ICE: `SizeOf MIR operator called for unsized type`

[matthiaskrgr]

auto-reduced (treereduce-rust):

use std::mem::{align_of, size_of};

#[repr(C)]

pub struct p0f_api_query {
    pub magic: u32,
    pub addr_type: str,
    pub addr: [u8; 16],
}

pub fn main() {
    assert_eq!(size_of::<p0f_api_query>(), 21);
}

original code

original:

//@ run-pass

#![allow(dead_code)]

use std::mem::{size_of, align_of};
use std::os::raw::c_int;

// The two enums that follow are designed so that bugs trigger layout optimization.
// Specifically, if either of the following reprs used here is not detected by the compiler,
// then the sizes will be wrong.

#[repr(C, u8)]
enum E1 {
    A(u8, u16, u8),
    B(u8, u16, u8)
}

#[repr(u8, irving)]
enum E2 {
    A(u8, X),
    B(u8, u16, u8)
}

// Check that repr(int) and repr(C) are in fact different from the above

#[repr(u8)]
enum E3 {
    A(u8, u16, u8),
    B([u8; 7], bool)
}

#[repr(u16)]
enum E4 {
    A(u8, u16, u8),
    Bar {
        a: isize,
        b: isize
    }
}

#[repr(u32)]
enum E5 {
    A(u8, u16, u8),
    B(u8, u16, u8)
}

#[repr(u64)]
enum E6 {
    A(u8, u16, u8),
    B(u8, u16, u8)
}

#[repr(C)]
enum E7 {
    A(u8, u16, u8),
    B(u8, u16, u8)
}

// From pr 37429

#[repr(C,packed)]
pub struct p0f_api_query {
    pub magic: u32,
    pub addr_type: str,
    pub addr: [u8; 16],
}

pub fn main() {
    assert_eq!(size_of::<E1>(), 8);
    assert_eq!(size_of::<E2>(), 8);
    assert_eq!(size_of::<E3>(), 6);
    assert_eq!(size_of::<E4>(), 8);
    assert_eq!(size_of::<E5>(), align_size(10, align_of::<u32>()));
    assert_eq!(size_of::<E6>(), align_size(14, align_of::<u64>()));
    assert_eq!(size_of::<E7>(), align_size(6 + size_of::<c_int>(), align_of::<c_int>()));
    assert_eq!(size_of::<p0f_api_query>(), 21);
}

fn align_size(size: usize, align: usize) -> usize {
    if size % align != 0 {
        size + (align - (size % align))
    } else {
        size
    }
}

Version information

rustc 1.78.0-nightly (f8131a48a 2024-02-21)
binary: rustc
commit-hash: f8131a48a46ac3bc8a3d0fe0477055b132cffdc3
commit-date: 2024-02-21
host: x86_64-unknown-linux-gnu
release: 1.78.0-nightly
LLVM version: 18.1.0

Command:
/home/matthias/.rustup/toolchains/master/bin/rustc

Program output

warning: unused import: `align_of`
 --> /tmp/icemaker_global_tempdir.TBHuutByqHGC/rustc_testrunner_tmpdir_reporting.9iS1p4GVIV9c/mvce.rs:1:16
  |
1 | use std::mem::{align_of, size_of};
  |                ^^^^^^^^
  |
  = note: `#[warn(unused_imports)]` on by default

error[E0277]: the size for values of type `str` cannot be known at compilation time
 --> /tmp/icemaker_global_tempdir.TBHuutByqHGC/rustc_testrunner_tmpdir_reporting.9iS1p4GVIV9c/mvce.rs:7:20
  |
7 |     pub addr_type: str,
  |                    ^^^ doesn't have a size known at compile-time
  |
  = help: the trait `Sized` is not implemented for `str`
  = note: only the last field of a struct may have a dynamically sized type
  = help: change the field's type to have a statically known size
help: borrowed types always have a statically known size
  |
7 |     pub addr_type: &str,
  |                    +
help: the `Box` type always has a statically known size and allocates its contents in the heap
  |
7 |     pub addr_type: Box<str>,
  |                    ++++   +

error: internal compiler error: compiler/rustc_const_eval/src/interpret/step.rs:243:21: SizeOf MIR operator called for unsized type p0f_api_query
   --> /home/matthias/.rustup/toolchains/master/lib/rustlib/src/rust/library/core/src/mem/mod.rs:313:5
    |
313 |     intrinsics::size_of::<T>()
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^

thread 'rustc' panicked at /rustc/f8131a48a46ac3bc8a3d0fe0477055b132cffdc3/compiler/rustc_middle/src/util/bug.rs:34:50:
Box<dyn Any>
stack backtrace:
   0:     0x7f7bfab8caf6 - std::backtrace_rs::backtrace::libunwind::trace::hbec2edc838b433e2
                               at /rustc/f8131a48a46ac3bc8a3d0fe0477055b132cffdc3/library/std/src/../../backtrace/src/backtrace/libunwind.rs:104:5
   1:     0x7f7bfab8caf6 - std::backtrace_rs::backtrace::trace_unsynchronized::h88c30257ee0dd166
                               at /rustc/f8131a48a46ac3bc8a3d0fe0477055b132cffdc3/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2:     0x7f7bfab8caf6 - std::sys_common::backtrace::_print_fmt::h9176654d509e3088
                               at /rustc/f8131a48a46ac3bc8a3d0fe0477055b132cffdc3/library/std/src/sys_common/backtrace.rs:68:5
   3:     0x7f7bfab8caf6 - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h671feaee1776bf19
                               at /rustc/f8131a48a46ac3bc8a3d0fe0477055b132cffdc3/library/std/src/sys_common/backtrace.rs:44:22
   4:     0x7f7bfabdda7c - core::fmt::rt::Argument::fmt::h59605c83ae32d935
                               at /rustc/f8131a48a46ac3bc8a3d0fe0477055b132cffdc3/library/core/src/fmt/rt.rs:142:9
   5:     0x7f7bfabdda7c - core::fmt::write::hf7af8dfcfd20db5b
                               at /rustc/f8131a48a46ac3bc8a3d0fe0477055b132cffdc3/library/core/src/fmt/mod.rs:1120:17
   6:     0x7f7bfab814bf - std::io::Write::write_fmt::h92a5dbf489025e71
                               at /rustc/f8131a48a46ac3bc8a3d0fe0477055b132cffdc3/library/std/src/io/mod.rs:1846:15
   7:     0x7f7bfab8c8a4 - std::sys_common::backtrace::_print::h00080302d23998ae
                               at /rustc/f8131a48a46ac3bc8a3d0fe0477055b132cffdc3/library/std/src/sys_common/backtrace.rs:47:5
   8:     0x7f7bfab8c8a4 - std::sys_common::backtrace::print::h6b23124445400245
                               at /rustc/f8131a48a46ac3bc8a3d0fe0477055b132cffdc3/library/std/src/sys_common/backtrace.rs:34:9
   9:     0x7f7bfab8f5eb - std::panicking::default_hook::{{closure}}::hd67b2f9d36675a28
  10:     0x7f7bfab8f339 - std::panicking::default_hook::h10a39ef11c714e42
                               at /rustc/f8131a48a46ac3bc8a3d0fe0477055b132cffdc3/library/std/src/panicking.rs:292:9
  11:     0x7f7bfda7a94c - std[5a8e7f94216a9138]::panicking::update_hook::<alloc[e14ab1f516d287ab]::boxed::Box<rustc_driver_impl[e279e4f1fedd9109]::install_ice_hook::{closure#0}>>::{closure#0}
  12:     0x7f7bfab8fd50 - <alloc::boxed::Box<F,A> as core::ops::function::Fn<Args>>::call::h37ba37dc48823c1d
                               at /rustc/f8131a48a46ac3bc8a3d0fe0477055b132cffdc3/library/alloc/src/boxed.rs:2030:9
  13:     0x7f7bfab8fd50 - std::panicking::rust_panic_with_hook::he3e3bc7c345bf54b
                               at /rustc/f8131a48a46ac3bc8a3d0fe0477055b132cffdc3/library/std/src/panicking.rs:786:13
  14:     0x7f7bfdaa7524 - std[5a8e7f94216a9138]::panicking::begin_panic::<rustc_errors[34364e5c712fab73]::ExplicitBug>::{closure#0}
  15:     0x7f7bfdaa4176 - std[5a8e7f94216a9138]::sys_common::backtrace::__rust_end_short_backtrace::<std[5a8e7f94216a9138]::panicking::begin_panic<rustc_errors[34364e5c712fab73]::ExplicitBug>::{closure#0}, !>
  16:     0x7f7bfda9f936 - std[5a8e7f94216a9138]::panicking::begin_panic::<rustc_errors[34364e5c712fab73]::ExplicitBug>
  17:     0x7f7bfc417631 - <rustc_errors[34364e5c712fab73]::diagnostic::BugAbort as rustc_errors[34364e5c712fab73]::diagnostic::EmissionGuarantee>::emit_producing_guarantee
  18:     0x7f7bfda01f60 - rustc_middle[446dd094ad85939e]::util::bug::opt_span_bug_fmt::<rustc_span[adb133ac03280fc1]::span_encoding::Span>::{closure#0}
  19:     0x7f7bfda0217a - rustc_middle[446dd094ad85939e]::ty::context::tls::with_opt::<rustc_middle[446dd094ad85939e]::util::bug::opt_span_bug_fmt<rustc_span[adb133ac03280fc1]::span_encoding::Span>::{closure#0}, !>::{closure#0}
  20:     0x7f7bfd9f8e48 - rustc_middle[446dd094ad85939e]::ty::context::tls::with_context_opt::<rustc_middle[446dd094ad85939e]::ty::context::tls::with_opt<rustc_middle[446dd094ad85939e]::util::bug::opt_span_bug_fmt<rustc_span[adb133ac03280fc1]::span_encoding::Span>::{closure#0}, !>::{closure#0}, !>
  21:     0x7f7bfd050f54 - rustc_middle[446dd094ad85939e]::util::bug::span_bug_fmt::<rustc_span[adb133ac03280fc1]::span_encoding::Span>
  22:     0x7f7bffcfbef6 - rustc_const_eval[b7e9a6566b8f5ff6]::const_eval::eval_queries::eval_body_using_ecx::{closure#0}
  23:     0x7f7bffc76f23 - rustc_const_eval[b7e9a6566b8f5ff6]::const_eval::eval_queries::eval_in_interpreter
  24:     0x7f7bff1fa938 - rustc_const_eval[b7e9a6566b8f5ff6]::const_eval::eval_queries::eval_to_allocation_raw_provider
  25:     0x7f7bff1fa706 - rustc_query_impl[9d4c51777e2bb749]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[9d4c51777e2bb749]::query_impl::eval_to_allocation_raw::dynamic_query::{closure#2}::{closure#0}, rustc_middle[446dd094ad85939e]::query::erase::Erased<[u8; 24usize]>>
  26:     0x7f7bff80ba51 - rustc_query_system[9b2ccfe41ae3bb1b]::query::plumbing::try_execute_query::<rustc_query_impl[9d4c51777e2bb749]::DynamicConfig<rustc_query_system[9b2ccfe41ae3bb1b]::query::caches::DefaultCache<rustc_middle[446dd094ad85939e]::ty::ParamEnvAnd<rustc_middle[446dd094ad85939e]::mir::interpret::GlobalId>, rustc_middle[446dd094ad85939e]::query::erase::Erased<[u8; 24usize]>>, false, false, false>, rustc_query_impl[9d4c51777e2bb749]::plumbing::QueryCtxt, false>
  27:     0x7f7bff80b62c - rustc_query_impl[9d4c51777e2bb749]::query_impl::eval_to_allocation_raw::get_query_non_incr::__rust_end_short_backtrace
  28:     0x7f7bff1fb60d - rustc_const_eval[b7e9a6566b8f5ff6]::const_eval::eval_queries::eval_to_const_value_raw_provider
  29:     0x7f7bff1fb40c - rustc_query_impl[9d4c51777e2bb749]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[9d4c51777e2bb749]::query_impl::eval_to_const_value_raw::dynamic_query::{closure#2}::{closure#0}, rustc_middle[446dd094ad85939e]::query::erase::Erased<[u8; 24usize]>>
  30:     0x7f7bff80ba14 - rustc_query_system[9b2ccfe41ae3bb1b]::query::plumbing::try_execute_query::<rustc_query_impl[9d4c51777e2bb749]::DynamicConfig<rustc_query_system[9b2ccfe41ae3bb1b]::query::caches::DefaultCache<rustc_middle[446dd094ad85939e]::ty::ParamEnvAnd<rustc_middle[446dd094ad85939e]::mir::interpret::GlobalId>, rustc_middle[446dd094ad85939e]::query::erase::Erased<[u8; 24usize]>>, false, false, false>, rustc_query_impl[9d4c51777e2bb749]::plumbing::QueryCtxt, false>
  31:     0x7f7bff80b530 - rustc_query_impl[9d4c51777e2bb749]::query_impl::eval_to_const_value_raw::get_query_non_incr::__rust_end_short_backtrace
  32:     0x7f7bfd01c265 - <rustc_middle[446dd094ad85939e]::ty::context::TyCtxt>::const_eval_resolve
  33:     0x7f7bfc6400a0 - <rustc_mir_transform[2f80b166b66099ac]::known_panics_lint::ConstPropagator as rustc_middle[446dd094ad85939e]::mir::visit::Visitor>::visit_operand
  34:     0x7f7bfc641835 - <rustc_mir_transform[2f80b166b66099ac]::known_panics_lint::ConstPropagator as rustc_middle[446dd094ad85939e]::mir::visit::Visitor>::visit_assign
  35:     0x7f7bff40911b - <rustc_mir_transform[2f80b166b66099ac]::known_panics_lint::ConstPropagator as rustc_middle[446dd094ad85939e]::mir::visit::Visitor>::visit_body
  36:     0x7f7bfc63cc69 - <rustc_mir_transform[2f80b166b66099ac]::known_panics_lint::KnownPanicsLint as rustc_mir_transform[2f80b166b66099ac]::pass_manager::MirLint>::run_lint
  37:     0x7f7bfee12689 - rustc_mir_transform[2f80b166b66099ac]::pass_manager::run_passes_inner
  38:     0x7f7bff042806 - rustc_mir_transform[2f80b166b66099ac]::mir_drops_elaborated_and_const_checked
  39:     0x7f7bff04213d - rustc_query_impl[9d4c51777e2bb749]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[9d4c51777e2bb749]::query_impl::mir_drops_elaborated_and_const_checked::dynamic_query::{closure#2}::{closure#0}, rustc_middle[446dd094ad85939e]::query::erase::Erased<[u8; 8usize]>>
  40:     0x7f7bfef098b0 - rustc_query_system[9b2ccfe41ae3bb1b]::query::plumbing::try_execute_query::<rustc_query_impl[9d4c51777e2bb749]::DynamicConfig<rustc_query_system[9b2ccfe41ae3bb1b]::query::caches::VecCache<rustc_span[adb133ac03280fc1]::def_id::LocalDefId, rustc_middle[446dd094ad85939e]::query::erase::Erased<[u8; 8usize]>>, false, false, false>, rustc_query_impl[9d4c51777e2bb749]::plumbing::QueryCtxt, false>
  41:     0x7f7bfef0919e - rustc_query_impl[9d4c51777e2bb749]::query_impl::mir_drops_elaborated_and_const_checked::get_query_non_incr::__rust_end_short_backtrace
  42:     0x7f7bff8a333f - rustc_interface[7ca501d7f8f3a34f]::passes::analysis
  43:     0x7f7bff8a2a29 - rustc_query_impl[9d4c51777e2bb749]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[9d4c51777e2bb749]::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle[446dd094ad85939e]::query::erase::Erased<[u8; 1usize]>>
  44:     0x7f7bffb3d4a5 - rustc_query_system[9b2ccfe41ae3bb1b]::query::plumbing::try_execute_query::<rustc_query_impl[9d4c51777e2bb749]::DynamicConfig<rustc_query_system[9b2ccfe41ae3bb1b]::query::caches::SingleCache<rustc_middle[446dd094ad85939e]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[9d4c51777e2bb749]::plumbing::QueryCtxt, false>
  45:     0x7f7bffb3d209 - rustc_query_impl[9d4c51777e2bb749]::query_impl::analysis::get_query_non_incr::__rust_end_short_backtrace
  46:     0x7f7bffb4c719 - rustc_interface[7ca501d7f8f3a34f]::interface::run_compiler::<core[85b4fd477ce5bb21]::result::Result<(), rustc_span[adb133ac03280fc1]::ErrorGuaranteed>, rustc_driver_impl[e279e4f1fedd9109]::run_compiler::{closure#0}>::{closure#0}
  47:     0x7f7bffdbe705 - std[5a8e7f94216a9138]::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface[7ca501d7f8f3a34f]::util::run_in_thread_with_globals<rustc_interface[7ca501d7f8f3a34f]::util::run_in_thread_pool_with_globals<rustc_interface[7ca501d7f8f3a34f]::interface::run_compiler<core[85b4fd477ce5bb21]::result::Result<(), rustc_span[adb133ac03280fc1]::ErrorGuaranteed>, rustc_driver_impl[e279e4f1fedd9109]::run_compiler::{closure#0}>::{closure#0}, core[85b4fd477ce5bb21]::result::Result<(), rustc_span[adb133ac03280fc1]::ErrorGuaranteed>>::{closure#0}, core[85b4fd477ce5bb21]::result::Result<(), rustc_span[adb133ac03280fc1]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[85b4fd477ce5bb21]::result::Result<(), rustc_span[adb133ac03280fc1]::ErrorGuaranteed>>
  48:     0x7f7bffdbe532 - <<std[5a8e7f94216a9138]::thread::Builder>::spawn_unchecked_<rustc_interface[7ca501d7f8f3a34f]::util::run_in_thread_with_globals<rustc_interface[7ca501d7f8f3a34f]::util::run_in_thread_pool_with_globals<rustc_interface[7ca501d7f8f3a34f]::interface::run_compiler<core[85b4fd477ce5bb21]::result::Result<(), rustc_span[adb133ac03280fc1]::ErrorGuaranteed>, rustc_driver_impl[e279e4f1fedd9109]::run_compiler::{closure#0}>::{closure#0}, core[85b4fd477ce5bb21]::result::Result<(), rustc_span[adb133ac03280fc1]::ErrorGuaranteed>>::{closure#0}, core[85b4fd477ce5bb21]::result::Result<(), rustc_span[adb133ac03280fc1]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[85b4fd477ce5bb21]::result::Result<(), rustc_span[adb133ac03280fc1]::ErrorGuaranteed>>::{closure#1} as core[85b4fd477ce5bb21]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  49:     0x7f7bfab99725 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h1bff3efb61c3fa6b
                               at /rustc/f8131a48a46ac3bc8a3d0fe0477055b132cffdc3/library/alloc/src/boxed.rs:2016:9
  50:     0x7f7bfab99725 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h83141cf549dced8a
                               at /rustc/f8131a48a46ac3bc8a3d0fe0477055b132cffdc3/library/alloc/src/boxed.rs:2016:9
  51:     0x7f7bfab99725 - std::sys::pal::unix::thread::Thread::new::thread_start::hbe9287fdd7c325bc
                               at /rustc/f8131a48a46ac3bc8a3d0fe0477055b132cffdc3/library/std/src/sys/pal/unix/thread.rs:108:17
  52:     0x7f7bfa94b9eb - <unknown>
  53:     0x7f7bfa9cf7cc - <unknown>
  54:                0x0 - <unknown>

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: rustc 1.78.0-nightly (f8131a48a 2024-02-21) running on x86_64-unknown-linux-gnu

query stack during panic:
#0 [eval_to_allocation_raw] const-evaluating + checking `main::promoted[1]`
#1 [eval_to_const_value_raw] simplifying constant for the type system `main::promoted[1]`  |  = note: this failure-note originates in the macro `assert_eq` (in Nightly builds, run with -Z macro-backtrace for more info)

#2 [mir_drops_elaborated_and_const_checked] elaborating drops for `main`
#3 [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 E0277`.

[matthiaskrgr]

#120847 cc @oli-obk

[gurry]

@rustbot claim

[gurry]

Reduced slightly more:

use std::mem::size_of;

pub struct p0f_api_query {
    pub addr_type: str,
    pub addr: [u8; 16],
}

pub fn main() {
    assert_eq!(size_of::<p0f_api_query>(), 21);
}

[oli-obk]

oof, this is something that @davidtwco has been working on before. If a struct's fields have errors, it's very hard to taint the MIR or const eval in order to not run at all. But changing const eval to be permissive of errors that should have caused const eval to never run is also not great.

That said, it makes no sense that p0f_api_query is considered unsized. Layout computation should probably just error out due to addr_type not being the last field.

this is all under the assumption that

error[E0277]: the size for values of type str cannot be known at compilation time

is emitted in wfcheck and not somewhere else. If it is emitted somewhere else, we may be able to taint the context at the emission site.

[gurry]

It's being emitted only in wfcheck not anywhere else :(