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Jun 9, 2025
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const-eval error: always say in which item the error occurred #142008

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8 changes: 3 additions & 5 deletions compiler/rustc_const_eval/messages.ftl
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Expand Up @@ -88,11 +88,9 @@ const_eval_division_overflow =
const_eval_dyn_call_not_a_method =
`dyn` call trying to call something that is not a method

const_eval_error = {$error_kind ->
[static] evaluation of static initializer failed here
[const] evaluation of constant value failed here
[const_with_path] evaluation of `{$instance}` failed here
*[other] {""}
const_eval_error = evaluation of `{$instance}` failed {$num_frames ->
[0] here
*[other] inside this call
}

const_eval_exact_div_has_remainder =
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18 changes: 3 additions & 15 deletions compiler/rustc_const_eval/src/const_eval/eval_queries.rs
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Expand Up @@ -430,27 +430,15 @@ fn report_eval_error<'tcx>(
let (error, backtrace) = error.into_parts();
backtrace.print_backtrace();

let (kind, instance) = if ecx.tcx.is_static(cid.instance.def_id()) {
("static", String::new())
} else {
// If the current item has generics, we'd like to enrich the message with the
// instance and its args: to show the actual compile-time values, in addition to
// the expression, leading to the const eval error.
let instance = &cid.instance;
if !instance.args.is_empty() {
let instance = with_no_trimmed_paths!(instance.to_string());
("const_with_path", instance)
} else {
("const", String::new())
}
};
let instance = with_no_trimmed_paths!(cid.instance.to_string());
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@RalfJung would it be possible to reuse some of the machinery from #137201 to ensure that long types aren't printed to the terminal, and instead get written to disk?

I saw a test with content like "evaluation of <() as ConstGenericTrait<{my_fn(2)}>>::{constant#0} failed inside this call" and I'm concerned that we could easily end up with really verbose output unnecessarily.

p-low

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@RalfJung RalfJung Jul 14, 2025 •
edited
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Possible? Probably. But it might be very hard...
And I am sure const-eval is not the only component putting types into the output, so this seems to me to demand a more fundamental solution than playing whack-a-mole with compiler components putting types into their diagnostics.

Please file an issue.

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Do note that structured errors can display anything that implements IntoDiagArg as text, so a structured error that has a Ty<'_> field then it gets evaluated by the long type trimming logic, so we get that behavior for free when using structured errors.

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Ah, maybe there's a way to use that here... but generally structured errors have caused huge amounts of pain and boilerplate in const-eval so we have some loose plans to get rid of them again.


super::report(
*ecx.tcx,
error,
DUMMY_SP,
|| super::get_span_and_frames(ecx.tcx, ecx.stack()),
|diag, span, frames| {
let num_frames = frames.len();
// FIXME(oli-obk): figure out how to use structured diagnostics again.
diag.code(E0080);
diag.span_label(span, crate::fluent_generated::const_eval_error);
Expand All @@ -459,7 +447,7 @@ fn report_eval_error<'tcx>(
}
// Add after the frame rendering above, as it adds its own `instance` args.
diag.arg("instance", instance);
diag.arg("error_kind", kind);
diag.arg("num_frames", num_frames);
},
)
}
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2 changes: 1 addition & 1 deletion src/tools/miri/tests/fail/const-ub-checks.stderr
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Expand Up @@ -2,7 +2,7 @@ error[E0080]: accessing memory based on pointer with alignment ALIGN, but alignm
--> tests/fail/const-ub-checks.rs:LL:CC
|
LL | ptr.read();
| ^^^^^^^^^^ evaluation of constant value failed here
| ^^^^^^^^^^ evaluation of `UNALIGNED_READ` failed here

note: erroneous constant encountered
--> tests/fail/const-ub-checks.rs:LL:CC
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2 changes: 1 addition & 1 deletion src/tools/miri/tests/fail/erroneous_const2.stderr
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Expand Up @@ -2,7 +2,7 @@ error[E0080]: attempt to compute `5_u32 - 6_u32`, which would overflow
--> tests/fail/erroneous_const2.rs:LL:CC
|
LL | const FOO: u32 = [X - Y, Y - X][(X < Y) as usize];
| ^^^^^ evaluation of constant value failed here
| ^^^^^ evaluation of `FOO` failed here

note: erroneous constant encountered
--> tests/fail/erroneous_const2.rs:LL:CC
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2 changes: 1 addition & 1 deletion tests/rustdoc-ui/const-evalutation-ice.stderr
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Expand Up @@ -2,7 +2,7 @@ error[E0080]: attempt to compute `0_usize - 1_usize`, which would overflow
--> $DIR/const-evalutation-ice.rs:10:22
|
LL | pub const N: usize = 0 - (mem::size_of::<S>() != 400) as usize;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ evaluation of constant value failed here
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ evaluation of `N` failed here

error: aborting due to 1 previous error

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2 changes: 1 addition & 1 deletion tests/ui/array-slice-vec/array_const_index-0.stderr
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Expand Up @@ -2,7 +2,7 @@ error[E0080]: index out of bounds: the length is 0 but the index is 1
--> $DIR/array_const_index-0.rs:2:16
|
LL | const B: i32 = (&A)[1];
| ^^^^^^^ evaluation of constant value failed here
| ^^^^^^^ evaluation of `B` failed here

error: aborting due to 1 previous error

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2 changes: 1 addition & 1 deletion tests/ui/array-slice-vec/array_const_index-1.stderr
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Expand Up @@ -2,7 +2,7 @@ error[E0080]: index out of bounds: the length is 0 but the index is 1
--> $DIR/array_const_index-1.rs:2:16
|
LL | const B: i32 = A[1];
| ^^^^ evaluation of constant value failed here
| ^^^^ evaluation of `B` failed here

error: aborting due to 1 previous error

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2 changes: 1 addition & 1 deletion tests/ui/borrowck/issue-81899.stderr
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Expand Up @@ -2,7 +2,7 @@ error[E0080]: evaluation panicked: explicit panic
--> $DIR/issue-81899.rs:6:24
|
LL | const _CONST: &[u8] = &f(&[], |_| {});
| ^^^^^^^^^^^^^^ evaluation of constant value failed here
| ^^^^^^^^^^^^^^ evaluation of `_CONST` failed inside this call
|
note: inside `f::<{closure@$DIR/issue-81899.rs:6:31: 6:34}>`
--> $DIR/issue-81899.rs:13:5
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2 changes: 1 addition & 1 deletion tests/ui/borrowck/issue-88434-minimal-example.stderr
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Expand Up @@ -2,7 +2,7 @@ error[E0080]: evaluation panicked: explicit panic
--> $DIR/issue-88434-minimal-example.rs:5:22
|
LL | const _CONST: &() = &f(&|_| {});
| ^^^^^^^^^^ evaluation of constant value failed here
| ^^^^^^^^^^ evaluation of `_CONST` failed inside this call
|
note: inside `f::<{closure@$DIR/issue-88434-minimal-example.rs:5:25: 5:28}>`
--> $DIR/issue-88434-minimal-example.rs:12:5
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2 changes: 1 addition & 1 deletion tests/ui/borrowck/issue-88434-removal-index-should-be-less.stderr
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Expand Up @@ -2,7 +2,7 @@ error[E0080]: evaluation panicked: explicit panic
--> $DIR/issue-88434-removal-index-should-be-less.rs:5:24
|
LL | const _CONST: &[u8] = &f(&[], |_| {});
| ^^^^^^^^^^^^^^ evaluation of constant value failed here
| ^^^^^^^^^^^^^^ evaluation of `_CONST` failed inside this call
|
note: inside `f::<{closure@$DIR/issue-88434-removal-index-should-be-less.rs:5:31: 5:34}>`
--> $DIR/issue-88434-removal-index-should-be-less.rs:12:5
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4 changes: 2 additions & 2 deletions tests/ui/coherence/const-errs-dont-conflict-103369.stderr
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Expand Up @@ -2,7 +2,7 @@ error[E0080]: evaluation panicked: Some error occurred
--> $DIR/const-errs-dont-conflict-103369.rs:5:25
|
LL | impl ConstGenericTrait<{my_fn(1)}> for () {}
| ^^^^^^^^ evaluation of constant value failed here
| ^^^^^^^^ evaluation of `<() as ConstGenericTrait<{my_fn(1)}>>::{constant#0}` failed inside this call
|
note: inside `my_fn`
--> $DIR/const-errs-dont-conflict-103369.rs:10:5
Expand All @@ -14,7 +14,7 @@ error[E0080]: evaluation panicked: Some error occurred
--> $DIR/const-errs-dont-conflict-103369.rs:7:25
|
LL | impl ConstGenericTrait<{my_fn(2)}> for () {}
| ^^^^^^^^ evaluation of constant value failed here
| ^^^^^^^^ evaluation of `<() as ConstGenericTrait<{my_fn(2)}>>::{constant#0}` failed inside this call
|
note: inside `my_fn`
--> $DIR/const-errs-dont-conflict-103369.rs:10:5
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2 changes: 1 addition & 1 deletion tests/ui/const-generics/defaults/default-param-wf-concrete.next.stderr
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Expand Up @@ -2,7 +2,7 @@ error[E0080]: attempt to compute `u8::MAX + 1_u8`, which would overflow
--> $DIR/default-param-wf-concrete.rs:4:28
|
LL | struct Foo<const N: u8 = { 255 + 1 }>;
| ^^^^^^^ evaluation of constant value failed here
| ^^^^^^^ evaluation of `Foo::{constant#0}` failed here

error: aborting due to 1 previous error

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2 changes: 1 addition & 1 deletion tests/ui/const-generics/defaults/default-param-wf-concrete.old.stderr
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Expand Up @@ -2,7 +2,7 @@ error[E0080]: attempt to compute `u8::MAX + 1_u8`, which would overflow
--> $DIR/default-param-wf-concrete.rs:4:28
|
LL | struct Foo<const N: u8 = { 255 + 1 }>;
| ^^^^^^^ evaluation of constant value failed here
| ^^^^^^^ evaluation of `Foo::{constant#0}` failed here

error: aborting due to 1 previous error

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2 changes: 1 addition & 1 deletion tests/ui/const-generics/defaults/wfness.stderr
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Expand Up @@ -2,7 +2,7 @@ error[E0080]: attempt to compute `u8::MAX + 1_u8`, which would overflow
--> $DIR/wfness.rs:1:33
|
LL | struct Ooopsies<const N: u8 = { u8::MAX + 1 }>;
| ^^^^^^^^^^^ evaluation of constant value failed here
| ^^^^^^^^^^^ evaluation of `Ooopsies::{constant#0}` failed here

error[E0277]: the trait bound `(): Trait<2>` is not satisfied
--> $DIR/wfness.rs:8:9
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2 changes: 1 addition & 1 deletion tests/ui/const-generics/issues/issue-100313.stderr
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Expand Up @@ -2,7 +2,7 @@ error[E0080]: writing to ALLOC0 which is read-only
--> $DIR/issue-100313.rs:18:5
|
LL | x.set_false();
| ^^^^^^^^^^^^^ evaluation of constant value failed here
| ^^^^^^^^^^^^^ evaluation of `_` failed inside this call
|
note: inside `T::<&true>::set_false`
--> $DIR/issue-100313.rs:11:13
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4 changes: 2 additions & 2 deletions tests/ui/const-generics/min_const_generics/invalid-patterns.32bit.stderr
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Expand Up @@ -2,7 +2,7 @@ error[E0080]: using uninitialized data, but this operation requires initialized
--> $DIR/invalid-patterns.rs:40:32
|
LL | get_flag::<false, { unsafe { char_raw.character } }>();
| ^^^^^^^^^^^^^^^^^^ evaluation of constant value failed here
| ^^^^^^^^^^^^^^^^^^ evaluation of `main::{constant#7}` failed here

error[E0080]: constructing invalid value: encountered 0x42, but expected a boolean
--> $DIR/invalid-patterns.rs:42:14
Expand Down Expand Up @@ -30,7 +30,7 @@ error[E0080]: using uninitialized data, but this operation requires initialized
--> $DIR/invalid-patterns.rs:44:58
|
LL | get_flag::<{ unsafe { bool_raw.boolean } }, { unsafe { char_raw.character } }>();
| ^^^^^^^^^^^^^^^^^^ evaluation of constant value failed here
| ^^^^^^^^^^^^^^^^^^ evaluation of `main::{constant#11}` failed here

error[E0308]: mismatched types
--> $DIR/invalid-patterns.rs:31:21
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4 changes: 2 additions & 2 deletions tests/ui/const-generics/min_const_generics/invalid-patterns.64bit.stderr
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Expand Up @@ -2,7 +2,7 @@ error[E0080]: using uninitialized data, but this operation requires initialized
--> $DIR/invalid-patterns.rs:40:32
|
LL | get_flag::<false, { unsafe { char_raw.character } }>();
| ^^^^^^^^^^^^^^^^^^ evaluation of constant value failed here
| ^^^^^^^^^^^^^^^^^^ evaluation of `main::{constant#7}` failed here

error[E0080]: constructing invalid value: encountered 0x42, but expected a boolean
--> $DIR/invalid-patterns.rs:42:14
Expand Down Expand Up @@ -30,7 +30,7 @@ error[E0080]: using uninitialized data, but this operation requires initialized
--> $DIR/invalid-patterns.rs:44:58
|
LL | get_flag::<{ unsafe { bool_raw.boolean } }, { unsafe { char_raw.character } }>();
| ^^^^^^^^^^^^^^^^^^ evaluation of constant value failed here
| ^^^^^^^^^^^^^^^^^^ evaluation of `main::{constant#11}` failed here

error[E0308]: mismatched types
--> $DIR/invalid-patterns.rs:31:21
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10 changes: 5 additions & 5 deletions tests/ui/const-ptr/forbidden_slices.stderr
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Expand Up @@ -103,13 +103,13 @@ error[E0080]: evaluation panicked: assertion failed: 0 < pointee_size && pointee
--> $DIR/forbidden_slices.rs:50:33
|
LL | pub static R1: &[()] = unsafe { from_ptr_range(ptr::null()..ptr::null()) }; // errors inside libcore
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ evaluation of static initializer failed here
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ evaluation of `R1` failed here

error[E0080]: in-bounds pointer arithmetic failed: attempting to offset pointer by 8 bytes, but got ALLOC10 which is only 4 bytes from the end of the allocation
--> $DIR/forbidden_slices.rs:54:25
|
LL | from_ptr_range(ptr..ptr.add(2)) // errors inside libcore
| ^^^^^^^^^^ evaluation of static initializer failed here
| ^^^^^^^^^^ evaluation of `R2` failed here

error[E0080]: constructing invalid value at .<deref>[0]: encountered uninitialized memory, but expected an integer
--> $DIR/forbidden_slices.rs:57:1
Expand Down Expand Up @@ -161,19 +161,19 @@ error[E0080]: in-bounds pointer arithmetic failed: attempting to offset pointer
--> $DIR/forbidden_slices.rs:79:25
|
LL | from_ptr_range(ptr..ptr.add(1))
| ^^^^^^^^^^ evaluation of static initializer failed here
| ^^^^^^^^^^ evaluation of `R8` failed here

error[E0080]: `ptr_offset_from_unsigned` called on two different pointers that are not both derived from the same allocation
--> $DIR/forbidden_slices.rs:85:34
|
LL | pub static R9: &[u32] = unsafe { from_ptr_range(&D0..(&D0 as *const u32).add(1)) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ evaluation of static initializer failed here
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ evaluation of `R9` failed here

error[E0080]: `ptr_offset_from_unsigned` called on two different pointers that are not both derived from the same allocation
--> $DIR/forbidden_slices.rs:87:35
|
LL | pub static R10: &[u32] = unsafe { from_ptr_range(&D0..&D0) };
| ^^^^^^^^^^^^^^^^^^^^^^^^ evaluation of static initializer failed here
| ^^^^^^^^^^^^^^^^^^^^^^^^ evaluation of `R10` failed here

error: aborting due to 18 previous errors

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6 changes: 3 additions & 3 deletions tests/ui/const-ptr/out_of_bounds_read.stderr
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Expand Up @@ -2,19 +2,19 @@ error[E0080]: memory access failed: attempting to access 4 bytes, but got ALLOC0
--> $DIR/out_of_bounds_read.rs:8:33
|
LL | const _READ: u32 = unsafe { ptr::read(PAST_END_PTR) };
| ^^^^^^^^^^^^^^^^^^^^^^^ evaluation of constant value failed here
| ^^^^^^^^^^^^^^^^^^^^^^^ evaluation of `main::_READ` failed here

error[E0080]: memory access failed: attempting to access 4 bytes, but got ALLOC0+0x4 which is at or beyond the end of the allocation of size 4 bytes
--> $DIR/out_of_bounds_read.rs:10:39
|
LL | const _CONST_READ: u32 = unsafe { PAST_END_PTR.read() };
| ^^^^^^^^^^^^^^^^^^^ evaluation of constant value failed here
| ^^^^^^^^^^^^^^^^^^^ evaluation of `main::_CONST_READ` failed here

error[E0080]: memory access failed: attempting to access 4 bytes, but got ALLOC0+0x4 which is at or beyond the end of the allocation of size 4 bytes
--> $DIR/out_of_bounds_read.rs:12:37
|
LL | const _MUT_READ: u32 = unsafe { (PAST_END_PTR as *mut u32).read() };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ evaluation of constant value failed here
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ evaluation of `main::_MUT_READ` failed here

error: aborting due to 3 previous errors

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6 changes: 3 additions & 3 deletions tests/ui/consts/assert-type-intrinsics.stderr
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Expand Up @@ -2,19 +2,19 @@ error[E0080]: evaluation panicked: aborted execution: attempted to instantiate u
--> $DIR/assert-type-intrinsics.rs:11:9
|
LL | MaybeUninit::<!>::uninit().assume_init();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ evaluation of constant value failed here
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ evaluation of `main::_BAD1` failed here

error[E0080]: evaluation panicked: aborted execution: attempted to leave type `&i32` uninitialized, which is invalid
--> $DIR/assert-type-intrinsics.rs:15:9
|
LL | intrinsics::assert_mem_uninitialized_valid::<&'static i32>();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ evaluation of constant value failed here
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ evaluation of `main::_BAD2` failed here

error[E0080]: evaluation panicked: aborted execution: attempted to zero-initialize type `&i32`, which is invalid
--> $DIR/assert-type-intrinsics.rs:19:9
|
LL | intrinsics::assert_zero_valid::<&'static i32>();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ evaluation of constant value failed here
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ evaluation of `main::_BAD3` failed here

error: aborting due to 3 previous errors

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4 changes: 2 additions & 2 deletions tests/ui/consts/const-array-oob.stderr
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Expand Up @@ -2,13 +2,13 @@ error[E0080]: index out of bounds: the length is 3 but the index is 4
--> $DIR/const-array-oob.rs:5:19
|
LL | const BLUB: [u32; FOO[4]] = [5, 6];
| ^^^^^^ evaluation of constant value failed here
| ^^^^^^ evaluation of `BLUB::{constant#0}` failed here

error[E0080]: index out of bounds: the length is 3 but the index is 5
--> $DIR/const-array-oob.rs:2:20
|
LL | const BAR: usize = FOO[5];
| ^^^^^^ evaluation of constant value failed here
| ^^^^^^ evaluation of `BAR` failed here

error: aborting due to 2 previous errors

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2 changes: 1 addition & 1 deletion tests/ui/consts/const-assert-unchecked-ub.stderr
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Expand Up @@ -2,7 +2,7 @@ error[E0080]: `assume` called with `false`
--> $DIR/const-assert-unchecked-ub.rs:3:5
|
LL | std::hint::assert_unchecked(n < 32);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ evaluation of constant value failed here
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ evaluation of `_` failed here

error: aborting due to 1 previous error

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16 changes: 8 additions & 8 deletions tests/ui/consts/const-compare-bytes-ub.stderr
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Expand Up @@ -2,49 +2,49 @@ error[E0080]: memory access failed: attempting to access 1 byte, but got null po
--> $DIR/const-compare-bytes-ub.rs:9:9
|
LL | compare_bytes(0 as *const u8, 2 as *const u8, 1)
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ evaluation of constant value failed here
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ evaluation of `main::LHS_NULL` failed here

error[E0080]: memory access failed: attempting to access 1 byte, but got 0x1[noalloc] which is a dangling pointer (it has no provenance)
--> $DIR/const-compare-bytes-ub.rs:13:9
|
LL | compare_bytes(1 as *const u8, 0 as *const u8, 1)
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ evaluation of constant value failed here
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ evaluation of `main::RHS_NULL` failed here

error[E0080]: memory access failed: attempting to access 1 byte, but got 0x1[noalloc] which is a dangling pointer (it has no provenance)
--> $DIR/const-compare-bytes-ub.rs:17:9
|
LL | compare_bytes(1 as *const u8, 2 as *const u8, 1)
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ evaluation of constant value failed here
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ evaluation of `main::DANGLING_PTR_NON_ZERO_LENGTH` failed here

error[E0080]: memory access failed: attempting to access 4 bytes, but got ALLOC0 which is only 3 bytes from the end of the allocation
--> $DIR/const-compare-bytes-ub.rs:21:9
|
LL | compare_bytes([1, 2, 3].as_ptr(), [1, 2, 3, 4].as_ptr(), 4)
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ evaluation of constant value failed here
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ evaluation of `main::LHS_OUT_OF_BOUNDS` failed here

error[E0080]: memory access failed: attempting to access 4 bytes, but got ALLOC1 which is only 3 bytes from the end of the allocation
--> $DIR/const-compare-bytes-ub.rs:25:9
|
LL | compare_bytes([1, 2, 3, 4].as_ptr(), [1, 2, 3].as_ptr(), 4)
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ evaluation of constant value failed here
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ evaluation of `main::RHS_OUT_OF_BOUNDS` failed here

error[E0080]: reading memory at ALLOC2[0x0..0x1], but memory is uninitialized at [0x0..0x1], and this operation requires initialized memory
--> $DIR/const-compare-bytes-ub.rs:29:9
|
LL | compare_bytes(MaybeUninit::uninit().as_ptr(), [1].as_ptr(), 1)
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ evaluation of constant value failed here
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ evaluation of `main::LHS_UNINIT` failed here

error[E0080]: reading memory at ALLOC3[0x0..0x1], but memory is uninitialized at [0x0..0x1], and this operation requires initialized memory
--> $DIR/const-compare-bytes-ub.rs:33:9
|
LL | compare_bytes([1].as_ptr(), MaybeUninit::uninit().as_ptr(), 1)
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ evaluation of constant value failed here
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ evaluation of `main::RHS_UNINIT` failed here

error[E0080]: unable to turn pointer into integer
--> $DIR/const-compare-bytes-ub.rs:37:9
|
LL | compare_bytes([&1].as_ptr().cast(), [&2].as_ptr().cast(), std::mem::size_of::<usize>())
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ evaluation of constant value failed here
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ evaluation of `main::WITH_PROVENANCE` failed here
|
= help: this code performed an operation that depends on the underlying bytes representing a pointer
= help: the absolute address of a pointer is not known at compile-time, so such operations are not supported
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