//! Type-checking for the `#[rustc_intrinsic]` intrinsics that the compiler exposes.

use rustc_abi::ExternAbi;
use rustc_errors::DiagMessage;
use rustc_hir::{self as hir, LangItem};
use rustc_middle::traits::{ObligationCause, ObligationCauseCode};
use rustc_middle::ty::{self, Ty, TyCtxt};
use rustc_span::def_id::LocalDefId;
use rustc_span::{Span, Symbol, sym};

use crate::check::check_function_signature;
use crate::errors::{UnrecognizedIntrinsicFunction, WrongNumberOfGenericArgumentsToIntrinsic};

fn equate_intrinsic_type<'tcx>(
    tcx: TyCtxt<'tcx>,
    span: Span,
    def_id: LocalDefId,
    n_tps: usize,
    n_lts: usize,
    n_cts: usize,
    sig: ty::PolyFnSig<'tcx>,
) {
    let (generics, span) = match tcx.hir_node_by_def_id(def_id) {
        hir::Node::Item(hir::Item { kind: hir::ItemKind::Fn { generics, .. }, .. }) => {
            (tcx.generics_of(def_id), generics.span)
        }
        _ => tcx.dcx().span_bug(span, "intrinsic must be a function"),
    };
    let own_counts = generics.own_counts();

    let gen_count_ok = |found: usize, expected: usize, descr: &str| -> bool {
        if found != expected {
            tcx.dcx().emit_err(WrongNumberOfGenericArgumentsToIntrinsic {
                span,
                found,
                expected,
                descr,
            });
            false
        } else {
            true
        }
    };

    // the host effect param should be invisible as it shouldn't matter
    // whether effects is enabled for the intrinsic provider crate.
    if gen_count_ok(own_counts.lifetimes, n_lts, "lifetime")
        && gen_count_ok(own_counts.types, n_tps, "type")
        && gen_count_ok(own_counts.consts, n_cts, "const")
    {
        let _ = check_function_signature(
            tcx,
            ObligationCause::new(span, def_id, ObligationCauseCode::IntrinsicType),
            def_id.into(),
            sig,
        );
    }
}

/// Returns the unsafety of the given intrinsic.
fn intrinsic_operation_unsafety(tcx: TyCtxt<'_>, intrinsic_id: LocalDefId) -> hir::Safety {
    let is_in_list = match tcx.item_name(intrinsic_id) {
        // When adding a new intrinsic to this list,
        // it's usually worth updating that intrinsic's documentation
        // to note that it's safe to call, since
        // safe extern fns are otherwise unprecedented.
        sym::abort
        | sym::assert_inhabited
        | sym::assert_zero_valid
        | sym::assert_mem_uninitialized_valid
        | sym::box_new
        | sym::breakpoint
        | sym::size_of
        | sym::align_of
        | sym::needs_drop
        | sym::caller_location
        | sym::add_with_overflow
        | sym::sub_with_overflow
        | sym::mul_with_overflow
        | sym::carrying_mul_add
        | sym::wrapping_add
        | sym::wrapping_sub
        | sym::wrapping_mul
        | sym::saturating_add
        | sym::saturating_sub
        | sym::rotate_left
        | sym::rotate_right
        | sym::ctpop
        | sym::ctlz
        | sym::cttz
        | sym::bswap
        | sym::bitreverse
        | sym::three_way_compare
        | sym::discriminant_value
        | sym::type_id
        | sym::type_id_eq
        | sym::select_unpredictable
        | sym::cold_path
        | sym::ptr_guaranteed_cmp
        | sym::minnumf16
        | sym::minnumf32
        | sym::minnumf64
        | sym::minnumf128
        | sym::minimumf16
        | sym::minimumf32
        | sym::minimumf64
        | sym::minimumf128
        | sym::maxnumf16
        | sym::maxnumf32
        | sym::maxnumf64
        | sym::maxnumf128
        | sym::maximumf16
        | sym::maximumf32
        | sym::maximumf64
        | sym::maximumf128
        | sym::rustc_peek
        | sym::type_name
        | sym::forget
        | sym::black_box
        | sym::variant_count
        | sym::is_val_statically_known
        | sym::ptr_mask
        | sym::aggregate_raw_ptr
        | sym::ptr_metadata
        | sym::ub_checks
        | sym::contract_checks
        | sym::contract_check_requires
        | sym::contract_check_ensures
        | sym::fadd_algebraic
        | sym::fsub_algebraic
        | sym::fmul_algebraic
        | sym::fdiv_algebraic
        | sym::frem_algebraic
        | sym::round_ties_even_f16
        | sym::round_ties_even_f32
        | sym::round_ties_even_f64
        | sym::round_ties_even_f128
        | sym::autodiff
        | sym::prefetch_read_data
        | sym::prefetch_write_data
        | sym::prefetch_read_instruction
        | sym::prefetch_write_instruction
        | sym::const_eval_select => hir::Safety::Safe,
        _ => hir::Safety::Unsafe,
    };

    if tcx.fn_sig(intrinsic_id).skip_binder().safety() != is_in_list {
        tcx.dcx().struct_span_err(
            tcx.def_span(intrinsic_id),
            DiagMessage::from(format!(
                "intrinsic safety mismatch between list of intrinsics within the compiler and core library intrinsics for intrinsic `{}`",
                tcx.item_name(intrinsic_id)
            )
        )).emit();
    }

    is_in_list
}

/// Remember to add all intrinsics here, in `compiler/rustc_codegen_llvm/src/intrinsic.rs`,
/// and in `library/core/src/intrinsics.rs`.
pub(crate) fn check_intrinsic_type(
    tcx: TyCtxt<'_>,
    intrinsic_id: LocalDefId,
    span: Span,
    intrinsic_name: Symbol,
) {
    let generics = tcx.generics_of(intrinsic_id);
    let param = |n| {
        if let &ty::GenericParamDef { name, kind: ty::GenericParamDefKind::Type { .. }, .. } =
            generics.param_at(n as usize, tcx)
        {
            Ty::new_param(tcx, n, name)
        } else {
            Ty::new_error_with_message(tcx, span, "expected param")
        }
    };

    let bound_vars = tcx.mk_bound_variable_kinds(&[
        ty::BoundVariableKind::Region(ty::BoundRegionKind::Anon),
        ty::BoundVariableKind::Region(ty::BoundRegionKind::Anon),
        ty::BoundVariableKind::Region(ty::BoundRegionKind::ClosureEnv),
    ]);
    let mk_va_list_ty = |mutbl| {
        let did = tcx.require_lang_item(LangItem::VaList, span);
        let region = ty::Region::new_bound(
            tcx,
            ty::INNERMOST,
            ty::BoundRegion { var: ty::BoundVar::ZERO, kind: ty::BoundRegionKind::Anon },
        );
        let env_region = ty::Region::new_bound(
            tcx,
            ty::INNERMOST,
            ty::BoundRegion {
                var: ty::BoundVar::from_u32(2),
                kind: ty::BoundRegionKind::ClosureEnv,
            },
        );
        let va_list_ty = tcx.type_of(did).instantiate(tcx, &[region.into()]);
        (Ty::new_ref(tcx, env_region, va_list_ty, mutbl), va_list_ty)
    };

    let safety = intrinsic_operation_unsafety(tcx, intrinsic_id);
    let n_lts = 0;
    let (n_tps, n_cts, inputs, output) = match intrinsic_name {
        sym::autodiff => (4, 0, vec![param(0), param(1), param(2)], param(3)),
        sym::abort => (0, 0, vec![], tcx.types.never),
        sym::unreachable => (0, 0, vec![], tcx.types.never),
        sym::breakpoint => (0, 0, vec![], tcx.types.unit),
        sym::size_of | sym::align_of | sym::variant_count => (1, 0, vec![], tcx.types.usize),
        sym::size_of_val | sym::align_of_val => {
            (1, 0, vec![Ty::new_imm_ptr(tcx, param(0))], tcx.types.usize)
        }
        sym::rustc_peek => (1, 0, vec![param(0)], param(0)),
        sym::caller_location => (0, 0, vec![], tcx.caller_location_ty()),
        sym::assert_inhabited | sym::assert_zero_valid | sym::assert_mem_uninitialized_valid => {
            (1, 0, vec![], tcx.types.unit)
        }
        sym::forget => (1, 0, vec![param(0)], tcx.types.unit),
        sym::transmute | sym::transmute_unchecked => (2, 0, vec![param(0)], param(1)),
        sym::prefetch_read_data
        | sym::prefetch_write_data
        | sym::prefetch_read_instruction
        | sym::prefetch_write_instruction => {
            (1, 1, vec![Ty::new_imm_ptr(tcx, param(0))], tcx.types.unit)
        }
        sym::needs_drop => (1, 0, vec![], tcx.types.bool),

        sym::type_name => (1, 0, vec![], Ty::new_static_str(tcx)),
        sym::type_id => {
            (1, 0, vec![], tcx.type_of(tcx.lang_items().type_id().unwrap()).instantiate_identity())
        }
        sym::type_id_eq => {
            let type_id = tcx.type_of(tcx.lang_items().type_id().unwrap()).instantiate_identity();
            (0, 0, vec![type_id, type_id], tcx.types.bool)
        }
        sym::offset => (2, 0, vec![param(0), param(1)], param(0)),
        sym::arith_offset => (
            1,
            0,
            vec![Ty::new_imm_ptr(tcx, param(0)), tcx.types.isize],
            Ty::new_imm_ptr(tcx, param(0)),
        ),
        sym::slice_get_unchecked => (3, 0, vec![param(1), tcx.types.usize], param(0)),
        sym::ptr_mask => (
            1,
            0,
            vec![Ty::new_imm_ptr(tcx, param(0)), tcx.types.usize],
            Ty::new_imm_ptr(tcx, param(0)),
        ),

        sym::copy | sym::copy_nonoverlapping => (
            1,
            0,
            vec![Ty::new_imm_ptr(tcx, param(0)), Ty::new_mut_ptr(tcx, param(0)), tcx.types.usize],
            tcx.types.unit,
        ),
        sym::volatile_copy_memory | sym::volatile_copy_nonoverlapping_memory => (
            1,
            0,
            vec![Ty::new_mut_ptr(tcx, param(0)), Ty::new_imm_ptr(tcx, param(0)), tcx.types.usize],
            tcx.types.unit,
        ),
        sym::compare_bytes => {
            let byte_ptr = Ty::new_imm_ptr(tcx, tcx.types.u8);
            (0, 0, vec![byte_ptr, byte_ptr, tcx.types.usize], tcx.types.i32)
        }
        sym::write_bytes | sym::volatile_set_memory => (
            1,
            0,
            vec![Ty::new_mut_ptr(tcx, param(0)), tcx.types.u8, tcx.types.usize],
            tcx.types.unit,
        ),

        sym::sqrtf16 => (0, 0, vec![tcx.types.f16], tcx.types.f16),
        sym::sqrtf32 => (0, 0, vec![tcx.types.f32], tcx.types.f32),
        sym::sqrtf64 => (0, 0, vec![tcx.types.f64], tcx.types.f64),
        sym::sqrtf128 => (0, 0, vec![tcx.types.f128], tcx.types.f128),

        sym::powif16 => (0, 0, vec![tcx.types.f16, tcx.types.i32], tcx.types.f16),
        sym::powif32 => (0, 0, vec![tcx.types.f32, tcx.types.i32], tcx.types.f32),
        sym::powif64 => (0, 0, vec![tcx.types.f64, tcx.types.i32], tcx.types.f64),
        sym::powif128 => (0, 0, vec![tcx.types.f128, tcx.types.i32], tcx.types.f128),

        sym::sinf16 => (0, 0, vec![tcx.types.f16], tcx.types.f16),
        sym::sinf32 => (0, 0, vec![tcx.types.f32], tcx.types.f32),
        sym::sinf64 => (0, 0, vec![tcx.types.f64], tcx.types.f64),
        sym::sinf128 => (0, 0, vec![tcx.types.f128], tcx.types.f128),

        sym::cosf16 => (0, 0, vec![tcx.types.f16], tcx.types.f16),
        sym::cosf32 => (0, 0, vec![tcx.types.f32], tcx.types.f32),
        sym::cosf64 => (0, 0, vec![tcx.types.f64], tcx.types.f64),
        sym::cosf128 => (0, 0, vec![tcx.types.f128], tcx.types.f128),

        sym::powf16 => (0, 0, vec![tcx.types.f16, tcx.types.f16], tcx.types.f16),
        sym::powf32 => (0, 0, vec![tcx.types.f32, tcx.types.f32], tcx.types.f32),
        sym::powf64 => (0, 0, vec![tcx.types.f64, tcx.types.f64], tcx.types.f64),
        sym::powf128 => (0, 0, vec![tcx.types.f128, tcx.types.f128], tcx.types.f128),

        sym::expf16 => (0, 0, vec![tcx.types.f16], tcx.types.f16),
        sym::expf32 => (0, 0, vec![tcx.types.f32], tcx.types.f32),
        sym::expf64 => (0, 0, vec![tcx.types.f64], tcx.types.f64),
        sym::expf128 => (0, 0, vec![tcx.types.f128], tcx.types.f128),

        sym::exp2f16 => (0, 0, vec![tcx.types.f16], tcx.types.f16),
        sym::exp2f32 => (0, 0, vec![tcx.types.f32], tcx.types.f32),
        sym::exp2f64 => (0, 0, vec![tcx.types.f64], tcx.types.f64),
        sym::exp2f128 => (0, 0, vec![tcx.types.f128], tcx.types.f128),

        sym::logf16 => (0, 0, vec![tcx.types.f16], tcx.types.f16),
        sym::logf32 => (0, 0, vec![tcx.types.f32], tcx.types.f32),
        sym::logf64 => (0, 0, vec![tcx.types.f64], tcx.types.f64),
        sym::logf128 => (0, 0, vec![tcx.types.f128], tcx.types.f128),

        sym::log10f16 => (0, 0, vec![tcx.types.f16], tcx.types.f16),
        sym::log10f32 => (0, 0, vec![tcx.types.f32], tcx.types.f32),
        sym::log10f64 => (0, 0, vec![tcx.types.f64], tcx.types.f64),
        sym::log10f128 => (0, 0, vec![tcx.types.f128], tcx.types.f128),

        sym::log2f16 => (0, 0, vec![tcx.types.f16], tcx.types.f16),
        sym::log2f32 => (0, 0, vec![tcx.types.f32], tcx.types.f32),
        sym::log2f64 => (0, 0, vec![tcx.types.f64], tcx.types.f64),
        sym::log2f128 => (0, 0, vec![tcx.types.f128], tcx.types.f128),

        sym::fmaf16 => (0, 0, vec![tcx.types.f16, tcx.types.f16, tcx.types.f16], tcx.types.f16),
        sym::fmaf32 => (0, 0, vec![tcx.types.f32, tcx.types.f32, tcx.types.f32], tcx.types.f32),
        sym::fmaf64 => (0, 0, vec![tcx.types.f64, tcx.types.f64, tcx.types.f64], tcx.types.f64),
        sym::fmaf128 => {
            (0, 0, vec![tcx.types.f128, tcx.types.f128, tcx.types.f128], tcx.types.f128)
        }

        sym::fmuladdf16 => (0, 0, vec![tcx.types.f16, tcx.types.f16, tcx.types.f16], tcx.types.f16),
        sym::fmuladdf32 => (0, 0, vec![tcx.types.f32, tcx.types.f32, tcx.types.f32], tcx.types.f32),
        sym::fmuladdf64 => (0, 0, vec![tcx.types.f64, tcx.types.f64, tcx.types.f64], tcx.types.f64),
        sym::fmuladdf128 => {
            (0, 0, vec![tcx.types.f128, tcx.types.f128, tcx.types.f128], tcx.types.f128)
        }

        sym::fabsf16 => (0, 0, vec![tcx.types.f16], tcx.types.f16),
        sym::fabsf32 => (0, 0, vec![tcx.types.f32], tcx.types.f32),
        sym::fabsf64 => (0, 0, vec![tcx.types.f64], tcx.types.f64),
        sym::fabsf128 => (0, 0, vec![tcx.types.f128], tcx.types.f128),

        sym::minnumf16 => (0, 0, vec![tcx.types.f16, tcx.types.f16], tcx.types.f16),
        sym::minnumf32 => (0, 0, vec![tcx.types.f32, tcx.types.f32], tcx.types.f32),
        sym::minnumf64 => (0, 0, vec![tcx.types.f64, tcx.types.f64], tcx.types.f64),
        sym::minnumf128 => (0, 0, vec![tcx.types.f128, tcx.types.f128], tcx.types.f128),

        sym::minimumf16 => (0, 0, vec![tcx.types.f16, tcx.types.f16], tcx.types.f16),
        sym::minimumf32 => (0, 0, vec![tcx.types.f32, tcx.types.f32], tcx.types.f32),
        sym::minimumf64 => (0, 0, vec![tcx.types.f64, tcx.types.f64], tcx.types.f64),
        sym::minimumf128 => (0, 0, vec![tcx.types.f128, tcx.types.f128], tcx.types.f128),

        sym::maxnumf16 => (0, 0, vec![tcx.types.f16, tcx.types.f16], tcx.types.f16),
        sym::maxnumf32 => (0, 0, vec![tcx.types.f32, tcx.types.f32], tcx.types.f32),
        sym::maxnumf64 => (0, 0, vec![tcx.types.f64, tcx.types.f64], tcx.types.f64),
        sym::maxnumf128 => (0, 0, vec![tcx.types.f128, tcx.types.f128], tcx.types.f128),

        sym::maximumf16 => (0, 0, vec![tcx.types.f16, tcx.types.f16], tcx.types.f16),
        sym::maximumf32 => (0, 0, vec![tcx.types.f32, tcx.types.f32], tcx.types.f32),
        sym::maximumf64 => (0, 0, vec![tcx.types.f64, tcx.types.f64], tcx.types.f64),
        sym::maximumf128 => (0, 0, vec![tcx.types.f128, tcx.types.f128], tcx.types.f128),

        sym::copysignf16 => (0, 0, vec![tcx.types.f16, tcx.types.f16], tcx.types.f16),
        sym::copysignf32 => (0, 0, vec![tcx.types.f32, tcx.types.f32], tcx.types.f32),
        sym::copysignf64 => (0, 0, vec![tcx.types.f64, tcx.types.f64], tcx.types.f64),
        sym::copysignf128 => (0, 0, vec![tcx.types.f128, tcx.types.f128], tcx.types.f128),

        sym::floorf16 => (0, 0, vec![tcx.types.f16], tcx.types.f16),
        sym::floorf32 => (0, 0, vec![tcx.types.f32], tcx.types.f32),
        sym::floorf64 => (0, 0, vec![tcx.types.f64], tcx.types.f64),
        sym::floorf128 => (0, 0, vec![tcx.types.f128], tcx.types.f128),

        sym::ceilf16 => (0, 0, vec![tcx.types.f16], tcx.types.f16),
        sym::ceilf32 => (0, 0, vec![tcx.types.f32], tcx.types.f32),
        sym::ceilf64 => (0, 0, vec![tcx.types.f64], tcx.types.f64),
        sym::ceilf128 => (0, 0, vec![tcx.types.f128], tcx.types.f128),

        sym::truncf16 => (0, 0, vec![tcx.types.f16], tcx.types.f16),
        sym::truncf32 => (0, 0, vec![tcx.types.f32], tcx.types.f32),
        sym::truncf64 => (0, 0, vec![tcx.types.f64], tcx.types.f64),
        sym::truncf128 => (0, 0, vec![tcx.types.f128], tcx.types.f128),

        sym::round_ties_even_f16 => (0, 0, vec![tcx.types.f16], tcx.types.f16),
        sym::round_ties_even_f32 => (0, 0, vec![tcx.types.f32], tcx.types.f32),
        sym::round_ties_even_f64 => (0, 0, vec![tcx.types.f64], tcx.types.f64),
        sym::round_ties_even_f128 => (0, 0, vec![tcx.types.f128], tcx.types.f128),

        sym::roundf16 => (0, 0, vec![tcx.types.f16], tcx.types.f16),
        sym::roundf32 => (0, 0, vec![tcx.types.f32], tcx.types.f32),
        sym::roundf64 => (0, 0, vec![tcx.types.f64], tcx.types.f64),
        sym::roundf128 => (0, 0, vec![tcx.types.f128], tcx.types.f128),

        sym::volatile_load | sym::unaligned_volatile_load => {
            (1, 0, vec![Ty::new_imm_ptr(tcx, param(0))], param(0))
        }
        sym::volatile_store | sym::unaligned_volatile_store => {
            (1, 0, vec![Ty::new_mut_ptr(tcx, param(0)), param(0)], tcx.types.unit)
        }

        sym::ctpop | sym::ctlz | sym::ctlz_nonzero | sym::cttz | sym::cttz_nonzero => {
            (1, 0, vec![param(0)], tcx.types.u32)
        }

        sym::bswap | sym::bitreverse => (1, 0, vec![param(0)], param(0)),

        sym::three_way_compare => (1, 0, vec![param(0), param(0)], tcx.ty_ordering_enum(span)),

        sym::add_with_overflow | sym::sub_with_overflow | sym::mul_with_overflow => {
            (1, 0, vec![param(0), param(0)], Ty::new_tup(tcx, &[param(0), tcx.types.bool]))
        }

        sym::carrying_mul_add => (2, 0, vec![param(0); 4], Ty::new_tup(tcx, &[param(1), param(0)])),

        sym::ptr_guaranteed_cmp => (
            1,
            0,
            vec![Ty::new_imm_ptr(tcx, param(0)), Ty::new_imm_ptr(tcx, param(0))],
            tcx.types.u8,
        ),

        sym::const_allocate => {
            (0, 0, vec![tcx.types.usize, tcx.types.usize], Ty::new_mut_ptr(tcx, tcx.types.u8))
        }
        sym::const_deallocate => (
            0,
            0,
            vec![Ty::new_mut_ptr(tcx, tcx.types.u8), tcx.types.usize, tcx.types.usize],
            tcx.types.unit,
        ),
        sym::const_make_global => {
            (0, 0, vec![Ty::new_mut_ptr(tcx, tcx.types.u8)], Ty::new_imm_ptr(tcx, tcx.types.u8))
        }

        sym::ptr_offset_from => (
            1,
            0,
            vec![Ty::new_imm_ptr(tcx, param(0)), Ty::new_imm_ptr(tcx, param(0))],
            tcx.types.isize,
        ),
        sym::ptr_offset_from_unsigned => (
            1,
            0,
            vec![Ty::new_imm_ptr(tcx, param(0)), Ty::new_imm_ptr(tcx, param(0))],
            tcx.types.usize,
        ),
        sym::unchecked_div | sym::unchecked_rem | sym::exact_div | sym::disjoint_bitor => {
            (1, 0, vec![param(0), param(0)], param(0))
        }
        sym::unchecked_shl | sym::unchecked_shr => (2, 0, vec![param(0), param(1)], param(0)),
        sym::rotate_left | sym::rotate_right => (1, 0, vec![param(0), tcx.types.u32], param(0)),
        sym::unchecked_funnel_shl | sym::unchecked_funnel_shr => {
            (1, 0, vec![param(0), param(0), tcx.types.u32], param(0))
        }
        sym::unchecked_add | sym::unchecked_sub | sym::unchecked_mul => {
            (1, 0, vec![param(0), param(0)], param(0))
        }
        sym::wrapping_add | sym::wrapping_sub | sym::wrapping_mul => {
            (1, 0, vec![param(0), param(0)], param(0))
        }
        sym::saturating_add | sym::saturating_sub => (1, 0, vec![param(0), param(0)], param(0)),
        sym::fadd_fast | sym::fsub_fast | sym::fmul_fast | sym::fdiv_fast | sym::frem_fast => {
            (1, 0, vec![param(0), param(0)], param(0))
        }
        sym::fadd_algebraic
        | sym::fsub_algebraic
        | sym::fmul_algebraic
        | sym::fdiv_algebraic
        | sym::frem_algebraic => (1, 0, vec![param(0), param(0)], param(0)),
        sym::float_to_int_unchecked => (2, 0, vec![param(0)], param(1)),

        sym::assume => (0, 0, vec![tcx.types.bool], tcx.types.unit),
        sym::select_unpredictable => (1, 0, vec![tcx.types.bool, param(0), param(0)], param(0)),
        sym::cold_path => (0, 0, vec![], tcx.types.unit),

        sym::read_via_copy => (1, 0, vec![Ty::new_imm_ptr(tcx, param(0))], param(0)),
        sym::write_via_move => {
            (1, 0, vec![Ty::new_mut_ptr(tcx, param(0)), param(0)], tcx.types.unit)
        }

        sym::typed_swap_nonoverlapping => {
            (1, 0, vec![Ty::new_mut_ptr(tcx, param(0)); 2], tcx.types.unit)
        }

        sym::discriminant_value => {
            let assoc_items = tcx.associated_item_def_ids(
                tcx.require_lang_item(hir::LangItem::DiscriminantKind, span),
            );
            let discriminant_def_id = assoc_items[0];

            let br = ty::BoundRegion { var: ty::BoundVar::ZERO, kind: ty::BoundRegionKind::Anon };
            (
                1,
                0,
                vec![Ty::new_imm_ref(tcx, ty::Region::new_bound(tcx, ty::INNERMOST, br), param(0))],
                Ty::new_projection_from_args(
                    tcx,
                    discriminant_def_id,
                    tcx.mk_args(&[param(0).into()]),
                ),
            )
        }

        sym::catch_unwind => {
            let mut_u8 = Ty::new_mut_ptr(tcx, tcx.types.u8);
            let try_fn_ty = ty::Binder::dummy(tcx.mk_fn_sig(
                [mut_u8],
                tcx.types.unit,
                false,
                hir::Safety::Safe,
                ExternAbi::Rust,
            ));
            let catch_fn_ty = ty::Binder::dummy(tcx.mk_fn_sig(
                [mut_u8, mut_u8],
                tcx.types.unit,
                false,
                hir::Safety::Safe,
                ExternAbi::Rust,
            ));
            (
                0,
                0,
                vec![Ty::new_fn_ptr(tcx, try_fn_ty), mut_u8, Ty::new_fn_ptr(tcx, catch_fn_ty)],
                tcx.types.i32,
            )
        }

        sym::va_start | sym::va_end => {
            (0, 0, vec![mk_va_list_ty(hir::Mutability::Mut).0], tcx.types.unit)
        }

        sym::va_copy => {
            let (va_list_ref_ty, va_list_ty) = mk_va_list_ty(hir::Mutability::Not);
            let va_list_ptr_ty = Ty::new_mut_ptr(tcx, va_list_ty);
            (0, 0, vec![va_list_ptr_ty, va_list_ref_ty], tcx.types.unit)
        }

        sym::va_arg => (1, 0, vec![mk_va_list_ty(hir::Mutability::Mut).0], param(0)),

        sym::nontemporal_store => {
            (1, 0, vec![Ty::new_mut_ptr(tcx, param(0)), param(0)], tcx.types.unit)
        }

        sym::raw_eq => {
            let br = ty::BoundRegion { var: ty::BoundVar::ZERO, kind: ty::BoundRegionKind::Anon };
            let param_ty_lhs =
                Ty::new_imm_ref(tcx, ty::Region::new_bound(tcx, ty::INNERMOST, br), param(0));
            let br =
                ty::BoundRegion { var: ty::BoundVar::from_u32(1), kind: ty::BoundRegionKind::Anon };
            let param_ty_rhs =
                Ty::new_imm_ref(tcx, ty::Region::new_bound(tcx, ty::INNERMOST, br), param(0));
            (1, 0, vec![param_ty_lhs, param_ty_rhs], tcx.types.bool)
        }

        sym::black_box => (1, 0, vec![param(0)], param(0)),

        sym::is_val_statically_known => (1, 0, vec![param(0)], tcx.types.bool),

        sym::const_eval_select => (4, 0, vec![param(0), param(1), param(2)], param(3)),

        sym::vtable_size | sym::vtable_align => {
            (0, 0, vec![Ty::new_imm_ptr(tcx, tcx.types.unit)], tcx.types.usize)
        }

        // This type check is not particularly useful, but the `where` bounds
        // on the definition in `core` do the heavy lifting for checking it.
        sym::aggregate_raw_ptr => (3, 0, vec![param(1), param(2)], param(0)),
        sym::ptr_metadata => (2, 0, vec![Ty::new_imm_ptr(tcx, param(0))], param(1)),

        sym::ub_checks => (0, 0, Vec::new(), tcx.types.bool),

        sym::box_new => (1, 0, vec![param(0)], Ty::new_box(tcx, param(0))),

        // contract_checks() -> bool
        sym::contract_checks => (0, 0, Vec::new(), tcx.types.bool),
        // contract_check_requires::<C>(C) -> bool, where C: impl Fn() -> bool
        sym::contract_check_requires => (1, 0, vec![param(0)], tcx.types.unit),
        sym::contract_check_ensures => (2, 0, vec![param(0), param(1)], param(1)),

        sym::simd_eq | sym::simd_ne | sym::simd_lt | sym::simd_le | sym::simd_gt | sym::simd_ge => {
            (2, 0, vec![param(0), param(0)], param(1))
        }
        sym::simd_add
        | sym::simd_sub
        | sym::simd_mul
        | sym::simd_rem
        | sym::simd_div
        | sym::simd_shl
        | sym::simd_shr
        | sym::simd_and
        | sym::simd_or
        | sym::simd_xor
        | sym::simd_fmin
        | sym::simd_fmax
        | sym::simd_saturating_add
        | sym::simd_saturating_sub => (1, 0, vec![param(0), param(0)], param(0)),
        sym::simd_arith_offset => (2, 0, vec![param(0), param(1)], param(0)),
        sym::simd_neg
        | sym::simd_bswap
        | sym::simd_bitreverse
        | sym::simd_ctlz
        | sym::simd_cttz
        | sym::simd_ctpop
        | sym::simd_fsqrt
        | sym::simd_fsin
        | sym::simd_fcos
        | sym::simd_fexp
        | sym::simd_fexp2
        | sym::simd_flog2
        | sym::simd_flog10
        | sym::simd_flog
        | sym::simd_fabs
        | sym::simd_ceil
        | sym::simd_floor
        | sym::simd_round
        | sym::simd_round_ties_even
        | sym::simd_trunc => (1, 0, vec![param(0)], param(0)),
        sym::simd_fma | sym::simd_relaxed_fma | sym::simd_funnel_shl | sym::simd_funnel_shr => {
            (1, 0, vec![param(0), param(0), param(0)], param(0))
        }
        sym::simd_gather => (3, 0, vec![param(0), param(1), param(2)], param(0)),
        sym::simd_masked_load => (3, 0, vec![param(0), param(1), param(2)], param(2)),
        sym::simd_masked_store => (3, 0, vec![param(0), param(1), param(2)], tcx.types.unit),
        sym::simd_scatter => (3, 0, vec![param(0), param(1), param(2)], tcx.types.unit),
        sym::simd_insert | sym::simd_insert_dyn => {
            (2, 0, vec![param(0), tcx.types.u32, param(1)], param(0))
        }
        sym::simd_extract | sym::simd_extract_dyn => {
            (2, 0, vec![param(0), tcx.types.u32], param(1))
        }
        sym::simd_cast
        | sym::simd_as
        | sym::simd_cast_ptr
        | sym::simd_expose_provenance
        | sym::simd_with_exposed_provenance => (2, 0, vec![param(0)], param(1)),
        sym::simd_bitmask => (2, 0, vec![param(0)], param(1)),
        sym::simd_select | sym::simd_select_bitmask => {
            (2, 0, vec![param(0), param(1), param(1)], param(1))
        }
        sym::simd_reduce_all | sym::simd_reduce_any => (1, 0, vec![param(0)], tcx.types.bool),
        sym::simd_reduce_add_ordered | sym::simd_reduce_mul_ordered => {
            (2, 0, vec![param(0), param(1)], param(1))
        }
        sym::simd_reduce_add_unordered
        | sym::simd_reduce_mul_unordered
        | sym::simd_reduce_and
        | sym::simd_reduce_or
        | sym::simd_reduce_xor
        | sym::simd_reduce_min
        | sym::simd_reduce_max => (2, 0, vec![param(0)], param(1)),
        sym::simd_shuffle => (3, 0, vec![param(0), param(0), param(1)], param(2)),
        sym::simd_shuffle_const_generic => (2, 1, vec![param(0), param(0)], param(1)),

        sym::atomic_cxchg | sym::atomic_cxchgweak => (
            1,
            2,
            vec![Ty::new_mut_ptr(tcx, param(0)), param(0), param(0)],
            Ty::new_tup(tcx, &[param(0), tcx.types.bool]),
        ),
        sym::atomic_load => (1, 1, vec![Ty::new_imm_ptr(tcx, param(0))], param(0)),
        sym::atomic_store => (1, 1, vec![Ty::new_mut_ptr(tcx, param(0)), param(0)], tcx.types.unit),

        sym::atomic_xchg
        | sym::atomic_max
        | sym::atomic_min
        | sym::atomic_umax
        | sym::atomic_umin => (1, 1, vec![Ty::new_mut_ptr(tcx, param(0)), param(0)], param(0)),
        sym::atomic_xadd
        | sym::atomic_xsub
        | sym::atomic_and
        | sym::atomic_nand
        | sym::atomic_or
        | sym::atomic_xor => (2, 1, vec![Ty::new_mut_ptr(tcx, param(0)), param(1)], param(0)),
        sym::atomic_fence | sym::atomic_singlethreadfence => (0, 1, Vec::new(), tcx.types.unit),

        other => {
            tcx.dcx().emit_err(UnrecognizedIntrinsicFunction { span, name: other });
            return;
        }
    };
    let sig = tcx.mk_fn_sig(inputs, output, false, safety, ExternAbi::Rust);
    let sig = ty::Binder::bind_with_vars(sig, bound_vars);
    equate_intrinsic_type(tcx, span, intrinsic_id, n_tps, n_lts, n_cts, sig)
}