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Rollup merge of #126833 - RalfJung:extern-type-field-ice, r=compiler-errors
don't ICE when encountering an extern type field during validation "extern type" is a pain that keeps on giving... Fixes #126814 r? ```@oli-obk```
2 parents 0a7adaf + 763e313 commit a9959bd

15 files changed

+96
-81
lines changed

‎compiler/rustc_const_eval/messages.ftl

+2
Original file line numberDiff line numberDiff line change
@@ -89,6 +89,8 @@ const_eval_exact_div_has_remainder =
8989
9090
const_eval_extern_static =
9191
cannot access extern static ({$did})
92+
const_eval_extern_type_field = `extern type` field does not have a known offset
93+
9294
const_eval_fn_ptr_call =
9395
function pointers need an RFC before allowed to be called in {const_eval_const_context}s
9496
const_eval_for_loop_into_iter_non_const =

‎compiler/rustc_const_eval/src/const_eval/eval_queries.rs

+44-32
Original file line numberDiff line numberDiff line change
@@ -386,33 +386,8 @@ fn eval_in_interpreter<'tcx, R: InterpretationResult<'tcx>>(
386386
CompileTimeMachine::new(CanAccessMutGlobal::from(is_static), CheckAlignment::Error),
387387
);
388388
let res = ecx.load_mir(cid.instance.def, cid.promoted);
389-
res.and_then(|body| eval_body_using_ecx(&mut ecx, cid, body)).map_err(|error| {
390-
let (error, backtrace) = error.into_parts();
391-
backtrace.print_backtrace();
392-
393-
let (kind, instance) = if ecx.tcx.is_static(cid.instance.def_id()) {
394-
("static", String::new())
395-
} else {
396-
// If the current item has generics, we'd like to enrich the message with the
397-
// instance and its args: to show the actual compile-time values, in addition to
398-
// the expression, leading to the const eval error.
399-
let instance = &cid.instance;
400-
if !instance.args.is_empty() {
401-
let instance = with_no_trimmed_paths!(instance.to_string());
402-
("const_with_path", instance)
403-
} else {
404-
("const", String::new())
405-
}
406-
};
407-
408-
super::report(
409-
*ecx.tcx,
410-
error,
411-
DUMMY_SP,
412-
|| super::get_span_and_frames(ecx.tcx, ecx.stack()),
413-
|span, frames| ConstEvalError { span, error_kind: kind, instance, frame_notes: frames },
414-
)
415-
})
389+
res.and_then(|body| eval_body_using_ecx(&mut ecx, cid, body))
390+
.map_err(|error| report_eval_error(&ecx, cid, error))
416391
}
417392

418393
#[inline(always)]
@@ -438,24 +413,61 @@ fn const_validate_mplace<'tcx>(
438413
ecx.const_validate_operand(&mplace.into(), path, &mut ref_tracking, mode)
439414
// Instead of just reporting the `InterpError` via the usual machinery, we give a more targeted
440415
// error about the validation failure.
441-
.map_err(|error| report_validation_error(&ecx, error, alloc_id))?;
416+
.map_err(|error| report_validation_error(&ecx, cid, error, alloc_id))?;
442417
inner = true;
443418
}
444419

445420
Ok(())
446421
}
447422

448-
#[inline(always)]
423+
#[inline(never)]
424+
fn report_eval_error<'tcx>(
425+
ecx: &InterpCx<'tcx, CompileTimeMachine<'tcx>>,
426+
cid: GlobalId<'tcx>,
427+
error: InterpErrorInfo<'tcx>,
428+
) -> ErrorHandled {
429+
let (error, backtrace) = error.into_parts();
430+
backtrace.print_backtrace();
431+
432+
let (kind, instance) = if ecx.tcx.is_static(cid.instance.def_id()) {
433+
("static", String::new())
434+
} else {
435+
// If the current item has generics, we'd like to enrich the message with the
436+
// instance and its args: to show the actual compile-time values, in addition to
437+
// the expression, leading to the const eval error.
438+
let instance = &cid.instance;
439+
if !instance.args.is_empty() {
440+
let instance = with_no_trimmed_paths!(instance.to_string());
441+
("const_with_path", instance)
442+
} else {
443+
("const", String::new())
444+
}
445+
};
446+
447+
super::report(
448+
*ecx.tcx,
449+
error,
450+
DUMMY_SP,
451+
|| super::get_span_and_frames(ecx.tcx, ecx.stack()),
452+
|span, frames| ConstEvalError { span, error_kind: kind, instance, frame_notes: frames },
453+
)
454+
}
455+
456+
#[inline(never)]
449457
fn report_validation_error<'tcx>(
450458
ecx: &InterpCx<'tcx, CompileTimeMachine<'tcx>>,
459+
cid: GlobalId<'tcx>,
451460
error: InterpErrorInfo<'tcx>,
452461
alloc_id: AllocId,
453462
) -> ErrorHandled {
463+
if !matches!(error.kind(), InterpError::UndefinedBehavior(_)) {
464+
// Some other error happened during validation, e.g. an unsupported operation.
465+
return report_eval_error(ecx, cid, error);
466+
}
467+
454468
let (error, backtrace) = error.into_parts();
455469
backtrace.print_backtrace();
456470

457-
let ub_note = matches!(error, InterpError::UndefinedBehavior(_)).then(|| {});
458-
459471
let bytes = ecx.print_alloc_bytes_for_diagnostics(alloc_id);
460472
let (size, align, _) = ecx.get_alloc_info(alloc_id);
461473
let raw_bytes = errors::RawBytesNote { size: size.bytes(), align: align.bytes(), bytes };
@@ -465,6 +477,6 @@ fn report_validation_error<'tcx>(
465477
error,
466478
DUMMY_SP,
467479
|| crate::const_eval::get_span_and_frames(ecx.tcx, ecx.stack()),
468-
move |span, frames| errors::ValidationFailure { span, ub_note, frames, raw_bytes },
480+
move |span, frames| errors::ValidationFailure { span, ub_note: (), frames, raw_bytes },
469481
)
470482
}

‎compiler/rustc_const_eval/src/errors.rs

+6-2
Original file line numberDiff line numberDiff line change
@@ -425,7 +425,7 @@ pub struct ValidationFailure {
425425
#[primary_span]
426426
pub span: Span,
427427
#[note(const_eval_validation_failure_note)]
428-
pub ub_note: Option<()>,
428+
pub ub_note: (),
429429
#[subdiagnostic]
430430
pub frames: Vec<FrameNote>,
431431
#[subdiagnostic]
@@ -825,6 +825,7 @@ impl ReportErrorExt for UnsupportedOpInfo {
825825
use crate::fluent_generated::*;
826826
match self {
827827
UnsupportedOpInfo::Unsupported(s) => s.clone().into(),
828+
UnsupportedOpInfo::ExternTypeField => const_eval_extern_type_field,
828829
UnsupportedOpInfo::UnsizedLocal => const_eval_unsized_local,
829830
UnsupportedOpInfo::OverwritePartialPointer(_) => const_eval_partial_pointer_overwrite,
830831
UnsupportedOpInfo::ReadPartialPointer(_) => const_eval_partial_pointer_copy,
@@ -845,7 +846,10 @@ impl ReportErrorExt for UnsupportedOpInfo {
845846
// `ReadPointerAsInt(Some(info))` is never printed anyway, it only serves as an error to
846847
// be further processed by validity checking which then turns it into something nice to
847848
// print. So it's not worth the effort of having diagnostics that can print the `info`.
848-
UnsizedLocal | Unsupported(_) | ReadPointerAsInt(_) => {}
849+
UnsizedLocal
850+
| UnsupportedOpInfo::ExternTypeField
851+
| Unsupported(_)
852+
| ReadPointerAsInt(_) => {}
849853
OverwritePartialPointer(ptr) | ReadPartialPointer(ptr) => {
850854
diag.arg("ptr", ptr);
851855
}

‎compiler/rustc_const_eval/src/interpret/projection.rs

+3-3
Original file line numberDiff line numberDiff line change
@@ -21,7 +21,7 @@ use rustc_target::abi::{self, VariantIdx};
2121
use tracing::{debug, instrument};
2222

2323
use super::{
24-
throw_ub, throw_unsup_format, InterpCx, InterpResult, MPlaceTy, Machine, MemPlaceMeta, OpTy,
24+
throw_ub, throw_unsup, InterpCx, InterpResult, MPlaceTy, Machine, MemPlaceMeta, OpTy,
2525
Provenance, Scalar,
2626
};
2727

@@ -186,8 +186,8 @@ where
186186
(base_meta, offset)
187187
}
188188
None => {
189-
// We don't know the alignment of this field, so we cannot adjust.
190-
throw_unsup_format!("`extern type` does not have a known offset")
189+
// We cannot know the alignment of this field, so we cannot adjust.
190+
throw_unsup!(ExternTypeField)
191191
}
192192
}
193193
} else {

‎compiler/rustc_const_eval/src/interpret/validity.rs

+6-4
Original file line numberDiff line numberDiff line change
@@ -5,6 +5,7 @@
55
//! to be const-safe.
66
77
use std::fmt::Write;
8+
use std::hash::Hash;
89
use std::num::NonZero;
910

1011
use either::{Left, Right};
@@ -17,7 +18,8 @@ use rustc_hir as hir;
1718
use rustc_middle::bug;
1819
use rustc_middle::mir::interpret::{
1920
ExpectedKind, InterpError, InvalidMetaKind, Misalignment, PointerKind, Provenance,
20-
ValidationErrorInfo, ValidationErrorKind, ValidationErrorKind::*,
21+
UnsupportedOpInfo, ValidationErrorInfo,
22+
ValidationErrorKind::{self, *},
2123
};
2224
use rustc_middle::ty::layout::{LayoutOf, TyAndLayout};
2325
use rustc_middle::ty::{self, Ty};
@@ -26,8 +28,6 @@ use rustc_target::abi::{
2628
Abi, FieldIdx, Scalar as ScalarAbi, Size, VariantIdx, Variants, WrappingRange,
2729
};
2830

29-
use std::hash::Hash;
30-
3131
use super::{
3232
err_ub, format_interp_error, machine::AllocMap, throw_ub, AllocId, AllocKind, CheckInAllocMsg,
3333
GlobalAlloc, ImmTy, Immediate, InterpCx, InterpResult, MPlaceTy, Machine, MemPlaceMeta, OpTy,
@@ -1028,7 +1028,9 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
10281028
Err(err)
10291029
if matches!(
10301030
err.kind(),
1031-
err_ub!(ValidationError { .. }) | InterpError::InvalidProgram(_)
1031+
err_ub!(ValidationError { .. })
1032+
| InterpError::InvalidProgram(_)
1033+
| InterpError::Unsupported(UnsupportedOpInfo::ExternTypeField)
10321034
) =>
10331035
{
10341036
Err(err)

‎compiler/rustc_middle/src/mir/interpret/error.rs

+2
Original file line numberDiff line numberDiff line change
@@ -520,6 +520,8 @@ pub enum UnsupportedOpInfo {
520520
Unsupported(String),
521521
/// Unsized local variables.
522522
UnsizedLocal,
523+
/// Extern type field with an indeterminate offset.
524+
ExternTypeField,
523525
//
524526
// The variants below are only reachable from CTFE/const prop, miri will never emit them.
525527
//

‎src/tools/miri/src/diagnostics.rs

+3-1
Original file line numberDiff line numberDiff line change
@@ -311,7 +311,9 @@ pub fn report_error<'tcx>(
311311
ResourceExhaustion(_) => "resource exhaustion",
312312
Unsupported(
313313
// We list only the ones that can actually happen.
314-
UnsupportedOpInfo::Unsupported(_) | UnsupportedOpInfo::UnsizedLocal,
314+
UnsupportedOpInfo::Unsupported(_)
315+
| UnsupportedOpInfo::UnsizedLocal
316+
| UnsupportedOpInfo::ExternTypeField,
315317
) => "unsupported operation",
316318
InvalidProgram(
317319
// We list only the ones that can actually happen.

‎src/tools/miri/tests/fail/extern-type-field-offset.stderr

+2-2
Original file line numberDiff line numberDiff line change
@@ -1,8 +1,8 @@
1-
error: unsupported operation: `extern type` does not have a known offset
1+
error: unsupported operation: `extern type` field does not have a known offset
22
--> $DIR/extern-type-field-offset.rs:LL:CC
33
|
44
LL | let _field = &x.a;
5-
| ^^^^ `extern type` does not have a known offset
5+
| ^^^^ `extern type` field does not have a known offset
66
|
77
= help: this is likely not a bug in the program; it indicates that the program performed an operation that Miri does not support
88
= note: BACKTRACE:

‎tests/ui/consts/const-eval/issue-91827-extern-types-field-offset.stderr

+1-1
Original file line numberDiff line numberDiff line change
@@ -2,7 +2,7 @@ error[E0080]: evaluation of constant value failed
22
--> $DIR/issue-91827-extern-types-field-offset.rs:38:17
33
|
44
LL | let field = &x.a;
5-
| ^^^^ `extern type` does not have a known offset
5+
| ^^^^ `extern type` field does not have a known offset
66

77
error: aborting due to 1 previous error
88

‎tests/ui/consts/const-eval/validation-ice-extern-type-field.rs

+15
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,15 @@
1+
#![feature(extern_types)]
2+
3+
extern {
4+
type Opaque;
5+
}
6+
7+
struct ThinDst {
8+
x: u8,
9+
tail: Opaque,
10+
}
11+
12+
const C1: &ThinDst = unsafe { std::mem::transmute(b"d".as_ptr()) };
13+
//~^ERROR: evaluation of constant value failed
14+
15+
fn main() {}

‎tests/ui/consts/const-eval/validation-ice-extern-type-field.stderr

+9
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,9 @@
1+
error[E0080]: evaluation of constant value failed
2+
--> $DIR/validation-ice-extern-type-field.rs:12:1
3+
|
4+
LL | const C1: &ThinDst = unsafe { std::mem::transmute(b"d".as_ptr()) };
5+
| ^^^^^^^^^^^^^^^^^^ `extern type` field does not have a known offset
6+
7+
error: aborting due to 1 previous error
8+
9+
For more information about this error, try `rustc --explain E0080`.

‎tests/ui/sized/stack-overflow-trait-infer-98842.32bit.stderr

+1-5
Original file line numberDiff line numberDiff line change
@@ -9,15 +9,11 @@ LL | const _: *const Foo = 0 as _;
99
| ^^^^^^^^^^^^^^^^^^^
1010
= note: see https://rustc-dev-guide.rust-lang.org/overview.html#queries and https://rustc-dev-guide.rust-lang.org/query.html for more information
1111

12-
error[E0080]: it is undefined behavior to use this value
12+
error[E0080]: evaluation of constant value failed
1313
--> $DIR/stack-overflow-trait-infer-98842.rs:15:1
1414
|
1515
LL | const _: *const Foo = 0 as _;
1616
| ^^^^^^^^^^^^^^^^^^^ a cycle occurred during layout computation
17-
|
18-
= note: the raw bytes of the constant (size: 4, align: 4) {
19-
00 00 00 00 │ ....
20-
}
2117

2218
error: aborting due to 2 previous errors
2319

‎tests/ui/sized/stack-overflow-trait-infer-98842.64bit.stderr

+1-5
Original file line numberDiff line numberDiff line change
@@ -9,15 +9,11 @@ LL | const _: *const Foo = 0 as _;
99
| ^^^^^^^^^^^^^^^^^^^
1010
= note: see https://rustc-dev-guide.rust-lang.org/overview.html#queries and https://rustc-dev-guide.rust-lang.org/query.html for more information
1111

12-
error[E0080]: it is undefined behavior to use this value
12+
error[E0080]: evaluation of constant value failed
1313
--> $DIR/stack-overflow-trait-infer-98842.rs:15:1
1414
|
1515
LL | const _: *const Foo = 0 as _;
1616
| ^^^^^^^^^^^^^^^^^^^ a cycle occurred during layout computation
17-
|
18-
= note: the raw bytes of the constant (size: 8, align: 8) {
19-
00 00 00 00 00 00 00 00 │ ........
20-
}
2117

2218
error: aborting due to 2 previous errors
2319

‎tests/ui/sized/stack-overflow-trait-infer-98842.rs

+1-1
Original file line numberDiff line numberDiff line change
@@ -13,6 +13,6 @@ struct Foo(<&'static Foo as ::core::ops::Deref>::Target);
1313
// and it will infinitely recurse somewhere trying to figure out the
1414
// size of this pointer (is my guess):
1515
const _: *const Foo = 0 as _;
16-
//~^ ERROR it is undefined behavior to use this value
16+
//~^ ERROR evaluation of constant value failed
1717

1818
pub fn main() {}

‎tests/ui/sized/stack-overflow-trait-infer-98842.stderr

-25
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