `rustc --explain E0080`.
14 changes: 14 additions & 0 deletions src/test/ui/consts/issue-83182.64bit.stderr
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@@ -0,0 +1,14 @@
error[E0080]: it is undefined behavior to use this value
--> $DIR/issue-83182.rs:5:1
|
LL | const MYSTR_NO_INIT: &MyStr = unsafe { mem::transmute::<&[_], _>(&[&()]) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ type validation failed: encountered a pointer in `str` at .<deref>.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 rustc repository if you believe it should not be considered undefined behavior.
= note: the raw bytes of the constant (size: 16, align: 8) {
╾───────alloc3────────╼ 01 00 00 00 00 00 00 00 │ ╾──────╼........
}

error: aborting due to previous error

For more information about this error, try `rustc --explain E0080`.
8 changes: 8 additions & 0 deletions src/test/ui/consts/issue-83182.rs
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@@ -0,0 +1,8 @@
// stderr-per-bitwidth

use std::mem;
struct MyStr(str);
const MYSTR_NO_INIT: &MyStr = unsafe { mem::transmute::<&[_], _>(&[&()]) };
//~^ ERROR: it is undefined behavior to use this value
//~| type validation failed: encountered a pointer in `str`
fn main() {}
12 changes: 4 additions & 8 deletions src/test/ui/consts/miri_unleashed/const_refers_to_static2.32bit.stderr
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Expand Up @@ -3,8 +3,6 @@ error[E0080]: it is undefined behavior to use this value
|
LL | / const REF_INTERIOR_MUT: &usize = {
LL | |
LL | |
LL | |
LL | | static FOO: AtomicUsize = AtomicUsize::new(0);
LL | | unsafe { &*(&FOO as *const _ as *const usize) }
LL | | };
Expand All @@ -16,12 +14,10 @@ LL | | };
}

error[E0080]: it is undefined behavior to use this value
--> $DIR/const_refers_to_static2.rs:20:1
--> $DIR/const_refers_to_static2.rs:18:1
|
LL | / const READ_IMMUT: &usize = {
LL | |
LL | |
LL | |
LL | | static FOO: usize = 0;
LL | | &FOO
LL | | };
Expand All @@ -35,17 +31,17 @@ LL | | };
warning: skipping const checks
|
help: skipping check that does not even have a feature gate
--> $DIR/const_refers_to_static2.rs:16:18
--> $DIR/const_refers_to_static2.rs:14:18
|
LL | unsafe { &*(&FOO as *const _ as *const usize) }
| ^^^
help: skipping check for `const_raw_ptr_deref` feature
--> $DIR/const_refers_to_static2.rs:16:14
--> $DIR/const_refers_to_static2.rs:14:14
|
LL | unsafe { &*(&FOO as *const _ as *const usize) }
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
help: skipping check that does not even have a feature gate
--> $DIR/const_refers_to_static2.rs:25:6
--> $DIR/const_refers_to_static2.rs:21:6
|
LL | &FOO
| ^^^
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12 changes: 4 additions & 8 deletions src/test/ui/consts/miri_unleashed/const_refers_to_static2.64bit.stderr
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Expand Up @@ -3,8 +3,6 @@ error[E0080]: it is undefined behavior to use this value
|
LL | / const REF_INTERIOR_MUT: &usize = {
LL | |
LL | |
LL | |
LL | | static FOO: AtomicUsize = AtomicUsize::new(0);
LL | | unsafe { &*(&FOO as *const _ as *const usize) }
LL | | };
Expand All @@ -16,12 +14,10 @@ LL | | };
}

error[E0080]: it is undefined behavior to use this value
--> $DIR/const_refers_to_static2.rs:20:1
--> $DIR/const_refers_to_static2.rs:18:1
|
LL | / const READ_IMMUT: &usize = {
LL | |
LL | |
LL | |
LL | | static FOO: usize = 0;
LL | | &FOO
LL | | };
Expand All @@ -35,17 +31,17 @@ LL | | };
warning: skipping const checks
|
help: skipping check that does not even have a feature gate
--> $DIR/const_refers_to_static2.rs:16:18
--> $DIR/const_refers_to_static2.rs:14:18
|
LL | unsafe { &*(&FOO as *const _ as *const usize) }
| ^^^
help: skipping check for `const_raw_ptr_deref` feature
--> $DIR/const_refers_to_static2.rs:16:14
--> $DIR/const_refers_to_static2.rs:14:14
|
LL | unsafe { &*(&FOO as *const _ as *const usize) }
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
help: skipping check that does not even have a feature gate
--> $DIR/const_refers_to_static2.rs:25:6
--> $DIR/const_refers_to_static2.rs:21:6
|
LL | &FOO
| ^^^
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8 changes: 2 additions & 6 deletions src/test/ui/consts/miri_unleashed/const_refers_to_static2.rs
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Expand Up @@ -9,18 +9,14 @@ use std::sync::atomic::Ordering;
// so they cause an immediate error when *defining* the const.

const REF_INTERIOR_MUT: &usize = { //~ ERROR undefined behavior to use this value
//~| NOTE encountered a reference pointing to a static variable
//~| NOTE undefined behavior
//~| NOTE the raw bytes of the constant
//~| encountered a reference pointing to a static variable
static FOO: AtomicUsize = AtomicUsize::new(0);
unsafe { &*(&FOO as *const _ as *const usize) }
};

// ok some day perhaps
const READ_IMMUT: &usize = { //~ ERROR it is undefined behavior to use this value
//~| NOTE encountered a reference pointing to a static variable
//~| NOTE undefined behavior
//~| NOTE the raw bytes of the constant
//~| encountered a reference pointing to a static variable
static FOO: usize = 0;
&FOO
};
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54 changes: 24 additions & 30 deletions src/test/ui/consts/miri_unleashed/const_refers_to_static_cross_crate.32bit.stderr
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Expand Up @@ -3,8 +3,6 @@ error[E0080]: it is undefined behavior to use this value
|
LL | / const SLICE_MUT: &[u8; 1] = {
LL | |
LL | |
LL | |
LL | | unsafe { &static_cross_crate::ZERO }
LL | | };
| |__^ type validation failed: encountered a reference pointing to a static variable
Expand All @@ -15,18 +13,16 @@ LL | | };
}

error: could not evaluate constant pattern
--> $DIR/const_refers_to_static_cross_crate.rs:47:9
--> $DIR/const_refers_to_static_cross_crate.rs:40:9
|
LL | SLICE_MUT => true,
| ^^^^^^^^^

error[E0080]: it is undefined behavior to use this value
--> $DIR/const_refers_to_static_cross_crate.rs:19:1
--> $DIR/const_refers_to_static_cross_crate.rs:17:1
|
LL | / const U8_MUT: &u8 = {
LL | |
LL | |
LL | |
LL | | unsafe { &static_cross_crate::ZERO[0] }
LL | | };
| |__^ type validation failed: encountered a reference pointing to a static variable
Expand All @@ -37,143 +33,141 @@ LL | | };
}

error: could not evaluate constant pattern
--> $DIR/const_refers_to_static_cross_crate.rs:56:9
--> $DIR/const_refers_to_static_cross_crate.rs:49:9
|
LL | U8_MUT => true,
| ^^^^^^

warning: any use of this value will cause an error
--> $DIR/const_refers_to_static_cross_crate.rs:29:15
--> $DIR/const_refers_to_static_cross_crate.rs:25:15
|
LL | / const U8_MUT2: &u8 = {
LL | | unsafe { &(*static_cross_crate::ZERO_REF)[0] }
| | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ constant accesses static
LL | |
LL | |
LL | |
LL | |
LL | | };
| |__-
|
note: the lint level is defined here
--> $DIR/const_refers_to_static_cross_crate.rs:27:8
--> $DIR/const_refers_to_static_cross_crate.rs:23:8
|
LL | #[warn(const_err)]
| ^^^^^^^^^
= warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
= note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>

error: could not evaluate constant pattern
--> $DIR/const_refers_to_static_cross_crate.rs:67:9
--> $DIR/const_refers_to_static_cross_crate.rs:60:9
|
LL | U8_MUT2 => true,
| ^^^^^^^

warning: any use of this value will cause an error
--> $DIR/const_refers_to_static_cross_crate.rs:37:51
--> $DIR/const_refers_to_static_cross_crate.rs:32:51
|
LL | / const U8_MUT3: &u8 = {
LL | | unsafe { match static_cross_crate::OPT_ZERO { Some(ref u) => u, None => panic!() } }
| | ^^^^^^^^^^^ constant accesses static
LL | |
LL | |
... |
LL | |
LL | | };
| |__-
|
note: the lint level is defined here
--> $DIR/const_refers_to_static_cross_crate.rs:35:8
--> $DIR/const_refers_to_static_cross_crate.rs:30:8
|
LL | #[warn(const_err)]
| ^^^^^^^^^
= warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
= note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>

error: could not evaluate constant pattern
--> $DIR/const_refers_to_static_cross_crate.rs:75:9
--> $DIR/const_refers_to_static_cross_crate.rs:68:9
|
LL | U8_MUT3 => true,
| ^^^^^^^

error: could not evaluate constant pattern
--> $DIR/const_refers_to_static_cross_crate.rs:47:9
--> $DIR/const_refers_to_static_cross_crate.rs:40:9
|
LL | SLICE_MUT => true,
| ^^^^^^^^^

error: could not evaluate constant pattern
--> $DIR/const_refers_to_static_cross_crate.rs:56:9
--> $DIR/const_refers_to_static_cross_crate.rs:49:9
|
LL | U8_MUT => true,
| ^^^^^^

error: could not evaluate constant pattern
--> $DIR/const_refers_to_static_cross_crate.rs:67:9
--> $DIR/const_refers_to_static_cross_crate.rs:60:9
|
LL | U8_MUT2 => true,
| ^^^^^^^

error: could not evaluate constant pattern
--> $DIR/const_refers_to_static_cross_crate.rs:75:9
--> $DIR/const_refers_to_static_cross_crate.rs:68:9
|
LL | U8_MUT3 => true,
| ^^^^^^^

warning: skipping const checks
|
help: skipping check that does not even have a feature gate
--> $DIR/const_refers_to_static_cross_crate.rs:16:15
--> $DIR/const_refers_to_static_cross_crate.rs:14:15
|
LL | unsafe { &static_cross_crate::ZERO }
| ^^^^^^^^^^^^^^^^^^^^^^^^
help: skipping check that does not even have a feature gate
--> $DIR/const_refers_to_static_cross_crate.rs:16:15
--> $DIR/const_refers_to_static_cross_crate.rs:14:15
|
LL | unsafe { &static_cross_crate::ZERO }
| ^^^^^^^^^^^^^^^^^^^^^^^^
help: skipping check that does not even have a feature gate
--> $DIR/const_refers_to_static_cross_crate.rs:23:15
--> $DIR/const_refers_to_static_cross_crate.rs:19:15
|
LL | unsafe { &static_cross_crate::ZERO[0] }
| ^^^^^^^^^^^^^^^^^^^^^^^^
help: skipping check that does not even have a feature gate
--> $DIR/const_refers_to_static_cross_crate.rs:23:15
--> $DIR/const_refers_to_static_cross_crate.rs:19:15
|
LL | unsafe { &static_cross_crate::ZERO[0] }
| ^^^^^^^^^^^^^^^^^^^^^^^^
help: skipping check that does not even have a feature gate
--> $DIR/const_refers_to_static_cross_crate.rs:23:15
--> $DIR/const_refers_to_static_cross_crate.rs:19:15
|
LL | unsafe { &static_cross_crate::ZERO[0] }
| ^^^^^^^^^^^^^^^^^^^^^^^^
help: skipping check that does not even have a feature gate
--> $DIR/const_refers_to_static_cross_crate.rs:29:17
--> $DIR/const_refers_to_static_cross_crate.rs:25:17
|
LL | unsafe { &(*static_cross_crate::ZERO_REF)[0] }
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
help: skipping check that does not even have a feature gate
--> $DIR/const_refers_to_static_cross_crate.rs:37:20
--> $DIR/const_refers_to_static_cross_crate.rs:32:20
|
LL | unsafe { match static_cross_crate::OPT_ZERO { Some(ref u) => u, None => panic!() } }
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
help: skipping check that does not even have a feature gate
--> $DIR/const_refers_to_static_cross_crate.rs:37:20
--> $DIR/const_refers_to_static_cross_crate.rs:32:20
|
LL | unsafe { match static_cross_crate::OPT_ZERO { Some(ref u) => u, None => panic!() } }
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
help: skipping check that does not even have a feature gate
--> $DIR/const_refers_to_static_cross_crate.rs:37:20
--> $DIR/const_refers_to_static_cross_crate.rs:32:20
|
LL | unsafe { match static_cross_crate::OPT_ZERO { Some(ref u) => u, None => panic!() } }
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
help: skipping check for `const_panic` feature
--> $DIR/const_refers_to_static_cross_crate.rs:37:77
--> $DIR/const_refers_to_static_cross_crate.rs:32:77
|
LL | unsafe { match static_cross_crate::OPT_ZERO { Some(ref u) => u, None => panic!() } }
| ^^^^^^^^
help: skipping check that does not even have a feature gate
--> $DIR/const_refers_to_static_cross_crate.rs:37:20
--> $DIR/const_refers_to_static_cross_crate.rs:32:20
|
LL | unsafe { match static_cross_crate::OPT_ZERO { Some(ref u) => u, None => panic!() } }
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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