ICE: `offset of not-statically-aligned field (...) cannot be computed statically` in `rustc_middle/src/ty/layout.rs`

[cushionbadak]

Code

(hand-reduced)

#![feature(builtin_syntax)]

trait MyTrait<'a> {}

struct S { f: MyTrait, }

fn t3() {
    builtin # offset_of(S, f);
}

fn main() {}

(original)

// Tests that we still detect defining usages when
// lifetimes are used in an associated opaque type
//@ check-pass

#![feature(impl_trait_in_assoc_type)]

trait UnwrapItemsExt<'a> {
    type Iter;
    fn unwrap_items(self) -> Self::Iter;
}

struct MyStruct {}

trait MyTrait<'a> {}

impl<'a> MyTrait<'a> for MyStruct {}

impl<'a, I> UnwrapItemsExt<'a> for I {
    type Iter = impl MyTrait<'a>;

    fn unwrap_items(self) -> Self::Iter {
        MyStruct {}
    }
}

fn main() {}


#![feature(builtin_syntax)]

// For the exposed macro we already test these errors in the other files,
// but this test helps to make sure the builtin construct also errors.
// This has the same examples as offset-of-arg-count.rs

fn main() {
    builtin # offset_of(NotEnoughArguments); //~ ERROR expected one of
}
fn t1() {
    builtin # offset_of(NotEnoughArgumentsWithAComma, ); //~ ERROR expected expression
}
fn t2() {
    builtin # offset_of(S, f, too many arguments); //~ ERROR expected `)`, found `too`
}
fn t3() {
    builtin # offset_of(S, f); // compiles fine
}
fn t4() {
    builtin # offset_of(S, f.); //~ ERROR unexpected token
}
fn t5() {
    builtin # offset_of(S, f.,); //~ ERROR unexpected token
}
fn t6() {
    builtin # offset_of(S, f..); //~ ERROR offset_of expects dot-separated field and variant names
}
fn t7() {
    builtin # offset_of(S, f..,); //~ ERROR offset_of expects dot-separated field and variant names
}

struct S { f: MyTrait, }

Meta

rustc --version --verbose:

rustc 1.80.0-nightly (6f3df08aa 2024-05-30)
binary: rustc
commit-hash: 6f3df08aadf71e8d4bf7e49f5dc10dfa6f254cb4
commit-date: 2024-05-30
host: x86_64-apple-darwin
release: 1.80.0-nightly
LLVM version: 18.1.6

Error output

Command: rustc

error[E0106]: missing lifetime specifier
 --> r_mod_FA6845.rs:5:15
  |
5 | struct S { f: MyTrait, }
  |               ^^^^^^^ expected named lifetime parameter
  |
help: consider introducing a named lifetime parameter
  |
5 | struct S<'a> { f: MyTrait<'a>, }
  |         ++++             ++++

warning: trait objects without an explicit `dyn` are deprecated
 --> r_mod_FA6845.rs:5:15
  |
5 | struct S { f: MyTrait, }
  |               ^^^^^^^
  |
  = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
  = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
  = note: `#[warn(bare_trait_objects)]` on by default
help: if this is an object-safe trait, use `dyn`
  |
5 | struct S { f: dyn MyTrait, }
  |               +++

Backtrace

thread 'rustc' panicked at /rustc/6f3df08aadf71e8d4bf7e49f5dc10dfa6f254cb4/compiler/rustc_target/src/abi/mod.rs:272:13:
offset of unsized field (type dyn [Binder(Trait(MyTrait<'_>), [])] + '{erased}) cannot be computed statically
stack backtrace:
   0: _rust_begin_unwind
   1: core::panicking::panic_fmt
   2: <rustc_target::abi::TyAndLayout<rustc_middle::ty::Ty>>::offset_of_subfield::<rustc_mir_transform::known_panics_lint::ConstPropagator, core::iter::adapters::copied::Copied<core::slice::iter::Iter<(rustc_target::abi::VariantIdx, rustc_target::abi::FieldIdx)>>>
   3: <rustc_mir_transform::known_panics_lint::ConstPropagator as rustc_middle::mir::visit::Visitor>::visit_assign
   4: <rustc_mir_transform::known_panics_lint::ConstPropagator as rustc_middle::mir::visit::Visitor>::visit_basic_block_data
   5: <rustc_mir_transform::known_panics_lint::ConstPropagator as rustc_middle::mir::visit::Visitor>::visit_body
   6: <rustc_mir_transform::known_panics_lint::KnownPanicsLint as rustc_mir_transform::pass_manager::MirLint>::run_lint
   7: rustc_mir_transform::pass_manager::run_passes_inner
   8: rustc_mir_transform::run_analysis_to_runtime_passes
   9: rustc_mir_transform::mir_drops_elaborated_and_const_checked
      [... omitted 1 frame ...]
  10: rustc_interface::passes::run_required_analyses
  11: rustc_interface::passes::analysis
      [... omitted 1 frame ...]
  12: <rustc_interface::queries::QueryResult<&rustc_middle::ty::context::GlobalCtxt>>::enter::<core::result::Result<(), rustc_span::ErrorGuaranteed>, rustc_driver_impl::run_compiler::{closure#0}::{closure#1}::{closure#3}>
  13: rustc_interface::interface::run_compiler::<core::result::Result<(), rustc_span::ErrorGuaranteed>, rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

error: the compiler unexpectedly panicked. this is a bug.

note: we would appreciate a bug report: https://github.com/rust-lang/rust/issues/new?labels=C-bug%2C+I-ICE%2C+T-compiler&template=ice.md

note: please make sure that you have updated to the latest nightly

note: please attach the file at `/Volumes/T7/workspace/240530_100chaos_tree_combine_typ/icefiles/rustc-ice-2024-05-31T08_16_43-23629.txt` to your bug report

query stack during panic:
#0 [mir_drops_elaborated_and_const_checked] elaborating drops for `t3`
#1 [analysis] running analysis passes on this crate
end of query stack
error: aborting due to 1 previous error; 1 warning emitted

For more information about this error, try `rustc --explain E0106`.

Note

• ICE location: rustc_target/src/abi/mod.rs L272-L276
  

  rust/compiler/rustc_target/src/abi/mod.rs

  Lines 267 to 276 in 6f3df08

  	for (variant, field) in indices {
  	layout = layout.for_variant(cx, variant);
  	let index = field.index();
  	offset += layout.fields.offset(index);
  	layout = layout.field(cx, index);
  	assert!(
  	layout.is_sized(),
  	"offset of unsized field (type {:?}) cannot be computed statically",
  	layout.ty
  	);

• ICE: offset of unsized field (type dyn [Binder(Trait(std::fmt::Debug), [])] + '{erased}) cannot be computed statically #125680 has identical ICE location, but has different query stack & feature.

[compiler-errors]

Please don't fuzz for builtin_syntax, that feature is never expected to work for users. This feature can be reproduced with the offset_of macro:

use core::mem::offset_of;

trait MyTrait<'a> {}

struct S { f: MyTrait, }

fn t3() {
    offset_of!(S, f);
}

fn main() {}

[cushionbadak]

Okay, I'll be careful from now on.

[cushionbadak]

After some investigation, I found that the ICE triggering code I report does not show ICE if every builtin_syntax is converted into offset_of! macro. I guess this issue can be closed.

---

By the way, the reduced builtin_syntax ICE-triggering code causes ICE from 2024-03-22.

Regression in rust-lang-ci@fa215ae
The PR introducing the regression in this rollup is #122749: make type_flags(ReError) & HAS_ERROR

searched nightlies: from nightly-2023-01-01 to nightly-2024-05-30
regressed nightly: nightly-2024-03-22
searched commit range: 1388d7a...0ad927c
regressed commit: 6a6cd65

bisected with cargo-bisect-rustc v0.6.8

Host triple: x86_64-unknown-linux-gnu
Reproduce with:

cargo bisect-rustc --start=2023-01-01 --end=2024-05-30 --regress=ice --script=rustc --preserve -- 125805.rs

[cushionbadak]

ICE update

Code

trait X<'a> {}

use std::mem::offset_of;

struct T {
    y: X,
}

fn other() {
    offset_of!(T, y);
}

fn main() {}

Meta

rustc --version --verbose:

rustc 1.81.0-nightly (6b0f4b5ec 2024-06-24)
binary: rustc
commit-hash: 6b0f4b5ec3aa707ecaa78230722117324a4ce23c
commit-date: 2024-06-24
host: x86_64-apple-darwin
release: 1.81.0-nightly
LLVM version: 18.1.7

Error output

Command: rustc

error[E0106]: missing lifetime specifier
 --> E0F03.rs:6:8
  |
6 |     y: X,
  |        ^ expected named lifetime parameter
  |
help: consider introducing a named lifetime parameter
  |
5 ~ struct T<'a> {
6 ~     y: X<'a>,
  |

warning: trait objects without an explicit `dyn` are deprecated
 --> E0F03.rs:6:8
  |
6 |     y: X,
  |        ^
  |
  = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
  = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
  = note: `#[warn(bare_trait_objects)]` on by default
help: if this is an object-safe trait, use `dyn`
  |
6 |     y: dyn X,
  |        +++

Backtrace

error: internal compiler error: /rustc/6b0f4b5ec3aa707ecaa78230722117324a4ce23c/compiler/rustc_middle/src/ty/layout.rs:1344:21: offset of not-statically-aligned field (type dyn [Binder { value: Trait(X<'_>), bound_vars: [] }] + '{erased}) cannot be computed statically

thread 'rustc' panicked at /rustc/6b0f4b5ec3aa707ecaa78230722117324a4ce23c/compiler/rustc_middle/src/ty/layout.rs:1344:21:
Box<dyn Any>
stack backtrace:
   0: std::panicking::begin_panic::<rustc_errors::ExplicitBug>
   1: <rustc_errors::diagnostic::BugAbort as rustc_errors::diagnostic::EmissionGuarantee>::emit_producing_guarantee
   2: rustc_middle::util::bug::opt_span_bug_fmt::<rustc_span::span_encoding::Span>::{closure#0}
   3: rustc_middle::ty::context::tls::with_opt::<rustc_middle::util::bug::opt_span_bug_fmt<rustc_span::span_encoding::Span>::{closure#0}, !>::{closure#0}
   4: rustc_middle::ty::context::tls::with_context_opt::<rustc_middle::ty::context::tls::with_opt<rustc_middle::util::bug::opt_span_bug_fmt<rustc_span::span_encoding::Span>::{closure#0}, !>::{closure#0}, !>
   5: rustc_middle::util::bug::bug_fmt
   6: <rustc_middle::ty::context::TyCtxt>::offset_of_subfield::<core::iter::adapters::copied::Copied<core::slice::iter::Iter<(rustc_target::abi::VariantIdx, rustc_target::abi::FieldIdx)>>>
   7: <rustc_mir_transform::known_panics_lint::ConstPropagator as rustc_middle::mir::visit::Visitor>::visit_assign
   8: <rustc_mir_transform::known_panics_lint::ConstPropagator as rustc_middle::mir::visit::Visitor>::visit_basic_block_data
   9: <rustc_mir_transform::known_panics_lint::ConstPropagator as rustc_middle::mir::visit::Visitor>::visit_body
  10: <rustc_mir_transform::known_panics_lint::KnownPanicsLint as rustc_mir_transform::pass_manager::MirLint>::run_lint
  11: rustc_mir_transform::pass_manager::run_passes_inner
  12: rustc_mir_transform::run_analysis_to_runtime_passes
  13: rustc_mir_transform::mir_drops_elaborated_and_const_checked
      [... omitted 1 frame ...]
  14: rustc_interface::passes::run_required_analyses
  15: rustc_interface::passes::analysis
      [... omitted 1 frame ...]
  16: <rustc_interface::queries::QueryResult<&rustc_middle::ty::context::GlobalCtxt>>::enter::<core::result::Result<(), rustc_span::ErrorGuaranteed>, rustc_driver_impl::run_compiler::{closure#0}::{closure#1}::{closure#3}>
  17: rustc_interface::interface::run_compiler::<core::result::Result<(), rustc_span::ErrorGuaranteed>, rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

note: we would appreciate a bug report: https://github.com/rust-lang/rust/issues/new?labels=C-bug%2C+I-ICE%2C+T-compiler&template=ice.md

note: please make sure that you have updated to the latest nightly

note: please attach the file at `/Volumes/T7/workspace/placeholder_rustexec/0625/rustc-ice-2024-06-25T10_05_21-45421.txt` to your bug report

query stack during panic:
#0 [mir_drops_elaborated_and_const_checked] elaborating drops for `other`
#1 [analysis] running analysis passes on this crate
end of query stack
error: aborting due to 2 previous errors; 1 warning emitted

For more information about this error, try `rustc --explain E0106`.

Note

• ICE location: rustc_middle/src/ty/layout.rs#L1344
  

  rust/compiler/rustc_middle/src/ty/layout.rs

  Lines 1342 to 1348 in 6b0f4b5

  	let tail = self.struct_tail_erasing_lifetimes(layout.ty, param_env);
  	if !matches!(tail.kind(), ty::Slice(..)) {
  	bug!(
  	"offset of not-statically-aligned field (type {:?}) cannot be computed statically",
  	layout.ty
  	);
  	}

  • offset_of: allow (unstably) taking the offset of slice tail fields #126150 moves the location of the function offset_of_subfield from rustc_target/src/abi/mod.rs to rustc_middle/src/ty/layout.rs

[adwinwhite]

Cannot reproduce on nightly 2024-8-12. Maybe already fixed.

[cyrgani]

@rustbot label E-needs-test