std.builtin

pub const StackTrace = struct {
    index: usize,
    instruction_addresses: []usize,

    pub fn format(self: StackTrace, writer: *std.io.Writer) std.io.Writer.Error!void {
        // TODO: re-evaluate whether to use format() methods at all.
        // Until then, avoid an error when using GeneralPurposeAllocator with WebAssembly
        // where it tries to call detectTTYConfig here.
        if (builtin.os.tag == .freestanding) return;

        const debug_info = std.debug.getSelfDebugInfo() catch |err| {
            return writer.print("\nUnable to print stack trace: Unable to open debug info: {s}\n", .{@errorName(err)});
        };
        const tty_config = std.io.tty.detectConfig(std.fs.File.stderr());
        try writer.writeAll("\n");
        std.debug.writeStackTrace(self, writer, debug_info, tty_config) catch |err| {
            try writer.print("Unable to print stack trace: {s}\n", .{@errorName(err)});
        };
    }
}

pub const GlobalLinkage = enum(u2) {
    internal,
    strong,
    weak,
    link_once,
}

pub const SymbolVisibility = enum(u2) {
    default,
    hidden,
    protected,
}

pub const AtomicOrder = enum {
    unordered,
    monotonic,
    acquire,
    release,
    acq_rel,
    seq_cst,
}

pub const ReduceOp = enum {
    And,
    Or,
    Xor,
    Min,
    Max,
    Add,
    Mul,
}

pub const AtomicRmwOp = enum {
    /// Exchange - store the operand unmodified.
    /// Supports enums, integers, and floats.
    Xchg,
    /// Add operand to existing value.
    /// Supports integers and floats.
    /// For integers, two's complement wraparound applies.
    Add,
    /// Subtract operand from existing value.
    /// Supports integers and floats.
    /// For integers, two's complement wraparound applies.
    Sub,
    /// Perform bitwise AND on existing value with operand.
    /// Supports integers.
    And,
    /// Perform bitwise NAND on existing value with operand.
    /// Supports integers.
    Nand,
    /// Perform bitwise OR on existing value with operand.
    /// Supports integers.
    Or,
    /// Perform bitwise XOR on existing value with operand.
    /// Supports integers.
    Xor,
    /// Store operand if it is larger than the existing value.
    /// Supports integers and floats.
    Max,
    /// Store operand if it is smaller than the existing value.
    /// Supports integers and floats.
    Min,
}

pub const CodeModel = enum {
    default,
    extreme,
    kernel,
    large,
    medany,
    medium,
    medlow,
    medmid,
    normal,
    small,
    tiny,
}

pub const OptimizeMode = enum {
    Debug,
    ReleaseSafe,
    ReleaseFast,
    ReleaseSmall,
}

pub const AddressSpace = enum(u5) {
    /// The places where a user can specify an address space attribute
    pub const Context = enum {
        /// A function is specified to be placed in a certain address space.
        function,
        /// A (global) variable is specified to be placed in a certain address space.
        /// In contrast to .constant, these values (and thus the address space they will be
        /// placed in) are required to be mutable.
        variable,
        /// A (global) constant value is specified to be placed in a certain address space.
        /// In contrast to .variable, values placed in this address space are not required to be mutable.
        constant,
        /// A pointer is ascripted to point into a certain address space.
        pointer,
    };

    // CPU address spaces.
    generic,
    gs,
    fs,
    ss,

    // GPU address spaces.
    global,
    constant,
    param,
    shared,
    local,
    input,
    output,
    uniform,
    push_constant,
    storage_buffer,
    physical_storage_buffer,

    // AVR address spaces.
    flash,
    flash1,
    flash2,
    flash3,
    flash4,
    flash5,

    // Propeller address spaces.

    /// This address space only addresses the cog-local ram.
    cog,

    /// This address space only addresses shared hub ram.
    hub,

    /// This address space only addresses the "lookup" ram
    lut,
}

pub const SourceLocation = struct {
    /// The name chosen when compiling. Not a file path.
    module: [:0]const u8,
    /// Relative to the root directory of its module.
    file: [:0]const u8,
    fn_name: [:0]const u8,
    line: u32,
    column: u32,
}

pub const FloatMode = enum {
    strict,
    optimized,
}

pub const Endian = enum {
    big,
    little,
}

pub const Signedness = enum(u1) {
    signed,
    unsigned,
}

pub const OutputMode = enum {
    Exe,
    Lib,
    Obj,
}

pub const LinkMode = enum {
    static,
    dynamic,
}

pub const UnwindTables = enum {
    none,
    sync,
    async,
}

pub const WasiExecModel = enum {
    command,
    reactor,
}

pub const CallModifier = enum {
    /// Equivalent to function call syntax.
    auto,
    /// Prevents tail call optimization. This guarantees that the return
    /// address will point to the callsite, as opposed to the callsite's
    /// callsite. If the call is otherwise required to be tail-called
    /// or inlined, a compile error is emitted instead.
    never_tail,
    /// Guarantees that the call will not be inlined. If the call is
    /// otherwise required to be inlined, a compile error is emitted instead.
    never_inline,
    /// Asserts that the function call will not suspend. This allows a
    /// non-async function to call an async function.
    no_suspend,
    /// Guarantees that the call will be generated with tail call optimization.
    /// If this is not possible, a compile error is emitted instead.
    always_tail,
    /// Guarantees that the call will be inlined at the callsite.
    /// If this is not possible, a compile error is emitted instead.
    always_inline,
    /// Evaluates the call at compile-time. If the call cannot be completed at
    /// compile-time, a compile error is emitted instead.
    compile_time,
}

pub const VaListAarch64 = extern struct {
    __stack: *anyopaque,
    __gr_top: *anyopaque,
    __vr_top: *anyopaque,
    __gr_offs: c_int,
    __vr_offs: c_int,
}

pub const VaListHexagon = extern struct {
    __gpr: c_long,
    __fpr: c_long,
    __overflow_arg_area: *anyopaque,
    __reg_save_area: *anyopaque,
}

pub const VaListPowerPc = extern struct {
    gpr: u8,
    fpr: u8,
    reserved: c_ushort,
    overflow_arg_area: *anyopaque,
    reg_save_area: *anyopaque,
}

pub const VaListS390x = extern struct {
    __current_saved_reg_area_pointer: *anyopaque,
    __saved_reg_area_end_pointer: *anyopaque,
    __overflow_area_pointer: *anyopaque,
}

pub const VaListX86_64 = extern struct {
    gp_offset: c_uint,
    fp_offset: c_uint,
    overflow_arg_area: *anyopaque,
    reg_save_area: *anyopaque,
}

pub const VaListXtensa = extern struct {
    __va_stk: *c_int,
    __va_reg: *c_int,
    __va_ndx: c_int,
}

pub const PrefetchOptions = struct {
    /// Whether the prefetch should prepare for a read or a write.
    rw: Rw = .read,
    /// The data's locality in an inclusive range from 0 to 3.
    ///
    /// 0 means no temporal locality. That is, the data can be immediately
    /// dropped from the cache after it is accessed.
    ///
    /// 3 means high temporal locality. That is, the data should be kept in
    /// the cache as it is likely to be accessed again soon.
    locality: u2 = 3,
    /// The cache that the prefetch should be performed on.
    cache: Cache = .data,

    pub const Rw = enum(u1) {
        read,
        write,
    };

    pub const Cache = enum(u1) {
        instruction,
        data,
    };
}

pub const ExportOptions = struct {
    name: []const u8,
    linkage: GlobalLinkage = .strong,
    section: ?[]const u8 = null,
    visibility: SymbolVisibility = .default,
}

pub const ExternOptions = struct {
    name: []const u8,
    library_name: ?[]const u8 = null,
    linkage: GlobalLinkage = .strong,
    visibility: SymbolVisibility = .default,
    /// Setting this to `true` makes the `@extern` a runtime value.
    is_thread_local: bool = false,
    is_dll_import: bool = false,
    relocation: Relocation = .any,

    pub const Relocation = enum(u1) {
        /// Any type of relocation is allowed.
        any,
        /// A program-counter-relative relocation is required.
        /// Using this value makes the `@extern` a runtime value.
        pcrel,
    };
}

pub const BranchHint = enum(u3) {
    /// Equivalent to no hint given.
    none,
    /// This branch of control flow is more likely to be reached than its peers.
    /// The optimizer should optimize for reaching it.
    likely,
    /// This branch of control flow is less likely to be reached than its peers.
    /// The optimizer should optimize for not reaching it.
    unlikely,
    /// This branch of control flow is unlikely to *ever* be reached.
    /// The optimizer may place it in a different page of memory to optimize other branches.
    cold,
    /// It is difficult to predict whether this branch of control flow will be reached.
    /// The optimizer should avoid branching behavior with expensive mispredictions.
    unpredictable,
}

pub const CompilerBackend = enum(u64) {
    /// It is allowed for a compiler implementation to not reveal its identity,
    /// in which case this value is appropriate. Be cool and make sure your
    /// code supports `other` Zig compilers!
    other = 0,
    /// The original Zig compiler created in 2015 by Andrew Kelley. Implemented
    /// in C++. Used LLVM. Deleted from the ZSF ziglang/zig codebase on
    /// December 6th, 2022.
    stage1 = 1,
    /// The reference implementation self-hosted compiler of Zig, using the
    /// LLVM backend.
    stage2_llvm = 2,
    /// The reference implementation self-hosted compiler of Zig, using the
    /// backend that generates C source code.
    /// Note that one can observe whether the compilation will output C code
    /// directly with `object_format` value rather than the `compiler_backend` value.
    stage2_c = 3,
    /// The reference implementation self-hosted compiler of Zig, using the
    /// WebAssembly backend.
    stage2_wasm = 4,
    /// The reference implementation self-hosted compiler of Zig, using the
    /// arm backend.
    stage2_arm = 5,
    /// The reference implementation self-hosted compiler of Zig, using the
    /// x86_64 backend.
    stage2_x86_64 = 6,
    /// The reference implementation self-hosted compiler of Zig, using the
    /// aarch64 backend.
    stage2_aarch64 = 7,
    /// The reference implementation self-hosted compiler of Zig, using the
    /// x86 backend.
    stage2_x86 = 8,
    /// The reference implementation self-hosted compiler of Zig, using the
    /// riscv64 backend.
    stage2_riscv64 = 9,
    /// The reference implementation self-hosted compiler of Zig, using the
    /// sparc64 backend.
    stage2_sparc64 = 10,
    /// The reference implementation self-hosted compiler of Zig, using the
    /// spirv backend.
    stage2_spirv = 11,
    /// The reference implementation self-hosted compiler of Zig, using the
    /// powerpc backend.
    stage2_powerpc = 12,

    _,
}

pub const TestFn = struct {
    name: []const u8,
    func: *const fn () anyerror!void,
}

pub const assembly = @import("builtin/assembly.zig")

pub const subsystem: ?std.Target.SubSystem = blk: {
    if (@hasDecl(builtin, "explicit_subsystem")) break :blk builtin.explicit_subsystem;
    switch (builtin.os.tag) {
        .windows => {
            if (builtin.is_test) {
                break :blk std.Target.SubSystem.Console;
            }
            if (@hasDecl(root, "main") or
                @hasDecl(root, "WinMain") or
                @hasDecl(root, "wWinMain") or
                @hasDecl(root, "WinMainCRTStartup") or
                @hasDecl(root, "wWinMainCRTStartup"))
            {
                break :blk std.Target.SubSystem.Windows;
            } else {
                break :blk std.Target.SubSystem.Console;
            }
        },
        else => break :blk null,
    }
}

pub const CallingConvention = union(enum(u8)) {
    pub const Tag = @typeInfo(CallingConvention).@"union".tag_type.?;

    /// This is an alias for the default C calling convention for this target.
    /// Functions marked as `extern` or `export` are given this calling convention by default.
    pub const c = builtin.target.cCallingConvention().?;

    pub const winapi: CallingConvention = switch (builtin.target.cpu.arch) {
        .x86_64 => .{ .x86_64_win = .{} },
        .x86 => .{ .x86_stdcall = .{} },
        .aarch64 => .{ .aarch64_aapcs_win = .{} },
        .thumb => .{ .arm_aapcs_vfp = .{} },
        else => unreachable,
    };

    pub const kernel: CallingConvention = switch (builtin.target.cpu.arch) {
        .amdgcn => .amdgcn_kernel,
        .nvptx, .nvptx64 => .nvptx_kernel,
        .spirv32, .spirv64 => .spirv_kernel,
        else => unreachable,
    };

    /// The default Zig calling convention when neither `export` nor `inline` is specified.
    /// This calling convention makes no guarantees about stack alignment, registers, etc.
    /// It can only be used within this Zig compilation unit.
    auto,

    /// The calling convention of a function that can be called with `async` syntax. An `async` call
    /// of a runtime-known function must target a function with this calling convention.
    /// Comptime-known functions with other calling conventions may be coerced to this one.
    async,

    /// Functions with this calling convention have no prologue or epilogue, making the function
    /// uncallable in regular Zig code. This can be useful when integrating with assembly.
    naked,

    /// This calling convention is exactly equivalent to using the `inline` keyword on a function
    /// definition. This function will be semantically inlined by the Zig compiler at call sites.
    /// Pointers to inline functions are comptime-only.
    @"inline",

    // Calling conventions for the `x86_64` architecture.
    x86_64_sysv: CommonOptions,
    x86_64_win: CommonOptions,
    x86_64_regcall_v3_sysv: CommonOptions,
    x86_64_regcall_v4_win: CommonOptions,
    x86_64_vectorcall: CommonOptions,
    x86_64_interrupt: CommonOptions,

    // Calling conventions for the `x86` architecture.
    x86_sysv: X86RegparmOptions,
    x86_win: X86RegparmOptions,
    x86_stdcall: X86RegparmOptions,
    x86_fastcall: CommonOptions,
    x86_thiscall: CommonOptions,
    x86_thiscall_mingw: CommonOptions,
    x86_regcall_v3: CommonOptions,
    x86_regcall_v4_win: CommonOptions,
    x86_vectorcall: CommonOptions,
    x86_interrupt: CommonOptions,

    // Calling conventions for the `aarch64` and `aarch64_be` architectures.
    aarch64_aapcs: CommonOptions,
    aarch64_aapcs_darwin: CommonOptions,
    aarch64_aapcs_win: CommonOptions,
    aarch64_vfabi: CommonOptions,
    aarch64_vfabi_sve: CommonOptions,

    // Calling convetions for the `arm`, `armeb`, `thumb`, and `thumbeb` architectures.
    /// ARM Architecture Procedure Call Standard
    arm_aapcs: CommonOptions,
    /// ARM Architecture Procedure Call Standard Vector Floating-Point
    arm_aapcs_vfp: CommonOptions,
    arm_interrupt: ArmInterruptOptions,

    // Calling conventions for the `mips64` and `mips64el` architectures.
    mips64_n64: CommonOptions,
    mips64_n32: CommonOptions,
    mips64_interrupt: MipsInterruptOptions,

    // Calling conventions for the `mips` and `mipsel` architectures.
    mips_o32: CommonOptions,
    mips_interrupt: MipsInterruptOptions,

    // Calling conventions for the `riscv64` architecture.
    riscv64_lp64: CommonOptions,
    riscv64_lp64_v: CommonOptions,
    riscv64_interrupt: RiscvInterruptOptions,

    // Calling conventions for the `riscv32` architecture.
    riscv32_ilp32: CommonOptions,
    riscv32_ilp32_v: CommonOptions,
    riscv32_interrupt: RiscvInterruptOptions,

    // Calling conventions for the `sparc64` architecture.
    sparc64_sysv: CommonOptions,

    // Calling conventions for the `sparc` architecture.
    sparc_sysv: CommonOptions,

    // Calling conventions for the `powerpc64` and `powerpc64le` architectures.
    powerpc64_elf: CommonOptions,
    powerpc64_elf_altivec: CommonOptions,
    powerpc64_elf_v2: CommonOptions,

    // Calling conventions for the `powerpc` and `powerpcle` architectures.
    powerpc_sysv: CommonOptions,
    powerpc_sysv_altivec: CommonOptions,
    powerpc_aix: CommonOptions,
    powerpc_aix_altivec: CommonOptions,

    /// The standard `wasm32` and `wasm64` calling convention, as specified in the WebAssembly Tool Conventions.
    wasm_mvp: CommonOptions,

    /// The standard `arc` calling convention.
    arc_sysv: CommonOptions,

    // Calling conventions for the `avr` architecture.
    avr_gnu,
    avr_builtin,
    avr_signal,
    avr_interrupt,

    /// The standard `bpfel`/`bpfeb` calling convention.
    bpf_std: CommonOptions,

    // Calling conventions for the `csky` architecture.
    csky_sysv: CommonOptions,
    csky_interrupt: CommonOptions,

    // Calling conventions for the `hexagon` architecture.
    hexagon_sysv: CommonOptions,
    hexagon_sysv_hvx: CommonOptions,

    /// The standard `lanai` calling convention.
    lanai_sysv: CommonOptions,

    /// The standard `loongarch64` calling convention.
    loongarch64_lp64: CommonOptions,

    /// The standard `loongarch32` calling convention.
    loongarch32_ilp32: CommonOptions,

    // Calling conventions for the `m68k` architecture.
    m68k_sysv: CommonOptions,
    m68k_gnu: CommonOptions,
    m68k_rtd: CommonOptions,
    m68k_interrupt: CommonOptions,

    /// The standard `msp430` calling convention.
    msp430_eabi: CommonOptions,

    /// The standard `or1k` calling convention.
    or1k_sysv: CommonOptions,

    /// The standard `propeller` calling convention.
    propeller_sysv: CommonOptions,

    // Calling conventions for the `s390x` architecture.
    s390x_sysv: CommonOptions,
    s390x_sysv_vx: CommonOptions,

    /// The standard `ve` calling convention.
    ve_sysv: CommonOptions,

    // Calling conventions for the `xcore` architecture.
    xcore_xs1: CommonOptions,
    xcore_xs2: CommonOptions,

    // Calling conventions for the `xtensa` architecture.
    xtensa_call0: CommonOptions,
    xtensa_windowed: CommonOptions,

    // Calling conventions for the `amdgcn` architecture.
    amdgcn_device: CommonOptions,
    amdgcn_kernel,
    amdgcn_cs: CommonOptions,

    // Calling conventions for the `nvptx` and `nvptx64` architectures.
    nvptx_device,
    nvptx_kernel,

    // Calling conventions for kernels and shaders on the `spirv`, `spirv32`, and `spirv64` architectures.
    spirv_device,
    spirv_kernel,
    spirv_fragment,
    spirv_vertex,

    /// Options shared across most calling conventions.
    pub const CommonOptions = struct {
        /// The boundary the stack is aligned to when the function is called.
        /// `null` means the default for this calling convention.
        incoming_stack_alignment: ?u64 = null,
    };

    /// Options for x86 calling conventions which support the regparm attribute to pass some
    /// arguments in registers.
    pub const X86RegparmOptions = struct {
        /// The boundary the stack is aligned to when the function is called.
        /// `null` means the default for this calling convention.
        incoming_stack_alignment: ?u64 = null,
        /// The number of arguments to pass in registers before passing the remaining arguments
        /// according to the calling convention.
        /// Equivalent to `__attribute__((regparm(x)))` in Clang and GCC.
        register_params: u2 = 0,
    };

    /// Options for the `arm_interrupt` calling convention.
    pub const ArmInterruptOptions = struct {
        /// The boundary the stack is aligned to when the function is called.
        /// `null` means the default for this calling convention.
        incoming_stack_alignment: ?u64 = null,
        /// The kind of interrupt being received.
        type: InterruptType = .generic,

        pub const InterruptType = enum(u3) {
            generic,
            irq,
            fiq,
            swi,
            abort,
            undef,
        };
    };

    /// Options for the `mips_interrupt` and `mips64_interrupt` calling conventions.
    pub const MipsInterruptOptions = struct {
        /// The boundary the stack is aligned to when the function is called.
        /// `null` means the default for this calling convention.
        incoming_stack_alignment: ?u64 = null,
        /// The interrupt mode.
        mode: InterruptMode = .eic,

        pub const InterruptMode = enum(u4) {
            eic,
            sw0,
            sw1,
            hw0,
            hw1,
            hw2,
            hw3,
            hw4,
            hw5,
        };
    };

    /// Options for the `riscv32_interrupt` and `riscv64_interrupt` calling conventions.
    pub const RiscvInterruptOptions = struct {
        /// The boundary the stack is aligned to when the function is called.
        /// `null` means the default for this calling convention.
        incoming_stack_alignment: ?u64 = null,
        /// The privilege mode.
        mode: PrivilegeMode,

        pub const PrivilegeMode = enum(u2) {
            supervisor,
            machine,
        };
    };

    /// Returns the array of `std.Target.Cpu.Arch` to which this `CallingConvention` applies.
    /// Asserts that `cc` is not `.auto`, `.@"async"`, `.naked`, or `.@"inline"`.
    pub fn archs(cc: CallingConvention) []const std.Target.Cpu.Arch {
        return std.Target.Cpu.Arch.fromCallingConvention(cc);
    }

    pub fn eql(a: CallingConvention, b: CallingConvention) bool {
        return std.meta.eql(a, b);
    }

    pub fn withStackAlign(cc: CallingConvention, incoming_stack_alignment: u64) CallingConvention {
        const tag: CallingConvention.Tag = cc;
        var result = cc;
        @field(result, @tagName(tag)).incoming_stack_alignment = incoming_stack_alignment;
        return result;
    }
}

pub const TypeId = std.meta.Tag(Type)

pub const Type = union(enum) {
    type: void,
    void: void,
    bool: void,
    noreturn: void,
    int: Int,
    float: Float,
    pointer: Pointer,
    array: Array,
    @"struct": Struct,
    comptime_float: void,
    comptime_int: void,
    undefined: void,
    null: void,
    optional: Optional,
    error_union: ErrorUnion,
    error_set: ErrorSet,
    @"enum": Enum,
    @"union": Union,
    @"fn": Fn,
    @"opaque": Opaque,
    frame: Frame,
    @"anyframe": AnyFrame,
    vector: Vector,
    enum_literal: void,

    /// This data structure is used by the Zig language code generation and
    /// therefore must be kept in sync with the compiler implementation.
    pub const Int = struct {
        signedness: Signedness,
        bits: u16,
    };

    /// This data structure is used by the Zig language code generation and
    /// therefore must be kept in sync with the compiler implementation.
    pub const Float = struct {
        bits: u16,
    };

    /// This data structure is used by the Zig language code generation and
    /// therefore must be kept in sync with the compiler implementation.
    pub const Pointer = struct {
        size: Size,
        is_const: bool,
        is_volatile: bool,
        /// TODO make this u16 instead of comptime_int
        alignment: comptime_int,
        address_space: AddressSpace,
        child: type,
        is_allowzero: bool,

        /// The type of the sentinel is the element type of the pointer, which is
        /// the value of the `child` field in this struct. However there is no way
        /// to refer to that type here, so we use `*const anyopaque`.
        /// See also: `sentinel`
        sentinel_ptr: ?*const anyopaque,

        /// Loads the pointer type's sentinel value from `sentinel_ptr`.
        /// Returns `null` if the pointer type has no sentinel.
        pub inline fn sentinel(comptime ptr: Pointer) ?ptr.child {
            const sp: *const ptr.child = @ptrCast(@alignCast(ptr.sentinel_ptr orelse return null));
            return sp.*;
        }

        /// This data structure is used by the Zig language code generation and
        /// therefore must be kept in sync with the compiler implementation.
        pub const Size = enum(u2) {
            one,
            many,
            slice,
            c,
        };
    };

    /// This data structure is used by the Zig language code generation and
    /// therefore must be kept in sync with the compiler implementation.
    pub const Array = struct {
        len: comptime_int,
        child: type,

        /// The type of the sentinel is the element type of the array, which is
        /// the value of the `child` field in this struct. However there is no way
        /// to refer to that type here, so we use `*const anyopaque`.
        /// See also: `sentinel`.
        sentinel_ptr: ?*const anyopaque,

        /// Loads the array type's sentinel value from `sentinel_ptr`.
        /// Returns `null` if the array type has no sentinel.
        pub inline fn sentinel(comptime arr: Array) ?arr.child {
            const sp: *const arr.child = @ptrCast(@alignCast(arr.sentinel_ptr orelse return null));
            return sp.*;
        }
    };

    /// This data structure is used by the Zig language code generation and
    /// therefore must be kept in sync with the compiler implementation.
    pub const ContainerLayout = enum(u2) {
        auto,
        @"extern",
        @"packed",
    };

    /// This data structure is used by the Zig language code generation and
    /// therefore must be kept in sync with the compiler implementation.
    pub const StructField = struct {
        name: [:0]const u8,
        type: type,
        /// The type of the default value is the type of this struct field, which
        /// is the value of the `type` field in this struct. However there is no
        /// way to refer to that type here, so we use `*const anyopaque`.
        /// See also: `defaultValue`.
        default_value_ptr: ?*const anyopaque,
        is_comptime: bool,
        alignment: comptime_int,

        /// Loads the field's default value from `default_value_ptr`.
        /// Returns `null` if the field has no default value.
        pub inline fn defaultValue(comptime sf: StructField) ?sf.type {
            const dp: *const sf.type = @ptrCast(@alignCast(sf.default_value_ptr orelse return null));
            return dp.*;
        }
    };

    /// This data structure is used by the Zig language code generation and
    /// therefore must be kept in sync with the compiler implementation.
    pub const Struct = struct {
        layout: ContainerLayout,
        /// Only valid if layout is .@"packed"
        backing_integer: ?type = null,
        fields: []const StructField,
        decls: []const Declaration,
        is_tuple: bool,
    };

    /// This data structure is used by the Zig language code generation and
    /// therefore must be kept in sync with the compiler implementation.
    pub const Optional = struct {
        child: type,
    };

    /// This data structure is used by the Zig language code generation and
    /// therefore must be kept in sync with the compiler implementation.
    pub const ErrorUnion = struct {
        error_set: type,
        payload: type,
    };

    /// This data structure is used by the Zig language code generation and
    /// therefore must be kept in sync with the compiler implementation.
    pub const Error = struct {
        name: [:0]const u8,
    };

    /// This data structure is used by the Zig language code generation and
    /// therefore must be kept in sync with the compiler implementation.
    pub const ErrorSet = ?[]const Error;

    /// This data structure is used by the Zig language code generation and
    /// therefore must be kept in sync with the compiler implementation.
    pub const EnumField = struct {
        name: [:0]const u8,
        value: comptime_int,
    };

    /// This data structure is used by the Zig language code generation and
    /// therefore must be kept in sync with the compiler implementation.
    pub const Enum = struct {
        tag_type: type,
        fields: []const EnumField,
        decls: []const Declaration,
        is_exhaustive: bool,
    };

    /// This data structure is used by the Zig language code generation and
    /// therefore must be kept in sync with the compiler implementation.
    pub const UnionField = struct {
        name: [:0]const u8,
        type: type,
        alignment: comptime_int,
    };

    /// This data structure is used by the Zig language code generation and
    /// therefore must be kept in sync with the compiler implementation.
    pub const Union = struct {
        layout: ContainerLayout,
        tag_type: ?type,
        fields: []const UnionField,
        decls: []const Declaration,
    };

    /// This data structure is used by the Zig language code generation and
    /// therefore must be kept in sync with the compiler implementation.
    pub const Fn = struct {
        calling_convention: CallingConvention,
        is_generic: bool,
        is_var_args: bool,
        /// TODO change the language spec to make this not optional.
        return_type: ?type,
        params: []const Param,

        /// This data structure is used by the Zig language code generation and
        /// therefore must be kept in sync with the compiler implementation.
        pub const Param = struct {
            is_generic: bool,
            is_noalias: bool,
            type: ?type,
        };
    };

    /// This data structure is used by the Zig language code generation and
    /// therefore must be kept in sync with the compiler implementation.
    pub const Opaque = struct {
        decls: []const Declaration,
    };

    /// This data structure is used by the Zig language code generation and
    /// therefore must be kept in sync with the compiler implementation.
    pub const Frame = struct {
        function: *const anyopaque,
    };

    /// This data structure is used by the Zig language code generation and
    /// therefore must be kept in sync with the compiler implementation.
    pub const AnyFrame = struct {
        child: ?type,
    };

    /// This data structure is used by the Zig language code generation and
    /// therefore must be kept in sync with the compiler implementation.
    pub const Vector = struct {
        len: comptime_int,
        child: type,
    };

    /// This data structure is used by the Zig language code generation and
    /// therefore must be kept in sync with the compiler implementation.
    pub const Declaration = struct {
        name: [:0]const u8,
    };
}

pub const VaList = switch (builtin.cpu.arch) {
    .aarch64, .aarch64_be => switch (builtin.os.tag) {
        .windows => *u8,
        .ios, .macos, .tvos, .watchos, .visionos => *u8,
        else => switch (builtin.zig_backend) {
            else => VaListAarch64,
            .stage2_llvm => @compileError("disabled due to miscompilations"),
        },
    },
    .arm, .armeb, .thumb, .thumbeb => switch (builtin.os.tag) {
        .ios, .macos, .tvos, .watchos, .visionos => *u8,
        else => *anyopaque,
    },
    .amdgcn => *u8,
    .avr => *anyopaque,
    .bpfel, .bpfeb => *anyopaque,
    .hexagon => if (builtin.target.abi.isMusl()) VaListHexagon else *u8,
    .loongarch32, .loongarch64 => *anyopaque,
    .mips, .mipsel, .mips64, .mips64el => *anyopaque,
    .riscv32, .riscv64 => *anyopaque,
    .powerpc, .powerpcle => switch (builtin.os.tag) {
        .ios, .macos, .tvos, .watchos, .visionos, .aix => *u8,
        else => VaListPowerPc,
    },
    .powerpc64, .powerpc64le => *u8,
    .sparc, .sparc64 => *anyopaque,
    .spirv32, .spirv64 => *anyopaque,
    .s390x => VaListS390x,
    .wasm32, .wasm64 => *anyopaque,
    .x86 => *u8,
    .x86_64 => switch (builtin.os.tag) {
        .windows => switch (builtin.zig_backend) {
            else => *u8,
            .stage2_llvm => @compileError("disabled due to miscompilations"),
        },
        else => VaListX86_64,
    },
    .xtensa => VaListXtensa,
    else => @compileError("VaList not supported for this target yet"),
}

pub const panic: type = p: {
    if (@hasDecl(root, "panic")) {
        if (@TypeOf(root.panic) != type) {
            // Deprecated; make `panic` a namespace instead.
            break :p std.debug.FullPanic(struct {
                fn panic(msg: []const u8, ra: ?usize) noreturn {
                    root.panic(msg, @errorReturnTrace(), ra);
                }
            }.panic);
        }
        break :p root.panic;
    }
    break :p switch (builtin.zig_backend) {
        .stage2_powerpc,
        .stage2_riscv64,
        => std.debug.simple_panic,
        else => std.debug.FullPanic(std.debug.defaultPanic),
    };
}

pub noinline fn returnError() void {
    @branchHint(.unlikely);
    @setRuntimeSafety(false);
    const st = @errorReturnTrace().?;
    if (st.index < st.instruction_addresses.len)
        st.instruction_addresses[st.index] = @returnAddress();
    st.index += 1;
}