todo: typechecking, then ensure placeness and IR still work as expected

Cargo.toml

@@ -12,6 +12,7 @@ log = "0.4.22"
 num-bigint = "0.4.6"
 num-traits = "0.2.19"
 ordered-float = "4.2.2"
+paste = "1.0.15"
 petgraph = "0.6.5"
 thiserror = "1.0.63"
 unicode-xid = "0.2.4"

src/ast2/debug.rs

@@ -0,0 +1,159 @@
+use std::fmt::Display;
+
+use crate::{lexer::SourceLocation, writeln_indented};
+
+use super::{
+    intern::{self, InternPoolWrapper as InternPool},
+    visitor::AstVisitorTrait,
+    Ast, Children, ComptimeCache, Index, Tag, TypeCache,
+};
+
+struct AstRenderVisitor<'a, W: core::fmt::Write> {
+    syms: &'a crate::symbol_table::syms2::Symbols,
+    ip: &'a InternPool,
+    cache: TypeCache,
+    comptime_cache: ComptimeCache,
+    scopes: Vec<Index>,
+    w: &'a mut W,
+}
+
+impl<'a, W: core::fmt::Write> AstVisitorTrait<&'a Ast> for AstRenderVisitor<'_, W> {
+    type Error = core::fmt::Error;
+
+    type Value = ();
+
+    const UNIMPL: Self::Error = core::fmt::Error;
+
+    fn visit_any(&mut self, ast: &'a Ast, idx: Index) -> Result<Self::Value, Self::Error> {
+        let display = NodeDisplay::new(ast, self.ip, idx).with_indent(self.scopes.len() as u32 * 2);
+
+        match display.tag {
+            Tag::File
+            | Tag::FunctionDecl
+            | Tag::GlobalDecl
+            | Tag::Block
+            | Tag::BlockTrailingExpr => {
+                self.scopes.push(idx);
+            }
+            _ => {}
+        }
+
+        write!(self.w, "{display}")?;
+
+        for child in display.children.0 {
+            self.visit_any(ast, child)?;
+        }
+
+        match display.tag {
+            Tag::File
+            | Tag::FunctionDecl
+            | Tag::GlobalDecl
+            | Tag::Block
+            | Tag::BlockTrailingExpr => {
+                self.scopes.pop();
+            }
+            _ => {}
+        }
+
+        Ok(())
+    }
+}
+
+pub struct AstRenderer<'a> {
+    ast: &'a Ast,
+    #[allow(dead_code)]
+    syms: &'a crate::symbol_table::syms2::Symbols,
+    ip: &'a InternPool,
+    cache: TypeCache,
+    comptime_cache: ComptimeCache,
+}
+
+pub struct NodeDisplay {
+    node: Index,
+    tag: Tag,
+    loc: SourceLocation,
+    children: Children,
+    is_comptime: bool,
+    ty: intern::Index,
+    indent: u32,
+}
+
+impl NodeDisplay {
+    pub fn new(ast: &Ast, ip: &InternPool, node: Index) -> NodeDisplay {
+        let tag = ast.tags[node];
+        let loc = ast.source_locs[node];
+
+        let children = Children(ast.get_node_children(node));
+        let ty = ast.get_type_of_node(ip, &mut TypeCache::new(), node);
+
+        let is_comptime = ast.is_node_comptime_evaluable(&mut ComptimeCache::default(), node);
+
+        Self {
+            node,
+            tag,
+            loc,
+            children,
+            is_comptime,
+            ty,
+            indent: 0,
+        }
+    }
+    fn with_indent(self, indent: u32) -> Self {
+        Self { indent, ..self }
+    }
+}
+
+impl Display for NodeDisplay {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let Self {
+            node,
+            tag,
+            loc,
+            children,
+            is_comptime,
+            ty,
+            indent,
+        } = self;
+        writeln_indented!(
+            *indent,
+            f,
+            "{node} {}({ty}) = ({loc}) {tag:?} {children}",
+            if *is_comptime { "CONST " } else { "" }
+        )?;
+
+        Ok(())
+    }
+}
+
+impl<'a> AstRenderer<'a> {
+    pub fn new(
+        ast: &'a Ast,
+        ip: &'a InternPool,
+        syms: &'a crate::symbol_table::syms2::Symbols,
+    ) -> Self {
+        Self {
+            ast,
+            syms,
+            ip,
+            cache: TypeCache::new(),
+            comptime_cache: ComptimeCache::default(),
+        }
+    }
+
+    pub(crate) fn render<W: core::fmt::Write>(&mut self, w: &mut W) -> core::fmt::Result {
+        let mut visitor = AstRenderVisitor {
+            syms: self.syms,
+            ip: self.ip,
+            cache: TypeCache::new(),
+            comptime_cache: ComptimeCache::default(),
+            scopes: Vec::new(),
+            w,
+        };
+
+        for idx in self.ast.get_root_file_indices() {
+            visitor.visit_any(self.ast, idx)?;
+        }
+
+        Ok(())
+    }
+}

src/ast2/intern.rs

@@ -1382,6 +1382,13 @@ impl InternPool {
         }
     }
 
+    pub fn try_get_return_type(&self, func: Index) -> Option<Index> {
+        match self.get_key(func) {
+            Key::FunctionType { return_type, .. } => Some(return_type),
+            _ => None,
+        }
+    }
+
     pub fn get_pointer_type(&mut self, pointee: Index, flags: Option<PointerFlags>) -> Index {
         let key = Key::PointerType {
             pointee,

src/ast2/mod.rs

@@ -10,12 +10,15 @@ use num_bigint::BigInt;
 
 use crate::{
     ast::FloatingType, comptime::ComptimeNumber, lexer::SourceLocation,
-    symbol_table::syms2::DeclKind, tokens::Token, writeln_indented,
+    symbol_table::syms2::DeclKind, tokens::Token,
 };
 
+pub mod debug;
 pub mod intern;
 pub mod ir;
 pub mod parser;
+pub mod tag;
+pub mod typecheck;
 pub mod visitor;
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
@@ -26,6 +29,8 @@ pub enum Tag {
     File,
     /// `data` is an intern to a name, and an index into extra of [index: return_type, index: ParameterList]
     FunctionProto,
+    /// `data` is an intern to a name, and an intern to the function type
+    FunctionProtoInterned,
     /// `data` is an index to a FunctionProto and an index to a Block
     FunctionDecl,
     /// `data` is a range from a..b into extra of indices to parameters
@@ -56,9 +61,11 @@ pub enum Tag {
     GlobalDecl,
     /// `data` is an intern to a name, and an offset into extra of `[flags, type0 ,..., typeN ,name0 ,..., nameN]`
     StructDecl,
+    /// `data` is an intern to a name, and an intern to the type of the struct
+    StructDeclInterned,
     /// `data` is an index to a type, and an intern to a name
     FieldDecl,
-    /// `data` is an index to a VarDecl, GlobalDecl or FunctionDecl, and an opaque DeclKind
+    /// `data` is an index to a Parameter, VarDecl, GlobalDecl or FunctionDecl, and an opaque DeclKind
     DeclRef,
     /// `data` is an inlined key into the symbol table (scope: index, name: intern)
     DeclRefUnresolved,
@@ -130,6 +137,7 @@ impl Tag {
             | Tag::PointerType
             | Tag::InternedType
             | Tag::ArrayType
+            | Tag::StructDeclInterned
             | Tag::StructDecl => true,
             _ => false,
         }
@@ -164,6 +172,8 @@ impl Tag {
             | Tag::SubscriptExpr
             | Tag::IfExpr
             | Tag::IfElseExpr
+            | Tag::PlaceToValueConversion
+            | Tag::ValueToPlaceConversion
             | Tag::Block
             | &Tag::BlockTrailingExpr => true,
             _ => false,
@@ -172,7 +182,7 @@ impl Tag {
 }
 
 #[derive(Debug, Clone, Copy, thiserror::Error, PartialEq, Eq)]
-enum ParseError {
+pub enum ParseError {
     #[error("Unexpected end of token iter.")]
     UnexpectedEndOfTokens,
     #[error("Expected Token {0}.")]
@@ -367,6 +377,7 @@ impl From<(Tag, Data)> for ExpandedData {
             | Tag::CallExpr
             | Tag::ArrayType
             | Tag::FunctionDecl => Self::from_two_indices(data),
+            Tag::StructDeclInterned | Tag::FunctionProtoInterned => Self::from_two_interns(data),
             Tag::ReturnExprStmt
             | Tag::DeclRef
             | Tag::TypeDeclRef
@@ -488,7 +499,7 @@ impl Data {
 }
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
-enum PlaceOrValue {
+pub enum PlaceOrValue {
     Value(index::Index),
     Place(index::Index),
 }
@@ -521,6 +532,24 @@ impl PlaceOrValue {
             PlaceOrValue::Place(_) => Self::Place(index),
         }
     }
+    fn map_value<F>(self, f: F) -> Self
+    where
+        F: FnOnce(Index) -> Self,
+    {
+        match self {
+            PlaceOrValue::Value(index) => f(index),
+            _ => self,
+        }
+    }
+    fn map_place<F>(self, f: F) -> Self
+    where
+        F: FnOnce(Index) -> Self,
+    {
+        match self {
+            PlaceOrValue::Place(index) => f(index),
+            _ => self,
+        }
+    }
 }
 
 impl From<index::Index> for PlaceOrValue {
@@ -591,6 +620,14 @@ mod index {
 
             inner.map(Self)
         }
+
+        pub fn from_slice(slice: &[u32]) -> &[Option<Self>] {
+            unsafe { core::mem::transmute(slice) }
+        }
+        pub unsafe fn from_slice_unchecked(slice: &[u32]) -> &[Self] {
+            unsafe { core::mem::transmute(slice) }
+        }
+
         pub fn kind(&self) -> Kind {
             Kind::try_from(((self.0.get() >> 28) & 0b1111) as u8).unwrap()
         }
@@ -1024,21 +1061,37 @@ impl Ast {
     }
 
     /// converts from a place expression to a value expression.
-    fn push_place_to_value_conversion(&mut self, index: Index) -> Index {
+    fn push_place_to_value_conversion(&mut self, index: Index) -> PlaceOrValue {
         let loc = self.get_loc(index);
         let i = self.reserve_node_other();
         self.set_tag_data_source_loc(i, Tag::PlaceToValueConversion, Data::index(index), loc);
 
-        i
+        PlaceOrValue::Value(i)
     }
 
     /// converts from a value expression to a place expression.
-    fn push_value_to_place_conversion(&mut self, index: Index) -> Index {
+    fn push_value_to_place_conversion(&mut self, index: Index) -> PlaceOrValue {
         let loc = self.get_loc(index);
         let i = self.reserve_node_other();
         self.set_tag_data_source_loc(i, Tag::ValueToPlaceConversion, Data::index(index), loc);
 
-        i
+        PlaceOrValue::Place(i)
+    }
+
+    /// converts the expression to a value expression, if it isn't one already.
+    fn convert_to_value_expr(&mut self, lrvalue: PlaceOrValue) -> Index {
+        match lrvalue {
+            PlaceOrValue::Value(index) => index,
+            PlaceOrValue::Place(index) => self.push_place_to_value_conversion(index).into_index(),
+        }
+    }
+
+    /// converts the expression to a place expression, if it isn't one already.
+    fn convert_to_place_expr(&mut self, lrvalue: PlaceOrValue) -> Index {
+        match lrvalue {
+            PlaceOrValue::Place(index) => index,
+            PlaceOrValue::Value(index) => self.push_value_to_place_conversion(index).into_index(),
+        }
     }
 
     fn push_binary(&mut self, tag: Tag, lhs: Index, rhs: Index, loc: SourceLocation) -> Index {
@@ -1372,6 +1425,11 @@ impl Ast {
 
                 ip.as_mut().get_function_type(return_type, parameters)
             }
+            Tag::FunctionProtoInterned | Tag::StructDeclInterned => {
+                let (_, ty) = data.as_two_interns();
+
+                ty
+            }
             Tag::BlockTrailingExpr => {
                 let (_a, b) = data.as_extra_range();
                 self.get_type_of_node(ip, cache, Index::from_u32(self.extra[b - 1]).unwrap())
@@ -1448,6 +1506,7 @@ impl Ast {
                 // TODO: find out of the expression is const, volatile for flags
 
                 // ip.try_get_pointer_type(ty, None).unwrap()
+
                 // note: because of value-to-place and place-to-value,
                 // this is actually the same type.
                 ty
@@ -1542,6 +1601,9 @@ impl Ast {
                     .map(|&i| Index::from_u32(i).unwrap())
                     .collect()
             }
+            Tag::FunctionProtoInterned => {
+                vec![]
+            }
             Tag::FunctionDecl => {
                 let (a, b) = data.as_two_indices();
                 vec![a, b]
@@ -1641,6 +1703,7 @@ impl Ast {
                 let (a, _) = data.as_index_and_extra_offset();
                 vec![a]
             }
+            Tag::StructDeclInterned => vec![],
             Tag::StructDecl => {
                 let (_a, offset) = data.as_intern_and_extra_offset();
                 let flags = StructFlags::unpack(self.extra[offset]);
@@ -1688,15 +1751,16 @@ impl Ast {
             let is_comptime = match tag {
                 Tag::Parameter => false,
                 // TODO: figure out if there are function protos that arent const
-                // Tag::FunctionProto | Tag::FunctionDecl | Tag::Block | Tag::BlockTrailingExpr => {
-                //     are_children_comptime(self, cache)
-                // }
+                Tag::FunctionProto | Tag::FunctionProtoInterned| Tag::FunctionDecl | Tag::Block | Tag::BlockTrailingExpr => {
+                    //are_children_comptime(self, cache)
+                    false
+                }
                 Tag::Constant => true,
                 Tag::ReturnStmt => true,
                 Tag::ReturnExprStmt => are_children_comptime(self, cache),
                 Tag::MutVarDecl | Tag::MutVarDeclAssignment => false,
-                // Tag::VarDecl => true,
-                // Tag::ValueToPlaceConversion => false,
+                Tag::VarDecl => false,
+                Tag::ValueToPlaceConversion => false,
                 Tag::PlaceToValueConversion | Tag::VarDeclAssignment => {
                     are_children_comptime(self, cache)
                 }
@@ -1705,12 +1769,13 @@ impl Ast {
                 Tag::FieldDecl => true,
                 Tag::DeclRef => self.tags[data.as_index()] == Tag::GlobalDecl,
                 Tag::InternedType | Tag::PointerType | Tag::ArrayType | Tag::TypeDeclRef => true,
-                // Tag::CallExpr => are_children_comptime(self, cache),
-                // Tag::FieldAccess => {
+                Tag::CallExpr => false, // are_children_comptime(self, cache),
+                Tag::FieldAccess => {
                 //     let parent = data.as_index_intern().0;
                 //     cache.mark_as_dominated_by(index, parent);
                     //     self.is_node_comptime_evaluable(cache, parent)
-                // }
+                    false
+                }
                 Tag::ArgumentList => are_children_comptime(self, cache),
                 Tag::Argument => self.is_node_comptime_evaluable(cache, data.as_index()),
                 Tag::NamedArgument => {
@@ -1746,7 +1811,7 @@ impl Ast {
                     cache.mark_as_dominated_by(index, left);
                     are_children_comptime(self, cache)
                 }
-                // Tag::IfExpr | Tag::IfElseExpr => are_children_comptime(self, cache),
+                Tag::IfExpr | Tag::IfElseExpr => false, // are_children_comptime(self, cache),
                 Tag::Root
                 | Tag::File
                 | Tag::ParameterList
@@ -2192,75 +2257,3 @@ where
         }
     }
 }
-
-pub struct AstRenderer<'a> {
-    ast: &'a Ast,
-    #[allow(dead_code)]
-    syms: &'a crate::symbol_table::syms2::Symbols,
-    ip: &'a InternPool,
-    cache: TypeCache,
-    comptime_cache: ComptimeCache,
-}
-
-pub struct NodeDisplay<'a> {
-    node: Index,
-    ast: &'a Ast,
-    ip: &'a InternPool,
-}
-impl<'a> Display for NodeDisplay<'a> {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        let node = self.node;
-        let tag = self.ast.tags[node];
-        let loc = self.ast.source_locs[node];
-
-        let children = Children(self.ast.get_node_children(node));
-        let ty = self
-            .ast
-            .get_type_of_node(self.ip, &mut TypeCache::new(), node);
-
-        let is_comptime = self
-            .ast
-            .is_node_comptime_evaluable(&mut ComptimeCache::default(), node);
-        writeln!(
-            f,
-            "{node} {}({ty}) = ({loc}) {tag:?} {children}",
-            if is_comptime { "CONST " } else { "" }
-        )?;
-
-        Ok(())
-    }
-}
-
-impl<'a> AstRenderer<'a> {
-    pub fn new(
-        ast: &'a Ast,
-        ip: &'a InternPool,
-        syms: &'a crate::symbol_table::syms2::Symbols,
-    ) -> Self {
-        Self {
-            ast,
-            syms,
-            ip,
-            cache: TypeCache::new(),
-            comptime_cache: ComptimeCache::default(),
-        }
-    }
-
-    fn render<W: core::fmt::Write>(&mut self, w: &mut W) -> core::fmt::Result {
-        self.ast.visitor().visit_pre(|ast, scopes, node, tag, _| {
-            let loc = ast.source_locs[node];
-
-            let children = Children(ast.get_node_children(node));
-            let ty = self.ast.get_type_of_node(self.ip, &mut self.cache, node);
-            let is_comptime = ast.is_node_comptime_evaluable(&mut self.comptime_cache, node);
-            _ = writeln_indented!(
-                scopes.len() as u32 * 2,
-                w,
-                "{node} {}({ty}) = ({loc}) {tag:?} {children}",
-                if is_comptime { "CONST " } else { "" }
-            );
-        });
-
-        Ok(())
-    }
-}

src/ast2/parser.rs

@@ -47,16 +47,12 @@ impl Parser {
         }
     }
 
-    pub fn display(&self) -> AstRenderer<'_> {
-        AstRenderer::new(&self.ast, &self.intern, &self.syms)
+    pub fn display(&self) -> debug::AstRenderer<'_> {
+        debug::AstRenderer::new(&self.ast, &self.intern, &self.syms)
     }
 
-    pub fn node_display(&self, node: Index) -> NodeDisplay<'_> {
-        NodeDisplay {
-            node,
-            ast: &self.ast,
-            ip: &self.intern,
-        }
+    pub fn node_display(&self, node: Index) -> debug::NodeDisplay {
+        debug::NodeDisplay::new(&self.ast, &self.intern, node)
     }
 
     pub fn create_comptime_folding_graph(&mut self, pointer_bits: u16) {
@@ -153,6 +149,7 @@ impl Parser {
     /// folds more AST-patterns into structures that are easier to build the IR with
     pub fn fold_more_patterns(&mut self) {
         use visitor::AstExt;
+
         self.ast.visitor_mut().visit_post(|ast, _, _i, tag, data| {
             match tag {
                 // normalise functions with block-with-trailing-expr into block
@@ -1170,18 +1167,12 @@ impl Parser {
 
     /// converts the expression to a value expression, if it isn't one already.
     fn convert_to_value_expr(&mut self, lrvalue: PlaceOrValue) -> Index {
-        match lrvalue {
-            PlaceOrValue::Value(index) => index,
-            PlaceOrValue::Place(index) => self.ast.push_place_to_value_conversion(index),
-        }
+        self.ast.convert_to_value_expr(lrvalue)
     }
 
     /// converts the expression to a place expression, if it isn't one already.
     fn convert_to_place_expr(&mut self, lrvalue: PlaceOrValue) -> Index {
-        match lrvalue {
-            PlaceOrValue::Place(index) => index,
-            PlaceOrValue::Value(index) => self.ast.push_value_to_place_conversion(index),
-        }
+        self.ast.convert_to_place_expr(lrvalue)
     }
 
     /// PREFIX_EXPR <-

src/ast2/tag.rs

@@ -0,0 +1,631 @@
+use super::{
+    intern::{Index as Interned, PointerFlags, StructFlags},
+    visitor::AstExt,
+    Ast, Index, ParseError, Tag,
+};
+
+pub trait AstNodeExt {
+    fn get_ast_node(&self, idx: Index) -> AstNode;
+}
+
+impl AstNodeExt for &mut Ast {
+    fn get_ast_node(&self, idx: Index) -> AstNode {
+        <Ast as AstNodeExt>::get_ast_node(self, idx)
+    }
+}
+
+impl AstNodeExt for &Ast {
+    fn get_ast_node(&self, idx: Index) -> AstNode {
+        <Ast as AstNodeExt>::get_ast_node(self, idx)
+    }
+}
+
+impl AstNodeExt for Ast {
+    fn get_ast_node(&self, idx: Index) -> AstNode {
+        let (tag, data) = self.get_node_tag_and_data(idx);
+
+        match tag {
+            Tag::Root => {
+                unreachable!()
+            }
+            Tag::File => {
+                let (a, b) = data.as_extra_range();
+                let decls = unsafe { Index::from_slice_unchecked(&self.extra[a..b]).to_vec() };
+
+                AstNode::File { decls }
+            }
+            Tag::FunctionProto => {
+                let (name, extra) = data.as_intern_and_extra_offset();
+
+                let (return_type, parameter_list) = (
+                    Index::from_u32(self.extra[extra]).unwrap(),
+                    Index::from_u32(self.extra[extra + 1]).unwrap(),
+                );
+
+                AstNode::FunctionProto {
+                    name,
+                    return_type,
+                    parameter_list,
+                }
+            }
+            Tag::FunctionProtoInterned => {
+                let (name, ty) = data.as_two_interns();
+                AstNode::FunctionProtoInterned { name, ty }
+            }
+            Tag::FunctionDecl => {
+                let (proto, body) = data.as_two_indices();
+
+                AstNode::FunctionDecl { proto, body }
+            }
+            Tag::ParameterList => {
+                let (a, b) = data.as_extra_range();
+                let params = unsafe { Index::from_slice_unchecked(&self.extra[a..b]).to_vec() };
+
+                AstNode::ParameterList { params }
+            }
+            Tag::Parameter => {
+                let (ty, name) = data.as_index_intern();
+
+                AstNode::Parameter { ty, name }
+            }
+            Tag::Block => {
+                let (a, b) = data.as_extra_range();
+                let statements = unsafe { Index::from_slice_unchecked(&self.extra[a..b]).to_vec() };
+
+                AstNode::Block {
+                    statements,
+                    expr: None,
+                }
+            }
+            Tag::BlockTrailingExpr => {
+                let (a, b) = data.as_extra_range();
+                let (expr, statements) = unsafe {
+                    Index::from_slice_unchecked(&self.extra[a..b])
+                        .split_last()
+                        .unwrap()
+                };
+
+                AstNode::Block {
+                    statements: statements.to_vec(),
+                    expr: Some(*expr),
+                }
+            }
+            Tag::Constant => {
+                let (ty, value) = data.as_index_intern();
+                AstNode::Constant { ty, value }
+            }
+            Tag::ExprStmt => AstNode::ExprStmt {
+                expr: data.as_index(),
+            },
+            Tag::ReturnStmt => AstNode::ReturnStmt,
+            Tag::ReturnExprStmt => AstNode::ReturnExprStmt {
+                expr: data.as_index(),
+            },
+            Tag::VarDecl => {
+                let (a, _) = data.as_extra_range();
+                let name = Interned::from_u32(self.extra[a]);
+                let ty = Index::from_u32(self.extra[a + 1]).unwrap();
+
+                AstNode::VarDecl { name, ty }
+            }
+            Tag::MutVarDecl => {
+                let (a, _) = data.as_extra_range();
+                let name = Interned::from_u32(self.extra[a]);
+                let ty = Index::from_u32(self.extra[a + 1]).unwrap();
+
+                AstNode::MutVarDecl { name, ty }
+            }
+            Tag::VarDeclAssignment => {
+                let (a, b) = data.as_extra_range();
+                let extra = &self.extra[a..b];
+                let name = Interned::from_u32(*extra.get(0).unwrap());
+                let expr = Index::from_u32(*extra.get(1).unwrap()).unwrap();
+                let ty = extra.get(2).map(|&inner| Index::from_u32(inner).unwrap());
+
+                AstNode::MutVarDeclAssignment { name, expr, ty }
+            }
+            Tag::MutVarDeclAssignment => {
+                let (a, b) = data.as_extra_range();
+                let extra = &self.extra[a..b];
+                let name = Interned::from_u32(*extra.get(0).unwrap());
+                let expr = Index::from_u32(*extra.get(1).unwrap()).unwrap();
+                let ty = extra.get(2).map(|&inner| Index::from_u32(inner).unwrap());
+
+                AstNode::MutVarDeclAssignment { name, expr, ty }
+            }
+            Tag::GlobalDecl => {
+                let (name, offset) = data.as_intern_and_extra_offset();
+                let ty = Index::from_u32(self.extra[offset]).unwrap();
+                let expr = Index::from_u32(self.extra[offset + 1]).unwrap();
+
+                AstNode::GlobalDecl { name, expr, ty }
+            }
+            Tag::StructDecl => {
+                let (name, offset) = data.as_intern_and_extra_offset();
+                let flags = StructFlags::unpack(self.extra[offset]);
+
+                let types = (offset + 1)..(offset + 1 + flags.num_fields as usize);
+                let names = (offset + 1 + flags.num_fields as usize)
+                    ..(offset + 1 + flags.num_fields as usize * 2);
+
+                let field_types =
+                    unsafe { Index::from_slice_unchecked(&self.extra[types]).to_vec() };
+
+                let field_names = self.extra[names]
+                    .iter()
+                    .map(|&i| Interned::from_u32(i))
+                    .collect();
+
+                AstNode::StructDecl {
+                    name,
+                    flags,
+                    field_names,
+                    field_types,
+                }
+            }
+            Tag::StructDeclInterned => {
+                let (name, ty) = data.as_two_interns();
+
+                AstNode::StructDeclInterned { name, ty }
+            }
+            Tag::FieldDecl => {
+                let (ty, name) = data.as_index_intern();
+
+                AstNode::FieldDecl { name, ty }
+            }
+            Tag::DeclRef => AstNode::DeclRef {
+                decl: data.as_index(),
+            },
+            Tag::DeclRefUnresolved => {
+                let (scope, name) = data.as_index_intern();
+                AstNode::DeclRefUnresolved { scope, name }
+            }
+            Tag::InternedType => AstNode::InternedType {
+                intern: data.as_intern(),
+            },
+            Tag::TypeDeclRef => AstNode::TypeDeclRef {
+                decl: data.as_index(),
+            },
+            Tag::TypeDeclRefUnresolved => {
+                let (scope, name) = data.as_index_intern();
+                AstNode::TypeDeclRefUnresolved { scope, name }
+            }
+            Tag::PointerType => {
+                let (ty, flags) = data.as_index_and_opaque();
+                let flags = PointerFlags::unpack(flags as u8);
+                AstNode::PointerType { ty, flags }
+            }
+            Tag::ArrayType => {
+                let (length, pointer) = data.as_two_indices();
+
+                AstNode::ArrayType { length, pointer }
+            }
+            Tag::CallExpr => {
+                let (func, argument_list) = data.as_two_indices();
+                AstNode::CallExpr {
+                    func,
+                    argument_list,
+                }
+            }
+            Tag::FieldAccess => {
+                let (expr, field_name) = data.as_index_intern();
+                AstNode::FieldAccess { field_name, expr }
+            }
+            Tag::ArgumentList => {
+                let (a, b) = data.as_extra_range();
+                let arguments = unsafe { Index::from_slice_unchecked(&self.extra[a..b]).to_vec() };
+
+                AstNode::ArgumentList { arguments }
+            }
+            Tag::Argument => AstNode::Argument {
+                expr: data.as_index(),
+                name: None,
+            },
+            Tag::NamedArgument => {
+                let (expr, name) = data.as_index_intern();
+                AstNode::Argument {
+                    expr,
+                    name: Some(name),
+                }
+            }
+            Tag::ExplicitCast => {
+                let (expr, ty) = data.as_two_indices();
+
+                AstNode::ExplicitCast { expr, ty }
+            }
+            Tag::Deref => AstNode::Deref {
+                expr: data.as_index(),
+            },
+            Tag::AddressOf => AstNode::AddressOf {
+                expr: data.as_index(),
+            },
+            Tag::Not => AstNode::Not {
+                expr: data.as_index(),
+            },
+            Tag::Negate => AstNode::Negate {
+                expr: data.as_index(),
+            },
+            Tag::PlaceToValueConversion => AstNode::PlaceToValueConversion {
+                expr: data.as_index(),
+            },
+            Tag::ValueToPlaceConversion => AstNode::ValueToPlaceConversion {
+                expr: data.as_index(),
+            },
+            Tag::Or => {
+                let (lhs, rhs) = data.as_two_indices();
+                AstNode::Or { lhs, rhs }
+            }
+            Tag::And => {
+                let (lhs, rhs) = data.as_two_indices();
+                AstNode::And { lhs, rhs }
+            }
+            Tag::BitOr => {
+                let (lhs, rhs) = data.as_two_indices();
+                AstNode::BitOr { lhs, rhs }
+            }
+            Tag::BitXOr => {
+                let (lhs, rhs) = data.as_two_indices();
+                AstNode::BitXOr { lhs, rhs }
+            }
+            Tag::BitAnd => {
+                let (lhs, rhs) = data.as_two_indices();
+                AstNode::BitAnd { lhs, rhs }
+            }
+            Tag::Eq => {
+                let (lhs, rhs) = data.as_two_indices();
+                AstNode::Eq { lhs, rhs }
+            }
+            Tag::NEq => {
+                let (lhs, rhs) = data.as_two_indices();
+                AstNode::NEq { lhs, rhs }
+            }
+            Tag::Lt => {
+                let (lhs, rhs) = data.as_two_indices();
+                AstNode::Lt { lhs, rhs }
+            }
+            Tag::Gt => {
+                let (lhs, rhs) = data.as_two_indices();
+                AstNode::Gt { lhs, rhs }
+            }
+            Tag::Le => {
+                let (lhs, rhs) = data.as_two_indices();
+                AstNode::Le { lhs, rhs }
+            }
+            Tag::Ge => {
+                let (lhs, rhs) = data.as_two_indices();
+                AstNode::Ge { lhs, rhs }
+            }
+            Tag::Shl => {
+                let (lhs, rhs) = data.as_two_indices();
+                AstNode::Shl { lhs, rhs }
+            }
+            Tag::Shr => {
+                let (lhs, rhs) = data.as_two_indices();
+                AstNode::Shr { lhs, rhs }
+            }
+            Tag::Add => {
+                let (lhs, rhs) = data.as_two_indices();
+                AstNode::Add { lhs, rhs }
+            }
+            Tag::Sub => {
+                let (lhs, rhs) = data.as_two_indices();
+                AstNode::Sub { lhs, rhs }
+            }
+            Tag::Mul => {
+                let (lhs, rhs) = data.as_two_indices();
+                AstNode::Mul { lhs, rhs }
+            }
+            Tag::Div => {
+                let (lhs, rhs) = data.as_two_indices();
+                AstNode::Div { lhs, rhs }
+            }
+            Tag::Rem => {
+                let (lhs, rhs) = data.as_two_indices();
+                AstNode::Rem { lhs, rhs }
+            }
+            Tag::Assign => {
+                let (lhs, rhs) = data.as_two_indices();
+                AstNode::Assign { lhs, rhs }
+            }
+            Tag::SubscriptExpr => {
+                let (lhs, index) = data.as_two_indices();
+                AstNode::SubscriptExpr { lhs, index }
+            }
+            Tag::IfExpr => {
+                let (cond, body) = data.as_two_indices();
+                AstNode::IfExpr { cond, body }
+            }
+            Tag::IfElseExpr => {
+                let (cond, extra) = data.as_index_and_extra_offset();
+                let [a, b] = self.extra[extra..][..2] else {
+                    unreachable!()
+                };
+
+                AstNode::IfElseExpr {
+                    cond,
+                    a: Index::from_u32(a).unwrap(),
+                    b: Index::from_u32(b).unwrap(),
+                }
+            }
+            Tag::Error => AstNode::Error {
+                err: data.as_error(),
+            },
+            Tag::Undefined => AstNode::Undefined,
+        }
+    }
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum AstNode {
+    /// pseudo tag, contains a range from a..b into extra of all files.
+    Root {
+        files: Vec<Index>,
+    },
+    /// `data` is a range from a..b into extra of all global nodes.
+    File {
+        decls: Vec<Index>,
+    },
+    /// `data` is an intern to a name, and an index into extra of [index: return_type, index: ParameterList]
+    FunctionProto {
+        name: Interned,
+        return_type: Index,
+        parameter_list: Index,
+    },
+    /// `data` is an intern to a name, and an intern to the function type
+    FunctionProtoInterned {
+        name: Interned,
+        ty: Interned,
+    },
+    /// `data` is an index to a FunctionProto and an index to a Block
+    FunctionDecl {
+        proto: Index,
+        body: Index,
+    },
+    /// `data` is a range from a..b into extra of indices to parameters
+    ParameterList {
+        params: Vec<Index>,
+    },
+    /// `data` is an index to a type, and an intern to a name
+    Parameter {
+        ty: Index,
+        name: Interned,
+    },
+    /// `data` is range from a..b into `extra` of indices to statements
+    Block {
+        statements: Vec<Index>,
+        expr: Option<Index>,
+    },
+    /// `data` is an index to a type, and an intern to a value
+    Constant {
+        ty: Index,
+        value: Interned,
+    },
+    /// `data` is an index to an expression
+    ExprStmt {
+        expr: Index,
+    },
+    /// `data` is none
+    ReturnStmt,
+    /// `data` is an index to an expr
+    ReturnExprStmt {
+        expr: Index,
+    },
+    /// `data` is a range from a..b into `extra` of `[name: intern, type: index]`
+    VarDecl {
+        name: Interned,
+        ty: Index,
+    },
+    /// `data` is a range from a..b into `extra` of `[name: intern, type: index]`
+    MutVarDecl {
+        name: Interned,
+        ty: Index,
+    },
+    /// `data` is a range from a..b into `extra` of `[name: intern, expr: index, type?: index]`
+    VarDeclAssignment {
+        name: Interned,
+        expr: Index,
+        ty: Option<Index>,
+    },
+    /// `data` is a range from a..b into `extra` of `[name: intern, expr: index, type?: index]`
+    MutVarDeclAssignment {
+        name: Interned,
+        expr: Index,
+        ty: Option<Index>,
+    },
+    /// `data` is an intern to a name, and an offset into `extra` of `[type: index, expr: index]`
+    GlobalDecl {
+        name: Interned,
+        expr: Index,
+        ty: Index,
+    },
+    /// `data` is an intern to a name, and an offset into extra of `[flags, type0 ,..., typeN ,name0 ,..., nameN]`
+    StructDecl {
+        name: Interned,
+        flags: StructFlags,
+        field_names: Vec<Interned>,
+        field_types: Vec<Index>,
+    },
+    /// `data` is an intern to a name, and an intern to the type of the struct
+    StructDeclInterned {
+        name: Interned,
+        ty: Interned,
+    },
+    /// `data` is an index to a type, and an intern to a name
+    FieldDecl {
+        name: Interned,
+        ty: Index,
+    },
+    /// `data` is an index to a Parameter, VarDecl, GlobalDecl or FunctionDecl, and an opaque DeclKind
+    DeclRef {
+        decl: Index,
+    },
+    /// `data` is an inlined key into the symbol table (scope: index, name: intern)
+    DeclRefUnresolved {
+        scope: Index,
+        name: Interned,
+    },
+    /// `data` is an intern of a type
+    InternedType {
+        intern: Interned,
+    },
+    /// `data` is an index to a StructDecl
+    TypeDeclRef {
+        decl: Index,
+    },
+    /// `data` is an inlined key into the symbol table (scope: index, name: intern)
+    TypeDeclRefUnresolved {
+        scope: Index,
+        name: Interned,
+    },
+    /// `data` is an index to a Type and u32 PointerFlags (extra offset)
+    PointerType {
+        ty: Index,
+        flags: PointerFlags,
+    },
+    /// `data` is an index to a length expression, and an underlying pointer type
+    ArrayType {
+        length: Index,
+        pointer: Index,
+    },
+    /// `data` is an index to an expr and an index to an ArgumentList
+    CallExpr {
+        func: Index,
+        argument_list: Index,
+    },
+    /// `data` is an index to an expr and an intern to a field name
+    FieldAccess {
+        field_name: Interned,
+        expr: Index,
+    },
+    /// `data` is a range from a..b into extra of indices to arguments
+    ArgumentList {
+        arguments: Vec<Index>,
+    },
+    /// `data` is an index to an expression
+    Argument {
+        expr: Index,
+        name: Option<Interned>,
+    },
+    /// `data` is an index to lhs, and an index to the type
+    ExplicitCast {
+        expr: Index,
+        ty: Index,
+    },
+    /// `data` is a single index to an expr
+    Deref {
+        expr: Index,
+    },
+    AddressOf {
+        expr: Index,
+    },
+    Not {
+        expr: Index,
+    },
+    Negate {
+        expr: Index,
+    },
+    PlaceToValueConversion {
+        expr: Index,
+    },
+    ValueToPlaceConversion {
+        expr: Index,
+    },
+    /// data is two indices for `lhs` and `rhs`
+    Or {
+        lhs: Index,
+        rhs: Index,
+    },
+    And {
+        lhs: Index,
+        rhs: Index,
+    },
+    BitOr {
+        lhs: Index,
+        rhs: Index,
+    },
+    BitXOr {
+        lhs: Index,
+        rhs: Index,
+    },
+    BitAnd {
+        lhs: Index,
+        rhs: Index,
+    },
+    Eq {
+        lhs: Index,
+        rhs: Index,
+    },
+    NEq {
+        lhs: Index,
+        rhs: Index,
+    },
+    Lt {
+        lhs: Index,
+        rhs: Index,
+    },
+    Gt {
+        lhs: Index,
+        rhs: Index,
+    },
+    Le {
+        lhs: Index,
+        rhs: Index,
+    },
+    Ge {
+        lhs: Index,
+        rhs: Index,
+    },
+    Shl {
+        lhs: Index,
+        rhs: Index,
+    },
+    Shr {
+        lhs: Index,
+        rhs: Index,
+    },
+    Add {
+        lhs: Index,
+        rhs: Index,
+    },
+    Sub {
+        lhs: Index,
+        rhs: Index,
+    },
+    Mul {
+        lhs: Index,
+        rhs: Index,
+    },
+    Div {
+        lhs: Index,
+        rhs: Index,
+    },
+    Rem {
+        lhs: Index,
+        rhs: Index,
+    },
+    Assign {
+        lhs: Index,
+        rhs: Index,
+    },
+    SubscriptExpr {
+        lhs: Index,
+        index: Index,
+    },
+    IfExpr {
+        cond: Index,
+        body: Index,
+    },
+    /// `data` is an index to an expression and an index into extra for [if, else]
+    IfElseExpr {
+        cond: Index,
+        a: Index,
+        b: Index,
+    },
+    // TODO:
+    /// `data` is a ParseError
+    Error {
+        err: ParseError,
+    },
+    /// placeholder tag for reserved indices/nodes, `data` is none
+    Undefined,
+}

src/ast2/typecheck.rs

@@ -0,0 +1,499 @@
+use crate::variant;
+
+use super::{
+    intern::{self},
+    tag::{AstNode, AstNodeExt},
+    visitor::{AstExt, AstVisitorTrait},
+    Ast, Data, Index, Tag,
+};
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+enum ErrorKind {
+    MismatchingTypes,
+    DerefNonPointer,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+struct Error {
+    idx: Index,
+    kind: ErrorKind,
+}
+
+struct TypeChecker<'a> {
+    ip: &'a mut intern::InternPool,
+    errors: Vec<Error>,
+}
+
+impl<'a> TypeChecker<'a> {
+    fn visit_children<'b>(
+        &mut self,
+        ast: &'b mut super::Ast,
+        idx: Index,
+    ) -> Result<Option<intern::Index>, ()> {
+        for child in ast.get_node_children(idx) {
+            self.visit_any(ast, child)?;
+        }
+
+        Ok(None)
+    }
+}
+
+// TODO: actually handle errors here instead of aborting.
+impl<'a> AstVisitorTrait<&'a mut Ast> for TypeChecker<'_> {
+    type Error = ();
+
+    type Value = Option<intern::Index>;
+
+    const UNIMPL: Self::Error = ();
+
+    fn visit_parameter_impl(
+        &mut self,
+        ast: &'a mut Ast,
+        idx: Index,
+        ty: Index,
+        name: intern::Index,
+    ) -> Result<Self::Value, Self::Error> {
+        _ = (idx, name);
+        self.visit_any(ast, ty)
+    }
+
+    fn visit_array_type_impl(
+        &mut self,
+        ast: &'a mut Ast,
+        idx: Index,
+        length: Index,
+        pointer: Index,
+    ) -> Result<Self::Value, Self::Error> {
+        _ = self.visit_any(ast, length)?;
+        let pointee = self.visit_any(ast, pointer)?.expect("no type?");
+
+        variant!(self.ip.get_key(pointee) => intern::Key::PointerType { pointee, flags });
+
+        // get interened value from constant node
+        let length = {
+            let value = ast.datas[length].as_index_intern().1;
+
+            match self.ip.get_key(value) {
+                intern::Key::SIntSmall { bits } => bits as u32,
+                intern::Key::UIntSmall { bits } => bits as u32,
+                intern::Key::SInt64 { bits } => bits as u32,
+                intern::Key::UInt64 { bits } => bits as u32,
+                intern::Key::NegativeInt { bigint } | intern::Key::PositiveInt { bigint } => {
+                    bigint.iter_u32_digits().next().unwrap_or(0)
+                }
+                _ => 0,
+            }
+        };
+
+        let ty = self.ip.get_array_type(pointee, Some(flags), length);
+        ast.tags[idx] = Tag::InternedType;
+        ast.datas[idx] = Data::intern(ty);
+
+        Ok(Some(ty))
+    }
+
+    fn visit_pointer_type_impl(
+        &mut self,
+        ast: &'a mut Ast,
+        idx: Index,
+        ty: Index,
+        flags: intern::PointerFlags,
+    ) -> Result<Self::Value, Self::Error> {
+        let pointee = self.visit_any(ast, ty)?.expect("no type?");
+
+        let ty = self.ip.get_pointer_type(pointee, Some(flags));
+
+        ast.tags[idx] = Tag::InternedType;
+        ast.datas[idx] = Data::intern(ty);
+
+        Ok(Some(ty))
+    }
+
+    fn visit_type_decl_ref_impl(
+        &mut self,
+        ast: &'a mut Ast,
+        idx: Index,
+        decl: Index,
+    ) -> Result<Self::Value, Self::Error> {
+        let ty = self.visit_any(ast, decl)?.expect("no type?");
+
+        ast.tags[idx] = Tag::InternedType;
+        ast.datas[idx] = Data::intern(ty);
+
+        Ok(Some(ty))
+    }
+
+    fn visit_function_proto_impl(
+        &mut self,
+        ast: &'a mut Ast,
+        idx: Index,
+        name: intern::Index,
+        return_type: Index,
+        parameter_list: Index,
+    ) -> Result<Self::Value, Self::Error> {
+        variant!(ast.get_ast_node(parameter_list) => AstNode::ParameterList { params });
+
+        let return_type = self.visit_any(ast, return_type)?.expect("no type?");
+
+        let params = params
+            .into_iter()
+            .map(|param| self.visit_parameter(ast, param).map(|a| a.unwrap()))
+            .collect::<Result<Vec<_>, _>>()?;
+
+        let ty = self.ip.get_function_type(return_type, params);
+
+        ast.tags[idx] = Tag::FunctionProtoInterned;
+        ast.datas[idx] = Data::two_interns(name, ty);
+
+        Ok(Some(ty))
+    }
+
+    fn visit_function_proto_interned_impl(
+        &mut self,
+        ast: &'a mut Ast,
+        idx: Index,
+        name: intern::Index,
+        ty: intern::Index,
+    ) -> Result<Self::Value, Self::Error> {
+        Ok(Some(ty))
+    }
+
+    fn visit_struct_decl_impl(
+        &mut self,
+        ast: &'a mut Ast,
+        idx: Index,
+        name: intern::Index,
+        flags: intern::StructFlags,
+        field_names: Vec<intern::Index>,
+        field_types: Vec<Index>,
+    ) -> Result<Self::Value, Self::Error> {
+        let types = field_types
+            .into_iter()
+            .map(|i| self.visit_any(ast, i).map(Option::unwrap))
+            .collect::<Result<Vec<_>, _>>()?;
+
+        let ty = self.ip.insert_or_replace_struct_type(
+            name,
+            idx,
+            flags.packed,
+            flags.c_like,
+            field_names.into_iter().zip(types),
+        );
+
+        ast.tags[idx] = Tag::StructDeclInterned;
+        ast.datas[idx] = Data::two_interns(name, ty);
+
+        Ok(Some(ty))
+    }
+
+    fn visit_function_decl_impl(
+        &mut self,
+        ast: &'a mut Ast,
+        idx: Index,
+        proto: Index,
+        body: Index,
+    ) -> Result<Self::Value, Self::Error> {
+        let ty = self.visit_any(ast, proto)?.expect("no type?");
+        let body = self.visit_block(ast, body)?.unwrap_or(intern::Index::VOID);
+
+        let ret_ty = self.ip.try_get_return_type(ty).expect("no type?");
+
+        if body != ret_ty {
+            self.errors.push(Error {
+                idx,
+                kind: ErrorKind::MismatchingTypes,
+            });
+            Ok(Some(intern::Index::VOID))
+        } else {
+            Ok(Some(ty))
+        }
+    }
+
+    fn visit_block_impl(
+        &mut self,
+        ast: &'a mut Ast,
+        idx: Index,
+        statements: Vec<Index>,
+        expr: Option<Index>,
+    ) -> Result<Self::Value, Self::Error> {
+        for stmt in statements {
+            self.visit_any(ast, stmt)?;
+        }
+
+        expr.map(|expr| self.visit_any(ast, expr))
+            .transpose()
+            .map(Option::flatten)
+    }
+
+    fn visit_file_impl(
+        &mut self,
+        ast: &'a mut Ast,
+        idx: Index,
+        decls: Vec<Index>,
+    ) -> Result<Self::Value, Self::Error> {
+        for decl in decls {
+            self.visit_any(ast, decl)?;
+        }
+
+        Ok(None)
+    }
+
+    fn visit_struct_decl_interned_impl(
+        &mut self,
+        ast: &'a mut Ast,
+        idx: Index,
+        name: intern::Index,
+        ty: intern::Index,
+    ) -> Result<Self::Value, Self::Error> {
+        Ok(Some(ty))
+    }
+
+    fn visit_interned_type_impl(
+        &mut self,
+        ast: &'a mut Ast,
+        idx: Index,
+        intern: intern::Index,
+    ) -> Result<Self::Value, Self::Error> {
+        Ok(Some(intern))
+    }
+
+    fn visit_any(
+        &mut self,
+        ast: &'a mut Ast,
+        idx: super::Index,
+    ) -> Result<Self::Value, Self::Error> {
+        let (tag, data) = ast.get_node_tag_and_data(idx);
+
+        let _ty = match tag {
+            Tag::Root => unreachable!(),
+            Tag::InternedType => Some(data.as_intern()),
+            Tag::File => self.visit_file(ast, idx)?,
+            Tag::ArrayType => self.visit_array_type(ast, idx)?,
+            Tag::PointerType => self.visit_pointer_type(ast, idx)?,
+            Tag::TypeDeclRef => self.visit_type_decl_ref(ast, idx)?,
+            Tag::FunctionProtoInterned => self.visit_function_proto_interned(ast, idx)?,
+            Tag::FunctionProto => self.visit_function_proto(ast, idx)?,
+            Tag::Parameter => self.visit_parameter(ast, idx)?,
+            Tag::StructDecl => self.visit_struct_decl(ast, idx)?,
+            Tag::StructDeclInterned => self.visit_struct_decl_interned(ast, idx)?,
+            Tag::FunctionDecl => self.visit_function_decl(ast, idx)?,
+            Tag::ParameterList => todo!(),
+            Tag::Block | Tag::BlockTrailingExpr => self.visit_block(ast, idx)?,
+            Tag::Constant => self.visit_constant(ast, idx)?,
+            Tag::ExprStmt => self.visit_expr_stmt(ast, idx)?,
+            Tag::ReturnStmt => self.visit_return_stmt(ast, idx)?,
+            Tag::ReturnExprStmt => todo!(),
+            Tag::VarDecl => todo!(),
+            Tag::MutVarDecl => todo!(),
+            Tag::VarDeclAssignment => todo!(),
+            Tag::MutVarDeclAssignment => todo!(),
+            Tag::GlobalDecl => todo!(),
+            Tag::FieldDecl => todo!(),
+            Tag::DeclRef => todo!(),
+            Tag::DeclRefUnresolved => todo!(),
+            Tag::TypeDeclRefUnresolved => todo!(),
+            Tag::CallExpr => todo!(),
+            Tag::FieldAccess => todo!(),
+            Tag::ArgumentList => todo!(),
+            Tag::Argument => todo!(),
+            Tag::NamedArgument => todo!(),
+            Tag::ExplicitCast => self.visit_explicit_cast(ast, idx)?,
+            Tag::Deref => self.visit_deref(ast, idx)?,
+            Tag::AddressOf => self.visit_address_of(ast, idx)?,
+            Tag::Not | Tag::Negate => {
+                let ty = self.visit_any(ast, data.as_index())?;
+                ty
+            }
+            Tag::PlaceToValueConversion => self.visit_place_to_value_conversion(ast, idx)?,
+            Tag::ValueToPlaceConversion => self.visit_value_to_place_conversion(ast, idx)?,
+            Tag::Or
+            | Tag::And
+            | Tag::BitOr
+            | Tag::BitXOr
+            | Tag::BitAnd
+            | Tag::Eq
+            | Tag::NEq
+            | Tag::Lt
+            | Tag::Gt
+            | Tag::Le
+            | Tag::Ge
+            | Tag::Shl
+            | Tag::Shr
+            | Tag::Add
+            | Tag::Sub
+            | Tag::Mul
+            | Tag::Div
+            | Tag::Rem => {
+                let (lhs, rhs) = data.as_two_indices();
+                let lhs = self.visit_any(ast, lhs)?.unwrap();
+                let rhs = self.visit_any(ast, rhs)?.unwrap();
+
+                if lhs != rhs {
+                    self.errors.push(Error {
+                        idx,
+                        kind: ErrorKind::MismatchingTypes,
+                    });
+                }
+
+                Some(lhs)
+            }
+            Tag::Assign => self.visit_assign(ast, idx)?,
+            Tag::SubscriptExpr => self.visit_subscript_expr(ast, idx)?,
+            Tag::IfExpr => self.visit_if_expr(ast, idx)?,
+            Tag::IfElseExpr => self.visit_if_else_expr(ast, idx)?,
+            Tag::Error => todo!(),
+            Tag::Undefined => todo!(),
+        };
+
+        todo!()
+    }
+
+    fn visit_explicit_cast_impl(
+        &mut self,
+        ast: &'a mut Ast,
+        idx: Index,
+        expr: Index,
+        ty: Index,
+    ) -> Result<Self::Value, Self::Error> {
+        _ = self.visit_any(ast, expr)?;
+        // TODO: make sure this cast is legal
+        let ty = self.visit_any(ast, ty)?;
+
+        Ok(ty)
+    }
+
+    fn visit_address_of_impl(
+        &mut self,
+        ast: &'a mut Ast,
+        idx: Index,
+        expr: Index,
+    ) -> Result<Self::Value, Self::Error> {
+        self.visit_any(ast, expr)
+    }
+
+    fn visit_deref_impl(
+        &mut self,
+        ast: &'a mut Ast,
+        idx: Index,
+        expr: Index,
+    ) -> Result<Self::Value, Self::Error> {
+        let ty = self.visit_any(ast, expr)?.unwrap();
+        if let intern::Key::PointerType { pointee, .. } = self.ip.get_key(ty) {
+            Ok(Some(pointee))
+        } else {
+            Ok(None)
+        }
+    }
+
+    fn visit_place_to_value_conversion_impl(
+        &mut self,
+        ast: &'a mut Ast,
+        idx: Index,
+        expr: Index,
+    ) -> Result<Self::Value, Self::Error> {
+        let ty = self.visit_any(ast, expr)?;
+
+        if let Some(ty) = ty {
+            Ok(self.ip.try_get_pointee_type(ty))
+        } else {
+            self.errors.push(Error {
+                idx,
+                kind: ErrorKind::DerefNonPointer,
+            });
+            Ok(None)
+        }
+    }
+
+    fn visit_value_to_place_conversion_impl(
+        &mut self,
+        ast: &'a mut Ast,
+        idx: Index,
+        expr: Index,
+    ) -> Result<Self::Value, Self::Error> {
+        let ty = self.visit_any(ast, expr)?;
+
+        if let Some(ty) = ty {
+            Ok(Some(self.ip.get_pointer_type(ty, None)))
+        } else {
+            Ok(None)
+        }
+    }
+
+    fn visit_if_else_expr_impl(
+        &mut self,
+        ast: &'a mut Ast,
+        idx: Index,
+        cond: Index,
+        a: Index,
+        b: Index,
+    ) -> Result<Self::Value, Self::Error> {
+        self.visit_any(ast, cond)?;
+        let a = self.visit_block(ast, a)?;
+        let b = self.visit_block(ast, b)?;
+
+        if a != b {
+            self.errors.push(Error {
+                idx,
+                kind: ErrorKind::MismatchingTypes,
+            });
+        }
+
+        Ok(a)
+    }
+
+    fn visit_if_expr_impl(
+        &mut self,
+        ast: &'a mut Ast,
+        idx: Index,
+        cond: Index,
+        body: Index,
+    ) -> Result<Self::Value, Self::Error> {
+        self.visit_any(ast, cond)?;
+        self.visit_block(ast, body)?;
+
+        Ok(None)
+    }
+
+    fn visit_subscript_expr_impl(
+        &mut self,
+        ast: &'a mut Ast,
+        idx: Index,
+        lhs: Index,
+        index: Index,
+    ) -> Result<Self::Value, Self::Error> {
+        let lhs = self.visit_any(ast, lhs)?.unwrap();
+        let index = self.visit_any(ast, index)?.unwrap();
+
+        if index != intern::Index::USIZE {
+            self.errors.push(Error {
+                idx,
+                kind: ErrorKind::MismatchingTypes,
+            });
+        }
+
+        let pointee = self.ip.try_get_pointee_type(lhs).unwrap();
+        let pointer = self.ip.get_pointer_type(pointee, None);
+
+        Ok(Some(pointer))
+    }
+
+    fn visit_assign_impl(
+        &mut self,
+        ast: &'a mut Ast,
+        idx: Index,
+        lhs: Index,
+        rhs: Index,
+    ) -> Result<Self::Value, Self::Error> {
+        let lhs = self.visit_any(ast, lhs)?.unwrap();
+        let rhs = self.visit_any(ast, rhs)?.unwrap();
+
+        if self.ip.try_get_pointee_type(lhs) != Some(rhs) {
+            self.errors.push(Error {
+                idx,
+                kind: ErrorKind::MismatchingTypes,
+            });
+        }
+
+        Ok(None)
+    }
+}

src/ast2/visitor.rs

@@ -1,7 +1,24 @@
-use super::*;
+use crate::{ast2::tag::AstNode, variant};
+
+use super::{tag::AstNodeExt, *};
+
 pub trait AstExt {
     fn get_node_children(&self, node: Index) -> Vec<Index>;
     fn get_node_tag_and_data(&self, node: Index) -> (Tag, Data);
+
+    fn get_node_data_for_tag(&self, idx: Index, tag: Tag) -> Option<Data> {
+        let (t, data) = self.get_node_tag_and_data(idx);
+        if t == tag {
+            Some(data)
+        } else {
+            None
+        }
+    }
+
+    fn expect_node_data_for_tag(&self, idx: Index, tag: Tag) -> Data {
+        self.get_node_data_for_tag(idx, tag)
+            .expect(&format!("node {idx} is not a {tag:?}"))
+    }
 }
 
 impl AstExt for &Ast {
@@ -13,6 +30,7 @@ impl AstExt for &Ast {
         (self.tags[node], self.datas[node])
     }
 }
+
 impl AstExt for &mut Ast {
     fn get_node_children(&self, node: Index) -> Vec<Index> {
         Ast::get_node_children(self, node)
@@ -236,393 +254,372 @@ impl Ast {
     }
 }
 
-impl Ast {
-    pub fn visit_all_functions_mut<V>(&mut self, visitor: &mut impl AstVisitorTrait) {
-        for i in
-            (0..self.tags.functions.len()).map(|i| Index::new(Kind::Function, i as u32).unwrap())
-        {
-            visitor.visit_function_decl(self, i);
-        }
-    }
+macro_rules! tag_visit_fn {
+    ($($tag:tt {$($field_name:ident : $field_ty:ty),* $(,)?}),* $(,)?) => {
+        $(
+            paste::paste! {
 
-    pub fn visit_function_mut<F: FnMut(&mut Self)>(&mut self) {}
+                fn [<visit_ $tag:snake>](&mut self, ast: Ast, idx: Index) -> Result<Self::Value, Self::Error> {
+                    variant!(ast.get_ast_node(idx) => AstNode::$tag { $($field_name),* });
+                    self.[<visit_ $tag:snake _impl>](ast, idx, $($field_name),*)
+                }
+                fn [<visit_ $tag:snake _impl>](&mut self, ast: Ast, idx: Index, $($field_name: $field_ty),*) -> Result<Self::Value, Self::Error> {
+                    _ = (ast, idx, $($field_name),*);
+                    Err(Self::UNIMPL)
+                }
+            }
+        )*
+    };
 }
 
-pub trait AstVisitorTrait {
+use intern::Index as Interned;
+
+pub trait AstVisitorTrait<Ast: AstExt + AstNodeExt> {
     type Error;
     type Value;
     const UNIMPL: Self::Error;
 
-    fn visit_function_decl(
-        &mut self,
-        ast: &mut Ast,
-        idx: Index,
-    ) -> Result<Self::Value, Self::Error> {
-        _ = (ast, idx);
-        Err(Self::UNIMPL)
-    }
-    fn visit_parameter(&mut self, ast: &mut Ast, idx: Index) -> Result<Self::Value, Self::Error> {
-        _ = (ast, idx);
-        Err(Self::UNIMPL)
-    }
-    fn visit_parameter_list(
-        &mut self,
-        ast: &mut Ast,
-        idx: Index,
-    ) -> Result<Self::Value, Self::Error> {
-        _ = (ast, idx);
-        Err(Self::UNIMPL)
-    }
-    fn visit_block(&mut self, ast: &mut Ast, idx: Index) -> Result<Self::Value, Self::Error> {
-        _ = (ast, idx);
-        Err(Self::UNIMPL)
-    }
-    fn visit_block_trailing_expr(
-        &mut self,
-        ast: &mut Ast,
-        idx: Index,
-    ) -> Result<Self::Value, Self::Error> {
-        _ = (ast, idx);
-        Err(Self::UNIMPL)
-    }
-    fn visit_block_maybe_trailing(
-        &mut self,
-        ast: &mut Ast,
-        idx: Index,
-    ) -> Result<Self::Value, Self::Error> {
-        use visitor::AstExt;
-        match ast.get_node_tag_and_data(idx).0 {
-            Tag::BlockTrailingExpr => self.visit_block(ast, idx),
-            Tag::Block => self.visit_block_trailing_expr(ast, idx),
-            _ => unreachable!(),
-        }
-    }
-    fn visit_function_proto(
-        &mut self,
-        ast: &mut Ast,
-        idx: Index,
-    ) -> Result<Self::Value, Self::Error> {
-        _ = (ast, idx);
-        Err(Self::UNIMPL)
-    }
-    fn visit_call_expr(&mut self, ast: &mut Ast, idx: Index) -> Result<Self::Value, Self::Error> {
-        _ = (ast, idx);
-        Err(Self::UNIMPL)
-    }
-    fn visit_add_expr(&mut self, ast: &mut Ast, idx: Index) -> Result<Self::Value, Self::Error> {
-        _ = (ast, idx);
-        Err(Self::UNIMPL)
-    }
-    fn visit_sub_expr(&mut self, ast: &mut Ast, idx: Index) -> Result<Self::Value, Self::Error> {
-        _ = (ast, idx);
-        Err(Self::UNIMPL)
-    }
-    fn visit_mul_expr(&mut self, ast: &mut Ast, idx: Index) -> Result<Self::Value, Self::Error> {
-        _ = (ast, idx);
-        Err(Self::UNIMPL)
-    }
-    fn visit_div_expr(&mut self, ast: &mut Ast, idx: Index) -> Result<Self::Value, Self::Error> {
-        _ = (ast, idx);
-        Err(Self::UNIMPL)
-    }
-    fn visit_rem_expr(&mut self, ast: &mut Ast, idx: Index) -> Result<Self::Value, Self::Error> {
-        _ = (ast, idx);
-        Err(Self::UNIMPL)
-    }
-    fn visit_eq_expr(&mut self, ast: &mut Ast, idx: Index) -> Result<Self::Value, Self::Error> {
-        _ = (ast, idx);
-        Err(Self::UNIMPL)
-    }
-    fn visit_neq_expr(&mut self, ast: &mut Ast, idx: Index) -> Result<Self::Value, Self::Error> {
-        _ = (ast, idx);
-        Err(Self::UNIMPL)
-    }
-    fn visit_lt_expr(&mut self, ast: &mut Ast, idx: Index) -> Result<Self::Value, Self::Error> {
-        _ = (ast, idx);
-        Err(Self::UNIMPL)
-    }
-    fn visit_gt_expr(&mut self, ast: &mut Ast, idx: Index) -> Result<Self::Value, Self::Error> {
-        _ = (ast, idx);
-        Err(Self::UNIMPL)
-    }
-    fn visit_le_expr(&mut self, ast: &mut Ast, idx: Index) -> Result<Self::Value, Self::Error> {
-        _ = (ast, idx);
-        Err(Self::UNIMPL)
-    }
-    fn visit_ge_expr(&mut self, ast: &mut Ast, idx: Index) -> Result<Self::Value, Self::Error> {
-        _ = (ast, idx);
-        Err(Self::UNIMPL)
-    }
-    fn visit_shl_expr(&mut self, ast: &mut Ast, idx: Index) -> Result<Self::Value, Self::Error> {
-        _ = (ast, idx);
-        Err(Self::UNIMPL)
-    }
-    fn visit_shr_expr(&mut self, ast: &mut Ast, idx: Index) -> Result<Self::Value, Self::Error> {
-        _ = (ast, idx);
-        Err(Self::UNIMPL)
-    }
-    fn visit_bitor_expr(&mut self, ast: &mut Ast, idx: Index) -> Result<Self::Value, Self::Error> {
-        _ = (ast, idx);
-        Err(Self::UNIMPL)
-    }
-    fn visit_bitxor_expr(&mut self, ast: &mut Ast, idx: Index) -> Result<Self::Value, Self::Error> {
-        _ = (ast, idx);
-        Err(Self::UNIMPL)
-    }
-    fn visit_bitand_expr(&mut self, ast: &mut Ast, idx: Index) -> Result<Self::Value, Self::Error> {
-        _ = (ast, idx);
-        Err(Self::UNIMPL)
-    }
-    fn visit_or_expr(&mut self, ast: &mut Ast, idx: Index) -> Result<Self::Value, Self::Error> {
-        _ = (ast, idx);
-        Err(Self::UNIMPL)
-    }
-    fn visit_and_expr(&mut self, ast: &mut Ast, idx: Index) -> Result<Self::Value, Self::Error> {
-        _ = (ast, idx);
-        Err(Self::UNIMPL)
-    }
-    fn visit_not_expr(&mut self, ast: &mut Ast, idx: Index) -> Result<Self::Value, Self::Error> {
-        _ = (ast, idx);
-        Err(Self::UNIMPL)
-    }
-    fn visit_negate_expr(&mut self, ast: &mut Ast, idx: Index) -> Result<Self::Value, Self::Error> {
-        _ = (ast, idx);
-        Err(Self::UNIMPL)
-    }
-    fn visit_deref_expr(&mut self, ast: &mut Ast, idx: Index) -> Result<Self::Value, Self::Error> {
-        _ = (ast, idx);
-        Err(Self::UNIMPL)
-    }
-    fn visit_address_of_expr(
-        &mut self,
-        ast: &mut Ast,
-        idx: Index,
-    ) -> Result<Self::Value, Self::Error> {
-        _ = (ast, idx);
-        Err(Self::UNIMPL)
-    }
-    fn visit_explicit_cast_expr(
-        &mut self,
-        ast: &mut Ast,
-        idx: Index,
-    ) -> Result<Self::Value, Self::Error> {
-        _ = (ast, idx);
-        Err(Self::UNIMPL)
-    }
-    fn visit_assign(&mut self, ast: &mut Ast, idx: Index) -> Result<Self::Value, Self::Error> {
-        _ = (ast, idx);
-        Err(Self::UNIMPL)
-    }
-    fn visit_subscript_expr(
-        &mut self,
-        ast: &mut Ast,
-        idx: Index,
-    ) -> Result<Self::Value, Self::Error> {
-        _ = (ast, idx);
-        Err(Self::UNIMPL)
-    }
-    fn visit_if_expr(&mut self, ast: &mut Ast, idx: Index) -> Result<Self::Value, Self::Error> {
-        _ = (ast, idx);
-        Err(Self::UNIMPL)
-    }
-    fn visit_if_else_expr(
-        &mut self,
-        ast: &mut Ast,
-        idx: Index,
-    ) -> Result<Self::Value, Self::Error> {
-        _ = (ast, idx);
-        Err(Self::UNIMPL)
-    }
-    fn visit_argument(&mut self, ast: &mut Ast, idx: Index) -> Result<Self::Value, Self::Error> {
-        _ = (ast, idx);
-        Err(Self::UNIMPL)
-    }
+    tag_visit_fn!(
+        File {
+            decls: Vec<Index>,
+        },
+        FunctionProto {
+            name: Interned,
+            return_type: Index,
+            parameter_list: Index,
+        },
+        FunctionProtoInterned {
+            name: Interned,
+            ty: Interned,
+        },
+        FunctionDecl {
+            proto: Index,
+            body: Index,
+        },
+        ParameterList {
+            params: Vec<Index>,
+        },
+        Parameter {
+            ty: Index,
+            name: Interned,
+        },
+        Block {
+            statements: Vec<Index>,
+            expr: Option<Index>,
+        },
+        Constant {
+            ty: Index,
+            value: Interned,
+        },
+        ExprStmt {
+            expr: Index,
+        },
+        ReturnStmt {},
+        ReturnExprStmt {
+            expr: Index,
+        },
+        VarDecl {
+            name: Interned,
+            ty: Index,
+        },
+        MutVarDecl {
+            name: Interned,
+            ty: Index,
+        },
+        VarDeclAssignment {
+            name: Interned,
+            expr: Index,
+            ty: Option<Index>,
+        },
+        MutVarDeclAssignment {
+            name: Interned,
+            expr: Index,
+            ty: Option<Index>,
+        },
+        GlobalDecl {
+            name: Interned,
+            expr: Index,
+            ty: Index,
+        },
+        StructDecl {
+            name: Interned,
+            flags: StructFlags,
+            field_names: Vec<Interned>,
+            field_types: Vec<Index>,
+        },
+        StructDeclInterned {
+            name: Interned,
+            ty: Interned,
+        },
+        FieldDecl {
+            name: Interned,
+            ty: Index,
+        },
+        DeclRef {
+            decl: Index,
+        },
+        DeclRefUnresolved {
+            scope: Index,
+            name: Interned,
+        },
+        InternedType {
+            intern: Interned,
+        },
+        TypeDeclRef {
+            decl: Index,
+        },
+        TypeDeclRefUnresolved {
+            scope: Index,
+            name: Interned,
+        },
+        PointerType {
+            ty: Index,
+            flags: PointerFlags,
+        },
+        ArrayType {
+            length: Index,
+            pointer: Index,
+        },
+        CallExpr {
+            func: Index,
+            argument_list: Index,
+        },
+        FieldAccess {
+            field_name: Interned,
+            expr: Index,
+        },
+        ArgumentList {
+            arguments: Vec<Index>,
+        },
+        Argument {
+            expr: Index,
+            name: Option<Interned>,
+        },
+        ExplicitCast {
+            expr: Index,
+            ty: Index,
+        },
+        Deref {
+            expr: Index,
+        },
+        AddressOf {
+            expr: Index,
+        },
+        Not {
+            expr: Index,
+        },
+        Negate {
+            expr: Index,
+        },
+        PlaceToValueConversion {
+            expr: Index,
+        },
+        ValueToPlaceConversion {
+            expr: Index,
+        },
+        Or {
+            lhs: Index,
+            rhs: Index,
+        },
+        And {
+            lhs: Index,
+            rhs: Index,
+        },
+        BitOr {
+            lhs: Index,
+            rhs: Index,
+        },
+        BitXOr {
+            lhs: Index,
+            rhs: Index,
+        },
+        BitAnd {
+            lhs: Index,
+            rhs: Index,
+        },
+        Eq {
+            lhs: Index,
+            rhs: Index,
+        },
+        NEq {
+            lhs: Index,
+            rhs: Index,
+        },
+        Lt {
+            lhs: Index,
+            rhs: Index,
+        },
+        Gt {
+            lhs: Index,
+            rhs: Index,
+        },
+        Le {
+            lhs: Index,
+            rhs: Index,
+        },
+        Ge {
+            lhs: Index,
+            rhs: Index,
+        },
+        Shl {
+            lhs: Index,
+            rhs: Index,
+        },
+        Shr {
+            lhs: Index,
+            rhs: Index,
+        },
+        Add {
+            lhs: Index,
+            rhs: Index,
+        },
+        Sub {
+            lhs: Index,
+            rhs: Index,
+        },
+        Mul {
+            lhs: Index,
+            rhs: Index,
+        },
+        Div {
+            lhs: Index,
+            rhs: Index,
+        },
+        Rem {
+            lhs: Index,
+            rhs: Index,
+        },
+        Assign {
+            lhs: Index,
+            rhs: Index,
+        },
+        SubscriptExpr {
+            lhs: Index,
+            index: Index,
+        },
+        IfExpr {
+            cond: Index,
+            body: Index,
+        },
+        IfElseExpr {
+            cond: Index,
+            a: Index,
+            b: Index,
+        },
+        Error {
+            err: ParseError,
+        },
+        Undefined {},
+    );
 
-    fn visit_any_argument(
-        &mut self,
-        ast: &mut Ast,
-        idx: Index,
-    ) -> Result<Self::Value, Self::Error> {
-        use visitor::AstExt;
-        match ast.get_node_tag_and_data(idx).0 {
-            Tag::Argument => self.visit_argument(ast, idx),
-            Tag::NamedArgument => self.visit_named_argument(ast, idx),
-            _ => unreachable!(),
+    fn visit_any(&mut self, ast: Ast, idx: Index) -> Result<Self::Value, Self::Error> {
+        match ast.get_ast_node(idx) {
+            AstNode::File { decls } => self.visit_file_impl(ast, idx, decls),
+            AstNode::FunctionProto {
+                name,
+                return_type,
+                parameter_list,
+            } => self.visit_function_proto_impl(ast, idx, name, return_type, parameter_list),
+            AstNode::FunctionProtoInterned { name, ty } => {
+                self.visit_function_proto_interned_impl(ast, idx, name, ty)
             }
+            AstNode::FunctionDecl { proto, body } => {
+                self.visit_function_decl_impl(ast, idx, proto, body)
             }
-
-    fn visit_named_argument(
-        &mut self,
-        ast: &mut Ast,
-        idx: Index,
-    ) -> Result<Self::Value, Self::Error> {
-        _ = (ast, idx);
-        Err(Self::UNIMPL)
+            AstNode::ParameterList { params } => self.visit_parameter_list_impl(ast, idx, params),
+            AstNode::Parameter { ty, name } => self.visit_parameter_impl(ast, idx, ty, name),
+            AstNode::Block { statements, expr } => {
+                self.visit_block_impl(ast, idx, statements, expr)
             }
-
-    fn visit_argument_list(
-        &mut self,
-        ast: &mut Ast,
-        idx: Index,
-    ) -> Result<Self::Value, Self::Error> {
-        _ = (ast, idx);
-        Err(Self::UNIMPL)
+            AstNode::Constant { ty, value } => self.visit_constant_impl(ast, idx, ty, value),
+            AstNode::ExprStmt { expr } => self.visit_expr_stmt_impl(ast, idx, expr),
+            AstNode::ReturnStmt => self.visit_return_stmt_impl(ast, idx),
+            AstNode::ReturnExprStmt { expr } => self.visit_return_expr_stmt_impl(ast, idx, expr),
+            AstNode::VarDecl { name, ty } => self.visit_var_decl_impl(ast, idx, name, ty),
+            AstNode::MutVarDecl { name, ty } => self.visit_mut_var_decl_impl(ast, idx, name, ty),
+            AstNode::VarDeclAssignment { name, expr, ty } => {
+                self.visit_var_decl_assignment_impl(ast, idx, name, expr, ty)
             }
-
-    fn visit_constant(&mut self, ast: &mut Ast, idx: Index) -> Result<Self::Value, Self::Error> {
-        _ = (ast, idx);
-        Err(Self::UNIMPL)
+            AstNode::MutVarDeclAssignment { name, expr, ty } => {
+                self.visit_mut_var_decl_assignment_impl(ast, idx, name, expr, ty)
             }
-
-    fn visit_return(&mut self, ast: &mut Ast, idx: Index) -> Result<Self::Value, Self::Error> {
-        _ = (ast, idx);
-        Err(Self::UNIMPL)
+            AstNode::GlobalDecl { name, expr, ty } => {
+                self.visit_global_decl_impl(ast, idx, name, expr, ty)
             }
-    fn visit_return_expr(&mut self, ast: &mut Ast, idx: Index) -> Result<Self::Value, Self::Error> {
-        _ = (ast, idx);
-        Err(Self::UNIMPL)
+            AstNode::StructDecl {
+                name,
+                flags,
+                field_names,
+                field_types,
+            } => self.visit_struct_decl_impl(ast, idx, name, flags, field_names, field_types),
+            AstNode::StructDeclInterned { name, ty } => {
+                self.visit_struct_decl_interned_impl(ast, idx, name, ty)
             }
-    fn visit_global_decl(&mut self, ast: &mut Ast, idx: Index) -> Result<Self::Value, Self::Error> {
-        _ = (ast, idx);
-        Err(Self::UNIMPL)
+            AstNode::FieldDecl { name, ty } => self.visit_field_decl_impl(ast, idx, name, ty),
+            AstNode::DeclRef { decl } => self.visit_decl_ref_impl(ast, idx, decl),
+            AstNode::DeclRefUnresolved { scope, name } => {
+                self.visit_decl_ref_unresolved_impl(ast, idx, scope, name)
             }
-    fn visit_var_decl(&mut self, ast: &mut Ast, idx: Index) -> Result<Self::Value, Self::Error> {
-        _ = (ast, idx);
-        Err(Self::UNIMPL)
+            AstNode::InternedType { intern } => self.visit_interned_type_impl(ast, idx, intern),
+            AstNode::TypeDeclRef { decl } => self.visit_type_decl_ref_impl(ast, idx, decl),
+            AstNode::TypeDeclRefUnresolved { scope, name } => {
+                self.visit_type_decl_ref_unresolved_impl(ast, idx, scope, name)
             }
-    fn visit_mut_var_decl(
-        &mut self,
-        ast: &mut Ast,
-        idx: Index,
-    ) -> Result<Self::Value, Self::Error> {
-        _ = (ast, idx);
-        Err(Self::UNIMPL)
+            AstNode::PointerType { ty, flags } => self.visit_pointer_type_impl(ast, idx, ty, flags),
+            AstNode::ArrayType { length, pointer } => {
+                self.visit_array_type_impl(ast, idx, length, pointer)
             }
-    fn visit_var_assign_decl(
-        &mut self,
-        ast: &mut Ast,
-        idx: Index,
-    ) -> Result<Self::Value, Self::Error> {
-        _ = (ast, idx);
-        Err(Self::UNIMPL)
+            AstNode::CallExpr {
+                func,
+                argument_list,
+            } => self.visit_call_expr_impl(ast, idx, func, argument_list),
+            AstNode::FieldAccess { field_name, expr } => {
+                self.visit_field_access_impl(ast, idx, field_name, expr)
             }
-    fn visit_mut_var_assign_decl(
-        &mut self,
-        ast: &mut Ast,
-        idx: Index,
-    ) -> Result<Self::Value, Self::Error> {
-        _ = (ast, idx);
-        Err(Self::UNIMPL)
+            AstNode::ArgumentList { arguments } => {
+                self.visit_argument_list_impl(ast, idx, arguments)
             }
-    fn visit_decl_ref(&mut self, ast: &mut Ast, idx: Index) -> Result<Self::Value, Self::Error> {
-        _ = (ast, idx);
-        Err(Self::UNIMPL)
+            AstNode::Argument { expr, name } => self.visit_argument_impl(ast, idx, expr, name),
+            AstNode::ExplicitCast { expr, ty } => self.visit_explicit_cast_impl(ast, idx, expr, ty),
+            AstNode::Deref { expr } => self.visit_deref_impl(ast, idx, expr),
+            AstNode::AddressOf { expr } => self.visit_address_of_impl(ast, idx, expr),
+            AstNode::Not { expr } => self.visit_not_impl(ast, idx, expr),
+            AstNode::Negate { expr } => self.visit_negate_impl(ast, idx, expr),
+            AstNode::PlaceToValueConversion { expr } => {
+                self.visit_place_to_value_conversion_impl(ast, idx, expr)
             }
-    fn visit_value_to_place_conversion(
-        &mut self,
-        ast: &mut Ast,
-        idx: Index,
-    ) -> Result<Self::Value, Self::Error> {
-        let idx = ast
-            .get_node_data_for_tag(idx, Tag::ValueToPlaceConversion)
-            .unwrap()
-            .as_index();
-        self.visit_any(ast, idx)
+            AstNode::ValueToPlaceConversion { expr } => {
+                self.visit_value_to_place_conversion_impl(ast, idx, expr)
             }
-    fn visit_place_to_value_conversion(
-        &mut self,
-        ast: &mut Ast,
-        idx: Index,
-    ) -> Result<Self::Value, Self::Error> {
-        let idx = ast
-            .get_node_data_for_tag(idx, Tag::PlaceToValueConversion)
-            .unwrap()
-            .as_index();
-        self.visit_any(ast, idx)
+            AstNode::Or { lhs, rhs } => self.visit_or_impl(ast, idx, lhs, rhs),
+            AstNode::And { lhs, rhs } => self.visit_and_impl(ast, idx, lhs, rhs),
+            AstNode::BitOr { lhs, rhs } => self.visit_bit_or_impl(ast, idx, lhs, rhs),
+            AstNode::BitXOr { lhs, rhs } => self.visit_bit_x_or_impl(ast, idx, lhs, rhs),
+            AstNode::BitAnd { lhs, rhs } => self.visit_bit_and_impl(ast, idx, lhs, rhs),
+            AstNode::Eq { lhs, rhs } => self.visit_eq_impl(ast, idx, lhs, rhs),
+            AstNode::NEq { lhs, rhs } => self.visit_n_eq_impl(ast, idx, lhs, rhs),
+            AstNode::Lt { lhs, rhs } => self.visit_lt_impl(ast, idx, lhs, rhs),
+            AstNode::Gt { lhs, rhs } => self.visit_gt_impl(ast, idx, lhs, rhs),
+            AstNode::Le { lhs, rhs } => self.visit_le_impl(ast, idx, lhs, rhs),
+            AstNode::Ge { lhs, rhs } => self.visit_ge_impl(ast, idx, lhs, rhs),
+            AstNode::Shl { lhs, rhs } => self.visit_shl_impl(ast, idx, lhs, rhs),
+            AstNode::Shr { lhs, rhs } => self.visit_shr_impl(ast, idx, lhs, rhs),
+            AstNode::Add { lhs, rhs } => self.visit_add_impl(ast, idx, lhs, rhs),
+            AstNode::Sub { lhs, rhs } => self.visit_sub_impl(ast, idx, lhs, rhs),
+            AstNode::Mul { lhs, rhs } => self.visit_mul_impl(ast, idx, lhs, rhs),
+            AstNode::Div { lhs, rhs } => self.visit_div_impl(ast, idx, lhs, rhs),
+            AstNode::Rem { lhs, rhs } => self.visit_rem_impl(ast, idx, lhs, rhs),
+            AstNode::Assign { lhs, rhs } => self.visit_assign_impl(ast, idx, lhs, rhs),
+            AstNode::SubscriptExpr { lhs, index: rhs } => {
+                self.visit_subscript_expr_impl(ast, idx, lhs, rhs)
             }
-
-    fn visit_any(&mut self, ast: &mut Ast, idx: Index) -> Result<Self::Value, Self::Error> {
-        use visitor::AstExt;
-        match ast.get_node_tag_and_data(idx).0 {
-            Tag::FunctionProto => self.visit_function_proto(ast, idx),
-            Tag::FunctionDecl => self.visit_function_decl(ast, idx),
-            Tag::ParameterList => self.visit_parameter_list(ast, idx),
-            Tag::Parameter => self.visit_parameter(ast, idx),
-            Tag::Block => self.visit_block(ast, idx),
-            Tag::BlockTrailingExpr => self.visit_block_trailing_expr(ast, idx),
-            Tag::Constant => self.visit_constant(ast, idx),
-            Tag::ExprStmt => todo!(),
-            Tag::ReturnStmt => self.visit_return(ast, idx),
-            Tag::ReturnExprStmt => self.visit_return_expr(ast, idx),
-            Tag::VarDecl => self.visit_var_decl(ast, idx),
-            Tag::MutVarDecl => self.visit_mut_var_decl(ast, idx),
-            Tag::VarDeclAssignment => self.visit_var_assign_decl(ast, idx),
-            Tag::MutVarDeclAssignment => self.visit_mut_var_assign_decl(ast, idx),
-            Tag::GlobalDecl => self.visit_global_decl(ast, idx),
-            Tag::StructDecl => todo!(),
-            Tag::FieldDecl => todo!(),
-            Tag::DeclRef => self.visit_decl_ref(ast, idx),
-            Tag::DeclRefUnresolved => todo!(),
-            Tag::InternedType => todo!(),
-            Tag::TypeDeclRef => todo!(),
-            Tag::TypeDeclRefUnresolved => todo!(),
-            Tag::PointerType => todo!(),
-            Tag::ArrayType => todo!(),
-            Tag::CallExpr => self.visit_call_expr(ast, idx),
-            Tag::FieldAccess => todo!(),
-            Tag::ArgumentList => self.visit_argument_list(ast, idx),
-            Tag::Argument => self.visit_argument(ast, idx),
-            Tag::NamedArgument => self.visit_named_argument(ast, idx),
-            Tag::ExplicitCast => self.visit_explicit_cast_expr(ast, idx),
-            Tag::Deref => self.visit_deref_expr(ast, idx),
-            Tag::AddressOf => self.visit_add_expr(ast, idx),
-            Tag::Not => self.visit_not_expr(ast, idx),
-            Tag::Negate => self.visit_negate_expr(ast, idx),
-            Tag::Or => self.visit_or_expr(ast, idx),
-            Tag::And => self.visit_and_expr(ast, idx),
-            Tag::BitOr => self.visit_bitor_expr(ast, idx),
-            Tag::BitXOr => self.visit_bitxor_expr(ast, idx),
-            Tag::BitAnd => self.visit_bitand_expr(ast, idx),
-            Tag::Eq => self.visit_eq_expr(ast, idx),
-            Tag::NEq => self.visit_neq_expr(ast, idx),
-            Tag::Lt => self.visit_lt_expr(ast, idx),
-            Tag::Gt => self.visit_gt_expr(ast, idx),
-            Tag::Le => self.visit_le_expr(ast, idx),
-            Tag::Ge => self.visit_ge_expr(ast, idx),
-            Tag::Shl => self.visit_shl_expr(ast, idx),
-            Tag::Shr => self.visit_shr_expr(ast, idx),
-            Tag::Add => self.visit_add_expr(ast, idx),
-            Tag::Sub => self.visit_sub_expr(ast, idx),
-            Tag::Mul => self.visit_mul_expr(ast, idx),
-            Tag::Div => self.visit_div_expr(ast, idx),
-            Tag::Rem => self.visit_rem_expr(ast, idx),
-            Tag::Assign => self.visit_assign(ast, idx),
-            Tag::SubscriptExpr => self.visit_subscript_expr(ast, idx),
-            Tag::IfExpr => self.visit_if_expr(ast, idx),
-            Tag::IfElseExpr => self.visit_if_else_expr(ast, idx),
-            Tag::PlaceToValueConversion => self.visit_place_to_value_conversion(ast, idx),
-            Tag::ValueToPlaceConversion => self.visit_value_to_place_conversion(ast, idx),
-            Tag::Error => todo!(),
-            Tag::Undefined => todo!(),
-            Tag::Root => todo!(),
-            Tag::File => todo!(),
+            AstNode::IfExpr { cond, body } => self.visit_if_expr_impl(ast, idx, cond, body),
+            AstNode::IfElseExpr { cond, a, b } => {
+                self.visit_if_else_expr_impl(ast, idx, cond, a, b)
+            }
+            AstNode::Error { err } => self.visit_error_impl(ast, idx, err),
+            AstNode::Undefined => self.visit_undefined_impl(ast, idx),
+            AstNode::Root { .. } => unreachable!(),
         }
     }
 }
-
-impl Ast {
-    pub fn get_node_data_for_tag(&self, idx: Index, tag: Tag) -> Option<Data> {
-        use visitor::AstExt;
-        let (t, data) = self.get_node_tag_and_data(idx);
-        if t == tag {
-            Some(data)
-        } else {
-            None
-        }
-    }
-
-    pub fn expect_node_data_for_tag(&self, idx: Index, tag: Tag) -> Data {
-        self.get_node_data_for_tag(idx, tag)
-            .expect(&format!("node {idx} is not a {tag:?}"))
-    }
-}

src/lib.rs

@@ -1,8 +1,6 @@
 #![feature(
-    extract_if,
     iter_advance_by,
     box_into_inner,
-    hash_extract_if,
     bigint_helper_methods,
     map_try_insert,
     iter_intersperse,
@@ -29,6 +27,9 @@ pub mod symbol_table;
 pub mod tokens;
 pub mod triples;
 
+pub mod utils;
+use utils::unit;
+
 pub fn tokenize<'a>(
     bytes: &'a [u8],
 ) -> Result<lexer::Tokenizer<'a>, (lexer::Tokenizer<'a>, Vec<lexer::TokenizeError>)> {
@@ -70,5 +71,3 @@ impl BitSize for &[u8] {
         bits as u32
     }
 }
-
-pub fn unit<T>(_: T) {}

src/utils.rs

@@ -0,0 +1,25 @@
+use core::{cell::UnsafeCell, mem::ManuallyDrop};
+
+pub fn unit<T>(_: T) {}
+
+pub struct DropGuard<F: FnOnce()>(UnsafeCell<ManuallyDrop<F>>);
+
+impl<F> DropGuard<F>
+where
+    F: FnOnce(),
+{
+    pub fn new(f: F) -> DropGuard<F> {
+        Self(UnsafeCell::new(ManuallyDrop::new(f)))
+    }
+}
+
+impl<F> Drop for DropGuard<F>
+where
+    F: FnOnce(),
+{
+    fn drop(&mut self) {
+        unsafe {
+            ManuallyDrop::take(&mut *self.0.get())();
+        }
+    }
+}