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RalfJungRalfJung
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miri: improve errors for type validity assertion failures
1 parent f51c987 commit 8362508

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14 files changed

+82
-107
lines changed

14 files changed

+82
-107
lines changed

‎compiler/rustc_const_eval/src/const_eval/machine.rs

Lines changed: 41 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -10,7 +10,7 @@ use rustc_hir::{self as hir, CRATE_HIR_ID, LangItem};
1010
use rustc_middle::mir::AssertMessage;
1111
use rustc_middle::mir::interpret::ReportedErrorInfo;
1212
use rustc_middle::query::TyCtxtAt;
13-
use rustc_middle::ty::layout::{HasTypingEnv, TyAndLayout};
13+
use rustc_middle::ty::layout::{HasTypingEnv, TyAndLayout, ValidityRequirement};
1414
use rustc_middle::ty::{self, Ty, TyCtxt};
1515
use rustc_middle::{bug, mir};
1616
use rustc_span::{Span, Symbol, sym};
@@ -23,8 +23,8 @@ use crate::fluent_generated as fluent;
2323
use crate::interpret::{
2424
self, AllocId, AllocInit, AllocRange, ConstAllocation, CtfeProvenance, FnArg, Frame,
2525
GlobalAlloc, ImmTy, InterpCx, InterpResult, OpTy, PlaceTy, Pointer, RangeSet, Scalar,
26-
compile_time_machine, interp_ok, throw_exhaust, throw_inval, throw_ub, throw_ub_custom,
27-
throw_unsup, throw_unsup_format,
26+
compile_time_machine, err_inval, interp_ok, throw_exhaust, throw_inval, throw_ub,
27+
throw_ub_custom, throw_unsup, throw_unsup_format,
2828
};
2929

3030
/// When hitting this many interpreted terminators we emit a deny by default lint
@@ -462,6 +462,44 @@ impl<'tcx> interpret::Machine<'tcx> for CompileTimeMachine<'tcx> {
462462
// (We know the value here in the machine of course, but this is the runtime of that code,
463463
// not the optimization stage.)
464464
sym::is_val_statically_known => ecx.write_scalar(Scalar::from_bool(false), dest)?,
465+
466+
// We handle these here since Miri does not want to have them.
467+
sym::assert_inhabited
468+
| sym::assert_zero_valid
469+
| sym::assert_mem_uninitialized_valid => {
470+
let ty = instance.args.type_at(0);
471+
let requirement = ValidityRequirement::from_intrinsic(intrinsic_name).unwrap();
472+
473+
let should_panic = !ecx
474+
.tcx
475+
.check_validity_requirement((requirement, ecx.typing_env().as_query_input(ty)))
476+
.map_err(|_| err_inval!(TooGeneric))?;
477+
478+
if should_panic {
479+
let layout = ecx.layout_of(ty)?;
480+
481+
let msg = match requirement {
482+
// For *all* intrinsics we first check `is_uninhabited` to give a more specific
483+
// error message.
484+
_ if layout.is_uninhabited() => format!(
485+
"aborted execution: attempted to instantiate uninhabited type `{ty}`"
486+
),
487+
ValidityRequirement::Inhabited => bug!("handled earlier"),
488+
ValidityRequirement::Zero => format!(
489+
"aborted execution: attempted to zero-initialize type `{ty}`, which is invalid"
490+
),
491+
ValidityRequirement::UninitMitigated0x01Fill => format!(
492+
"aborted execution: attempted to leave type `{ty}` uninitialized, which is invalid"
493+
),
494+
ValidityRequirement::Uninit => bug!("assert_uninit_valid doesn't exist"),
495+
};
496+
497+
Self::panic_nounwind(ecx, &msg)?;
498+
// Skip the `return_to_block` at the end (we panicked, we do not return).
499+
return interp_ok(None);
500+
}
501+
}
502+
465503
_ => {
466504
// We haven't handled the intrinsic, let's see if we can use a fallback body.
467505
if ecx.tcx.intrinsic(instance.def_id()).unwrap().must_be_overridden {

‎compiler/rustc_const_eval/src/interpret/intrinsics.rs

Lines changed: 3 additions & 38 deletions
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@ use std::assert_matches::assert_matches;
77
use rustc_abi::Size;
88
use rustc_apfloat::ieee::{Double, Half, Quad, Single};
99
use rustc_middle::mir::{self, BinOp, ConstValue, NonDivergingIntrinsic};
10-
use rustc_middle::ty::layout::{TyAndLayout, ValidityRequirement};
10+
use rustc_middle::ty::layout::TyAndLayout;
1111
use rustc_middle::ty::{Ty, TyCtxt};
1212
use rustc_middle::{bug, ty};
1313
use rustc_span::{Symbol, sym};
@@ -17,8 +17,8 @@ use super::memory::MemoryKind;
1717
use super::util::ensure_monomorphic_enough;
1818
use super::{
1919
Allocation, CheckInAllocMsg, ConstAllocation, ImmTy, InterpCx, InterpResult, Machine, OpTy,
20-
PlaceTy, Pointer, PointerArithmetic, Provenance, Scalar, err_inval, err_ub_custom,
21-
err_unsup_format, interp_ok, throw_inval, throw_ub_custom, throw_ub_format,
20+
PlaceTy, Pointer, PointerArithmetic, Provenance, Scalar, err_ub_custom, err_unsup_format,
21+
interp_ok, throw_inval, throw_ub_custom, throw_ub_format,
2222
};
2323
use crate::fluent_generated as fluent;
2424

@@ -372,41 +372,6 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
372372
self.exact_div(&val, &size, dest)?;
373373
}
374374

375-
sym::assert_inhabited
376-
| sym::assert_zero_valid
377-
| sym::assert_mem_uninitialized_valid => {
378-
let ty = instance.args.type_at(0);
379-
let requirement = ValidityRequirement::from_intrinsic(intrinsic_name).unwrap();
380-
381-
let should_panic = !self
382-
.tcx
383-
.check_validity_requirement((requirement, self.typing_env.as_query_input(ty)))
384-
.map_err(|_| err_inval!(TooGeneric))?;
385-
386-
if should_panic {
387-
let layout = self.layout_of(ty)?;
388-
389-
let msg = match requirement {
390-
// For *all* intrinsics we first check `is_uninhabited` to give a more specific
391-
// error message.
392-
_ if layout.is_uninhabited() => format!(
393-
"aborted execution: attempted to instantiate uninhabited type `{ty}`"
394-
),
395-
ValidityRequirement::Inhabited => bug!("handled earlier"),
396-
ValidityRequirement::Zero => format!(
397-
"aborted execution: attempted to zero-initialize type `{ty}`, which is invalid"
398-
),
399-
ValidityRequirement::UninitMitigated0x01Fill => format!(
400-
"aborted execution: attempted to leave type `{ty}` uninitialized, which is invalid"
401-
),
402-
ValidityRequirement::Uninit => bug!("assert_uninit_valid doesn't exist"),
403-
};
404-
405-
M::panic_nounwind(self, &msg)?;
406-
// Skip the `return_to_block` at the end (we panicked, we do not return).
407-
return interp_ok(true);
408-
}
409-
}
410375
sym::simd_insert => {
411376
let index = u64::from(self.read_scalar(&args[1])?.to_u32()?);
412377
let elem = &args[2];

‎library/core/src/intrinsics/mod.rs

Lines changed: 8 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -472,7 +472,8 @@ pub fn select_unpredictable<T>(b: bool, true_val: T, false_val: T) -> T {
472472
}
473473

474474
/// A guard for unsafe functions that cannot ever be executed if `T` is uninhabited:
475-
/// This will statically either panic, or do nothing.
475+
/// This will statically either panic, or do nothing. It does not *guarantee* to ever panic,
476+
/// and should only be called if an assertion failure will imply language UB in the following code.
476477
///
477478
/// This intrinsic does not have a stable counterpart.
478479
#[rustc_intrinsic_const_stable_indirect]
@@ -481,15 +482,19 @@ pub fn select_unpredictable<T>(b: bool, true_val: T, false_val: T) -> T {
481482
pub const fn assert_inhabited<T>();
482483

483484
/// A guard for unsafe functions that cannot ever be executed if `T` does not permit
484-
/// zero-initialization: This will statically either panic, or do nothing.
485+
/// zero-initialization: This will statically either panic, or do nothing. It does not *guarantee*
486+
/// to ever panic, and should only be called if an assertion failure will imply language UB in the
487+
/// following code.
485488
///
486489
/// This intrinsic does not have a stable counterpart.
487490
#[rustc_intrinsic_const_stable_indirect]
488491
#[rustc_nounwind]
489492
#[rustc_intrinsic]
490493
pub const fn assert_zero_valid<T>();
491494

492-
/// A guard for `std::mem::uninitialized`. This will statically either panic, or do nothing.
495+
/// A guard for `std::mem::uninitialized`. This will statically either panic, or do nothing. It does
496+
/// not *guarantee* to ever panic, and should only be called if an assertion failure will imply
497+
/// language UB in the following code.
493498
///
494499
/// This intrinsic does not have a stable counterpart.
495500
#[rustc_intrinsic_const_stable_indirect]

‎library/core/src/mem/maybe_uninit.rs

Lines changed: 3 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -616,7 +616,9 @@ impl<T> MaybeUninit<T> {
616616
// This also means that `self` must be a `value` variant.
617617
unsafe {
618618
intrinsics::assert_inhabited::<T>();
619-
ManuallyDrop::into_inner(self.value)
619+
// We do this via a raw ptr read instead of `ManuallyDrop::into_inner` so that there's
620+
// no trace of `ManuallyDrop` in Miri's error messages here.
621+
(&raw const self.value).cast::<T>().read()
620622
}
621623
}
622624

‎src/tools/miri/src/intrinsics/mod.rs

Lines changed: 4 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -457,6 +457,10 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
457457
throw_machine_stop!(TerminationInfo::Abort(format!("trace/breakpoint trap")))
458458
}
459459

460+
"assert_inhabited" | "assert_zero_valid" | "assert_mem_uninitialized_valid" => {
461+
// Make these a NOP, so we get the better Miri-native error messages.
462+
}
463+
460464
_ => return interp_ok(EmulateItemResult::NotSupported),
461465
}
462466

‎src/tools/miri/tests/fail-dep/libc/libc-read-and-uninit-premature-eof.rs

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -20,7 +20,7 @@ fn main() {
2020
let mut buf: MaybeUninit<[u8; 4]> = std::mem::MaybeUninit::uninit();
2121
// Read 4 bytes from a 3-byte file.
2222
assert_eq!(libc::read(fd, buf.as_mut_ptr().cast::<std::ffi::c_void>(), 4), 3);
23-
buf.assume_init(); //~ERROR: Undefined Behavior: constructing invalid value at .value[3]: encountered uninitialized memory, but expected an integer
23+
buf.assume_init(); //~ERROR: encountered uninitialized memory, but expected an integer
2424
assert_eq!(libc::close(fd), 0);
2525
}
2626
remove_file(&path).unwrap();

‎src/tools/miri/tests/fail-dep/libc/libc-read-and-uninit-premature-eof.stderr

Lines changed: 3 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -1,8 +1,8 @@
1-
error: Undefined Behavior: constructing invalid value at .value[3]: encountered uninitialized memory, but expected an integer
1+
error: Undefined Behavior: constructing invalid value at [3]: encountered uninitialized memory, but expected an integer
22
--> tests/fail-dep/libc/libc-read-and-uninit-premature-eof.rs:LL:CC
33
|
4-
LL | ... buf.assume_init();
5-
| ^^^^^^^^^^^^^^^^^ Undefined Behavior occurred here
4+
LL | buf.assume_init();
5+
| ^^^^^^^^^^^^^^^^^ Undefined Behavior occurred here
66
|
77
= help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
88
= help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information

‎src/tools/miri/tests/fail/intrinsics/uninit_uninhabited_type.rs

Lines changed: 1 addition & 6 deletions
Original file line numberDiff line numberDiff line change
@@ -1,11 +1,6 @@
1-
//@normalize-stderr-test: "\|.*::abort\(\).*" -> "| ABORT()"
2-
//@normalize-stderr-test: "\| +\^+" -> "| ^"
3-
//@normalize-stderr-test: "\n +[0-9]+:[^\n]+" -> ""
4-
//@normalize-stderr-test: "\n +at [^\n]+" -> ""
5-
//@error-in-other-file: aborted execution
61
#![feature(never_type)]
72

83
#[allow(deprecated, invalid_value)]
94
fn main() {
10-
let _ = unsafe { std::mem::uninitialized::<!>() };
5+
let _ = unsafe { std::mem::uninitialized::<!>() }; //~ERROR: constructing invalid value
116
}

‎src/tools/miri/tests/fail/intrinsics/uninit_uninhabited_type.stderr

Lines changed: 7 additions & 21 deletions
Original file line numberDiff line numberDiff line change
@@ -1,27 +1,13 @@
1-
2-
thread 'main' panicked at RUSTLIB/core/src/panicking.rs:LL:CC:
3-
aborted execution: attempted to instantiate uninhabited type `!`
4-
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
5-
note: in Miri, you may have to set `MIRIFLAGS=-Zmiri-env-forward=RUST_BACKTRACE` for the environment variable to have an effect
6-
thread caused non-unwinding panic. aborting.
7-
error: abnormal termination: the program aborted execution
8-
--> RUSTLIB/std/src/sys/pal/PLATFORM/mod.rs:LL:CC
9-
|
10-
LL | ABORT()
11-
| ^ abnormal termination occurred here
12-
|
13-
= note: BACKTRACE:
14-
= note: inside `std::sys::pal::PLATFORM::abort_internal` at RUSTLIB/std/src/sys/pal/PLATFORM/mod.rs:LL:CC
15-
= note: inside `std::panicking::rust_panic_with_hook` at RUSTLIB/std/src/panicking.rs:LL:CC
16-
= note: inside closure at RUSTLIB/std/src/panicking.rs:LL:CC
17-
= note: inside `std::sys::backtrace::__rust_end_short_backtrace::<{closure@std::panicking::begin_panic_handler::{closure#0}}, !>` at RUSTLIB/std/src/sys/backtrace.rs:LL:CC
18-
= note: inside `std::panicking::begin_panic_handler` at RUSTLIB/std/src/panicking.rs:LL:CC
19-
= note: inside `core::panicking::panic_nounwind` at RUSTLIB/core/src/panicking.rs:LL:CC
20-
note: inside `main`
1+
error: Undefined Behavior: constructing invalid value: encountered a value of the never type `!`
212
--> tests/fail/intrinsics/uninit_uninhabited_type.rs:LL:CC
223
|
234
LL | let _ = unsafe { std::mem::uninitialized::<!>() };
24-
| ^
5+
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Undefined Behavior occurred here
6+
|
7+
= help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
8+
= help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information
9+
= note: BACKTRACE:
10+
= note: inside `main` at tests/fail/intrinsics/uninit_uninhabited_type.rs:LL:CC
2511

2612
note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
2713

‎src/tools/miri/tests/fail/intrinsics/zero_fn_ptr.rs

Lines changed: 1 addition & 7 deletions
Original file line numberDiff line numberDiff line change
@@ -1,10 +1,4 @@
1-
//@normalize-stderr-test: "\|.*::abort\(\).*" -> "| ABORT()"
2-
//@normalize-stderr-test: "\| +\^+" -> "| ^"
3-
//@normalize-stderr-test: "\n +[0-9]+:[^\n]+" -> ""
4-
//@normalize-stderr-test: "\n +at [^\n]+" -> ""
5-
//@error-in-other-file: aborted execution
6-
71
#[allow(deprecated, invalid_value)]
82
fn main() {
9-
let _ = unsafe { std::mem::zeroed::<fn()>() };
3+
let _ = unsafe { std::mem::zeroed::<fn()>() }; //~ERROR: constructing invalid value
104
}

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