ICE attempting to indirectly call a function that takes a reference through asm!

[sethp]

I'm attempting to call a function with a Rust ABI from a trap handler; in one of my attempts to shim in a spot for the compiler to emit a C ABI -> Rust ABI remapping I tried creating a generic shim and grabbing a reference to the compiler's instantiation with the concrete types I needed, as below.

I have no idea if this code would work, but a close cousin does seem to (if I define the shim with concrete types instead of generically).

Code

use core::arch::asm;

struct TrapFrame;

unsafe extern "C" fn _rust_abi_shim1<A, R>(arg: A, f: fn(A) -> R) -> R {
    f(arg)
}

unsafe extern "C" fn _start_trap() {
    extern "Rust" {
        fn interrupt(tf: &mut TrapFrame);
    }
    asm!(
        "
        la   a1, {irq}
        call {shim}
        ",
        shim = sym crate::_rust_abi_shim1::<&mut TrapFrame, ()>,
        irq = sym interrupt,
        options(noreturn)
    )
}

It doesn't seem to matter, but if it helps: I'm targeting the RISC-V architecture here.

Meta

rustc --version --verbose:

rustc 1.71.0-nightly (2f6bc5d25 2023-05-09)
binary: rustc
commit-hash: 2f6bc5d259e7ab25ddfdd33de53b892770218918
commit-date: 2023-05-09
host: x86_64-unknown-linux-gnu
release: 1.71.0-nightly
LLVM version: 16.0.2

I see the same thing in the rust playground as well: https://play.rust-lang.org/?version=nightly&mode=debug&edition=2021&gist=1042a83d1938b63786d81595a2cd1207

Error output

error: internal compiler error: compiler/rustc_borrowck/src/universal_regions.rs:882:36: cannot convert `ReErased` to a region vid

thread 'rustc' panicked at 'Box<dyn Any>', /rustc/e9e1bbc7a820c472b39d3de54b3049bf14050655/compiler/rustc_errors/src/lib.rs:1651:9

Backtrace

thread 'rustc' panicked at 'Box<dyn Any>', /rustc/e9e1bbc7a820c472b39d3de54b3049bf14050655/compiler/rustc_errors/src/lib.rs:1651:9
stack backtrace:
   0:     0x7f9a557606f1 - std::backtrace_rs::backtrace::libunwind::trace::hd7879cf2988ecd6e
                               at /rustc/e9e1bbc7a820c472b39d3de54b3049bf14050655/library/std/src/../../backtrace/src/backtrace/libunwind.rs:93:5
   1:     0x7f9a557606f1 - std::backtrace_rs::backtrace::trace_unsynchronized::hee6277a61ce80b8c
                               at /rustc/e9e1bbc7a820c472b39d3de54b3049bf14050655/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2:     0x7f9a557606f1 - std::sys_common::backtrace::_print_fmt::hf0363336a1427da3
                               at /rustc/e9e1bbc7a820c472b39d3de54b3049bf14050655/library/std/src/sys_common/backtrace.rs:65:5
   3:     0x7f9a557606f1 - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h9d01e31d8148bf09
                               at /rustc/e9e1bbc7a820c472b39d3de54b3049bf14050655/library/std/src/sys_common/backtrace.rs:44:22
   4:     0x7f9a557c0bff - core::fmt::rt::Argument::fmt::h768e4bfc36fb81cd
                               at /rustc/e9e1bbc7a820c472b39d3de54b3049bf14050655/library/core/src/fmt/rt.rs:138:9
   5:     0x7f9a557c0bff - core::fmt::write::h5d112ccebaed5a5e
                               at /rustc/e9e1bbc7a820c472b39d3de54b3049bf14050655/library/core/src/fmt/mod.rs:1094:21
   6:     0x7f9a55753951 - std::io::Write::write_fmt::h39434b96d0cdcd9c
                               at /rustc/e9e1bbc7a820c472b39d3de54b3049bf14050655/library/std/src/io/mod.rs:1712:15
   7:     0x7f9a55760505 - std::sys_common::backtrace::_print::h39bc233d7cfbd0ab
                               at /rustc/e9e1bbc7a820c472b39d3de54b3049bf14050655/library/std/src/sys_common/backtrace.rs:47:5
   8:     0x7f9a55760505 - std::sys_common::backtrace::print::hd36e4d67701ad1f3
                               at /rustc/e9e1bbc7a820c472b39d3de54b3049bf14050655/library/std/src/sys_common/backtrace.rs:34:9
   9:     0x7f9a55763187 - std::panicking::default_hook::{{closure}}::hf720deff1479a836
  10:     0x7f9a55762f74 - std::panicking::default_hook::h8708bcc6c11edabe
                               at /rustc/e9e1bbc7a820c472b39d3de54b3049bf14050655/library/std/src/panicking.rs:288:9
  11:     0x7f9a588ef05b - <rustc_driver_impl[88bc38c0e277e71e]::install_ice_hook::{closure#0} as core[5af540a774a18c96]::ops::function::FnOnce<(&core[5af540a774a18c96]::panic::panic_info::PanicInfo,)>>::call_once::{shim:vtable#0}
  12:     0x7f9a557638a7 - <alloc::boxed::Box<F,A> as core::ops::function::Fn<Args>>::call::h8fd3dd7b4b7c7be6
                               at /rustc/e9e1bbc7a820c472b39d3de54b3049bf14050655/library/alloc/src/boxed.rs:1999:9
  13:     0x7f9a557638a7 - std::panicking::rust_panic_with_hook::hf12d457c63c5c6c0
                               at /rustc/e9e1bbc7a820c472b39d3de54b3049bf14050655/library/std/src/panicking.rs:695:13
  14:     0x7f9a58df7d81 - std[2d504a8cfdbfb29a]::panicking::begin_panic::<rustc_errors[b836519eec60c9cd]::ExplicitBug>::{closure#0}
  15:     0x7f9a58df0666 - std[2d504a8cfdbfb29a]::sys_common::backtrace::__rust_end_short_backtrace::<std[2d504a8cfdbfb29a]::panicking::begin_panic<rustc_errors[b836519eec60c9cd]::ExplicitBug>::{closure#0}, !>
  16:     0x7f9a58ded546 - std[2d504a8cfdbfb29a]::panicking::begin_panic::<rustc_errors[b836519eec60c9cd]::ExplicitBug>
  17:     0x7f9a58dea124 - <rustc_errors[b836519eec60c9cd]::HandlerInner>::bug::<alloc[19ccc0991a3daa1b]::string::String>
  18:     0x7f9a58de9ec6 - <rustc_errors[b836519eec60c9cd]::Handler>::bug::<alloc[19ccc0991a3daa1b]::string::String>
  19:     0x7f9a58e6bdbc - rustc_middle[bb0d7f547e4279ba]::util::bug::opt_span_bug_fmt::<rustc_span[933af9702833abc6]::span_encoding::Span>::{closure#0}
  20:     0x7f9a58e692aa - rustc_middle[bb0d7f547e4279ba]::ty::context::tls::with_opt::<rustc_middle[bb0d7f547e4279ba]::util::bug::opt_span_bug_fmt<rustc_span[933af9702833abc6]::span_encoding::Span>::{closure#0}, !>::{closure#0}
  21:     0x7f9a58e6927a - rustc_middle[bb0d7f547e4279ba]::ty::context::tls::with_context_opt::<rustc_middle[bb0d7f547e4279ba]::ty::context::tls::with_opt<rustc_middle[bb0d7f547e4279ba]::util::bug::opt_span_bug_fmt<rustc_span[933af9702833abc6]::span_encoding::Span>::{closure#0}, !>::{closure#0}, !>
  22:     0x7f9a5706ec1d - rustc_middle[bb0d7f547e4279ba]::util::bug::bug_fmt
  23:     0x7f9a585c09f7 - <rustc_borrowck[23c7c709334a1b56]::universal_regions::UniversalRegionIndices>::fold_to_region_vids::<rustc_middle[bb0d7f547e4279ba]::ty::Ty>::{closure#0}
  24:     0x7f9a56a86142 - <rustc_middle[bb0d7f547e4279ba]::ty::fold::RegionFolder as rustc_type_ir[97219bea72dce6b0]::fold::FallibleTypeFolder<rustc_middle[bb0d7f547e4279ba]::ty::context::TyCtxt>>::try_fold_ty
  25:     0x7f9a56a86780 - <rustc_middle[bb0d7f547e4279ba]::ty::fold::RegionFolder as rustc_type_ir[97219bea72dce6b0]::fold::FallibleTypeFolder<rustc_middle[bb0d7f547e4279ba]::ty::context::TyCtxt>>::try_fold_ty
  26:     0x7f9a5783f5b9 - <rustc_borrowck[23c7c709334a1b56]::universal_regions::UniversalRegions>::new
  27:     0x7f9a5782d1ff - rustc_borrowck[23c7c709334a1b56]::nll::replace_regions_in_mir
  28:     0x7f9a578133c1 - rustc_borrowck[23c7c709334a1b56]::do_mir_borrowck
  29:     0x7f9a57810ede - rustc_borrowck[23c7c709334a1b56]::mir_borrowck
  30:     0x7f9a578109b9 - <rustc_query_impl[30b71d9bb4f4eb03]::dynamic_query::mir_borrowck::{closure#2} as core[5af540a774a18c96]::ops::function::FnOnce<(rustc_middle[bb0d7f547e4279ba]::ty::context::TyCtxt, rustc_span[933af9702833abc6]::def_id::LocalDefId)>>::call_once
  31:     0x7f9a56a933ff - rustc_query_system[8066410b7fffb3bb]::query::plumbing::try_execute_query::<rustc_query_impl[30b71d9bb4f4eb03]::DynamicConfig<rustc_query_system[8066410b7fffb3bb]::query::caches::VecCache<rustc_span[933af9702833abc6]::def_id::LocalDefId, rustc_middle[bb0d7f547e4279ba]::query::erase::Erased<[u8; 8usize]>>, false, false, false>, rustc_query_impl[30b71d9bb4f4eb03]::plumbing::QueryCtxt, false>
  32:     0x7f9a582b9e61 - rustc_query_impl[30b71d9bb4f4eb03]::get_query_non_incr::mir_borrowck
  33:     0x7f9a571941ed - rustc_mir_transform[cd42bf1bef1bc297]::mir_drops_elaborated_and_const_checked
  34:     0x7f9a57193e09 - <rustc_query_impl[30b71d9bb4f4eb03]::dynamic_query::mir_drops_elaborated_and_const_checked::{closure#2} as core[5af540a774a18c96]::ops::function::FnOnce<(rustc_middle[bb0d7f547e4279ba]::ty::context::TyCtxt, rustc_span[933af9702833abc6]::def_id::LocalDefId)>>::call_once
  35:     0x7f9a56a933ff - rustc_query_system[8066410b7fffb3bb]::query::plumbing::try_execute_query::<rustc_query_impl[30b71d9bb4f4eb03]::DynamicConfig<rustc_query_system[8066410b7fffb3bb]::query::caches::VecCache<rustc_span[933af9702833abc6]::def_id::LocalDefId, rustc_middle[bb0d7f547e4279ba]::query::erase::Erased<[u8; 8usize]>>, false, false, false>, rustc_query_impl[30b71d9bb4f4eb03]::plumbing::QueryCtxt, false>
  36:     0x7f9a582b6ca1 - rustc_query_impl[30b71d9bb4f4eb03]::get_query_non_incr::mir_drops_elaborated_and_const_checked
  37:     0x7f9a5773e78c - rustc_mir_transform[cd42bf1bef1bc297]::mir_for_ctfe
  38:     0x7f9a59186663 - <rustc_query_impl[30b71d9bb4f4eb03]::dynamic_query::mir_for_ctfe::{closure#2} as core[5af540a774a18c96]::ops::function::FnOnce<(rustc_middle[bb0d7f547e4279ba]::ty::context::TyCtxt, rustc_span[933af9702833abc6]::def_id::DefId)>>::call_once
  39:     0x7f9a56989327 - rustc_query_system[8066410b7fffb3bb]::query::plumbing::try_execute_query::<rustc_query_impl[30b71d9bb4f4eb03]::DynamicConfig<rustc_query_system[8066410b7fffb3bb]::query::caches::DefaultCache<rustc_span[933af9702833abc6]::def_id::DefId, rustc_middle[bb0d7f547e4279ba]::query::erase::Erased<[u8; 8usize]>>, false, false, false>, rustc_query_impl[30b71d9bb4f4eb03]::plumbing::QueryCtxt, false>
  40:     0x7f9a582b6db4 - rustc_query_impl[30b71d9bb4f4eb03]::get_query_non_incr::mir_for_ctfe
  41:     0x7f9a56d89440 - <rustc_const_eval[db30e05fc82f6865]::interpret::eval_context::InterpCx<rustc_const_eval[db30e05fc82f6865]::const_eval::machine::CompileTimeInterpreter>>::load_mir
  42:     0x7f9a56cb3a31 - rustc_const_eval[db30e05fc82f6865]::const_eval::eval_queries::eval_to_allocation_raw_provider
  43:     0x7f9a575cf0c4 - rustc_query_system[8066410b7fffb3bb]::query::plumbing::try_execute_query::<rustc_query_impl[30b71d9bb4f4eb03]::DynamicConfig<rustc_query_system[8066410b7fffb3bb]::query::caches::DefaultCache<rustc_middle[bb0d7f547e4279ba]::ty::ParamEnvAnd<rustc_middle[bb0d7f547e4279ba]::mir::interpret::GlobalId>, rustc_middle[bb0d7f547e4279ba]::query::erase::Erased<[u8; 16usize]>>, false, false, false>, rustc_query_impl[30b71d9bb4f4eb03]::plumbing::QueryCtxt, false>
  44:     0x7f9a575ced9d - rustc_query_impl[30b71d9bb4f4eb03]::get_query_non_incr::eval_to_allocation_raw
  45:     0x7f9a57e4feb8 - rustc_const_eval[db30e05fc82f6865]::const_eval::eval_queries::eval_to_const_value_raw_provider
  46:     0x7f9a5724590c - rustc_query_system[8066410b7fffb3bb]::query::plumbing::try_execute_query::<rustc_query_impl[30b71d9bb4f4eb03]::DynamicConfig<rustc_query_system[8066410b7fffb3bb]::query::caches::DefaultCache<rustc_middle[bb0d7f547e4279ba]::ty::ParamEnvAnd<rustc_middle[bb0d7f547e4279ba]::mir::interpret::GlobalId>, rustc_middle[bb0d7f547e4279ba]::query::erase::Erased<[u8; 32usize]>>, false, false, false>, rustc_query_impl[30b71d9bb4f4eb03]::plumbing::QueryCtxt, false>
  47:     0x7f9a5724553d - rustc_query_impl[30b71d9bb4f4eb03]::get_query_non_incr::eval_to_const_value_raw
  48:     0x7f9a57718059 - rustc_middle[bb0d7f547e4279ba]::query::plumbing::query_get_at::<rustc_query_system[8066410b7fffb3bb]::query::caches::DefaultCache<rustc_middle[bb0d7f547e4279ba]::ty::ParamEnvAnd<rustc_middle[bb0d7f547e4279ba]::mir::interpret::GlobalId>, rustc_middle[bb0d7f547e4279ba]::query::erase::Erased<[u8; 32usize]>>>
  49:     0x7f9a577140eb - <rustc_middle[bb0d7f547e4279ba]::ty::context::TyCtxt>::const_eval_resolve
  50:     0x7f9a58db47c2 - <rustc_middle[bb0d7f547e4279ba]::mir::ConstantKind>::from_anon_const
  51:     0x7f9a56cacad2 - <core[5af540a774a18c96]::iter::adapters::map::Map<core[5af540a774a18c96]::slice::iter::Iter<(rustc_hir[e3f000cd749df977]::hir::InlineAsmOperand, rustc_span[933af9702833abc6]::span_encoding::Span)>, <rustc_mir_build[5c09840724c7611e]::thir::cx::Cx>::make_mirror_unadjusted::{closure#0}::{closure#10}> as core[5af540a774a18c96]::iter::traits::iterator::Iterator>::fold::<(), core[5af540a774a18c96]::iter::traits::iterator::Iterator::for_each::call<rustc_middle[bb0d7f547e4279ba]::thir::InlineAsmOperand, <alloc[19ccc0991a3daa1b]::vec::Vec<rustc_middle[bb0d7f547e4279ba]::thir::InlineAsmOperand>>::extend_trusted<core[5af540a774a18c96]::iter::adapters::map::Map<core[5af540a774a18c96]::slice::iter::Iter<(rustc_hir[e3f000cd749df977]::hir::InlineAsmOperand, rustc_span[933af9702833abc6]::span_encoding::Span)>, <rustc_mir_build[5c09840724c7611e]::thir::cx::Cx>::make_mirror_unadjusted::{closure#0}::{closure#10}>>::{closure#0}>::{closure#0}>
  52:     0x7f9a56cac38c - <alloc[19ccc0991a3daa1b]::vec::Vec<rustc_middle[bb0d7f547e4279ba]::thir::InlineAsmOperand> as alloc[19ccc0991a3daa1b]::vec::spec_from_iter::SpecFromIter<rustc_middle[bb0d7f547e4279ba]::thir::InlineAsmOperand, core[5af540a774a18c96]::iter::adapters::map::Map<core[5af540a774a18c96]::slice::iter::Iter<(rustc_hir[e3f000cd749df977]::hir::InlineAsmOperand, rustc_span[933af9702833abc6]::span_encoding::Span)>, <rustc_mir_build[5c09840724c7611e]::thir::cx::Cx>::make_mirror_unadjusted::{closure#0}::{closure#10}>>>::from_iter
  53:     0x7f9a56cac255 - <alloc[19ccc0991a3daa1b]::boxed::Box<[rustc_middle[bb0d7f547e4279ba]::thir::InlineAsmOperand]> as core[5af540a774a18c96]::iter::traits::collect::FromIterator<rustc_middle[bb0d7f547e4279ba]::thir::InlineAsmOperand>>::from_iter::<core[5af540a774a18c96]::iter::adapters::map::Map<core[5af540a774a18c96]::slice::iter::Iter<(rustc_hir[e3f000cd749df977]::hir::InlineAsmOperand, rustc_span[933af9702833abc6]::span_encoding::Span)>, <rustc_mir_build[5c09840724c7611e]::thir::cx::Cx>::make_mirror_unadjusted::{closure#0}::{closure#10}>>
  54:     0x7f9a56c9a072 - <rustc_mir_build[5c09840724c7611e]::thir::cx::Cx>::make_mirror_unadjusted::{closure#0}
  55:     0x7f9a56c9cd62 - <rustc_mir_build[5c09840724c7611e]::thir::cx::Cx>::mirror_expr
  56:     0x7f9a56c948db - <rustc_mir_build[5c09840724c7611e]::thir::cx::Cx>::make_mirror_unadjusted::{closure#0}
  57:     0x7f9a56c9cd62 - <rustc_mir_build[5c09840724c7611e]::thir::cx::Cx>::mirror_expr
  58:     0x7f9a5744a70d - rustc_mir_build[5c09840724c7611e]::thir::cx::thir_body
  59:     0x7f9a578118cc - rustc_query_system[8066410b7fffb3bb]::query::plumbing::try_execute_query::<rustc_query_impl[30b71d9bb4f4eb03]::DynamicConfig<rustc_query_system[8066410b7fffb3bb]::query::caches::VecCache<rustc_span[933af9702833abc6]::def_id::LocalDefId, rustc_middle[bb0d7f547e4279ba]::query::erase::Erased<[u8; 16usize]>>, false, false, false>, rustc_query_impl[30b71d9bb4f4eb03]::plumbing::QueryCtxt, false>
  60:     0x7f9a57b2ad23 - rustc_mir_build[5c09840724c7611e]::thir::pattern::check_match::check_match
  61:     0x7f9a5758b161 - rustc_query_system[8066410b7fffb3bb]::query::plumbing::try_execute_query::<rustc_query_impl[30b71d9bb4f4eb03]::DynamicConfig<rustc_query_system[8066410b7fffb3bb]::query::caches::VecCache<rustc_span[933af9702833abc6]::def_id::LocalDefId, rustc_middle[bb0d7f547e4279ba]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[30b71d9bb4f4eb03]::plumbing::QueryCtxt, false>
  62:     0x7f9a575853bf - rustc_mir_build[5c09840724c7611e]::build::mir_built
  63:     0x7f9a56a933ff - rustc_query_system[8066410b7fffb3bb]::query::plumbing::try_execute_query::<rustc_query_impl[30b71d9bb4f4eb03]::DynamicConfig<rustc_query_system[8066410b7fffb3bb]::query::caches::VecCache<rustc_span[933af9702833abc6]::def_id::LocalDefId, rustc_middle[bb0d7f547e4279ba]::query::erase::Erased<[u8; 8usize]>>, false, false, false>, rustc_query_impl[30b71d9bb4f4eb03]::plumbing::QueryCtxt, false>
  64:     0x7f9a57a517eb - rustc_mir_transform[cd42bf1bef1bc297]::check_unsafety::unsafety_check_result
  65:     0x7f9a56a933ff - rustc_query_system[8066410b7fffb3bb]::query::plumbing::try_execute_query::<rustc_query_impl[30b71d9bb4f4eb03]::DynamicConfig<rustc_query_system[8066410b7fffb3bb]::query::caches::VecCache<rustc_span[933af9702833abc6]::def_id::LocalDefId, rustc_middle[bb0d7f547e4279ba]::query::erase::Erased<[u8; 8usize]>>, false, false, false>, rustc_query_impl[30b71d9bb4f4eb03]::plumbing::QueryCtxt, false>
  66:     0x7f9a57ce980a - rustc_mir_transform[cd42bf1bef1bc297]::mir_const
  67:     0x7f9a57ce96d9 - <rustc_query_impl[30b71d9bb4f4eb03]::dynamic_query::mir_const::{closure#2} as core[5af540a774a18c96]::ops::function::FnOnce<(rustc_middle[bb0d7f547e4279ba]::ty::context::TyCtxt, rustc_span[933af9702833abc6]::def_id::LocalDefId)>>::call_once
  68:     0x7f9a56a933ff - rustc_query_system[8066410b7fffb3bb]::query::plumbing::try_execute_query::<rustc_query_impl[30b71d9bb4f4eb03]::DynamicConfig<rustc_query_system[8066410b7fffb3bb]::query::caches::VecCache<rustc_span[933af9702833abc6]::def_id::LocalDefId, rustc_middle[bb0d7f547e4279ba]::query::erase::Erased<[u8; 8usize]>>, false, false, false>, rustc_query_impl[30b71d9bb4f4eb03]::plumbing::QueryCtxt, false>
  69:     0x7f9a582b6a71 - rustc_query_impl[30b71d9bb4f4eb03]::get_query_non_incr::mir_const
  70:     0x7f9a577272a5 - rustc_mir_transform[cd42bf1bef1bc297]::mir_promoted
  71:     0x7f9a5781188c - rustc_query_system[8066410b7fffb3bb]::query::plumbing::try_execute_query::<rustc_query_impl[30b71d9bb4f4eb03]::DynamicConfig<rustc_query_system[8066410b7fffb3bb]::query::caches::VecCache<rustc_span[933af9702833abc6]::def_id::LocalDefId, rustc_middle[bb0d7f547e4279ba]::query::erase::Erased<[u8; 16usize]>>, false, false, false>, rustc_query_impl[30b71d9bb4f4eb03]::plumbing::QueryCtxt, false>
  72:     0x7f9a57810ad5 - rustc_borrowck[23c7c709334a1b56]::mir_borrowck
  73:     0x7f9a578109b9 - <rustc_query_impl[30b71d9bb4f4eb03]::dynamic_query::mir_borrowck::{closure#2} as core[5af540a774a18c96]::ops::function::FnOnce<(rustc_middle[bb0d7f547e4279ba]::ty::context::TyCtxt, rustc_span[933af9702833abc6]::def_id::LocalDefId)>>::call_once
  74:     0x7f9a56a933ff - rustc_query_system[8066410b7fffb3bb]::query::plumbing::try_execute_query::<rustc_query_impl[30b71d9bb4f4eb03]::DynamicConfig<rustc_query_system[8066410b7fffb3bb]::query::caches::VecCache<rustc_span[933af9702833abc6]::def_id::LocalDefId, rustc_middle[bb0d7f547e4279ba]::query::erase::Erased<[u8; 8usize]>>, false, false, false>, rustc_query_impl[30b71d9bb4f4eb03]::plumbing::QueryCtxt, false>
  75:     0x7f9a57d815c1 - rustc_data_structures[b495fb6cd5b06e12]::sync::par_for_each_in::<&[rustc_span[933af9702833abc6]::def_id::LocalDefId], <rustc_middle[bb0d7f547e4279ba]::hir::map::Map>::par_body_owners<rustc_interface[8c874ff40524f1a6]::passes::analysis::{closure#1}::{closure#0}>::{closure#0}>
  76:     0x7f9a57d81236 - <rustc_session[3cf81f91e01c2314]::session::Session>::time::<(), rustc_interface[8c874ff40524f1a6]::passes::analysis::{closure#1}>
  77:     0x7f9a57d80c3f - rustc_interface[8c874ff40524f1a6]::passes::analysis
  78:     0x7f9a59197627 - <rustc_query_impl[30b71d9bb4f4eb03]::dynamic_query::analysis::{closure#2} as core[5af540a774a18c96]::ops::function::FnOnce<(rustc_middle[bb0d7f547e4279ba]::ty::context::TyCtxt, ())>>::call_once
  79:     0x7f9a57fef654 - rustc_query_system[8066410b7fffb3bb]::query::plumbing::try_execute_query::<rustc_query_impl[30b71d9bb4f4eb03]::DynamicConfig<rustc_query_system[8066410b7fffb3bb]::query::caches::SingleCache<rustc_middle[bb0d7f547e4279ba]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[30b71d9bb4f4eb03]::plumbing::QueryCtxt, false>
  80:     0x7f9a57fef439 - rustc_query_impl[30b71d9bb4f4eb03]::get_query_non_incr::analysis
  81:     0x7f9a57b82f7c - <rustc_interface[8c874ff40524f1a6]::queries::QueryResult<&rustc_middle[bb0d7f547e4279ba]::ty::context::GlobalCtxt>>::enter::<core[5af540a774a18c96]::result::Result<(), rustc_span[933af9702833abc6]::ErrorGuaranteed>, rustc_driver_impl[88bc38c0e277e71e]::run_compiler::{closure#1}::{closure#2}::{closure#4}>
  82:     0x7f9a57b82135 - <rustc_interface[8c874ff40524f1a6]::interface::Compiler>::enter::<rustc_driver_impl[88bc38c0e277e71e]::run_compiler::{closure#1}::{closure#2}, core[5af540a774a18c96]::result::Result<core[5af540a774a18c96]::option::Option<rustc_interface[8c874ff40524f1a6]::queries::Linker>, rustc_span[933af9702833abc6]::ErrorGuaranteed>>
  83:     0x7f9a57b7f8da - std[2d504a8cfdbfb29a]::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface[8c874ff40524f1a6]::util::run_in_thread_pool_with_globals<rustc_interface[8c874ff40524f1a6]::interface::run_compiler<core[5af540a774a18c96]::result::Result<(), rustc_span[933af9702833abc6]::ErrorGuaranteed>, rustc_driver_impl[88bc38c0e277e71e]::run_compiler::{closure#1}>::{closure#0}, core[5af540a774a18c96]::result::Result<(), rustc_span[933af9702833abc6]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[5af540a774a18c96]::result::Result<(), rustc_span[933af9702833abc6]::ErrorGuaranteed>>
  84:     0x7f9a57b7f055 - <<std[2d504a8cfdbfb29a]::thread::Builder>::spawn_unchecked_<rustc_interface[8c874ff40524f1a6]::util::run_in_thread_pool_with_globals<rustc_interface[8c874ff40524f1a6]::interface::run_compiler<core[5af540a774a18c96]::result::Result<(), rustc_span[933af9702833abc6]::ErrorGuaranteed>, rustc_driver_impl[88bc38c0e277e71e]::run_compiler::{closure#1}>::{closure#0}, core[5af540a774a18c96]::result::Result<(), rustc_span[933af9702833abc6]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[5af540a774a18c96]::result::Result<(), rustc_span[933af9702833abc6]::ErrorGuaranteed>>::{closure#1} as core[5af540a774a18c96]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  85:     0x7f9a5576dd55 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::hd480bf283bbeb783
                               at /rustc/e9e1bbc7a820c472b39d3de54b3049bf14050655/library/alloc/src/boxed.rs:1985:9
  86:     0x7f9a5576dd55 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::hd53575de28446892
                               at /rustc/e9e1bbc7a820c472b39d3de54b3049bf14050655/library/alloc/src/boxed.rs:1985:9
  87:     0x7f9a5576dd55 - std::sys::unix::thread::Thread::new::thread_start::h260d6c60c2a2aae6
                               at /rustc/e9e1bbc7a820c472b39d3de54b3049bf14050655/library/std/src/sys/unix/thread.rs:108:17
  88:     0x7f9a5563d609 - start_thread
  89:     0x7f9a55560133 - clone
  90:                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 1.71.0-nightly (e9e1bbc7a 2023-05-17) running on x86_64-unknown-linux-gnu

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 [mir_borrowck] borrow-checking `_start_trap::{constant#0}`
#1 [mir_drops_elaborated_and_const_checked] elaborating drops for `_start_trap::{constant#0}`
#2 [mir_for_ctfe] caching mir of `_start_trap::{constant#0}` for CTFE
#3 [eval_to_allocation_raw] const-evaluating + checking `_start_trap::{constant#0}`
#4 [eval_to_const_value_raw] simplifying constant for the type system `_start_trap::{constant#0}`
#5 [thir_body] building THIR for `_start_trap`
#6 [check_match] match-checking `_start_trap`
#7 [mir_built] building MIR for `_start_trap`
#8 [unsafety_check_result] unsafety-checking `_start_trap`
#9 [mir_const] preparing `_start_trap` for borrow checking
#10 [mir_promoted] promoting constants in MIR for `_start_trap`
#11 [mir_borrowck] borrow-checking `_start_trap`
#12 [analysis] running analysis passes on this crate
end of query stack

[sethp]

I have no idea if this code would work, but a close cousin does seem to (if I define the shim with concrete types instead of generically).

Well, it does compile and run successfully if I change the reference to:

        shim = sym crate::_rust_abi_shim1::<*mut TrapFrame, ()>,

instead of

        shim = sym crate::_rust_abi_shim1::<&mut TrapFrame, ()>,

[workingjubilee]

Thank you for reporting a very interesting bug.

The presence of &mut TrapFrame requires rustc to think about lifetimes, because the expanded type without type elision is &'a mut TrapFrame, i.e. & or &mut has a lifetime generic even if you don't see it. But somehow the way that the lifetimes and generics interact here causes rustc to fail to compute the lifetime in a way that can produce a region variable ID.

I can't seem to reproduce this without inline assembly so I think it has to do specifically with an interaction with asm! causing the MIR to not be set up properly?

Ah, I should mention: The way that generics interact with extern "C" is... underdefined. I do not recommend doing so.

[sethp]

Thanks for taking a look! It's a good point about there being an (implicit) lifetime here. I'm not entirely sure what I'm expecting here, since I wouldn't expect rustc to be able to reason about my #[naked] function's contents at all, but the TrapFrame here is valid as long as _start_trap is on the stack. From a types-as-documentation perspective, would that be modeled with an explicit lifetime like fn _start_trap<'a>() { ... } and then writing &'a mut TrapFrame ?

Ah, I should mention: The way that generics interact with extern "C" is... underdefined. I do not recommend doing so.

Aha, you've intuited the question I was really trying to answer when I slipped on that ICE: I was half expecting rustc to shake its head sadly at me and say "no, you can't have generic parameters to extern "C" function" heh.

For what it's worth, they do seem to work exactly as I intended here; if I add a second reference that does have a distinct ABI like crate::_trap_rust_abi_shim1::<u128, ()>,, I get two function bodies that appear correct on inspection:

420015ec <esp_riscv_rt::_trap_rust_abi_shim1>:
extern "C" fn _trap_rust_abi_shim1<A, R>(arg: A, f: fn(A) -> R) -> R {
420015ec:       1101                    addi    sp,sp,-32
420015ee:       ce06                    sw      ra,28(sp)
420015f0:       4110                    lw      a2,0(a0)
420015f2:       4154                    lw      a3,4(a0)
420015f4:       4518                    lw      a4,8(a0)
420015f6:       4548                    lw      a0,12(a0)
    f(arg)
420015f8:       ca2a                    sw      a0,20(sp)
420015fa:       c83a                    sw      a4,16(sp)
420015fc:       c636                    sw      a3,12(sp)
420015fe:       0028                    addi    a0,sp,8
42001600:       c432                    sw      a2,8(sp)
42001602:       9582                    jalr    a1
}
42001604:       40f2                    lw      ra,28(sp)
42001606:       6105                    addi    sp,sp,32
42001608:       8082                    ret

4200160a <esp_riscv_rt::_trap_rust_abi_shim1>:
    f(arg)
4200160a:       8582                    jr      a1

I'm sure there's gnarlier edges out there than "pointer or u128", and I probably won't end up using the generic version, but I did think that was neat. Hopefully you do too!

[asquared31415]

Minimized example that also works on x86_64, so it's likely not arch dependent:

use core::arch::asm;

extern "C" fn test<T>() {}

fn uwu() {
    unsafe {
        asm!(
            "/* {0} */",
            sym test::<&mut ()>
        );
    }
}

playground

@rustbot label +A-inline-assembly

[asquared31415]

This previously compiled (using the at the time unstable asm_sym feature) until #94468
cc @Amanieu

[workingjubilee]

Aha, you've intuited the question I was really trying to answer when I slipped on that ICE: I was half expecting rustc to shake its head sadly at me and say "no, you can't have generic parameters to extern "C" function" heh.

For what it's worth, they do seem to work exactly as I intended here; if I add a second reference that does have a distinct ABI like crate::_trap_rust_abi_shim1::<u128, ()>, I get two function bodies that appear correct on inspection:

Right, when I say "underspecified" I basically mean that it can work, but it... is not necessarily going to work how you might naively expect it to. So for your future sanity, it's often best to avoid polymorphic declarations in extern blocks. But if you had, we might not have encountered this interesting error, and this should definitely not ICE.

[sethp]

I very much appreciate your feedback. I'm fairly certain I'll end up doing something very different in the end, but it was a fun exploration. I'm glad I tried it as well: just doing my part to uphold the law.

[apiraino]

WG-prioritization assigning priority (Zulip discussion).

@rustbot label -I-prioritize +P-medium