Compiler panics on #[repr(C)] + #[derive(debug)] + #[rustc_layout_scalar_valid_range_end(_)] on tuple structs

[mejrs]

The compiler will panic when all these attributes are enabled at once. Note the commented-out code that triggers a related panic.

Code

Playground

#![feature(rustc_attrs)]

// Uncommenting any of these attributes will successfully compile 
#[repr(C)]
#[derive(Debug)]
#[rustc_layout_scalar_valid_range_end(0x7F)]
struct Integer(u8);

// triggers different compiler panic
/*
#[repr(C)]
#[derive(Debug)]
#[rustc_layout_scalar_valid_range_end(0xFFFF)]
struct Integers(u8, u8);
*/

Meta

rustc --version --verbose:

rustc 1.52.0-nightly (8e54a2113 2021-02-13)
binary: rustc
commit-hash: 8e54a21139ae96a2aca3129100b057662e2799b9
commit-date: 2021-02-13
host: x86_64-pc-windows-msvc
release: 1.52.0-nightly
LLVM version: 11.0.1

Error output

thread 'rustc' panicked at 'nonscalar layout for layout_scalar_valid_range type Integer: Layout {
    fields: Arbitrary {
        offsets: [
            Size {
                raw: 0,
            },
        ],
        memory_index: [
            0,
        ],
    },
    variants: Single {
        index: 0,
    },
    abi: Aggregate {
        sized: true,
    },
    largest_niche: None,
    align: AbiAndPrefAlign {
        abi: Align {
            pow2: 0,
        },
        pref: Align {
            pow2: 3,
        },
    },
    size: Size {
        raw: 1,
    },
}', compiler\rustc_middle\src\ty\layout.rs:955:30
stack backtrace:
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

error: internal compiler error: unexpected panic

note: 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: rustc 1.52.0-nightly (8e54a2113 2021-02-13) running on x86_64-pc-windows-msvc

note: compiler flags: -C embed-bitcode=no -C debuginfo=2 -C incremental --crate-type lib

note: some of the compiler flags provided by cargo are hidden

query stack during panic:
#0 [layout_raw] computing layout of `Integer`
end of query stack

Backtrace

``` stack backtrace: 0: 0x7ff9efe0857e - ::fmt::h160322fcc0f12a19 1: 0x7ff9efe3461b - core::fmt::write::ha3ea633b18d2da75 2: 0x7ff9efdfb6c8 - ::fmt::h0112a934cd010a1c 3: 0x7ff9efe0c74d - std::panicking::take_hook::h7c389d310fc84231 4: 0x7ff9efe0c219 - std::panicking::take_hook::h7c389d310fc84231 5: 0x7ff9db5e7fb7 - rustc_driver::report_ice::hd4f773c8d782ddcc 6: 0x7ff9efe0d1b2 - std::panicking::rust_panic_with_hook::h13af0da83034d6f3 7: 0x7ff9efe0cca1 - rust_begin_unwind 8: 0x7ff9efe08f0f - ::fmt::h160322fcc0f12a19 9: 0x7ff9efe0cbf9 - rust_begin_unwind 10: 0x7ff9efe0cbac - std::panicking::begin_panic_fmt::he3c286d5fa8e7e0e 11: 0x7ff9df76efdc - rustc_middle::ty::layout::provide::h744eb072f27cc1fb 12: 0x7ff9df762eee - ::fmt::heca06e76b524fab9 13: 0x7ff9df6c733e - ::visit_lifetime::h8f7e64a9af649c18 14: 0x7ff9df92a7af - rustc_middle::dep_graph::::debug_node::h9ab25c38d7e58d1f 15: 0x7ff9df99538f - rustc_middle::ty::structural_impls::::lift_to_tcx::hb296e5db2f221b13 16: 0x7ff9df71ee49 - ::fmt::h92978b980e216966 17: 0x7ff9df68bc2c - ::visit_lifetime::h8f7e64a9af649c18 18: 0x7ff9df5ab1f9 - ::visit_lifetime::h8f7e64a9af649c18 19: 0x7ff9df772055 - as rustc_target::abi::LayoutOf>::layout_of::h163bea4617d945e6 20: 0x7ff9db9e8672 - ::layout_of::h8a1f9503e576acc2 21: 0x7ff9db8f7bbe - as rustc_codegen_llvm::abi::FnAbiLlvmExt>::apply_attrs_callsite::h7396d38e02214aaa 22: 0x7ff9db8b25ec - ::drop::ha2c97848c144591f 23: 0x7ff9db8b4747 - ::drop::ha2c97848c144591f 24: 0x7ff9db9db57a - ::fmt::he99486cc7e05be9d 25: 0x7ff9db8afa1f - ::drop::ha2c97848c144591f 26: 0x7ff9db8f0a8a - as rustc_codegen_llvm::abi::FnAbiLlvmExt>::apply_attrs_callsite::h7396d38e02214aaa 27: 0x7ff9db8b086e - ::drop::ha2c97848c144591f 28: 0x7ff9db9eb32a - rustc_codegen_llvm::mono_item::::predefine_fn::hedf0f64e9e762a10 29: 0x7ff9db8ac83b - ::next::h587d021e0c727ed0 30: 0x7ff9db8fc68e - as rustc_codegen_llvm::abi::FnAbiLlvmExt>::apply_attrs_callsite::h7396d38e02214aaa 31: 0x7ff9dba1ba25 - ::fmt::hdb8b973c68ec0bd5 32: 0x7ff9db8ac453 - ::next::h587d021e0c727ed0 33: 0x7ff9db9d38a1 - ::codegen_crate::hd916541c477771f1 34: 0x7ff9db801431 - rustc_interface::queries::Queries::ongoing_codegen::hf5bf7ace4f995c32 35: 0x7ff9db612ac4 - rustc_ast::util::parser::prec_let_scrutinee_needs_par::hfc7ab7b91c80b01e 36: 0x7ff9db5ec17c - ::fmt::h565c544a3fcd0386 37: 0x7ff9db609009 - ::fmt::h565c544a3fcd0386 38: 0x7ff9db615cee - rustc_ast::util::parser::prec_let_scrutinee_needs_par::hfc7ab7b91c80b01e 39: 0x7ff9db58962d - ::fmt::ha43055df5546b109 40: 0x7ff9efe1c9fa - std::sys::windows::thread::Thread::new::hd38a560d738a063d 41: 0x7ffa58957034 - BaseThreadInitThunk 42: 0x7ffa58d42651 - RtlUserThreadStart ```

[chengniansun]

A duplicate

#[rustc_layout_scalar_valid_range_start(1)]
struct S<T> {
    i: u8,
    t: T,
}
struct A((u32, u32));
static Ca: S<A>;

[JohnTitor]

Fixed on the latest nightly, marking as E-needs-test @rustbot labels: +E-needs-test

[the8472]

This still panics on current nightly

#![feature(rustc_attrs)]

#[rustc_layout_scalar_valid_range_end(38)]
#[repr(packed)]
struct Len(u16);

impl Clone for Len {
    fn clone(&self) -> Self { 
        unsafe { Len(self.0) }
     }
}

Backtrace

``` thread 'rustc' panicked at /rustc/d6d7a93866f2ffcfb51828b8859bdad760b54ce0/compiler/rustc_abi/src/layout.rs:281:22: nonscalar layout for layout_scalar_valid_range type: Layout { size: Size(2 bytes), align: AbiAndPrefAlign { abi: Align(1 bytes), pref: Align(1 bytes), }, abi: Aggregate { sized: true, }, fields: Arbitrary { offsets: [ Size(0 bytes), ], memory_index: [ 0, ], }, largest_niche: None, variants: Single { index: 0, }, max_repr_align: None, unadjusted_abi_align: Align(1 bytes), } stack backtrace: 0: 0x7f65e82d06f6 - std::backtrace_rs::backtrace::libunwind::trace::h4c39d39dfbe9783d at /rustc/d6d7a93866f2ffcfb51828b8859bdad760b54ce0/library/std/src/../../backtrace/src/backtrace/libunwind.rs:104:5 1: 0x7f65e82d06f6 - std::backtrace_rs::backtrace::trace_unsynchronized::h4dc8ace54ae311e5 at /rustc/d6d7a93866f2ffcfb51828b8859bdad760b54ce0/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5 2: 0x7f65e82d06f6 - std::sys_common::backtrace::_print_fmt::hb93bb30078f88f5e at /rustc/d6d7a93866f2ffcfb51828b8859bdad760b54ce0/library/std/src/sys_common/backtrace.rs:68:5 3: 0x7f65e82d06f6 - ::fmt::hc0a088b7e0825f6a at /rustc/d6d7a93866f2ffcfb51828b8859bdad760b54ce0/library/std/src/sys_common/backtrace.rs:44:22 4: 0x7f65e8322f40 - core::fmt::rt::Argument::fmt::h3bf37701eb7e7bdb at /rustc/d6d7a93866f2ffcfb51828b8859bdad760b54ce0/library/core/src/fmt/rt.rs:142:9 5: 0x7f65e8322f40 - core::fmt::write::h7e6ab5f6daf5c422 at /rustc/d6d7a93866f2ffcfb51828b8859bdad760b54ce0/library/core/src/fmt/mod.rs:1120:17 6: 0x7f65e82c44af - std::io::Write::write_fmt::h08c3306cb5bf723d at /rustc/d6d7a93866f2ffcfb51828b8859bdad760b54ce0/library/std/src/io/mod.rs:1810:15 7: 0x7f65e82d04d4 - std::sys_common::backtrace::_print::hafed43d2fa285a46 at /rustc/d6d7a93866f2ffcfb51828b8859bdad760b54ce0/library/std/src/sys_common/backtrace.rs:47:5 8: 0x7f65e82d04d4 - std::sys_common::backtrace::print::h39c23a58558ca2e2 at /rustc/d6d7a93866f2ffcfb51828b8859bdad760b54ce0/library/std/src/sys_common/backtrace.rs:34:9 9: 0x7f65e82d3267 - std::panicking::default_hook::{{closure}}::h33423deafbc8e615 10: 0x7f65e82d2fc9 - std::panicking::default_hook::h50ae27bf0009ee3b at /rustc/d6d7a93866f2ffcfb51828b8859bdad760b54ce0/library/std/src/panicking.rs:292:9 11: 0x7f65eb0c7ccc - std[3a009c5aa3cd6e18]::panicking::update_hook::>::{closure#0} 12: 0x7f65e82d39b6 - as core::ops::function::Fn>::call::h5ddf83902817cab1 at /rustc/d6d7a93866f2ffcfb51828b8859bdad760b54ce0/library/alloc/src/boxed.rs:2029:9 13: 0x7f65e82d39b6 - std::panicking::rust_panic_with_hook::hbc586ac9df6b73a8 at /rustc/d6d7a93866f2ffcfb51828b8859bdad760b54ce0/library/std/src/panicking.rs:783:13 14: 0x7f65e82d3702 - std::panicking::begin_panic_handler::{{closure}}::hf311b40154e75f12 at /rustc/d6d7a93866f2ffcfb51828b8859bdad760b54ce0/library/std/src/panicking.rs:657:13 15: 0x7f65e82d0bf6 - std::sys_common::backtrace::__rust_end_short_backtrace::he9e1eb231bad02f7 at /rustc/d6d7a93866f2ffcfb51828b8859bdad760b54ce0/library/std/src/sys_common/backtrace.rs:171:18 16: 0x7f65e82d3460 - rust_begin_unwind at /rustc/d6d7a93866f2ffcfb51828b8859bdad760b54ce0/library/std/src/panicking.rs:645:5 17: 0x7f65e831f645 - core::panicking::panic_fmt::hefa1490703b8b929 at /rustc/d6d7a93866f2ffcfb51828b8859bdad760b54ce0/library/core/src/panicking.rs:72:14 18: 0x7f65ec8ca304 - rustc_ty_utils[9a2fab9997b923d4]::layout::layout_of_uncached 19: 0x7f65ec8bfa12 - rustc_ty_utils[9a2fab9997b923d4]::layout::layout_of 20: 0x7f65ec8bf991 - rustc_query_impl[a5b594d180e67741]::plumbing::__rust_begin_short_backtrace::> 21: 0x7f65ec8becba - rustc_query_system[f0f2c4fcd6daa9a]::query::plumbing::try_execute_query::, rustc_middle[8402766bc0d86440]::query::erase::Erased<[u8; 16usize]>>, false, true, false>, rustc_query_impl[a5b594d180e67741]::plumbing::QueryCtxt, false> 22: 0x7f65ec8be938 - rustc_query_impl[a5b594d180e67741]::query_impl::layout_of::get_query_non_incr::__rust_end_short_backtrace 23: 0x7f65ecf83409 - ::check 24: 0x7f65ec56d491 - ::run_lint 25: 0x7f65ec3a7caf - rustc_mir_transform[19f7e7f8136d1e5c]::run_analysis_to_runtime_passes 26: 0x7f65e9cc7baf - rustc_mir_transform[19f7e7f8136d1e5c]::mir_drops_elaborated_and_const_checked 27: 0x7f65ec55b3b5 - rustc_query_impl[a5b594d180e67741]::plumbing::__rust_begin_short_backtrace::> 28: 0x7f65ec55b643 - rustc_query_system[f0f2c4fcd6daa9a]::query::plumbing::try_execute_query::>, false, false, false>, rustc_query_impl[a5b594d180e67741]::plumbing::QueryCtxt, false> 29: 0x7f65ec55af12 - rustc_query_impl[a5b594d180e67741]::query_impl::mir_drops_elaborated_and_const_checked::get_query_non_incr::__rust_end_short_backtrace 30: 0x7f65eca47a5b - rustc_interface[dfee6d40a3df20bb]::passes::analysis 31: 0x7f65eca4725d - rustc_query_impl[a5b594d180e67741]::plumbing::__rust_begin_short_backtrace::> 32: 0x7f65ed24dac0 - rustc_query_system[f0f2c4fcd6daa9a]::query::plumbing::try_execute_query::>, false, false, false>, rustc_query_impl[a5b594d180e67741]::plumbing::QueryCtxt, false> 33: 0x7f65ed24d8c7 - rustc_query_impl[a5b594d180e67741]::query_impl::analysis::get_query_non_incr::__rust_end_short_backtrace 34: 0x7f65ed2e4252 - rustc_interface[dfee6d40a3df20bb]::interface::run_compiler::, rustc_driver_impl[99e8362fbaa298ef]::run_compiler::{closure#0}>::{closure#0} 35: 0x7f65ed26a346 - std[3a009c5aa3cd6e18]::sys_common::backtrace::__rust_begin_short_backtrace::, rustc_driver_impl[99e8362fbaa298ef]::run_compiler::{closure#0}>::{closure#0}, core[2b984803ee3f5e21]::result::Result<(), rustc_span[fa12e73b1270738]::ErrorGuaranteed>>::{closure#0}, core[2b984803ee3f5e21]::result::Result<(), rustc_span[fa12e73b1270738]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[2b984803ee3f5e21]::result::Result<(), rustc_span[fa12e73b1270738]::ErrorGuaranteed>> 36: 0x7f65ed26a173 - <::spawn_unchecked_, rustc_driver_impl[99e8362fbaa298ef]::run_compiler::{closure#0}>::{closure#0}, core[2b984803ee3f5e21]::result::Result<(), rustc_span[fa12e73b1270738]::ErrorGuaranteed>>::{closure#0}, core[2b984803ee3f5e21]::result::Result<(), rustc_span[fa12e73b1270738]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[2b984803ee3f5e21]::result::Result<(), rustc_span[fa12e73b1270738]::ErrorGuaranteed>>::{closure#1} as core[2b984803ee3f5e21]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0} 37: 0x7f65e82dd8e5 - as core::ops::function::FnOnce>::call_once::h446fa4c55b1bf8c4 at /rustc/d6d7a93866f2ffcfb51828b8859bdad760b54ce0/library/alloc/src/boxed.rs:2015:9 38: 0x7f65e82dd8e5 - as core::ops::function::FnOnce>::call_once::hb661ed53115c5033 at /rustc/d6d7a93866f2ffcfb51828b8859bdad760b54ce0/library/alloc/src/boxed.rs:2015:9 39: 0x7f65e82dd8e5 - std::sys::unix::thread::Thread::new::thread_start::hbd74c47d36330101 at /rustc/d6d7a93866f2ffcfb51828b8859bdad760b54ce0/library/std/src/sys/unix/thread.rs:108:17 40: 0x7f65e81f0609 - start_thread 41: 0x7f65e8113353 - clone 42: 0x0 - error: the compiler unexpectedly panicked. this is a bug. note: using internal features is not supported and expected to cause internal compiler errors when used incorrectly note: please attach the file at `/playground/rustc-ice-2023-12-23T15_52_19-21.txt` to your bug report note: compiler flags: --crate-type lib -C embed-bitcode=no -C codegen-units=1 -C debuginfo=2 note: some of the compiler flags provided by cargo are hidden query stack during panic: #0 [layout_of] computing layout of `Len` #1 [mir_drops_elaborated_and_const_checked] elaborating drops for `::clone` #2 [analysis] running analysis passes on this crate end of query stack ```

[oli-obk]

Yea, that internal attribute may only be used in very specific circumstances that the layout code describes. Please do not use it outside the standard library or the compiler