// SPDX-License-Identifier: LGPL-3.0-or-later
// See Notices.txt for copyright information
#![allow(clippy::type_complexity)]
use crate::{
    annotations::{Annotation, IntoAnnotations, TargetedAnnotation},
    array::{ArrayType, ValueArrayOrSlice},
    bundle::{BundleType, BundleValue, DynBundle, DynBundleType, FieldType, FieldsHint},
    clock::ClockDomain,
    enum_::{DynEnum, EnumMatchVariantsIter, EnumType, EnumValue},
    expr::{
        ops::VariantAccess, Expr, Flow, Target, TargetBase, TargetPathArrayElement,
        TargetPathBundleField, TargetPathElement, ToExpr,
    },
    int::{DynUInt, DynUIntType, FixedOrDynIntType, IntValue, UInt},
    intern::{Intern, Interned},
    memory::{Mem, MemBuilder, MemBuilderTarget, PortName},
    reg::Reg,
    source_location::SourceLocation,
    ty::{
        CanonicalType, Connect, DynCanonicalType, DynCanonicalValue, DynType, FixedType, Type,
        TypeEnum, Value,
    },
    util::ConstBool,
    wire::Wire,
};
use hashbrown::{hash_map::Entry, HashMap, HashSet};
use num_bigint::BigInt;
use std::{
    cell::RefCell,
    collections::VecDeque,
    convert::Infallible,
    fmt,
    hash::{Hash, Hasher},
    iter::FusedIterator,
    marker::PhantomData,
    ops::Deref,
    rc::Rc,
    sync::Mutex,
};

pub mod transform;

mod module_building_status_sealed {
    pub trait Sealed {}
}

pub trait ModuleBuildingStatus:
    'static
    + Send
    + Sync
    + Copy
    + Ord
    + Hash
    + fmt::Debug
    + Default
    + module_building_status_sealed::Sealed
{
    type Block: 'static + Send + Sync + Copy + Eq + Hash + fmt::Debug;
    type ModuleBody;
    type StmtAnnotations: 'static + Send + Sync + Copy + Eq + Hash + fmt::Debug;
    type ModuleIOAnnotations;
}

#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Debug, Hash, Default)]
pub struct ModuleBuilt;

impl module_building_status_sealed::Sealed for ModuleBuilt {}

impl ModuleBuildingStatus for ModuleBuilt {
    type Block = Block;
    type ModuleBody = Block;
    type StmtAnnotations = Interned<[TargetedAnnotation]>;
    type ModuleIOAnnotations = Interned<[TargetedAnnotation]>;
}

#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Debug, Hash, Default)]
pub struct ModuleBuilding;

impl module_building_status_sealed::Sealed for ModuleBuilding {}

impl ModuleBuildingStatus for ModuleBuilding {
    type Block = BlockId;
    type ModuleBody = BuilderModuleBody;
    type StmtAnnotations = ();
    type ModuleIOAnnotations = Vec<TargetedAnnotation>;
}

#[derive(Debug)]
pub struct BuilderModuleBody {
    blocks: Vec<BuilderBlock>,
    annotations_map: HashMap<StmtDeclaration<ModuleBuilding>, Vec<TargetedAnnotation>>,
    memory_map: HashMap<ScopedNameId, Rc<RefCell<MemBuilderTarget>>>,
}

/// implicit name argument that's automatically provided by `#[hdl]` let
#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
pub struct ImplicitName<'a>(pub &'a str);

#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
pub struct BlockId(usize);

impl BlockId {
    pub const ENTRY_BLOCK: BlockId = BlockId(0);
    pub fn as_usize(self) -> usize {
        self.0
    }
}

impl fmt::Debug for BlockId {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(f, "block#{}", self.0)
    }
}

pub trait BlockRef: 'static + Send + Sync + Copy + Eq + Hash + fmt::Debug {}

impl BlockRef for BlockId {}

#[derive(Debug)]
pub struct BuilderBlock {
    memories: Vec<Rc<RefCell<MemBuilderTarget>>>,
    stmts: Vec<Stmt<ModuleBuilding>>,
}

#[derive(Copy, Clone, PartialEq, Eq, Hash, Default)]
pub struct Block {
    pub memories: Interned<[Mem<[DynCanonicalValue]>]>,
    pub stmts: Interned<[Stmt]>,
}

impl BlockRef for Block {}

impl fmt::Debug for Block {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.debug_list()
            .entries(self.memories)
            .entries(self.stmts)
            .finish()
    }
}

impl Block {
    pub fn child_blocks(
        &self,
    ) -> impl DoubleEndedIterator<Item = Block> + FusedIterator + Clone + '_ {
        self.stmts
            .iter()
            .flat_map(|stmt| stmt.sub_stmt_blocks())
            .copied()
    }
}

#[derive(Clone, PartialEq, Eq, Hash)]
pub struct StmtConnect {
    pub lhs: Expr<DynCanonicalValue>,
    pub rhs: Expr<DynCanonicalValue>,
    pub source_location: SourceLocation,
}

impl fmt::Debug for StmtConnect {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        let Self {
            lhs,
            rhs,
            source_location: _,
        } = self;
        f.debug_struct("StmtConnect")
            .field("lhs", lhs)
            .field("rhs", rhs)
            .finish_non_exhaustive()
    }
}

#[derive(Clone, PartialEq, Eq, Hash)]
pub struct StmtIf<S: ModuleBuildingStatus = ModuleBuilt> {
    pub cond: Expr<UInt<1>>,
    pub source_location: SourceLocation,
    pub blocks: [S::Block; 2],
}

impl<S: ModuleBuildingStatus> StmtIf<S> {
    pub fn then_block(&self) -> S::Block {
        self.blocks[0]
    }
    pub fn else_block(&self) -> S::Block {
        self.blocks[1]
    }
}

impl<S: ModuleBuildingStatus> fmt::Debug for StmtIf<S> {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        let Self {
            cond,
            source_location: _,
            blocks: _,
        } = self;
        f.debug_struct("StmtIf")
            .field("cond", cond)
            .field("then_block", &self.then_block())
            .field("else_block", &self.else_block())
            .finish_non_exhaustive()
    }
}

#[derive(Clone, PartialEq, Eq, Hash)]
pub struct StmtMatch<S: ModuleBuildingStatus = ModuleBuilt> {
    pub expr: Expr<DynEnum>,
    pub source_location: SourceLocation,
    pub blocks: Interned<[S::Block]>,
}

impl<S: ModuleBuildingStatus> fmt::Debug for StmtMatch<S> {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        let Self {
            expr,
            source_location: _,
            blocks,
        } = self;
        f.debug_struct("StmtMatch")
            .field("expr", expr)
            .field("blocks", blocks)
            .finish_non_exhaustive()
    }
}

macro_rules! wrapper_enum {
    (
        #[impl(
            ($($T_impl:tt)*) $impl_self:ident: $impl_type:ty = $impl_self_expr:expr
            $(, ($($T_impls:tt)*) $impls_self:ident: $impls_type:ty = $impls_self_expr:expr)*
        )]
        #[to($($T_to:tt $to_types:ty),*)]
        $(#[$enum_meta:meta])*
        $vis:vis enum $enum_name:ident<$T_enum:ident: $T_bound:ident = $T_enum_default:ident> {
            $(
                #[is = $is_fn:ident, as_ref = $as_ref_fn:ident]
                $(#[$variant_meta:meta])*
                $Variant:ident($VariantTy:ty),
            )*
        }
    ) => {
        wrapper_enum! {
            #[impl($(($($T_impls)*) $impls_self: $impls_type = $impls_self_expr),*)]
            #[to($($T_to $to_types),*)]
            $(#[$enum_meta])*
            $vis enum $enum_name<$T_enum: $T_bound = $T_enum_default> {
                $(
                    #[is = $is_fn, as_ref = $as_ref_fn]
                    $(#[$variant_meta])*
                    $Variant($VariantTy),
                )*
            }
        }

        impl $($T_impl)* $impl_type {
            $(
                $vis fn $is_fn(&self) -> bool {
                    self.$as_ref_fn().is_some()
                }
                $vis fn $as_ref_fn(&$impl_self) -> Option<&$VariantTy> {
                    match $impl_self_expr {
                        $enum_name::$Variant(value) => Some(value),
                        _ => None,
                    }
                }
            )*
        }
    };
    (
        #[impl()]
        #[to($T_to:tt $to_type:ty $(, $T_tos:tt $to_types:ty)*)]
        $(#[$enum_meta:meta])*
        $vis:vis enum $enum_name:ident<$T_enum:ident: $T_bound:ident = $T_enum_default:ident> {
            $(
                #[is = $is_fn:ident, as_ref = $as_ref_fn:ident]
                $(#[$variant_meta:meta])*
                $Variant:ident($VariantTy:ty),
            )*
        }
    ) => {
        wrapper_enum! {
            #[impl()]
            #[to($($T_tos $to_types),*)]
            $(#[$enum_meta])*
            $vis enum $enum_name<$T_enum: $T_bound = $T_enum_default> {
                $(
                    #[is = $is_fn, as_ref = $as_ref_fn]
                    $(#[$variant_meta])*
                    $Variant($VariantTy),
                )*
            }
        }

        $(
            wrapper_enum! {
                impl $T_to From<$VariantTy> for $to_type {
                    fn from(value: $VariantTy) -> Self {
                        $enum_name::$Variant(value).into()
                    }
                }
            }
        )*
    };
    (
        #[impl()]
        #[to()]
        $(#[$enum_meta:meta])*
        $vis:vis enum $enum_name:ident<$T_enum:ident: $T_bound:ident = $T_enum_default:ident> {
            $(
                #[is = $is_fn:ident, as_ref = $as_ref_fn:ident]
                $(#[$variant_meta:meta])*
                $Variant:ident($VariantTy:ty),
            )*
        }
    ) => {
        $(#[$enum_meta])*
        $vis enum $enum_name<$T_enum: $T_bound = $T_enum_default> {
            $(
                $(#[$variant_meta])*
                $Variant($VariantTy),
            )*
        }

        impl<$T_enum: fmt::Debug + $T_bound> fmt::Debug for $enum_name<$T_enum> {
            fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
                match self {
                    $(Self::$Variant(v) => v.fmt(f),)*
                }
            }
        }
    };
    (
        impl ($($T_to:tt)*) From<$VariantTy:ty> for $to_type:ty {
            $from:item
        }
    ) => {
        impl $($T_to)* From<$VariantTy> for $to_type {
            $from
        }
    };
}

#[derive(Clone, PartialEq, Eq, Hash, Debug)]
pub struct StmtWire<S: ModuleBuildingStatus = ModuleBuilt> {
    pub annotations: S::StmtAnnotations,
    pub wire: Wire<Interned<dyn DynCanonicalType>>,
}

#[derive(Clone, PartialEq, Eq, Hash, Debug)]
pub struct StmtReg<S: ModuleBuildingStatus = ModuleBuilt> {
    pub annotations: S::StmtAnnotations,
    pub reg: Reg<Interned<dyn DynCanonicalType>>,
}

#[derive(Clone, PartialEq, Eq, Hash, Debug)]
pub struct StmtInstance<S: ModuleBuildingStatus = ModuleBuilt> {
    pub annotations: S::StmtAnnotations,
    pub instance: Instance<DynBundle>,
}

wrapper_enum! {
    #[impl(
        (<S: ModuleBuildingStatus>) self: StmtDeclaration<S> = self,
        (<S: ModuleBuildingStatus>) self: Stmt<S> = self.declaration()?
    )]
    #[to((<S: ModuleBuildingStatus>) StmtDeclaration<S>, (<S: ModuleBuildingStatus>) Stmt<S>)]
    #[derive(Clone, PartialEq, Eq, Hash)]
    pub enum StmtDeclaration<S: ModuleBuildingStatus = ModuleBuilt> {
        #[is = is_wire, as_ref = wire]
        Wire(StmtWire<S>),
        #[is = is_reg, as_ref = reg]
        Reg(StmtReg<S>),
        #[is = is_instance, as_ref = instance]
        Instance(StmtInstance<S>),
    }
}

impl<S: ModuleBuildingStatus> StmtDeclaration<S> {
    pub fn annotations(&self) -> S::StmtAnnotations {
        match self {
            StmtDeclaration::Wire(v) => v.annotations,
            StmtDeclaration::Reg(v) => v.annotations,
            StmtDeclaration::Instance(v) => v.annotations,
        }
    }
    pub fn source_location(&self) -> SourceLocation {
        match self {
            StmtDeclaration::Wire(v) => v.wire.source_location(),
            StmtDeclaration::Reg(v) => v.reg.source_location(),
            StmtDeclaration::Instance(v) => v.instance.source_location(),
        }
    }
    pub fn scoped_name(&self) -> ScopedNameId {
        match self {
            StmtDeclaration::Wire(v) => v.wire.scoped_name(),
            StmtDeclaration::Reg(v) => v.reg.scoped_name(),
            StmtDeclaration::Instance(v) => v.instance.scoped_name(),
        }
    }
    pub fn sub_stmt_blocks(&self) -> &[S::Block] {
        match self {
            StmtDeclaration::Wire(_) | StmtDeclaration::Reg(_) | StmtDeclaration::Instance(_) => {
                &[]
            }
        }
    }
    pub fn canonical_ty(&self) -> Interned<dyn DynCanonicalType> {
        match self {
            StmtDeclaration::Wire(v) => v.wire.ty(),
            StmtDeclaration::Reg(v) => v.reg.ty(),
            StmtDeclaration::Instance(v) => v.instance.ty().canonical_dyn(),
        }
    }
}

wrapper_enum! {
    #[impl((<S: ModuleBuildingStatus>) self: Stmt<S> = self)]
    #[to((<S: ModuleBuildingStatus>) Stmt<S>)]
    #[derive(Clone, PartialEq, Eq, Hash)]
    pub enum Stmt<S: ModuleBuildingStatus = ModuleBuilt> {
        #[is = is_connect, as_ref = connect]
        Connect(StmtConnect),
        #[is = is_if, as_ref = if_]
        If(StmtIf<S>),
        #[is = is_match, as_ref = match_]
        Match(StmtMatch<S>),
        #[is = is_declaration, as_ref = declaration]
        Declaration(StmtDeclaration<S>),
    }
}

impl<S: ModuleBuildingStatus> Stmt<S> {
    pub fn sub_stmt_blocks(&self) -> &[S::Block] {
        match self {
            Stmt::Connect(_) => &[],
            Stmt::If(v) => &v.blocks,
            Stmt::Match(v) => &v.blocks,
            Stmt::Declaration(v) => v.sub_stmt_blocks(),
        }
    }
}

struct BlockStackEntry {
    // entries are marked removed instead of
    removed: bool,
    block_id: BlockId,
}

struct BlockStack(RefCell<Vec<BlockStackEntry>>);

impl BlockStack {
    fn new(top_block: BlockId) -> Self {
        Self(RefCell::new(vec![BlockStackEntry {
            removed: false,
            block_id: top_block,
        }]))
    }
    fn push_scope(self: Rc<Self>, block_id: BlockId) -> Scope {
        let mut block_stack = self.0.borrow_mut();
        Self::clean_stack_and_get_top(&mut block_stack);
        let block_stack_index = block_stack.len();
        block_stack.push(BlockStackEntry {
            removed: false,
            block_id,
        });
        drop(block_stack);
        Scope {
            block_id,
            block_stack_index,
            block_stack: self,
        }
    }
    fn clean_stack_and_get_top(block_stack: &mut Vec<BlockStackEntry>) -> &BlockStackEntry {
        for i in (0..block_stack.len()).rev() {
            if block_stack[i].removed {
                block_stack.pop();
            } else {
                return &block_stack[i];
            }
        }
        unreachable!("top block should never be popped from block stack");
    }
    fn top(&self) -> BlockId {
        let mut block_stack = self.0.borrow_mut();
        Self::clean_stack_and_get_top(&mut block_stack).block_id
    }
}

#[derive(Copy, Clone, Eq, PartialEq, Hash)]
pub struct NameId(pub Interned<str>, pub usize);

impl fmt::Debug for NameId {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        fmt::Display::fmt(self, f)
    }
}

impl fmt::Display for NameId {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        if self.0.is_empty() {
            write!(f, "{}", self.1)
        } else if self.1 == 0 {
            f.write_str(&self.0)
        } else {
            write!(f, "{}_{}", self.0, self.1)
        }
    }
}

#[derive(Copy, Clone, Eq, PartialEq, Hash)]
pub struct ScopedNameId(pub NameId, pub NameId);

impl fmt::Debug for ScopedNameId {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        self.0.fmt(f)?;
        f.write_str("::")?;
        self.1.fmt(f)
    }
}

#[derive(Copy, Clone, Eq, PartialEq, Hash)]
pub struct TargetName(pub ScopedNameId, pub Option<PortName>);

impl fmt::Debug for TargetName {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        self.0.fmt(f)?;
        if let Some(port_name) = self.1 {
            f.write_str("::")?;
            port_name.fmt(f)?;
        }
        Ok(())
    }
}

#[derive(Default)]
pub struct NameIdGen(HashMap<Interned<str>, usize>);

impl NameIdGen {
    pub fn gen(&mut self, name: Interned<str>) -> NameId {
        let next_id = self.0.entry(name).or_default();
        let id = *next_id;
        *next_id += 1;
        NameId(name, id)
    }
    pub fn mark_as_used(&mut self, name_id: NameId) {
        let next_id = self.0.entry(name_id.0).or_default();
        *next_id = (*next_id).max(name_id.1 + 1);
    }
    pub fn for_module(module: Module<DynBundle>) -> Self {
        let mut retval = Self::default();
        let Module {
            name: _,
            source_location: _,
            body,
            io_ty: _,
            module_io,
            module_annotations: _,
        } = module;
        for module_io in &module_io {
            retval.mark_as_used(module_io.module_io.name_id());
        }
        match body {
            ModuleBody::Extern(ExternModuleBody {
                verilog_name: _,
                parameters: _,
            }) => {}
            ModuleBody::Normal(NormalModuleBody { body }) => {
                let mut blocks = vec![body];
                while let Some(block) = blocks.pop() {
                    let Block { memories, stmts } = block;
                    for memory in memories {
                        retval.mark_as_used(memory.scoped_name().1);
                    }
                    for stmt in &stmts {
                        blocks.extend_from_slice(stmt.sub_stmt_blocks());
                        match stmt {
                            Stmt::Connect(StmtConnect {
                                lhs: _,
                                rhs: _,
                                source_location: _,
                            })
                            | Stmt::If(StmtIf {
                                cond: _,
                                source_location: _,
                                blocks: _,
                            })
                            | Stmt::Match(StmtMatch {
                                expr: _,
                                source_location: _,
                                blocks: _,
                            }) => {}
                            Stmt::Declaration(StmtDeclaration::Instance(StmtInstance {
                                annotations: _,
                                instance,
                            })) => {
                                retval.mark_as_used(instance.name_id());
                            }
                            Stmt::Declaration(StmtDeclaration::Reg(StmtReg {
                                annotations: _,
                                reg,
                            })) => {
                                retval.mark_as_used(reg.name_id());
                            }
                            Stmt::Declaration(StmtDeclaration::Wire(StmtWire {
                                annotations: _,
                                wire,
                            })) => {
                                retval.mark_as_used(wire.name_id());
                            }
                        }
                    }
                }
            }
        }
        retval
    }
    pub fn gen_module_name(name: Interned<str>) -> NameId {
        static MODULE_NAME_GEN: Mutex<Option<NameIdGen>> = Mutex::new(None);
        MODULE_NAME_GEN
            .lock()
            .unwrap()
            .get_or_insert_with(NameIdGen::default)
            .gen(name)
    }
}

pub struct Instance<T: BundleValue>
where
    T::Type: BundleType<Value = T>,
{
    scoped_name: ScopedNameId,
    instantiated: Interned<Module<T>>,
    source_location: SourceLocation,
}

impl<T: BundleValue> Clone for Instance<T>
where
    T::Type: BundleType<Value = T>,
{
    fn clone(&self) -> Self {
        *self
    }
}

impl<T: BundleValue> Copy for Instance<T> where T::Type: BundleType<Value = T> {}

impl<T: BundleValue> Eq for Instance<T> where T::Type: BundleType<Value = T> {}

impl<T: BundleValue> fmt::Debug for Instance<T>
where
    T::Type: BundleType<Value = T>,
{
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.debug_struct("Instance")
            .field("name", &self.scoped_name)
            .field("instantiated", &self.instantiated.debug_short())
            .finish()
    }
}

impl<T: BundleValue> PartialEq for Instance<T>
where
    T::Type: BundleType<Value = T>,
{
    fn eq(&self, other: &Self) -> bool {
        let Self {
            scoped_name,
            instantiated,
            source_location,
        } = *self;
        scoped_name == other.scoped_name
            && instantiated == other.instantiated
            && source_location == other.source_location
    }
}

impl<T: BundleValue> Hash for Instance<T>
where
    T::Type: BundleType<Value = T>,
{
    fn hash<H: Hasher>(&self, state: &mut H) {
        let Self {
            scoped_name,
            instantiated,
            source_location,
        } = self;
        scoped_name.hash(state);
        instantiated.hash(state);
        source_location.hash(state);
    }
}

impl<T: BundleValue> Instance<T>
where
    T::Type: BundleType<Value = T>,
{
    pub fn canonical(self) -> Instance<DynBundle> {
        let Self {
            scoped_name,
            instantiated,
            source_location,
        } = self;
        Instance {
            scoped_name,
            instantiated: instantiated.canonical().intern_sized(),
            source_location,
        }
    }
    pub fn containing_module_name(self) -> Interned<str> {
        self.containing_module_name_id().0
    }
    pub fn containing_module_name_id(self) -> NameId {
        self.scoped_name.0
    }
    pub fn name(self) -> Interned<str> {
        self.name_id().0
    }
    pub fn name_id(self) -> NameId {
        self.scoped_name.1
    }
    pub fn scoped_name(self) -> ScopedNameId {
        self.scoped_name
    }
    pub fn instantiated(self) -> Interned<Module<T>> {
        self.instantiated
    }
    pub fn source_location(self) -> SourceLocation {
        self.source_location
    }
    pub fn new_unchecked(
        scoped_name: ScopedNameId,
        instantiated: Interned<Module<T>>,
        source_location: SourceLocation,
    ) -> Self {
        Self {
            scoped_name,
            instantiated,
            source_location,
        }
    }
    pub fn flow(&self) -> Flow {
        Flow::Source
    }
    pub fn must_connect_to(&self) -> bool {
        true
    }
}

mod module_kind_trait_sealed {
    pub trait Sealed {}
}

pub trait ModuleKindTrait:
    Into<ModuleKind>
    + 'static
    + Send
    + Sync
    + Copy
    + Ord
    + Hash
    + fmt::Debug
    + Default
    + module_kind_trait_sealed::Sealed
{
    const MODULE_KIND: ModuleKind;
    type ModuleBuilderBody: fmt::Debug;
    type ModuleBody: Into<ModuleBody>
        + From<Self::ModuleBuilderBody>
        + 'static
        + Send
        + Sync
        + Copy
        + Eq
        + Hash
        + fmt::Debug;
    fn builder_normal_body(
        body: &mut Self::ModuleBuilderBody,
    ) -> Option<&mut NormalModuleBody<ModuleBuilding>>;
    fn new_body(module_name: NameId) -> Self::ModuleBuilderBody;
}

#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, Default)]
pub struct ExternModule;

impl From<ExternModule> for ModuleKind {
    fn from(value: ExternModule) -> Self {
        Self::Extern(value)
    }
}

impl module_kind_trait_sealed::Sealed for ExternModule {}

impl ModuleKindTrait for ExternModule {
    const MODULE_KIND: ModuleKind = ModuleKind::Extern(Self);
    type ModuleBuilderBody = ExternModuleBody<Vec<ExternModuleParameter>>;
    type ModuleBody = ExternModuleBody;
    fn builder_normal_body(
        _body: &mut Self::ModuleBuilderBody,
    ) -> Option<&mut NormalModuleBody<ModuleBuilding>> {
        None
    }
    fn new_body(name: NameId) -> Self::ModuleBuilderBody {
        ExternModuleBody {
            verilog_name: name.0,
            parameters: vec![],
        }
    }
}

#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, Default)]
pub struct NormalModule;

impl From<NormalModule> for ModuleKind {
    fn from(value: NormalModule) -> Self {
        Self::Normal(value)
    }
}

impl module_kind_trait_sealed::Sealed for NormalModule {}

impl ModuleKindTrait for NormalModule {
    const MODULE_KIND: ModuleKind = ModuleKind::Normal(Self);
    type ModuleBuilderBody = NormalModuleBody<ModuleBuilding>;
    type ModuleBody = NormalModuleBody;
    fn builder_normal_body(
        body: &mut Self::ModuleBuilderBody,
    ) -> Option<&mut NormalModuleBody<ModuleBuilding>> {
        Some(body)
    }
    fn new_body(_module_name: NameId) -> Self::ModuleBuilderBody {
        NormalModuleBody {
            body: BuilderModuleBody {
                blocks: vec![BuilderBlock {
                    memories: vec![],
                    stmts: vec![],
                }],
                annotations_map: HashMap::new(),
                memory_map: HashMap::new(),
            },
        }
    }
}

#[derive(Clone, PartialEq, Eq, Hash, Debug)]
pub struct AnnotatedModuleIO<S: ModuleBuildingStatus = ModuleBuilt> {
    pub annotations: S::ModuleIOAnnotations,
    pub module_io: ModuleIO<Interned<dyn DynCanonicalType>>,
}

#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
pub enum ModuleKind {
    Extern(ExternModule),
    Normal(NormalModule),
}

pub struct ModuleBuilder<T: BundleValue, Kind: ModuleKindTrait>
where
    T::Type: BundleType<Value = T>,
{
    name: NameId,
    body: Kind::ModuleBuilderBody,
    block_stack: Rc<BlockStack>,
    io: Vec<AnnotatedModuleIO<ModuleBuilding>>,
    io_indexes: HashMap<ModuleIO<Interned<dyn DynCanonicalType>>, usize>,
    io_fields_hint: FieldsHint,
    name_id_gen: NameIdGen,
    module_annotations: Vec<Annotation>,
    _phantom: PhantomData<fn(Kind) -> T::Type>,
}

#[must_use]
pub struct Scope {
    block_id: BlockId,
    block_stack_index: usize,
    block_stack: Rc<BlockStack>,
}

impl Drop for Scope {
    fn drop(&mut self) {
        let mut block_stack = self.block_stack.0.borrow_mut();
        let entry = &mut block_stack[self.block_stack_index];
        assert_eq!(
            entry.block_id, self.block_id,
            "block stack not managed properly",
        );
        assert!(!entry.removed, "block stack not managed properly",);
        entry.removed = true; // only mark removed and don't pop it here so scopes can be dropped out of order
    }
}

pub struct IfScope {
    then: Scope,
    else_block: BlockId,
}

impl IfScope {
    pub fn else_(self) -> Scope {
        let block_stack = self.then.block_stack.clone();
        drop(self.then);
        block_stack.push_scope(self.else_block)
    }
}

pub(crate) struct EnumMatchVariantAndInactiveScopeImpl<T: EnumType>
where
    T::Value: EnumValue<Type = T>,
{
    block_stack: Rc<BlockStack>,
    match_arm_block_id: BlockId,
    variant_access: Interned<VariantAccess<T, Interned<dyn DynCanonicalType>>>,
}

impl<T: EnumType> EnumMatchVariantAndInactiveScopeImpl<T>
where
    T::Value: EnumValue<Type = T>,
{
    pub(crate) fn activate(
        self,
    ) -> (
        Interned<VariantAccess<T, Interned<dyn DynCanonicalType>>>,
        Scope,
    ) {
        let scope = self.block_stack.push_scope(self.match_arm_block_id);
        (self.variant_access, scope)
    }
    pub(crate) fn variant_access(
        &self,
    ) -> Interned<VariantAccess<T, Interned<dyn DynCanonicalType>>> {
        self.variant_access
    }
}

#[derive(Clone)]
pub(crate) struct EnumMatchVariantsIterImpl<T> {
    block_stack: Rc<BlockStack>,
    blocks: Interned<[BlockId]>,
    base: Expr<DynEnum>,
    _phantom: PhantomData<T>,
}

impl<T: EnumType> EnumMatchVariantsIterImpl<T>
where
    T::Value: EnumValue<Type = T>,
{
    pub(crate) fn for_variant_index(
        &self,
        variant_index: usize,
    ) -> EnumMatchVariantAndInactiveScopeImpl<T> {
        EnumMatchVariantAndInactiveScopeImpl {
            block_stack: self.block_stack.clone(),
            match_arm_block_id: self.blocks[variant_index],
            variant_access: Intern::intern_sized(VariantAccess::new_unchecked(
                self.base,
                variant_index,
            )),
        }
    }
}

#[derive(PartialEq, Eq, Hash, Clone, Debug)]
pub enum ExternModuleParameterValue {
    Integer(BigInt),
    String(Interned<str>),
    RawVerilog(Interned<str>),
}

#[derive(PartialEq, Eq, Hash, Clone, Debug)]
pub struct ExternModuleParameter {
    pub name: Interned<str>,
    pub value: ExternModuleParameterValue,
}

#[derive(PartialEq, Eq, Hash, Copy, Clone, Debug)]
pub struct NormalModuleBody<S: ModuleBuildingStatus = ModuleBuilt> {
    pub body: S::ModuleBody,
}

impl From<NormalModuleBody<ModuleBuilding>> for NormalModuleBody {
    fn from(value: NormalModuleBody<ModuleBuilding>) -> Self {
        let NormalModuleBody {
            body:
                BuilderModuleBody {
                    mut blocks,
                    mut annotations_map,
                    memory_map: _,
                },
        } = value;
        fn finalize_block(
            blocks: &mut [BuilderBlock],
            annotations_map: &mut HashMap<StmtDeclaration<ModuleBuilding>, Vec<TargetedAnnotation>>,
            block_id: BlockId,
        ) -> Block {
            let BuilderBlock { memories, stmts } = &mut blocks[block_id.as_usize()];
            let memories = Interned::from_iter(
                memories
                    .drain(..)
                    .filter_map(|memory| memory.borrow().make_memory()),
            );
            let stmts = std::mem::take(stmts);
            let stmts = Interned::from_iter(stmts.into_iter().map(|stmt| {
                match stmt {
                    Stmt::Connect(stmt) => stmt.into(),
                    Stmt::If(StmtIf {
                        cond,
                        source_location,
                        blocks: if_blocks,
                    }) => StmtIf {
                        cond,
                        source_location,
                        blocks: if_blocks
                            .map(|block_id| finalize_block(blocks, annotations_map, block_id)),
                    }
                    .into(),
                    Stmt::Match(StmtMatch {
                        expr,
                        source_location,
                        blocks: match_blocks,
                    }) => StmtMatch {
                        expr,
                        source_location,
                        blocks: Interned::from_iter(
                            match_blocks
                                .into_iter()
                                .map(|block_id| finalize_block(blocks, annotations_map, block_id)),
                        ),
                    }
                    .into(),
                    Stmt::Declaration(decl) => {
                        let annotations = annotations_map
                            .remove(&decl)
                            .map(|v| Intern::intern_owned(v))
                            .unwrap_or_default();
                        match decl {
                            StmtDeclaration::Wire(StmtWire {
                                annotations: (),
                                wire,
                            }) => StmtWire { annotations, wire }.into(),
                            StmtDeclaration::Reg(StmtReg {
                                annotations: (),
                                reg,
                            }) => StmtReg { annotations, reg }.into(),
                            StmtDeclaration::Instance(StmtInstance {
                                annotations: (),
                                instance,
                            }) => StmtInstance {
                                annotations,
                                instance,
                            }
                            .into(),
                        }
                    }
                }
            }));
            Block { memories, stmts }
        }
        Self {
            body: finalize_block(&mut blocks, &mut annotations_map, BlockId::ENTRY_BLOCK),
        }
    }
}

impl From<NormalModuleBody> for ModuleBody {
    fn from(value: NormalModuleBody) -> Self {
        Self::Normal(value)
    }
}

#[derive(PartialEq, Eq, Hash, Copy, Clone, Debug)]
pub struct ExternModuleBody<
    P: Deref<Target = [ExternModuleParameter]> = Interned<[ExternModuleParameter]>,
> {
    pub verilog_name: Interned<str>,
    pub parameters: P,
}

impl From<ExternModuleBody<Vec<ExternModuleParameter>>> for ExternModuleBody {
    fn from(value: ExternModuleBody<Vec<ExternModuleParameter>>) -> Self {
        let ExternModuleBody {
            verilog_name,
            parameters,
        } = value;
        let parameters = Intern::intern_owned(parameters);
        Self {
            verilog_name,
            parameters,
        }
    }
}

impl From<ExternModuleBody> for ModuleBody {
    fn from(value: ExternModuleBody) -> Self {
        Self::Extern(value)
    }
}

#[derive(PartialEq, Eq, Hash, Copy, Clone, Debug)]
pub enum ModuleBody {
    Normal(NormalModuleBody),
    Extern(ExternModuleBody),
}

impl ModuleBody {
    pub fn kind(&self) -> ModuleKind {
        match self {
            Self::Normal(_) => ModuleKind::Normal(NormalModule),
            Self::Extern(_) => ModuleKind::Extern(ExternModule),
        }
    }
}

/// The runtime representation of a Fayalite module. The preferred way to create a [`Module`] is by
/// calling a function annotated with the [`#[hdl_module]`][`crate::hdl_module`] attribute.
#[derive(PartialEq, Eq, Hash)]
pub struct Module<T: BundleValue>
where
    T::Type: BundleType<Value = T>,
{
    name: NameId,
    source_location: SourceLocation,
    body: ModuleBody,
    io_ty: Interned<T::Type>,
    module_io: Interned<[AnnotatedModuleIO]>,
    module_annotations: Interned<[Annotation]>,
}

#[derive(Default)]
struct DebugFmtModulesState {
    seen: HashSet<NameId>,
    unwritten: VecDeque<(NameId, Box<dyn fmt::Debug>)>,
}

#[derive(Default)]
struct DebugFmtState {
    modules_state: RefCell<Option<DebugFmtModulesState>>,
}

impl DebugFmtState {
    fn with<F: FnOnce(&Self) -> R, R>(f: F) -> R {
        thread_local! {
            static STATE: RefCell<Option<DebugFmtState>> = RefCell::default();
        }
        let mut clear_on_drop = None;
        struct ClearOnDrop;
        impl Drop for ClearOnDrop {
            fn drop(&mut self) {
                STATE.with_borrow_mut(|v| *v = None);
            }
        }
        STATE.with(|state| {
            let mut read = state.borrow();
            if read.is_none() {
                drop(read);
                clear_on_drop = Some(ClearOnDrop);
                state.replace(Some(DebugFmtState::default()));
                read = state.borrow();
            }
            f(read.as_ref().unwrap())
        })
    }
    fn push_module_if_in_module<T: BundleValue>(&self, module: Module<T>) -> bool
    where
        T::Type: BundleType<Value = T>,
    {
        DebugFmtState::with(|state| {
            let mut modules_state_ref = state.modules_state.borrow_mut();
            if let Some(modules_state) = &mut *modules_state_ref {
                if modules_state.seen.insert(module.name) {
                    modules_state
                        .unwritten
                        .push_back((module.name, Box::new(DebugModuleBody(module))));
                    return true;
                }
            }
            false
        })
    }
}

struct DebugModuleBody<T: BundleValue>(Module<T>)
where
    T::Type: BundleType<Value = T>;

impl<T: BundleValue> fmt::Debug for DebugModuleBody<T>
where
    T::Type: BundleType<Value = T>,
{
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        let Module {
            name: _,
            body,
            io_ty,
            module_io,
            source_location: _,
            module_annotations,
        } = &self.0;
        let mut debug_struct = f.debug_struct("Module");
        let kind = body.kind();
        debug_struct
            .field("io_ty", io_ty)
            .field("module_io", module_io)
            .field("module_annotations", module_annotations)
            .field("kind", &kind);
        match body {
            ModuleBody::Normal(NormalModuleBody { body }) => {
                debug_struct.field("body", body);
            }
            ModuleBody::Extern(ExternModuleBody {
                verilog_name,
                parameters,
            }) => {
                debug_struct
                    .field("verilog_name", verilog_name)
                    .field("parameters", parameters);
            }
        }
        debug_struct.finish_non_exhaustive()
    }
}

pub struct ModuleDebugShort<T: BundleValue>(Module<T>)
where
    T::Type: BundleType<Value = T>;

impl<T: BundleValue> fmt::Debug for ModuleDebugShort<T>
where
    T::Type: BundleType<Value = T>,
{
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        DebugFmtState::with(|state| state.push_module_if_in_module(self.0));
        f.debug_struct("Module")
            .field("name", &self.0.name)
            .finish_non_exhaustive()
    }
}

impl<T: BundleValue> Module<T>
where
    T::Type: BundleType<Value = T>,
{
    pub fn debug_short(self) -> ModuleDebugShort<T> {
        ModuleDebugShort(self)
    }
}

impl<T: BundleValue> fmt::Debug for Module<T>
where
    T::Type: BundleType<Value = T>,
{
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        DebugFmtState::with(|state| {
            struct Outermost<'a>(&'a DebugFmtState);
            impl Drop for Outermost<'_> {
                fn drop(&mut self) {
                    self.0.modules_state.replace(None);
                }
            }
            let mut outermost: Option<Outermost<'_>> = None;
            state.modules_state.borrow_mut().get_or_insert_with(|| {
                outermost = Some(Outermost(state));
                DebugFmtModulesState::default()
            });
            state.push_module_if_in_module(*self);
            if outermost.is_some() {
                let mut debug = f.debug_map();
                loop {
                    let mut modules_state_ref = state.modules_state.borrow_mut();
                    let modules_state = modules_state_ref.as_mut().unwrap();
                    let Some((name, m)) = modules_state.unwritten.pop_front() else {
                        break;
                    };
                    drop(modules_state_ref);
                    debug.entry(&name, &m);
                }
                debug.finish()
            } else {
                self.debug_short().fmt(f)
            }
        })
    }
}

impl<T: BundleValue> Clone for Module<T>
where
    T::Type: BundleType<Value = T>,
{
    fn clone(&self) -> Self {
        *self
    }
}

impl<T: BundleValue> Copy for Module<T> where T::Type: BundleType<Value = T> {}

#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
pub struct SubBlockId {
    pub block: BlockId,
    pub stmt_index: usize,
    pub sub_stmt_index: usize,
}

#[derive(Copy, Clone, PartialEq, Eq, Debug, Default)]
enum TargetWritten {
    #[default]
    Unwritten,
    MaybeWritten,
    Written,
}

impl TargetWritten {
    fn conditional_merge_written(self, other: Self) -> Self {
        match (self, other) {
            (Self::Written, Self::Written) => Self::Written,
            (Self::MaybeWritten | Self::Written, _) | (_, Self::MaybeWritten | Self::Written) => {
                Self::MaybeWritten
            }
            (Self::Unwritten, Self::Unwritten) => Self::Unwritten,
        }
    }
    fn most_written(self, other: Self) -> Self {
        if self as u8 > other as u8 {
            self
        } else {
            other
        }
    }
}

#[derive(Debug)]
enum TargetStateInner {
    Single {
        declared_in_block: usize,
        written_in_blocks: RefCell<Vec<TargetWritten>>,
    },
    Decomposed {
        subtargets: HashMap<Interned<TargetPathElement>, TargetState>,
    },
}

#[derive(Debug)]
struct TargetState {
    target: Interned<Target>,
    inner: TargetStateInner,
}

impl TargetState {
    #[track_caller]
    fn assert_written(&self) {
        match &self.inner {
            TargetStateInner::Single {
                declared_in_block,
                written_in_blocks,
            } => {
                if self.target.flow() != Flow::Source {
                    match written_in_blocks
                        .borrow()
                        .get(*declared_in_block)
                        .copied()
                        .unwrap_or_default()
                    {
                        TargetWritten::Unwritten => panic!(
                            "at {}: {} is not connected to",
                            self.target.base().source_location(),
                            self.target,
                        ),
                        TargetWritten::MaybeWritten => panic!(
                            "at {}: {} is not always connected to",
                            self.target.base().source_location(),
                            self.target,
                        ),
                        TargetWritten::Written => {}
                    }
                }
            }
            TargetStateInner::Decomposed { subtargets } => {
                for subtarget in subtargets.values() {
                    subtarget.assert_written();
                }
            }
        }
    }
    fn merge_conditional_sub_blocks_into_block(
        &self,
        target_block: usize,
        sub_blocks: impl Clone + IntoIterator<Item = usize>,
    ) {
        match &self.inner {
            TargetStateInner::Single {
                declared_in_block: _,
                written_in_blocks,
            } => {
                let Some(written) = sub_blocks
                    .into_iter()
                    .map(|block| {
                        written_in_blocks
                            .borrow()
                            .get(block)
                            .copied()
                            .unwrap_or_default()
                    })
                    .reduce(TargetWritten::conditional_merge_written)
                else {
                    unreachable!("merge_conditional_sub_blocks_into_block must be called with at least one sub-block");
                };
                let mut written_in_blocks = written_in_blocks.borrow_mut();
                if target_block >= written_in_blocks.len() {
                    written_in_blocks.resize(target_block + 1, Default::default());
                }
                let target_written = &mut written_in_blocks[target_block];
                *target_written = target_written.most_written(written);
            }
            TargetStateInner::Decomposed { subtargets } => {
                for i in subtargets.values() {
                    i.merge_conditional_sub_blocks_into_block(target_block, sub_blocks.clone());
                }
            }
        }
    }
    fn new(target: Interned<Target>, declared_in_block: usize) -> Self {
        Self {
            target,
            inner: match target.canonical_ty().type_enum() {
                TypeEnum::BundleType(ty) => TargetStateInner::Decomposed {
                    subtargets: ty
                        .fields()
                        .iter()
                        .map(|&field| {
                            let path_element = TargetPathElement::intern_sized(
                                TargetPathBundleField { name: field.name }.into(),
                            );
                            (
                                path_element,
                                Self::new(
                                    Target::intern_sized(target.join(path_element)),
                                    declared_in_block,
                                ),
                            )
                        })
                        .collect(),
                },
                TypeEnum::ArrayType(ty) => TargetStateInner::Decomposed {
                    subtargets: (0..ty.len())
                        .map(|index| {
                            let path_element =
                                Intern::intern_sized(TargetPathArrayElement { index }.into());
                            (
                                path_element,
                                Self::new(
                                    Target::intern_sized(target.join(path_element)),
                                    declared_in_block,
                                ),
                            )
                        })
                        .collect(),
                },
                TypeEnum::EnumType(_)
                | TypeEnum::UInt(_)
                | TypeEnum::SInt(_)
                | TypeEnum::Clock(_)
                | TypeEnum::AsyncReset(_)
                | TypeEnum::SyncReset(_)
                | TypeEnum::Reset(_) => TargetStateInner::Single {
                    declared_in_block,
                    written_in_blocks: RefCell::default(),
                },
            },
        }
    }
}

struct AssertValidityState {
    module: Module<DynBundle>,
    blocks: Vec<Block>,
    target_states: HashMap<Interned<TargetBase>, TargetState>,
}

impl AssertValidityState {
    fn make_block_index(&mut self, block: Block) -> usize {
        let retval = self.blocks.len();
        self.blocks.push(block);
        retval
    }
    fn get_target_states<'a>(
        &'a self,
        target: &Target,
        process_target_state: &dyn Fn(&'a TargetState, bool),
    ) -> Result<(), ()> {
        match target {
            Target::Base(target_base) => {
                let target_state = self.get_base_state(*target_base)?;
                process_target_state(target_state, false);
                Ok(())
            }
            Target::Child(target_child) => self.get_target_states(
                &target_child.parent(),
                &|target_state, exact_target_unknown| {
                    let TargetStateInner::Decomposed { subtargets } = &target_state.inner else {
                        unreachable!(
                            "TargetState::new makes TargetState tree match the Target type"
                        );
                    };
                    match *target_child.path_element() {
                        TargetPathElement::BundleField(_) => process_target_state(
                            subtargets
                                .get(&target_child.path_element())
                                .expect("bundle fields filled in by TargetState::new"),
                            exact_target_unknown,
                        ),
                        TargetPathElement::ArrayElement(_) => process_target_state(
                            subtargets
                                .get(&target_child.path_element())
                                .expect("array elements filled in by TargetState::new"),
                            exact_target_unknown,
                        ),
                        TargetPathElement::DynArrayElement(_) => {
                            for target_state in subtargets.values() {
                                process_target_state(target_state, true);
                            }
                        }
                    }
                },
            ),
        }
    }
    fn get_base_state(&self, target_base: Interned<TargetBase>) -> Result<&TargetState, ()> {
        self.target_states.get(&target_base).ok_or(())
    }
    #[track_caller]
    fn insert_new_base(&mut self, target_base: Interned<TargetBase>, declared_in_block: usize) {
        match self.target_states.entry(target_base) {
            Entry::Occupied(_) => panic!(
                "at {}: duplicate declaration: {target_base}",
                target_base.source_location(),
            ),
            Entry::Vacant(entry) => {
                entry.insert(TargetState::new(
                    Target::intern_sized(target_base.into()),
                    declared_in_block,
                ));
            }
        }
    }
    fn set_connect_target_written(
        target_state: &TargetState,
        is_lhs: bool,
        block: usize,
        exact_target_unknown: bool,
    ) {
        match &target_state.inner {
            TargetStateInner::Single {
                declared_in_block: _,
                written_in_blocks,
            } => {
                if is_lhs {
                    let mut written_in_blocks = written_in_blocks.borrow_mut();
                    if block >= written_in_blocks.len() {
                        written_in_blocks.resize(block + 1, Default::default());
                    }
                    let written = &mut written_in_blocks[block];
                    if exact_target_unknown {
                        *written = written.most_written(TargetWritten::MaybeWritten);
                    } else {
                        *written = TargetWritten::Written;
                    }
                }
            }
            TargetStateInner::Decomposed { subtargets } => {
                for (&path_element, sub_target_state) in subtargets {
                    match &*path_element {
                        &TargetPathElement::BundleField(_) => {
                            let field = sub_target_state
                                .target
                                .child()
                                .expect("known to be a child")
                                .bundle_field()
                                .expect("known to be a bundle field");
                            let sub_is_lhs = if field.flipped { !is_lhs } else { is_lhs };
                            Self::set_connect_target_written(
                                sub_target_state,
                                sub_is_lhs,
                                block,
                                exact_target_unknown,
                            );
                        }
                        TargetPathElement::ArrayElement { .. } => {
                            Self::set_connect_target_written(
                                sub_target_state,
                                is_lhs,
                                block,
                                exact_target_unknown,
                            );
                        }
                        TargetPathElement::DynArrayElement { .. } => {
                            Self::set_connect_target_written(sub_target_state, is_lhs, block, true);
                        }
                    }
                }
            }
        }
    }
    #[track_caller]
    fn set_connect_side_written(
        &mut self,
        expr: Expr<DynCanonicalValue>,
        source_location: SourceLocation,
        is_lhs: bool,
        block: usize,
    ) {
        let Some(target) = expr.target() else {
            debug_assert!(!is_lhs, "the ModuleBuilder asserts lhs.target().is_some()");
            return;
        };
        let result = self.get_target_states(&target, &|target_state, exact_target_unknown| {
            Self::set_connect_target_written(target_state, is_lhs, block, exact_target_unknown);
        });
        if result.is_err() {
            if is_lhs {
                panic!("at {source_location}: tried to connect to not-yet-defined item: {target}");
            } else {
                panic!(
                    "at {source_location}: tried to connect from not-yet-defined item: {target}"
                );
            }
        }
    }
    fn process_conditional_sub_blocks(
        &mut self,
        parent_block: usize,
        sub_blocks: impl Clone + IntoIterator<Item = usize>,
    ) {
        for i in sub_blocks.clone() {
            self.assert_subtree_validity(i);
        }
        for i in self.target_states.values() {
            i.merge_conditional_sub_blocks_into_block(parent_block, sub_blocks.clone());
        }
    }
    #[track_caller]
    fn assert_subtree_validity(&mut self, block: usize) {
        let module = self.module;
        if block == 0 {
            for module_io in &*module.module_io {
                self.insert_new_base(
                    TargetBase::intern_sized(module_io.module_io.clone().into()),
                    block,
                );
            }
        }
        let Block { memories, stmts } = self.blocks[block];
        for m in memories {
            for port in m.ports() {
                self.insert_new_base(TargetBase::intern_sized((*port).into()), block);
            }
        }
        for stmt in stmts {
            match stmt {
                Stmt::Connect(StmtConnect {
                    lhs,
                    rhs,
                    source_location,
                }) => {
                    self.set_connect_side_written(lhs, source_location, true, block);
                    self.set_connect_side_written(rhs, source_location, false, block);
                }
                Stmt::If(if_stmt) => {
                    let sub_blocks = if_stmt.blocks.map(|block| self.make_block_index(block));
                    self.process_conditional_sub_blocks(block, sub_blocks)
                }
                Stmt::Match(match_stmt) => {
                    let sub_blocks = Vec::from_iter(
                        match_stmt
                            .blocks
                            .into_iter()
                            .map(|block| self.make_block_index(block)),
                    );
                    self.process_conditional_sub_blocks(block, sub_blocks.iter().copied())
                }
                Stmt::Declaration(StmtDeclaration::Wire(StmtWire {
                    annotations: _,
                    wire,
                })) => self.insert_new_base(TargetBase::intern_sized(wire.into()), block),
                Stmt::Declaration(StmtDeclaration::Reg(StmtReg {
                    annotations: _,
                    reg,
                })) => self.insert_new_base(TargetBase::intern_sized(reg.into()), block),
                Stmt::Declaration(StmtDeclaration::Instance(StmtInstance {
                    annotations: _,
                    instance,
                })) => self.insert_new_base(TargetBase::intern_sized(instance.into()), block),
            }
        }
    }
    #[track_caller]
    fn assert_validity(&mut self) {
        match self.module.body {
            ModuleBody::Extern(ExternModuleBody {
                verilog_name: _,
                parameters: _,
            }) => {}
            ModuleBody::Normal(NormalModuleBody { body }) => {
                let body = self.make_block_index(body);
                assert_eq!(body, 0);
                self.assert_subtree_validity(body);
                for (base, state) in &self.target_states {
                    if base.must_connect_to() {
                        state.assert_written();
                    }
                }
            }
        }
    }
}

impl<T: BundleValue> Module<T>
where
    T::Type: BundleType<Value = T>,
{
    /// you generally should use the [`#[hdl_module]`][`crate::hdl_module`] proc-macro and [`ModuleBuilder`] instead
    pub fn new_unchecked(
        name_id: NameId,
        source_location: SourceLocation,
        body: ModuleBody,
        module_io: impl IntoIterator<Item = AnnotatedModuleIO>,
        module_annotations: impl IntoAnnotations,
    ) -> Module<T> {
        let module_io: Interned<[_]> = module_io.into_iter().collect();
        let module_annotations = module_annotations.into_annotations().into_iter().collect();
        let retval = Module {
            name: name_id,
            source_location,
            body,
            io_ty: T::Type::from_canonical_type(DynBundleType::new(Intern::intern_owned(
                Vec::from_iter(module_io.iter().map(|io| io.module_io.field_type)),
            )))
            .intern_sized(),
            module_io,
            module_annotations,
        };
        retval.assert_validity();
        retval
    }
    pub fn canonical(self) -> Module<DynBundle> {
        Module {
            name: self.name,
            body: self.body,
            io_ty: self.io_ty.canonical().intern_sized(),
            module_io: self.module_io,
            source_location: self.source_location,
            module_annotations: self.module_annotations,
        }
    }
    pub fn from_canonical(canonical_module: Module<DynBundle>) -> Self {
        Module {
            name: canonical_module.name,
            body: canonical_module.body,
            io_ty: T::Type::from_canonical_type(*canonical_module.io_ty).intern_sized(),
            module_io: canonical_module.module_io,
            source_location: canonical_module.source_location,
            module_annotations: canonical_module.module_annotations,
        }
    }
    pub fn top_block(self) -> Option<Block> {
        match self.body {
            ModuleBody::Normal(NormalModuleBody { body }) => Some(body),
            ModuleBody::Extern(_) => None,
        }
    }
    pub fn kind(self) -> ModuleKind {
        self.body.kind()
    }
    pub fn body(self) -> ModuleBody {
        self.body
    }
    pub fn io_ty(self) -> Interned<T::Type> {
        self.io_ty
    }
    pub fn module_io(self) -> Interned<[AnnotatedModuleIO]> {
        self.module_io
    }
    pub fn name(self) -> Interned<str> {
        self.name_id().0
    }
    pub fn name_id(self) -> NameId {
        self.name
    }
    pub fn source_location(self) -> SourceLocation {
        self.source_location
    }
    pub fn module_annotations(self) -> Interned<[Annotation]> {
        self.module_annotations
    }
    #[track_caller]
    pub fn assert_validity(self) {
        AssertValidityState {
            module: self.canonical(),
            blocks: vec![],
            target_states: HashMap::with_capacity(64),
        }
        .assert_validity();
    }
}

#[must_use = "does nothing unless `build` is called"]
pub struct RegBuilder<'a, CD, I, V: Value> {
    scoped_name: ScopedNameId,
    source_location: SourceLocation,
    clock_domain: CD,
    init: I,
    ty: V::Type,
    stmts: &'a mut Vec<Stmt<ModuleBuilding>>,
}

impl<'a, CD> RegBuilder<'a, CD, (), ()> {
    pub fn no_reset<V: Value>(self, ty: V::Type) -> RegBuilder<'a, CD, Option<Expr<V>>, V> {
        let Self {
            scoped_name,
            source_location,
            clock_domain,
            init: _,
            ty: _,
            stmts,
        } = self;
        RegBuilder {
            scoped_name,
            source_location,
            clock_domain,
            init: None,
            ty,
            stmts,
        }
    }
    pub fn reset_default<V: Value + Default>(self) -> RegBuilder<'a, CD, Option<Expr<V>>, V>
    where
        V::Type: FixedType<Value = V>,
    {
        self.reset(V::default().to_expr())
    }
    pub fn opt_reset<T: Type>(
        self,
        ty: T,
        init: Option<impl ToExpr<Type = T>>,
    ) -> RegBuilder<'a, CD, Option<Expr<T::Value>>, T::Value> {
        let Self {
            scoped_name,
            source_location,
            clock_domain,
            init: _,
            ty: _,
            stmts,
        } = self;
        RegBuilder {
            scoped_name,
            source_location,
            clock_domain,
            init: init.map(|e| e.to_expr()),
            ty,
            stmts,
        }
    }
    pub fn reset<V: Value>(self, init: Expr<V>) -> RegBuilder<'a, CD, Option<Expr<V>>, V>
    where
        V::Type: Type<Value = V>,
    {
        let Self {
            scoped_name,
            source_location,
            clock_domain,
            init: _,
            ty: _,
            stmts,
        } = self;
        let ty = init.ty();
        RegBuilder {
            scoped_name,
            source_location,
            clock_domain,
            init: Some(init),
            ty,
            stmts,
        }
    }
}

impl<'a, I, V: Value> RegBuilder<'a, (), I, V> {
    pub fn clock_domain(
        self,
        clock_domain: impl ToExpr<Type = <ClockDomain as ToExpr>::Type>,
    ) -> RegBuilder<'a, Expr<ClockDomain>, I, V> {
        let Self {
            scoped_name,
            source_location,
            clock_domain: _,
            init,
            ty,
            stmts,
        } = self;
        RegBuilder {
            scoped_name,
            source_location,
            clock_domain: clock_domain.to_expr(),
            init,
            ty,
            stmts,
        }
    }
}

impl<V: Value> RegBuilder<'_, Expr<ClockDomain>, Option<Expr<V>>, V>
where
    V::Type: Type<Value = V>,
{
    #[track_caller]
    pub fn build(self) -> Expr<V> {
        let Self {
            scoped_name,
            source_location,
            clock_domain,
            init,
            ty,
            stmts,
        } = self;
        let reg =
            Reg::<V::Type>::new_unchecked(scoped_name, source_location, ty, clock_domain, init);
        let retval = reg.to_expr();
        stmts.push(
            StmtReg {
                annotations: (),
                reg: reg.to_dyn_canonical_reg(),
            }
            .into(),
        );
        retval
    }
}

impl<T: BundleValue, Kind: ModuleKindTrait> ModuleBuilder<T, Kind>
where
    T::Type: BundleType<Value = T>,
{
    #[track_caller]
    pub fn io_with_loc<IO: Value>(
        &mut self,
        name: &str,
        source_location: SourceLocation,
        is_input: bool,
        ty: IO::Type,
    ) -> Expr<IO>
    where
        IO::Type: Type<Value = IO>,
    {
        let module_io = ModuleIO::<IO::Type>::new_unchecked(
            self.name,
            name.intern(),
            source_location,
            is_input,
            ty,
        );
        if let Err(e) = self.io_fields_hint.check_field(
            self.io.len(),
            module_io
                .field_type
                .as_ref_ty()
                .map_ty(|v: &IO::Type| -> &dyn DynType { v }),
        ) {
            panic!("error: {source_location}: {e}");
        }
        let retval = module_io.to_expr();
        let module_io = module_io.to_canonical_dyn_module_io();
        self.io_indexes.insert(module_io.clone(), self.io.len());
        self.io.push(AnnotatedModuleIO {
            annotations: vec![],
            module_io,
        });
        retval
    }
    #[track_caller]
    pub fn io<IO: Value>(
        &mut self,
        implicit_name: ImplicitName<'_>,
        is_input: bool,
        ty: IO::Type,
    ) -> Expr<IO>
    where
        IO::Type: Type<Value = IO>,
    {
        self.io_with_loc(implicit_name.0, SourceLocation::caller(), is_input, ty)
    }
    #[track_caller]
    pub fn input_with_loc<IO: Value>(
        &mut self,
        name: &str,
        source_location: SourceLocation,
        ty: IO::Type,
    ) -> Expr<IO>
    where
        IO::Type: Type<Value = IO>,
    {
        self.io_with_loc(name, source_location, true, ty)
    }
    #[track_caller]
    pub fn output_with_loc<IO: Value>(
        &mut self,
        name: &str,
        source_location: SourceLocation,
        ty: IO::Type,
    ) -> Expr<IO>
    where
        IO::Type: Type<Value = IO>,
    {
        self.io_with_loc(name, source_location, false, ty)
    }
    #[track_caller]
    pub fn input<IO: Value>(&mut self, implicit_name: ImplicitName<'_>, ty: IO::Type) -> Expr<IO>
    where
        IO::Type: Type<Value = IO>,
    {
        self.input_with_loc(implicit_name.0, SourceLocation::caller(), ty)
    }
    #[track_caller]
    pub fn output<IO: Value>(&mut self, implicit_name: ImplicitName<'_>, ty: IO::Type) -> Expr<IO>
    where
        IO::Type: Type<Value = IO>,
    {
        self.output_with_loc(implicit_name.0, SourceLocation::caller(), ty)
    }
    #[track_caller]
    pub fn run<F: FnOnce(&mut Self)>(name: &str, f: F) -> Interned<Module<T>> {
        Self::run_with_loc(name, SourceLocation::caller(), f)
    }
    #[track_caller]
    pub fn try_run<F: FnOnce(&mut Self) -> Result<(), E>, E>(
        name: &str,
        f: F,
    ) -> Result<Interned<Module<T>>, E> {
        Self::try_run_with_loc(name, SourceLocation::caller(), f)
    }
    #[track_caller]
    pub fn run_with_loc<F: FnOnce(&mut Self)>(
        name: &str,
        source_location: SourceLocation,
        f: F,
    ) -> Interned<Module<T>> {
        Self::try_run_with_loc(name, source_location, |this| -> Result<(), Infallible> {
            f(this);
            Ok(())
        })
        .unwrap()
    }
    #[track_caller]
    pub fn try_run_with_loc<F: FnOnce(&mut Self) -> Result<(), E>, E>(
        name: &str,
        source_location: SourceLocation,
        f: F,
    ) -> Result<Interned<Module<T>>, E> {
        let name = NameIdGen::gen_module_name(name.intern());
        let body = Kind::new_body(name);
        let mut builder = Self {
            name,
            body,
            block_stack: Rc::new(BlockStack::new(BlockId(0))),
            io: vec![],
            io_indexes: HashMap::new(),
            io_fields_hint: T::Type::fields_hint(),
            name_id_gen: NameIdGen::default(),
            module_annotations: vec![],
            _phantom: PhantomData,
        };
        f(&mut builder)?;
        Ok(Module::new_unchecked(
            builder.name,
            source_location,
            Kind::ModuleBody::from(builder.body).into(),
            builder.io.into_iter().map(
                |AnnotatedModuleIO {
                     annotations,
                     module_io,
                 }| AnnotatedModuleIO {
                    annotations: Intern::intern_owned(annotations),
                    module_io,
                },
            ),
            builder.module_annotations,
        )
        .intern_sized())
    }
    #[track_caller]
    pub fn annotate_module(&mut self, annotations: impl IntoAnnotations) {
        self.module_annotations
            .extend(annotations.into_annotations());
    }
    #[track_caller]
    pub fn annotate<V: Value>(&mut self, target: Expr<V>, annotations: impl IntoAnnotations) {
        macro_rules! unwrap {
            ($v:expr) => {
                match $v {
                    Some(v) => v,
                    None => panic!("not a valid annotation target"),
                }
            };
        }
        let target = unwrap!(target.target());
        TargetedAnnotation::assert_valid_target(target);
        let apply_annotations = |targeted_annotations: &mut Vec<TargetedAnnotation>| {
            targeted_annotations.extend(
                annotations
                    .into_annotations()
                    .into_iter()
                    .map(|annotation| TargetedAnnotation::new(target, annotation)),
            )
        };
        let decl = match TargetBase::clone(&target.base()) {
            TargetBase::ModuleIO(v) => {
                apply_annotations(&mut self.io[*unwrap!(self.io_indexes.get(&v))].annotations);
                return;
            }
            TargetBase::MemPort(v) => {
                apply_annotations(
                    &mut unwrap!(unwrap!(Kind::builder_normal_body(&mut self.body))
                        .body
                        .memory_map
                        .get_mut(&v.mem_name()))
                    .borrow_mut()
                    .port_annotations,
                );
                return;
            }
            TargetBase::Reg(reg) => StmtReg {
                annotations: (),
                reg,
            }
            .into(),
            TargetBase::Wire(wire) => StmtWire {
                annotations: (),
                wire,
            }
            .into(),
            TargetBase::Instance(instance) => StmtInstance {
                annotations: (),
                instance,
            }
            .into(),
        };
        apply_annotations(
            unwrap!(Kind::builder_normal_body(&mut self.body))
                .body
                .annotations_map
                .entry(decl)
                .or_default(),
        );
    }
}

impl<T: BundleValue> ModuleBuilder<T, ExternModule>
where
    T::Type: BundleType<Value = T>,
{
    #[track_caller]
    pub fn verilog_name(&mut self, name: impl AsRef<str>) {
        let name = name.as_ref();
        assert!(
            name.chars()
                .all(|ch| ch.is_ascii_alphanumeric() || ch == '_'),
            "invalid verilog name -- FIRRTL doesn't yet support verilog names with special characters.\n\
            see https://github.com/chipsalliance/firrtl-spec/issues/134"
        );
        self.body.verilog_name = name.intern();
    }
    pub fn parameter(&mut self, name: impl AsRef<str>, value: ExternModuleParameterValue) {
        self.body.parameters.push(ExternModuleParameter {
            name: name.as_ref().intern(),
            value,
        });
    }
    pub fn parameter_int(&mut self, name: impl AsRef<str>, value: impl Into<BigInt>) {
        self.body.parameters.push(ExternModuleParameter {
            name: name.as_ref().intern(),
            value: ExternModuleParameterValue::Integer(value.into()),
        });
    }
    pub fn parameter_str(&mut self, name: impl AsRef<str>, value: impl AsRef<str>) {
        self.body.parameters.push(ExternModuleParameter {
            name: name.as_ref().intern(),
            value: ExternModuleParameterValue::String(value.as_ref().intern()),
        });
    }
    pub fn parameter_raw_verilog(&mut self, name: impl AsRef<str>, raw_verilog: impl AsRef<str>) {
        self.body.parameters.push(ExternModuleParameter {
            name: name.as_ref().intern(),
            value: ExternModuleParameterValue::RawVerilog(raw_verilog.as_ref().intern()),
        });
    }
}

impl<T: BundleValue> ModuleBuilder<T, NormalModule>
where
    T::Type: BundleType<Value = T>,
{
    fn block(&mut self, block_id: BlockId) -> &mut BuilderBlock {
        &mut self.body.body.blocks[block_id.as_usize()]
    }
    fn new_block(&mut self) -> BlockId {
        let index = self.body.body.blocks.len();
        self.body.body.blocks.push(BuilderBlock {
            memories: vec![],
            stmts: vec![],
        });
        BlockId(index)
    }
    pub fn wire_with_loc<V: Value>(
        &mut self,
        name: &str,
        source_location: SourceLocation,
        ty: V::Type,
    ) -> Expr<V>
    where
        V::Type: Type<Value = V>,
    {
        let wire = Wire::<V::Type>::new_unchecked(
            ScopedNameId(self.name, self.name_id_gen.gen(name.intern())),
            source_location,
            ty,
        );
        let retval = wire.to_expr();
        self.block(self.block_stack.top()).stmts.push(
            StmtWire {
                annotations: (),
                wire: wire.to_dyn_canonical_wire(),
            }
            .into(),
        );
        retval
    }
    #[track_caller]
    pub fn wire<V: Value>(&mut self, implicit_name: ImplicitName<'_>, ty: V::Type) -> Expr<V>
    where
        V::Type: Type<Value = V>,
    {
        self.wire_with_loc(implicit_name.0, SourceLocation::caller(), ty)
    }
    #[track_caller]
    pub fn reg_builder_with_loc<'a>(
        &'a mut self,
        name: &str,
        source_location: SourceLocation,
    ) -> RegBuilder<'a, (), (), ()> {
        let scoped_name = ScopedNameId(self.name, self.name_id_gen.gen(name.intern()));
        let stmts = &mut self.block(self.block_stack.top()).stmts;
        RegBuilder {
            scoped_name,
            source_location,
            clock_domain: (),
            init: (),
            ty: (),
            stmts,
        }
    }
    #[track_caller]
    pub fn reg_builder<'a>(
        &'a mut self,
        implicit_name: ImplicitName<'_>,
    ) -> RegBuilder<'a, (), (), ()> {
        self.reg_builder_with_loc(implicit_name.0, SourceLocation::caller())
    }
    // intentionally takes Expr instead of impl ToExpr to help prevent
    // `#[hdl] if a == b {}` instead of using `cmp_eq`
    #[track_caller]
    pub fn if_<Ty>(&mut self, cond: Expr<IntValue<Ty>>) -> IfScope
    where
        Ty: FixedOrDynIntType<
            1,
            Signed = ConstBool<false>,
            CanonicalType = DynUIntType,
            CanonicalValue = DynUInt,
        >,
    {
        self.if_with_loc(cond, SourceLocation::caller())
    }
    pub fn if_with_loc<Ty>(
        &mut self,
        cond: Expr<IntValue<Ty>>,
        source_location: SourceLocation,
    ) -> IfScope
    where
        Ty: FixedOrDynIntType<
            1,
            Signed = ConstBool<false>,
            CanonicalType = DynUIntType,
            CanonicalValue = DynUInt,
        >,
    {
        let cond = cond.as_bool();
        let outer_block = self.block_stack.top();
        let then_block = self.new_block();
        let else_block = self.new_block();
        self.block(outer_block).stmts.push(
            StmtIf {
                cond,
                source_location,
                blocks: [then_block, else_block],
            }
            .into(),
        );
        IfScope {
            then: self.block_stack.clone().push_scope(then_block),
            else_block,
        }
    }
    pub fn enum_match_variants_helper<Enum: EnumValue>(
        &mut self,
        base: Expr<Enum>,
        source_location: SourceLocation,
    ) -> EnumMatchVariantsIter<Enum::Type>
    where
        Enum::Type: EnumType<Value = Enum>,
    {
        let base = base.canonical();
        let enum_ty = base.ty();
        let outer_block = self.block_stack.top();
        let blocks = Intern::intern_owned(Vec::from_iter(
            enum_ty.variants().iter().map(|_| self.new_block()),
        ));
        self.block(outer_block).stmts.push(
            StmtMatch {
                expr: base,
                source_location,
                blocks,
            }
            .into(),
        );
        let block_stack = self.block_stack.clone();
        EnumMatchVariantsIter {
            inner: EnumMatchVariantsIterImpl {
                block_stack,
                blocks,
                base,
                _phantom: PhantomData,
            },
            variant_index: 0..blocks.len(),
        }
    }
    #[track_caller]
    pub fn match_<Ty: Type>(&mut self, expr: impl ToExpr<Type = Ty>) -> Ty::MatchVariantsIter {
        self.match_with_loc(expr, SourceLocation::caller())
    }
    pub fn match_with_loc<Ty: Type>(
        &mut self,
        expr: impl ToExpr<Type = Ty>,
        source_location: SourceLocation,
    ) -> Ty::MatchVariantsIter {
        Ty::match_variants(expr.to_expr(), self, source_location)
    }
    #[track_caller]
    pub fn connect_any_with_loc<Lhs: ToExpr, Rhs: ToExpr>(
        &mut self,
        lhs: Lhs,
        rhs: Rhs,
        source_location: SourceLocation,
    ) where
        Lhs::Type: Connect<Rhs::Type>
            + Type<
                CanonicalType = <Rhs::Type as Type>::CanonicalType,
                CanonicalValue = <Rhs::Type as Type>::CanonicalValue,
            >,
    {
        let lhs = lhs.to_expr();
        let rhs = rhs.to_expr();
        assert!(
            matches!(lhs.flow(), Flow::Sink | Flow::Duplex),
            "can't connect to source, connect lhs must have sink or duplex flow"
        );
        assert!(lhs.target().is_some(), "can't connect to non-target");
        match rhs.flow() {
            Flow::Source | Flow::Duplex => {}
            Flow::Sink => assert!(
                rhs.ty().is_passive(),
                "can't connect from sink with non-passive type"
            ),
        }
        assert!(
            lhs.canonical_type().can_connect(&rhs.canonical_type()),
            "can't connect types that are not equivalent:\nlhs type:\n{:?}\nrhs type:\n{:?}",
            lhs.ty(),
            rhs.ty()
        );
        self.block(self.block_stack.top()).stmts.push(
            StmtConnect {
                lhs: lhs.to_canonical_dyn(),
                rhs: rhs.to_canonical_dyn(),
                source_location,
            }
            .into(),
        );
    }
    #[track_caller]
    pub fn connect_any<Lhs: ToExpr, Rhs: ToExpr>(&mut self, lhs: Lhs, rhs: Rhs)
    where
        Lhs::Type: Connect<Rhs::Type>
            + Type<
                CanonicalType = <Rhs::Type as Type>::CanonicalType,
                CanonicalValue = <Rhs::Type as Type>::CanonicalValue,
            >,
    {
        self.connect_any_with_loc(lhs, rhs, SourceLocation::caller())
    }
    #[track_caller]
    pub fn connect<V: Value>(&mut self, lhs: Expr<V>, rhs: Expr<V>)
    where
        V::Type: Type<Value = V>,
    {
        self.connect_with_loc(lhs, rhs, SourceLocation::caller())
    }
    #[track_caller]
    pub fn connect_with_loc<V: Value>(
        &mut self,
        lhs: Expr<V>,
        rhs: Expr<V>,
        source_location: SourceLocation,
    ) where
        V::Type: Type<Value = V>,
    {
        self.connect_any_with_loc(lhs, rhs, source_location)
    }
    pub fn instance_with_loc<T2: BundleValue>(
        &mut self,
        name: &str,
        instantiated: Interned<Module<T2>>,
        source_location: SourceLocation,
    ) -> Expr<T2>
    where
        T2::Type: BundleType<Value = T2>,
    {
        let instance = Instance::<T2> {
            scoped_name: ScopedNameId(self.name, self.name_id_gen.gen(name.intern())),
            instantiated,
            source_location,
        };
        self.block(self.block_stack.top()).stmts.push(
            StmtInstance {
                annotations: (),
                instance: instance.canonical(),
            }
            .into(),
        );
        instance.to_expr()
    }
    #[track_caller]
    pub fn instance<T2: BundleValue>(
        &mut self,
        implicit_name: ImplicitName<'_>,
        instantiated: Interned<Module<T2>>,
    ) -> Expr<T2>
    where
        T2::Type: BundleType<Value = T2>,
    {
        self.instance_with_loc(implicit_name.0, instantiated, SourceLocation::caller())
    }
    #[track_caller]
    fn memory_impl<VA: ValueArrayOrSlice + ?Sized>(
        &mut self,
        name: &str,
        mem_element_type: VA::ElementType,
        source_location: SourceLocation,
    ) -> MemBuilder<VA> {
        let scoped_name = ScopedNameId(self.name, self.name_id_gen.gen(name.intern()));
        let (retval, target_mem) = MemBuilder::new(scoped_name, source_location, mem_element_type);
        self.block(self.block_stack.top())
            .memories
            .push(target_mem.clone());
        self.body.body.memory_map.insert(scoped_name, target_mem);
        retval
    }
    #[track_caller]
    pub fn memory_array_with_loc<VA: ValueArrayOrSlice + ?Sized>(
        &mut self,
        name: &str,
        mem_array_type: ArrayType<VA>,
        source_location: SourceLocation,
    ) -> MemBuilder<VA> {
        let mut retval = self.memory_impl(name, mem_array_type.element().clone(), source_location);
        retval.depth(mem_array_type.len());
        retval
    }
    #[track_caller]
    pub fn memory_array<VA: ValueArrayOrSlice + ?Sized>(
        &mut self,
        implicit_name: ImplicitName<'_>,
        mem_array_type: ArrayType<VA>,
    ) -> MemBuilder<VA> {
        self.memory_array_with_loc(implicit_name.0, mem_array_type, SourceLocation::caller())
    }
    #[track_caller]
    pub fn memory_with_init_and_loc<VA: ValueArrayOrSlice + ?Sized>(
        &mut self,
        name: &str,
        initial_value: impl ToExpr<Type = ArrayType<VA>>,
        source_location: SourceLocation,
    ) -> MemBuilder<VA> {
        let mut retval = self.memory_array_with_loc(name, initial_value.ty(), source_location);
        retval.initial_value(initial_value);
        retval
    }
    #[track_caller]
    pub fn memory_with_init<VA: ValueArrayOrSlice + ?Sized>(
        &mut self,
        implicit_name: ImplicitName<'_>,
        initial_value: impl ToExpr<Type = ArrayType<VA>>,
    ) -> MemBuilder<VA> {
        self.memory_with_init_and_loc(
            implicit_name.0,
            initial_value.to_expr(),
            SourceLocation::caller(),
        )
    }
    #[track_caller]
    pub fn memory_with_loc<Element: Value>(
        &mut self,
        name: &str,
        element_type: Element::Type,
        source_location: SourceLocation,
    ) -> MemBuilder<[Element]>
    where
        Element::Type: Type<Value = Element>,
    {
        self.memory_impl(name, element_type, source_location)
    }
    #[track_caller]
    pub fn memory<Element: Value>(
        &mut self,
        implicit_name: ImplicitName<'_>,
        element_type: Element::Type,
    ) -> MemBuilder<[Element]>
    where
        Element::Type: Type<Value = Element>,
    {
        self.memory_with_loc(implicit_name.0, element_type, SourceLocation::caller())
    }
}

#[derive(Clone, Eq, PartialEq, Hash)]
pub struct ModuleIO<T: Type> {
    containing_module_name: NameId,
    field_type: FieldType<T>,
    source_location: SourceLocation,
}

impl<T: Type> fmt::Debug for ModuleIO<T> {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.debug_struct("ModuleIO")
            .field("name", &self.scoped_name())
            .field("is_input", &self.is_input())
            .field("ty", &self.field_type().ty)
            .finish_non_exhaustive()
    }
}

impl<T: Type> ModuleIO<T> {
    pub fn canonical(&self) -> ModuleIO<T::CanonicalType> {
        let Self {
            containing_module_name,
            ref field_type,
            source_location,
        } = *self;
        ModuleIO {
            containing_module_name,
            field_type: field_type.canonical(),
            source_location,
        }
    }
    pub fn to_canonical_dyn_module_io(&self) -> ModuleIO<Interned<dyn DynCanonicalType>> {
        let Self {
            containing_module_name,
            ref field_type,
            source_location,
        } = *self;
        ModuleIO {
            containing_module_name,
            field_type: field_type.canonical_dyn(),
            source_location,
        }
    }
    pub fn field_type(&self) -> &FieldType<T> {
        &self.field_type
    }
    pub fn is_input(&self) -> bool {
        self.field_type.flipped
    }
    pub fn is_output(&self) -> bool {
        !self.field_type.flipped
    }
    pub fn containing_module_name(&self) -> Interned<str> {
        self.containing_module_name.0
    }
    pub fn containing_module_name_id(&self) -> NameId {
        self.containing_module_name
    }
    pub fn name(&self) -> Interned<str> {
        self.field_type.name
    }
    pub fn name_id(&self) -> NameId {
        NameId(self.field_type.name, 0)
    }
    pub fn scoped_name(&self) -> ScopedNameId {
        ScopedNameId(self.containing_module_name, self.name_id())
    }
    pub fn source_location(&self) -> SourceLocation {
        self.source_location
    }
    pub fn new_unchecked(
        containing_module_name: NameId,
        name: Interned<str>,
        source_location: SourceLocation,
        is_input: bool,
        ty: T,
    ) -> Self {
        Self {
            containing_module_name,
            field_type: FieldType {
                name,
                flipped: is_input,
                ty,
            },
            source_location,
        }
    }
    pub fn must_connect_to(&self) -> bool {
        true
    }
    pub fn flow(&self) -> Flow {
        if self.is_input() {
            Flow::Source
        } else if self.is_output() {
            Flow::Sink
        } else {
            unreachable!()
        }
    }
}