Feat: add type-state AST and semantic analysis pass

- Update ast.rs with Phase trait (Parsed/Typed), Ty enum, and generic
  AST nodes so the same tree works pre- and post-type-checking
- Add checker/ module implementing the 4-pass semantic analyser from
  SEMANTICS.md: struct/function collection, field resolution + size-cycle
  detection, full expression/statement type checking, and entry-point
  validation
- Wire checker into main; semantic errors are only run when the parse
  succeeds and are rendered with the same diagnostic machinery

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
This commit is contained in:
2026-03-11 15:12:10 +01:00
parent eda4f92900
commit aca0dae7de
6 changed files with 1715 additions and 47 deletions

View File

@@ -1,5 +1,187 @@
use crate::token::Span;
// ── Phase type-state ───────────────────────────────────────────────────────────
pub trait Phase {
type ExprExtra: std::fmt::Debug + Clone;
}
#[derive(Debug, Clone)]
pub struct Parsed;
#[derive(Debug, Clone)]
pub struct Typed;
impl Phase for Parsed {
type ExprExtra = ();
}
impl Phase for Typed {
type ExprExtra = Ty;
}
// ── Resolved type system ───────────────────────────────────────────────────────
#[derive(Debug, Clone, PartialEq, Eq)]
pub enum Ty {
// Unsigned integers
U8,
U16,
U32,
U64,
// Signed integers
I8,
I16,
I32,
I64,
// Floating-point
F32,
F64,
// Other primitives
Bool,
Char,
Unit,
// Pointer types
Ptr { mutable: bool, pointee: Box<Ty> },
OpaquePtr { mutable: bool },
// Array type
Array { elem: Box<Ty>, size: u64 },
// User-defined struct
Struct(String),
// Internal function signature (not user-facing)
FnSig { params: Vec<Ty>, ret: Box<Ty> },
// Error propagation sentinel
Error,
}
impl Ty {
pub fn is_error(&self) -> bool {
matches!(self, Ty::Error)
}
pub fn is_unsigned(&self) -> bool {
matches!(self, Ty::U8 | Ty::U16 | Ty::U32 | Ty::U64)
}
pub fn is_signed(&self) -> bool {
matches!(self, Ty::I8 | Ty::I16 | Ty::I32 | Ty::I64)
}
pub fn is_integer(&self) -> bool {
self.is_unsigned() || self.is_signed()
}
pub fn is_float(&self) -> bool {
matches!(self, Ty::F32 | Ty::F64)
}
pub fn is_numeric(&self) -> bool {
self.is_integer() || self.is_float()
}
/// Rank within a category: U8/I8=1, U16/I16=2, U32/I32=3, U64/I64=4, F32=1, F64=2
pub fn rank(&self) -> Option<u8> {
match self {
Ty::U8 | Ty::I8 => Some(1),
Ty::U16 | Ty::I16 => Some(2),
Ty::U32 | Ty::I32 => Some(3),
Ty::U64 | Ty::I64 => Some(4),
Ty::F32 => Some(1),
Ty::F64 => Some(2),
_ => None,
}
}
/// Returns true if `self` implicitly promotes to `target` under §5.2 rules.
pub fn promotes_to(&self, target: &Ty) -> bool {
// Refl
if self == target {
return true;
}
match (self, target) {
// Unsigned widening: same unsigned category, rank strictly increases
(a, b) if a.is_unsigned() && b.is_unsigned() => {
a.rank().unwrap_or(0) < b.rank().unwrap_or(0)
}
// Signed widening
(a, b) if a.is_signed() && b.is_signed() => {
a.rank().unwrap_or(0) < b.rank().unwrap_or(0)
}
// Float widening: F32 → F64
(Ty::F32, Ty::F64) => true,
// Char: char → U if U is unsigned and rank(U) >= 3 (u32 or u64)
(Ty::Char, b) if b.is_unsigned() => b.rank().unwrap_or(0) >= 3,
// Ptr-Coerce: *mut T promotes to *T (same pointee)
(
Ty::Ptr { mutable: true, pointee: pa },
Ty::Ptr { mutable: false, pointee: pb },
) => pa == pb,
_ => false,
}
}
/// Least upper bound under `promotes_to`.
/// Returns `Some(T)` where T is the common type, or `None` if incompatible.
pub fn common(a: &Ty, b: &Ty) -> Option<Ty> {
if a.is_error() || b.is_error() {
return Some(Ty::Error);
}
if b.promotes_to(a) {
return Some(a.clone());
}
if a.promotes_to(b) {
return Some(b.clone());
}
None
}
/// For pointer equality comparison.
pub fn ptr_common(a: &Ty, b: &Ty) -> Option<Ty> {
match (a, b) {
(
Ty::Ptr { mutable: ma, pointee: pa },
Ty::Ptr { mutable: mb, pointee: pb },
) if pa == pb => Some(Ty::Ptr {
mutable: *ma && *mb,
pointee: pa.clone(),
}),
(Ty::OpaquePtr { mutable: ma }, Ty::OpaquePtr { mutable: mb }) => {
Some(Ty::OpaquePtr { mutable: *ma && *mb })
}
_ => None,
}
}
pub fn display(&self) -> String {
match self {
Ty::U8 => "u8".to_string(),
Ty::U16 => "u16".to_string(),
Ty::U32 => "u32".to_string(),
Ty::U64 => "u64".to_string(),
Ty::I8 => "i8".to_string(),
Ty::I16 => "i16".to_string(),
Ty::I32 => "i32".to_string(),
Ty::I64 => "i64".to_string(),
Ty::F32 => "f32".to_string(),
Ty::F64 => "f64".to_string(),
Ty::Bool => "bool".to_string(),
Ty::Char => "char".to_string(),
Ty::Unit => "()".to_string(),
Ty::Ptr { mutable: true, pointee } => format!("*mut {}", pointee.display()),
Ty::Ptr { mutable: false, pointee } => format!("*{}", pointee.display()),
Ty::OpaquePtr { mutable: true } => "*mut opaque".to_string(),
Ty::OpaquePtr { mutable: false } => "*opaque".to_string(),
Ty::Array { elem, size } => format!("[{}; {}]", elem.display(), size),
Ty::Struct(name) => format!("struct {}", name),
Ty::FnSig { params, ret } => {
let ps: Vec<_> = params.iter().map(|p| p.display()).collect();
format!("fn({}) -> {}", ps.join(", "), ret.display())
}
Ty::Error => "<error>".to_string(),
}
}
}
// ── Operators ──────────────────────────────────────────────────────────────────
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
@@ -54,7 +236,7 @@ pub enum BinaryOp {
Assign, // `=`
}
// ── Types ──────────────────────────────────────────────────────────────────────
// ── Types (syntactic, from parser) ────────────────────────────────────────────
#[derive(Debug, Clone)]
pub enum Type {
@@ -74,6 +256,8 @@ pub enum Type {
// Other primitives
Bool,
Char,
// Unit type (explicit `-> ()`)
Unit,
// User-defined named type (e.g. a struct)
Named(String, Span),
// Typed pointer: `*type` (immutable) or `*mut type` (mutable)
@@ -89,28 +273,29 @@ pub enum Type {
// ── Struct literal field ───────────────────────────────────────────────────────
#[derive(Debug, Clone)]
pub struct StructField {
pub struct StructField<P: Phase> {
pub name: String,
pub name_span: Span,
pub value: Expr,
pub value: Expr<P>,
}
// ── Expression ────────────────────────────────────────────────────────────────
#[derive(Debug, Clone)]
pub struct Expr {
pub kind: ExprKind,
pub struct Expr<P: Phase> {
pub kind: ExprKind<P>,
pub span: Span,
pub ty: P::ExprExtra,
}
impl Expr {
pub fn new(kind: ExprKind, span: Span) -> Self {
Self { kind, span }
impl Expr<Parsed> {
pub fn new(kind: ExprKind<Parsed>, span: Span) -> Self {
Self { kind, span, ty: () }
}
}
#[derive(Debug, Clone)]
pub enum ExprKind {
pub enum ExprKind<P: Phase> {
// Literals
IntLit(String),
FloatLit(String),
@@ -125,46 +310,46 @@ pub enum ExprKind {
StructLit {
name: String,
name_span: Span,
fields: Vec<StructField>,
fields: Vec<StructField<P>>,
},
// Operators
Unary {
op: UnaryOp,
op_span: Span,
expr: Box<Expr>,
expr: Box<Expr<P>>,
},
Binary {
op: BinaryOp,
op_span: Span,
lhs: Box<Expr>,
rhs: Box<Expr>,
lhs: Box<Expr<P>>,
rhs: Box<Expr<P>>,
},
// Compound assignment: `lhs op= rhs` (expands to `lhs = lhs op rhs`)
CompoundAssign {
op: CompoundAssignOp,
op_span: Span,
lhs: Box<Expr>,
rhs: Box<Expr>,
lhs: Box<Expr<P>>,
rhs: Box<Expr<P>>,
},
// Postfix
Field {
expr: Box<Expr>,
expr: Box<Expr<P>>,
field: String,
field_span: Span,
},
Index {
expr: Box<Expr>,
index: Box<Expr>,
expr: Box<Expr<P>>,
index: Box<Expr<P>>,
},
Call {
callee: Box<Expr>,
args: Vec<Expr>,
callee: Box<Expr<P>>,
args: Vec<Expr<P>>,
},
// Parenthesised expression
Group(Box<Expr>),
Group(Box<Expr<P>>),
// Placeholder for parse errors — allows parsing to continue
Error,
@@ -173,57 +358,57 @@ pub enum ExprKind {
// ── Block ──────────────────────────────────────────────────────────────────────
#[derive(Debug, Clone)]
pub struct Block {
pub stmts: Vec<Stmt>,
pub struct Block<P: Phase> {
pub stmts: Vec<Stmt<P>>,
pub span: Span,
}
// ── Else branch ───────────────────────────────────────────────────────────────
#[derive(Debug, Clone)]
pub enum ElseBranch {
If(Box<Stmt>), // `else if …`
Block(Block), // `else { … }`
pub enum ElseBranch<P: Phase> {
If(Box<Stmt<P>>), // `else if …`
Block(Block<P>), // `else { … }`
}
// ── Statement ─────────────────────────────────────────────────────────────────
#[derive(Debug, Clone)]
pub struct Stmt {
pub kind: StmtKind,
pub struct Stmt<P: Phase> {
pub kind: StmtKind<P>,
pub span: Span,
}
#[derive(Debug, Clone)]
pub enum StmtKind {
pub enum StmtKind<P: Phase> {
/// `let [mut] name [: type] [= expr] ;`
Let {
mutable: bool,
name: String,
name_span: Span,
ty: Option<Type>,
init: Option<Expr>,
init: Option<Expr<P>>,
},
/// `return [expr] ;`
Return(Option<Expr>),
Return(Option<Expr<P>>),
/// `if expr_ns block [else else_branch]`
If {
cond: Expr,
then_block: Block,
else_branch: Option<ElseBranch>,
cond: Expr<P>,
then_block: Block<P>,
else_branch: Option<ElseBranch<P>>,
},
/// `while expr_ns block`
While { cond: Expr, body: Block },
While { cond: Expr<P>, body: Block<P> },
/// `loop block`
Loop { body: Block },
Loop { body: Block<P> },
/// `break ;`
Break,
/// `continue ;`
Continue,
/// `{ stmts }`
Block(Block),
Block(Block<P>),
/// `expr ;`
Expr(Expr),
Expr(Expr<P>),
/// Error placeholder — emitted during recovery so the parent can continue.
Error,
}
@@ -252,12 +437,12 @@ pub struct FieldDef {
/// `fn name ( params ) [ -> type ] block`
#[derive(Debug, Clone)]
pub struct FuncDef {
pub struct FuncDef<P: Phase> {
pub name: String,
pub name_span: Span,
pub params: Vec<Param>,
pub ret_ty: Option<Type>,
pub body: Block,
pub body: Block<P>,
}
/// `struct name { fields }`
@@ -269,14 +454,14 @@ pub struct StructDef {
}
#[derive(Debug, Clone)]
pub struct TopLevelDef {
pub kind: TopLevelDefKind,
pub struct TopLevelDef<P: Phase> {
pub kind: TopLevelDefKind<P>,
pub span: Span,
}
#[derive(Debug, Clone)]
pub enum TopLevelDefKind {
Func(FuncDef),
pub enum TopLevelDefKind<P: Phase> {
Func(FuncDef<P>),
Struct(StructDef),
/// Error placeholder for recovery.
Error,
@@ -284,7 +469,7 @@ pub enum TopLevelDefKind {
/// The root of the AST — a sequence of top-level definitions.
#[derive(Debug, Clone)]
pub struct Program {
pub defs: Vec<TopLevelDef>,
pub struct Program<P: Phase> {
pub defs: Vec<TopLevelDef<P>>,
pub span: Span,
}

158
fluxc/src/checker/env.rs Normal file
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@@ -0,0 +1,158 @@
use std::collections::{HashMap, HashSet};
use crate::ast::Ty;
use crate::token::Span;
// ── StructTable ────────────────────────────────────────────────────────────────
pub struct StructTable {
entries: HashMap<String, StructEntry>,
}
struct StructEntry {
name_span: Span,
fields: Vec<FieldEntry>,
}
pub struct FieldEntry {
pub name: String,
pub name_span: Span,
pub ty: Ty,
pub ty_span: Span,
}
impl StructTable {
pub fn new() -> Self {
Self { entries: HashMap::new() }
}
/// Insert a struct name; returns false if it was already present.
pub fn insert_name(&mut self, name: &str, span: Span) -> bool {
if self.entries.contains_key(name) {
return false;
}
self.entries.insert(name.to_string(), StructEntry { name_span: span, fields: Vec::new() });
true
}
pub fn contains(&self, name: &str) -> bool {
self.entries.contains_key(name)
}
pub fn add_field(&mut self, struct_name: &str, field: FieldEntry) {
if let Some(entry) = self.entries.get_mut(struct_name) {
entry.fields.push(field);
}
}
pub fn fields(&self, name: &str) -> Option<&[FieldEntry]> {
self.entries.get(name).map(|e| e.fields.as_slice())
}
pub fn name_span(&self, name: &str) -> Option<Span> {
self.entries.get(name).map(|e| e.name_span)
}
pub fn field_ty(&self, struct_name: &str, field_name: &str) -> Option<&Ty> {
self.entries.get(struct_name)?.fields.iter().find(|f| f.name == field_name).map(|f| &f.ty)
}
pub fn names_in_outer(&self, _saved: usize) -> HashSet<String> {
self.entries.keys().cloned().collect()
}
pub fn all_struct_names(&self) -> Vec<String> {
self.entries.keys().cloned().collect()
}
pub fn all_entries(&self) -> impl Iterator<Item = (&str, &StructEntry)> {
self.entries.iter().map(|(k, v)| (k.as_str(), v))
}
}
// ── FuncTable ──────────────────────────────────────────────────────────────────
pub struct FuncTable {
entries: HashMap<String, FuncEntry>,
}
pub struct FuncEntry {
pub name_span: Span,
pub params: Vec<ParamEntry>,
pub ret: Ty,
}
pub struct ParamEntry {
pub name: String,
pub name_span: Span,
pub ty: Ty,
pub mutable: bool,
}
impl FuncTable {
pub fn new() -> Self {
Self { entries: HashMap::new() }
}
/// Insert a function; returns false if the name was already present.
pub fn insert(&mut self, name: &str, span: Span, params: Vec<ParamEntry>, ret: Ty) -> bool {
if self.entries.contains_key(name) {
return false;
}
self.entries.insert(name.to_string(), FuncEntry { name_span: span, params, ret });
true
}
pub fn get(&self, name: &str) -> Option<&FuncEntry> {
self.entries.get(name)
}
pub fn contains(&self, name: &str) -> bool {
self.entries.contains_key(name)
}
}
// ── TypeEnv ───────────────────────────────────────────────────────────────────
#[derive(Clone)]
pub struct TypeEnv {
bindings: Vec<Binding>,
}
#[derive(Clone)]
pub struct Binding {
pub name: String,
pub ty: Ty,
pub mutable: bool,
}
impl TypeEnv {
pub fn new() -> Self {
Self { bindings: Vec::new() }
}
pub fn extend(&mut self, name: String, ty: Ty, mutable: bool) {
self.bindings.push(Binding { name, ty, mutable });
}
/// Look up a binding; rightmost (most recent) binding wins.
pub fn lookup(&self, name: &str) -> Option<(&Ty, bool)> {
self.bindings.iter().rev().find(|b| b.name == name).map(|b| (&b.ty, b.mutable))
}
pub fn contains(&self, name: &str) -> bool {
self.bindings.iter().any(|b| b.name == name)
}
pub fn save(&self) -> usize {
self.bindings.len()
}
pub fn restore(&mut self, saved: usize) {
self.bindings.truncate(saved);
}
/// Returns all binding names that were introduced after `saved`.
pub fn names_in_outer(&self, saved: usize) -> HashSet<String> {
self.bindings[saved..].iter().map(|b| b.name.clone()).collect()
}
}

677
fluxc/src/checker/expr.rs Normal file
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@@ -0,0 +1,677 @@
use std::collections::HashSet;
use crate::ast::{self, BinaryOp, CompoundAssignOp, ExprKind, Parsed, Ty, UnaryOp};
use crate::diagnostics::{Diagnostic, Label};
use crate::token::Span;
use super::env::TypeEnv;
use super::Checker;
impl Checker {
/// Type-check `expr` in environment `env` with definite-assignment set `assigned`.
/// Returns the resolved type. Does NOT mutate `env` or `assigned`.
pub fn check_expr(
&mut self,
expr: &ast::Expr<Parsed>,
env: &TypeEnv,
assigned: &HashSet<String>,
) -> Ty {
match &expr.kind {
// T-IntLit → i32
ExprKind::IntLit(_) => Ty::I32,
// T-FloatLit → f64
ExprKind::FloatLit(_) => Ty::F64,
// T-StringLit → *char
ExprKind::StringLit(_) => Ty::Ptr { mutable: false, pointee: Box::new(Ty::Char) },
// T-CharLit → char
ExprKind::CharLit(_) => Ty::Char,
// T-Bool → bool
ExprKind::Bool(_) => Ty::Bool,
// T-Ident
ExprKind::Ident(name) => match env.lookup(name) {
Some((ty, _)) => {
if !assigned.contains(name) {
self.emit(
Diagnostic::error(format!(
"use of potentially uninitialized variable `{name}`"
))
.with_label(Label::primary(expr.span)),
);
Ty::Error
} else {
ty.clone()
}
}
None => {
self.emit(
Diagnostic::error(format!("undefined variable `{name}`"))
.with_label(Label::primary(expr.span)),
);
Ty::Error
}
},
// T-StructLit
ExprKind::StructLit { name, name_span, fields } => {
if !self.sigma.contains(name) {
self.emit(
Diagnostic::error(format!("undefined struct `{name}`"))
.with_label(Label::primary(*name_span)),
);
// Still check field expressions for further errors
for sf in fields {
self.check_expr(&sf.value, env, assigned);
}
return Ty::Error;
}
let expected: Vec<(String, Ty)> = self
.sigma
.fields(name)
.unwrap_or(&[])
.iter()
.map(|f| (f.name.clone(), f.ty.clone()))
.collect();
let mut provided: HashSet<String> = HashSet::new();
for sf in fields {
let val_ty = self.check_expr(&sf.value, env, assigned);
if provided.contains(&sf.name) {
self.emit(
Diagnostic::error(format!(
"field `{}` specified more than once",
sf.name
))
.with_label(Label::primary(sf.name_span)),
);
continue;
}
provided.insert(sf.name.clone());
match expected.iter().find(|(n, _)| *n == sf.name) {
Some((_, exp_ty)) => {
if !val_ty.is_error()
&& !exp_ty.is_error()
&& !val_ty.promotes_to(exp_ty)
{
self.emit(
Diagnostic::error(format!(
"field `{}`: expected `{}`, got `{}`",
sf.name,
exp_ty.display(),
val_ty.display()
))
.with_label(Label::primary(sf.value.span)),
);
}
}
None => {
self.emit(
Diagnostic::error(format!(
"struct `{name}` has no field `{}`",
sf.name
))
.with_label(Label::primary(sf.name_span)),
);
}
}
}
for (fname, _) in &expected {
if !provided.contains(fname) {
self.emit(
Diagnostic::error(format!(
"missing field `{fname}` in struct literal `{name}`"
))
.with_label(Label::primary(*name_span)),
);
}
}
Ty::Struct(name.clone())
}
// T-Unary
ExprKind::Unary { op, op_span, expr: inner } => {
let inner_ty = self.check_expr(inner, env, assigned);
if inner_ty.is_error() {
return Ty::Error;
}
self.check_unary(*op, *op_span, inner, inner_ty, env)
}
// T-Binary
ExprKind::Binary { op, op_span, lhs, rhs } => {
self.check_binary(*op, *op_span, lhs, rhs, env, assigned)
}
// T-CompoundAssign: lhs op= rhs (expands to lhs = lhs op rhs)
ExprKind::CompoundAssign { op, op_span, lhs, rhs } => {
if !self.is_mutable_place(lhs, env) {
self.emit(
Diagnostic::error(
"left-hand side of compound assignment must be a mutable place",
)
.with_label(Label::primary(lhs.span)),
);
}
let lhs_ty = self.check_expr(lhs, env, assigned);
let rhs_ty = self.check_expr(rhs, env, assigned);
if !lhs_ty.is_error() && !rhs_ty.is_error() {
let bin_op = compound_to_binary(*op);
self.check_arith_or_shift(lhs_ty, rhs_ty, bin_op, *op_span);
}
Ty::Unit
}
// T-Field
ExprKind::Field { expr: inner, field, field_span } => {
let inner_ty = self.check_expr(inner, env, assigned);
if inner_ty.is_error() {
return Ty::Error;
}
let struct_name = match &inner_ty {
Ty::Struct(n) => n.clone(),
_ => {
self.emit(
Diagnostic::error(format!(
"field access on non-struct type `{}`",
inner_ty.display()
))
.with_label(Label::primary(*field_span)),
);
return Ty::Error;
}
};
match self.sigma.field_ty(&struct_name, field) {
Some(ty) => ty.clone(),
None => {
self.emit(
Diagnostic::error(format!(
"struct `{struct_name}` has no field `{field}`"
))
.with_label(Label::primary(*field_span)),
);
Ty::Error
}
}
}
// T-Index
ExprKind::Index { expr: inner, index } => {
let inner_ty = self.check_expr(inner, env, assigned);
let idx_ty = self.check_expr(index, env, assigned);
if inner_ty.is_error() {
return Ty::Error;
}
if !idx_ty.is_error() && !idx_ty.is_integer() {
self.emit(
Diagnostic::error(format!(
"index must be an integer type, got `{}`",
idx_ty.display()
))
.with_label(Label::primary(index.span)),
);
}
match inner_ty {
Ty::Array { elem, .. } => *elem,
Ty::Ptr { pointee, .. } => *pointee,
_ => {
self.emit(
Diagnostic::error(format!(
"indexing requires array or pointer, got `{}`",
inner_ty.display()
))
.with_label(Label::primary(inner.span)),
);
Ty::Error
}
}
}
// T-Call
ExprKind::Call { callee, args } => {
let func_name = match &callee.kind {
ExprKind::Ident(name) => name.clone(),
_ => {
self.emit(
Diagnostic::error("callee must be a function name")
.with_label(Label::primary(callee.span)),
);
for arg in args {
self.check_expr(arg, env, assigned);
}
return Ty::Error;
}
};
let (param_tys, ret_ty) = match self.phi.get(&func_name) {
Some(entry) => {
let pts: Vec<Ty> = entry.params.iter().map(|p| p.ty.clone()).collect();
let ret = entry.ret.clone();
(pts, ret)
}
None => {
self.emit(
Diagnostic::error(format!("undefined function `{func_name}`"))
.with_label(Label::primary(callee.span)),
);
for arg in args {
self.check_expr(arg, env, assigned);
}
return Ty::Error;
}
};
if args.len() != param_tys.len() {
self.emit(
Diagnostic::error(format!(
"`{func_name}` expects {} argument(s), got {}",
param_tys.len(),
args.len()
))
.with_label(Label::primary(callee.span)),
);
}
for (i, arg) in args.iter().enumerate() {
let arg_ty = self.check_expr(arg, env, assigned);
if let Some(exp) = param_tys.get(i) {
if !arg_ty.is_error() && !exp.is_error() && !arg_ty.promotes_to(exp) {
self.emit(
Diagnostic::error(format!(
"argument {}: expected `{}`, got `{}`",
i + 1,
exp.display(),
arg_ty.display()
))
.with_label(Label::primary(arg.span)),
);
}
}
}
ret_ty
}
ExprKind::Group(inner) => self.check_expr(inner, env, assigned),
ExprKind::Error => Ty::Error,
}
}
// ── Unary helper ──────────────────────────────────────────────────────────
fn check_unary(
&mut self,
op: UnaryOp,
op_span: Span,
inner: &ast::Expr<Parsed>,
inner_ty: Ty,
env: &TypeEnv,
) -> Ty {
match op {
UnaryOp::Neg => {
if !inner_ty.is_signed() && !inner_ty.is_float() {
self.emit(
Diagnostic::error(format!(
"unary `-` requires a signed integer or float, got `{}`",
inner_ty.display()
))
.with_label(Label::primary(op_span)),
);
Ty::Error
} else {
inner_ty
}
}
UnaryOp::Not => {
if inner_ty != Ty::Bool {
self.emit(
Diagnostic::error(format!(
"unary `!` requires `bool`, got `{}`",
inner_ty.display()
))
.with_label(Label::primary(op_span)),
);
Ty::Error
} else {
Ty::Bool
}
}
UnaryOp::BitNot => {
if !inner_ty.is_integer() {
self.emit(
Diagnostic::error(format!(
"unary `~` requires an integer type, got `{}`",
inner_ty.display()
))
.with_label(Label::primary(op_span)),
);
Ty::Error
} else {
inner_ty
}
}
UnaryOp::Deref => match &inner_ty {
Ty::Ptr { pointee, .. } => *pointee.clone(),
Ty::OpaquePtr { .. } => {
self.emit(
Diagnostic::error("cannot dereference an opaque pointer")
.with_label(Label::primary(op_span)),
);
Ty::Error
}
_ => {
self.emit(
Diagnostic::error(format!(
"unary `*` requires a pointer, got `{}`",
inner_ty.display()
))
.with_label(Label::primary(op_span)),
);
Ty::Error
}
},
UnaryOp::AddrOf => {
if !self.is_place(inner, env) {
self.emit(
Diagnostic::error("cannot take address of a non-place expression")
.with_label(Label::primary(op_span)),
);
return Ty::Error;
}
let mutable = self.is_mutable_place(inner, env);
Ty::Ptr { mutable, pointee: Box::new(inner_ty) }
}
}
}
// ── Binary helper ─────────────────────────────────────────────────────────
fn check_binary(
&mut self,
op: BinaryOp,
op_span: Span,
lhs: &ast::Expr<Parsed>,
rhs: &ast::Expr<Parsed>,
env: &TypeEnv,
assigned: &HashSet<String>,
) -> Ty {
match op {
// T-Assign
BinaryOp::Assign => {
if !self.is_mutable_place(lhs, env) {
self.emit(
Diagnostic::error(
"left-hand side of `=` must be a mutable place",
)
.with_label(Label::primary(lhs.span)),
);
}
let lhs_ty = self.check_expr(lhs, env, assigned);
let rhs_ty = self.check_expr(rhs, env, assigned);
if !lhs_ty.is_error() && !rhs_ty.is_error() && !rhs_ty.promotes_to(&lhs_ty) {
self.emit(
Diagnostic::error(format!(
"type mismatch: expected `{}`, got `{}`",
lhs_ty.display(),
rhs_ty.display()
))
.with_label(Label::primary(rhs.span)),
);
}
Ty::Unit
}
// Logical
BinaryOp::Or | BinaryOp::And => {
let lhs_ty = self.check_expr(lhs, env, assigned);
let rhs_ty = self.check_expr(rhs, env, assigned);
let kw = if op == BinaryOp::Or { "or" } else { "and" };
if !lhs_ty.is_error() && lhs_ty != Ty::Bool {
self.emit(
Diagnostic::error(format!(
"`{kw}` requires `bool` operands, left side is `{}`",
lhs_ty.display()
))
.with_label(Label::primary(lhs.span)),
);
}
if !rhs_ty.is_error() && rhs_ty != Ty::Bool {
self.emit(
Diagnostic::error(format!(
"`{kw}` requires `bool` operands, right side is `{}`",
rhs_ty.display()
))
.with_label(Label::primary(rhs.span)),
);
}
Ty::Bool
}
// Equality: compatible types OR pointer-compatible
BinaryOp::Eq | BinaryOp::Ne => {
let lhs_ty = self.check_expr(lhs, env, assigned);
let rhs_ty = self.check_expr(rhs, env, assigned);
if !lhs_ty.is_error() && !rhs_ty.is_error() {
let ok = Ty::common(&lhs_ty, &rhs_ty).is_some()
|| Ty::ptr_common(&lhs_ty, &rhs_ty).is_some();
if !ok {
self.emit(
Diagnostic::error(format!(
"cannot compare `{}` with `{}`",
lhs_ty.display(),
rhs_ty.display()
))
.with_label(Label::primary(op_span)),
);
}
}
Ty::Bool
}
// Ordering: numeric or char
BinaryOp::Lt | BinaryOp::Gt | BinaryOp::Le | BinaryOp::Ge => {
let lhs_ty = self.check_expr(lhs, env, assigned);
let rhs_ty = self.check_expr(rhs, env, assigned);
if !lhs_ty.is_error() && !rhs_ty.is_error() {
let ok = match Ty::common(&lhs_ty, &rhs_ty) {
Some(ref c) => c.is_numeric() || *c == Ty::Char,
None => false,
};
if !ok {
self.emit(
Diagnostic::error(format!(
"cannot order `{}` and `{}`",
lhs_ty.display(),
rhs_ty.display()
))
.with_label(Label::primary(op_span)),
);
}
}
Ty::Bool
}
// Bitwise: require matching integer types
BinaryOp::BitOr | BinaryOp::BitXor | BinaryOp::BitAnd => {
let lhs_ty = self.check_expr(lhs, env, assigned);
let rhs_ty = self.check_expr(rhs, env, assigned);
if lhs_ty.is_error() || rhs_ty.is_error() {
return Ty::Error;
}
match Ty::common(&lhs_ty, &rhs_ty) {
Some(ref c) if c.is_integer() => c.clone(),
_ => {
self.emit(
Diagnostic::error(format!(
"bitwise operator requires integer operands, got `{}` and `{}`",
lhs_ty.display(),
rhs_ty.display()
))
.with_label(Label::primary(op_span)),
);
Ty::Error
}
}
}
// Shift: LHS integer, RHS any integer; result type = LHS type
BinaryOp::Shl | BinaryOp::Shr => {
let lhs_ty = self.check_expr(lhs, env, assigned);
let rhs_ty = self.check_expr(rhs, env, assigned);
if lhs_ty.is_error() || rhs_ty.is_error() {
return Ty::Error;
}
if !lhs_ty.is_integer() {
self.emit(
Diagnostic::error(format!(
"shift requires an integer LHS, got `{}`",
lhs_ty.display()
))
.with_label(Label::primary(lhs.span)),
);
return Ty::Error;
}
if !rhs_ty.is_integer() {
self.emit(
Diagnostic::error(format!(
"shift amount must be an integer, got `{}`",
rhs_ty.display()
))
.with_label(Label::primary(rhs.span)),
);
return Ty::Error;
}
lhs_ty
}
// Arithmetic
BinaryOp::Add | BinaryOp::Sub | BinaryOp::Mul | BinaryOp::Div | BinaryOp::Rem => {
let lhs_ty = self.check_expr(lhs, env, assigned);
let rhs_ty = self.check_expr(rhs, env, assigned);
if lhs_ty.is_error() || rhs_ty.is_error() {
return Ty::Error;
}
self.check_arith_or_shift(lhs_ty, rhs_ty, op, op_span)
}
}
}
/// Check that `lhs_ty op rhs_ty` is a valid arithmetic expression;
/// returns the result type.
fn check_arith_or_shift(&mut self, lhs_ty: Ty, rhs_ty: Ty, op: BinaryOp, op_span: Span) -> Ty {
match Ty::common(&lhs_ty, &rhs_ty) {
Some(Ty::Error) => Ty::Error,
Some(ref c) if c.is_numeric() => c.clone(),
_ => {
let sym = match op {
BinaryOp::Add => "+",
BinaryOp::Sub => "-",
BinaryOp::Mul => "*",
BinaryOp::Div => "/",
BinaryOp::Rem => "%",
_ => "op",
};
self.emit(
Diagnostic::error(format!(
"`{sym}` requires numeric operands, got `{}` and `{}`",
lhs_ty.display(),
rhs_ty.display()
))
.with_label(Label::primary(op_span)),
);
Ty::Error
}
}
}
// ── Place predicates ──────────────────────────────────────────────────────
/// Returns true if `expr` is a syntactic place (lvalue).
pub fn is_place(&self, expr: &ast::Expr<Parsed>, env: &TypeEnv) -> bool {
match &expr.kind {
ExprKind::Ident(_) => true,
ExprKind::Unary { op: UnaryOp::Deref, .. } => true,
ExprKind::Field { expr: inner, .. } => self.is_place(inner, env),
ExprKind::Index { expr: inner, .. } => self.is_place(inner, env),
ExprKind::Group(inner) => self.is_place(inner, env),
_ => false,
}
}
/// Returns true if `expr` is a mutable place.
///
/// Rules (§6.3):
/// - `x` is mutable iff `x` is declared `mut`.
/// - `*e` is mutable iff `e` has type `*mut T`.
/// - `e.f` / `e[i]` is mutable iff `e` is mutable.
pub fn is_mutable_place(&self, expr: &ast::Expr<Parsed>, env: &TypeEnv) -> bool {
match &expr.kind {
ExprKind::Ident(name) => {
env.lookup(name).map(|(_, m)| m).unwrap_or(false)
}
ExprKind::Unary { op: UnaryOp::Deref, expr: inner, .. } => {
// Mutable iff inner's type is *mut T.
// We resolve the type of inner from env without emitting errors.
matches!(
self.peek_ty(inner, env),
Some(Ty::Ptr { mutable: true, .. })
)
}
ExprKind::Field { expr: inner, .. } => self.is_mutable_place(inner, env),
ExprKind::Index { expr: inner, .. } => self.is_mutable_place(inner, env),
ExprKind::Group(inner) => self.is_mutable_place(inner, env),
_ => false,
}
}
/// Lightweight type inference for place mutability — does NOT emit diagnostics.
fn peek_ty(&self, expr: &ast::Expr<Parsed>, env: &TypeEnv) -> Option<Ty> {
match &expr.kind {
ExprKind::Ident(name) => env.lookup(name).map(|(ty, _)| ty.clone()),
ExprKind::Group(inner) => self.peek_ty(inner, env),
ExprKind::Unary { op: UnaryOp::Deref, expr: inner, .. } => {
match self.peek_ty(inner, env)? {
Ty::Ptr { pointee, .. } => Some(*pointee),
_ => None,
}
}
ExprKind::Field { expr: inner, field, .. } => {
let Ty::Struct(sname) = self.peek_ty(inner, env)? else {
return None;
};
self.sigma.field_ty(&sname, field).cloned()
}
ExprKind::Index { expr: inner, .. } => {
match self.peek_ty(inner, env)? {
Ty::Array { elem, .. } => Some(*elem),
Ty::Ptr { pointee, .. } => Some(*pointee),
_ => None,
}
}
_ => None,
}
}
}
// ── Helpers ───────────────────────────────────────────────────────────────────
fn compound_to_binary(op: CompoundAssignOp) -> BinaryOp {
match op {
CompoundAssignOp::Add => BinaryOp::Add,
CompoundAssignOp::Sub => BinaryOp::Sub,
CompoundAssignOp::Mul => BinaryOp::Mul,
CompoundAssignOp::Div => BinaryOp::Div,
CompoundAssignOp::Rem => BinaryOp::Rem,
CompoundAssignOp::BitAnd => BinaryOp::BitAnd,
CompoundAssignOp::BitOr => BinaryOp::BitOr,
CompoundAssignOp::BitXor => BinaryOp::BitXor,
CompoundAssignOp::Shl => BinaryOp::Shl,
CompoundAssignOp::Shr => BinaryOp::Shr,
}
}

276
fluxc/src/checker/mod.rs Normal file
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pub mod env;
pub mod expr;
pub mod stmt;
use std::collections::HashSet;
use crate::ast::{self, Parsed, Ty, Type};
use crate::diagnostics::{Diagnostic, Label};
use crate::token::Span;
use env::{FieldEntry, FuncTable, ParamEntry, StructTable};
// ── Checker ────────────────────────────────────────────────────────────────────
pub struct Checker {
pub sigma: StructTable,
pub phi: FuncTable,
pub errors: Vec<Diagnostic>,
}
impl Checker {
fn new() -> Self {
let mut sigma = StructTable::new();
let phi = FuncTable::new();
// Pre-load `string_view` built-in (§3.1): { data: *char, size: u64 }
sigma.insert_name("string_view", Span::new(0, 0));
sigma.add_field(
"string_view",
FieldEntry {
name: "data".to_string(),
name_span: Span::new(0, 0),
ty: Ty::Ptr { mutable: false, pointee: Box::new(Ty::Char) },
ty_span: Span::new(0, 0),
},
);
sigma.add_field(
"string_view",
FieldEntry {
name: "size".to_string(),
name_span: Span::new(0, 0),
ty: Ty::U64,
ty_span: Span::new(0, 0),
},
);
Self { sigma, phi, errors: Vec::new() }
}
pub fn emit(&mut self, diag: Diagnostic) {
self.errors.push(diag);
}
/// Resolve a syntactic `ast::Type` to a semantic `Ty`.
pub fn resolve_type(&mut self, ty: &Type, span: Span) -> Ty {
match ty {
Type::U8 => Ty::U8,
Type::U16 => Ty::U16,
Type::U32 => Ty::U32,
Type::U64 => Ty::U64,
Type::I8 => Ty::I8,
Type::I16 => Ty::I16,
Type::I32 => Ty::I32,
Type::I64 => Ty::I64,
Type::F32 => Ty::F32,
Type::F64 => Ty::F64,
Type::Bool => Ty::Bool,
Type::Char => Ty::Char,
Type::Unit => Ty::Unit,
Type::Named(name, name_span) => {
if self.sigma.contains(name) {
Ty::Struct(name.clone())
} else {
self.emit(
Diagnostic::error(format!("undefined type `{name}`"))
.with_label(Label::primary(*name_span)),
);
Ty::Error
}
}
Type::Pointer { mutable, pointee } => {
let inner = self.resolve_type(pointee, span);
Ty::Ptr { mutable: *mutable, pointee: Box::new(inner) }
}
Type::OpaquePointer { mutable } => Ty::OpaquePtr { mutable: *mutable },
Type::Array { elem, size } => {
let elem_ty = self.resolve_type(elem, span);
match size.parse::<u64>() {
Ok(n) => Ty::Array { elem: Box::new(elem_ty), size: n },
Err(_) => {
self.emit(
Diagnostic::error(format!("invalid array size `{size}`"))
.with_label(Label::primary(span)),
);
Ty::Error
}
}
}
Type::Error => Ty::Error,
}
}
// ── Size-cycle detection ───────────────────────────────────────────────────
fn has_size_cycle(
&self,
name: &str,
gray: &mut HashSet<String>,
black: &mut HashSet<String>,
) -> bool {
if black.contains(name) {
return false;
}
if gray.contains(name) {
return true;
}
gray.insert(name.to_string());
// Collect field types to avoid holding an immutable borrow on self.sigma
// while recursing (which needs immutable access again).
let field_tys: Vec<Ty> = self
.sigma
.fields(name)
.unwrap_or(&[])
.iter()
.map(|f| f.ty.clone())
.collect();
for ty in &field_tys {
if let Some(inner) = value_struct_name(ty) {
if self.has_size_cycle(inner, gray, black) {
gray.remove(name);
return true;
}
}
}
gray.remove(name);
black.insert(name.to_string());
false
}
}
/// Returns the struct name embedded by-value in `ty` (if any).
/// Pointer-to-struct is NOT by-value, so it does not cause a size cycle.
fn value_struct_name(ty: &Ty) -> Option<&str> {
match ty {
Ty::Struct(name) => Some(name.as_str()),
Ty::Array { elem, .. } => value_struct_name(elem),
_ => None,
}
}
// ── Entry point ────────────────────────────────────────────────────────────────
pub fn check(program: &ast::Program<Parsed>) -> Vec<Diagnostic> {
let mut checker = Checker::new();
// ── Pass 1: collect struct names + function signatures ────────────────────
for def in &program.defs {
match &def.kind {
ast::TopLevelDefKind::Struct(s) => {
if s.name == "string_view" {
checker.emit(
Diagnostic::error("`string_view` is a reserved built-in name")
.with_label(Label::primary(s.name_span)),
);
} else if !checker.sigma.insert_name(&s.name, s.name_span) {
checker.emit(
Diagnostic::error(format!("duplicate struct `{}`", s.name))
.with_label(Label::primary(s.name_span)),
);
}
}
ast::TopLevelDefKind::Func(f) => {
let params: Vec<ParamEntry> = f
.params
.iter()
.map(|p| {
let ty = checker.resolve_type(&p.ty, p.name_span);
ParamEntry {
name: p.name.clone(),
name_span: p.name_span,
ty,
mutable: p.mutable,
}
})
.collect();
let ret = match &f.ret_ty {
Some(t) => checker.resolve_type(t, f.name_span),
None => Ty::Unit,
};
if !checker.phi.insert(&f.name, f.name_span, params, ret) {
checker.emit(
Diagnostic::error(format!("duplicate function `{}`", f.name))
.with_label(Label::primary(f.name_span)),
);
}
}
ast::TopLevelDefKind::Error => {}
}
}
// ── Pass 2: resolve struct field types + check for size cycles ────────────
for def in &program.defs {
if let ast::TopLevelDefKind::Struct(s) = &def.kind {
if s.name == "string_view" {
continue; // built-in, already populated
}
for field in &s.fields {
let ty = checker.resolve_type(&field.ty, field.name_span);
checker.sigma.add_field(
&s.name,
FieldEntry {
name: field.name.clone(),
name_span: field.name_span,
ty,
ty_span: field.name_span,
},
);
}
}
}
let struct_names = checker.sigma.all_struct_names();
let mut black = HashSet::new();
for name in struct_names {
let mut gray = HashSet::new();
if checker.has_size_cycle(&name, &mut gray, &mut black) {
if let Some(span) = checker.sigma.name_span(&name) {
checker.emit(
Diagnostic::error(format!(
"struct `{name}` has infinite size (recursive by value)"
))
.with_label(Label::primary(span)),
);
}
}
}
// ── Pass 3: check function bodies ─────────────────────────────────────────
for def in &program.defs {
if let ast::TopLevelDefKind::Func(f) = &def.kind {
checker.check_function(f);
}
}
// ── Pass 4: verify entry point ────────────────────────────────────────────
let main_info = checker
.phi
.get("main")
.map(|e| (e.name_span, e.params.len(), e.ret.clone()));
match main_info {
None => {
checker.emit(
Diagnostic::error("program has no `main` function")
.with_label(Label::primary(program.span)),
);
}
Some((name_span, param_count, ret)) => {
if param_count != 0 {
checker.emit(
Diagnostic::error("`main` must take no parameters")
.with_label(Label::primary(name_span)),
);
}
if ret != Ty::Unit && ret != Ty::I32 && !ret.is_error() {
checker.emit(
Diagnostic::error("`main` must return `()` or `i32`")
.with_label(Label::primary(name_span)),
);
}
}
}
checker.errors
}

365
fluxc/src/checker/stmt.rs Normal file
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use std::collections::HashSet;
use crate::ast::{self, BinaryOp, ElseBranch, ExprKind, Parsed, Ty};
use crate::diagnostics::{Diagnostic, Label};
use super::env::TypeEnv;
use super::Checker;
// ── Control flow ──────────────────────────────────────────────────────────────
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum Cf {
Normal,
Diverges,
}
// ── Check context ─────────────────────────────────────────────────────────────
pub struct CheckCtx {
pub ret_ty: Ty,
pub in_loop: bool,
}
impl CheckCtx {
fn loop_ctx(&self) -> CheckCtx {
CheckCtx { ret_ty: self.ret_ty.clone(), in_loop: true }
}
}
// ── Function entry ────────────────────────────────────────────────────────────
impl Checker {
pub fn check_function(&mut self, f: &ast::FuncDef<Parsed>) {
let (params_info, ret_ty) = {
let entry = self.phi.get(&f.name).expect("function must be in phi after pass 1");
let params: Vec<(String, Ty, bool)> = entry
.params
.iter()
.map(|p| (p.name.clone(), p.ty.clone(), p.mutable))
.collect();
(params, entry.ret.clone())
};
let mut env = TypeEnv::new();
let mut assigned: HashSet<String> = HashSet::new();
for (name, ty, mutable) in params_info {
env.extend(name.clone(), ty, mutable);
assigned.insert(name);
}
let ctx = CheckCtx { ret_ty: ret_ty.clone(), in_loop: false };
let cf = self.check_block(&f.body, &mut env, &mut assigned, &ctx);
// If the declared return type is non-unit and the body may not diverge,
// emit a missing-return error.
if ret_ty != Ty::Unit && !ret_ty.is_error() && cf != Cf::Diverges {
self.emit(
Diagnostic::error(format!(
"function `{}` must always return a value of type `{}`",
f.name,
ret_ty.display()
))
.with_label(Label::primary(f.body.span)),
);
}
}
// ── Block ─────────────────────────────────────────────────────────────────
pub fn check_block(
&mut self,
block: &ast::Block<Parsed>,
env: &mut TypeEnv,
assigned: &mut HashSet<String>,
ctx: &CheckCtx,
) -> Cf {
let saved = env.save();
let mut cf = Cf::Normal;
for stmt in &block.stmts {
if cf == Cf::Diverges {
self.emit(
Diagnostic::warning("unreachable statement")
.with_label(Label::primary(stmt.span)),
);
break;
}
cf = self.check_stmt(stmt, env, assigned, ctx);
}
// Remove block-local variables from assigned (they leave scope).
for var in env.names_in_outer(saved) {
assigned.remove(&var);
}
env.restore(saved);
cf
}
// ── Statement ─────────────────────────────────────────────────────────────
fn check_stmt(
&mut self,
stmt: &ast::Stmt<Parsed>,
env: &mut TypeEnv,
assigned: &mut HashSet<String>,
ctx: &CheckCtx,
) -> Cf {
match &stmt.kind {
// T-Let
ast::StmtKind::Let { mutable, name, name_span, ty, init } => {
let ann_ty = ty.as_ref().map(|t| self.resolve_type(t, *name_span));
let init_ty = init.as_ref().map(|e| {
let t = self.check_expr(e, env, assigned);
// Propagate inner assignments (e.g. `let x = (y = 5);`)
for var in collect_assigns(e) {
assigned.insert(var);
}
t
});
let init_span = init.as_ref().map(|e| e.span).unwrap_or(*name_span);
let resolved = match (ann_ty, init_ty) {
(Some(ann), Some(ref init_t)) => {
if !init_t.is_error() && !ann.is_error() && !init_t.promotes_to(&ann) {
self.emit(
Diagnostic::error(format!(
"type mismatch in `let`: expected `{}`, got `{}`",
ann.display(),
init_t.display()
))
.with_label(Label::primary(init_span)),
);
}
ann
}
(Some(ann), None) => ann,
(None, Some(init)) => init,
(None, None) => {
self.emit(
Diagnostic::error(format!(
"cannot infer type of `{name}`: add a type annotation or initialiser"
))
.with_label(Label::primary(*name_span)),
);
Ty::Error
}
};
env.extend(name.clone(), resolved, *mutable);
if init.is_some() {
assigned.insert(name.clone());
}
Cf::Normal
}
// T-Return
ast::StmtKind::Return(expr) => {
match expr {
Some(e) => {
let ty = self.check_expr(e, env, assigned);
if ctx.ret_ty == Ty::Unit {
if !ty.is_error() && ty != Ty::Unit {
self.emit(
Diagnostic::error(format!(
"this function returns `()`, cannot return `{}`",
ty.display()
))
.with_label(Label::primary(e.span)),
);
}
} else if !ty.is_error()
&& !ctx.ret_ty.is_error()
&& !ty.promotes_to(&ctx.ret_ty)
{
self.emit(
Diagnostic::error(format!(
"type mismatch: expected `{}`, got `{}`",
ctx.ret_ty.display(),
ty.display()
))
.with_label(Label::primary(e.span)),
);
}
}
None => {
if ctx.ret_ty != Ty::Unit && !ctx.ret_ty.is_error() {
self.emit(
Diagnostic::error(format!(
"missing return value: function must return `{}`",
ctx.ret_ty.display()
))
.with_label(Label::primary(stmt.span)),
);
}
}
}
Cf::Diverges
}
// T-If
ast::StmtKind::If { cond, then_block, else_branch } => {
let cond_ty = self.check_expr(cond, env, assigned);
if !cond_ty.is_error() && cond_ty != Ty::Bool {
self.emit(
Diagnostic::error(format!(
"condition must be `bool`, got `{}`",
cond_ty.display()
))
.with_label(Label::primary(cond.span)),
);
}
// Propagate assigns from condition expression
for var in collect_assigns(cond) {
assigned.insert(var);
}
let mut a_then = assigned.clone();
let cf_then = self.check_block(then_block, env, &mut a_then, ctx);
let cf_else = match else_branch {
Some(ElseBranch::Block(b)) => {
let mut a_else = assigned.clone();
let cf = self.check_block(b, env, &mut a_else, ctx);
// A_out = A_then ∩ A_else (both branches definitely assign)
*assigned = a_then.intersection(&a_else).cloned().collect();
cf
}
Some(ElseBranch::If(if_stmt)) => {
let mut a_else = assigned.clone();
let cf = self.check_stmt(if_stmt, env, &mut a_else, ctx);
*assigned = a_then.intersection(&a_else).cloned().collect();
cf
}
None => {
// No else: no new definite assignments (branch might not run)
Cf::Normal
}
};
if cf_then == Cf::Diverges && cf_else == Cf::Diverges {
Cf::Diverges
} else {
Cf::Normal
}
}
// T-While
ast::StmtKind::While { cond, body } => {
let cond_ty = self.check_expr(cond, env, assigned);
if !cond_ty.is_error() && cond_ty != Ty::Bool {
self.emit(
Diagnostic::error(format!(
"while condition must be `bool`, got `{}`",
cond_ty.display()
))
.with_label(Label::primary(cond.span)),
);
}
for var in collect_assigns(cond) {
assigned.insert(var);
}
let loop_ctx = ctx.loop_ctx();
let mut a_body = assigned.clone();
self.check_block(body, env, &mut a_body, &loop_ctx);
// Conservatively Normal: condition might be false on first iteration
Cf::Normal
}
// T-Loop
ast::StmtKind::Loop { body } => {
let loop_ctx = ctx.loop_ctx();
let mut a_body = assigned.clone();
self.check_block(body, env, &mut a_body, &loop_ctx);
// Conservatively Normal: might break
Cf::Normal
}
ast::StmtKind::Break => {
if !ctx.in_loop {
self.emit(
Diagnostic::error("`break` outside of a loop")
.with_label(Label::primary(stmt.span)),
);
}
Cf::Diverges
}
ast::StmtKind::Continue => {
if !ctx.in_loop {
self.emit(
Diagnostic::error("`continue` outside of a loop")
.with_label(Label::primary(stmt.span)),
);
}
Cf::Diverges
}
ast::StmtKind::Block(block) => self.check_block(block, env, assigned, ctx),
// T-ExprStmt
ast::StmtKind::Expr(expr) => {
self.check_expr(expr, env, assigned);
for var in collect_assigns(expr) {
assigned.insert(var);
}
Cf::Normal
}
ast::StmtKind::Error => Cf::Normal,
}
}
}
// ── assigns(e) — §8.5 ────────────────────────────────────────────────────────
/// Collect the set of variable names that are directly (re-)assigned as a
/// side-effect of evaluating `expr`. Only simple `ident = …` assignments
/// contribute; compound places (`s.f = …`) are excluded.
pub fn collect_assigns(expr: &ast::Expr<Parsed>) -> HashSet<String> {
let mut set = HashSet::new();
collect_assigns_inner(expr, &mut set);
set
}
fn collect_assigns_inner(expr: &ast::Expr<Parsed>, set: &mut HashSet<String>) {
match &expr.kind {
ExprKind::Binary { op, lhs, rhs, .. } => {
if *op == BinaryOp::Assign {
collect_assigns_inner(rhs, set);
if let ExprKind::Ident(name) = &lhs.kind {
set.insert(name.clone());
}
} else {
collect_assigns_inner(lhs, set);
collect_assigns_inner(rhs, set);
}
}
ExprKind::CompoundAssign { rhs, .. } => {
// Compound assign requires lhs to already be assigned (read side),
// so we only propagate from rhs.
collect_assigns_inner(rhs, set);
}
ExprKind::StructLit { fields, .. } => {
for f in fields {
collect_assigns_inner(&f.value, set);
}
}
ExprKind::Group(inner) => collect_assigns_inner(inner, set),
ExprKind::Unary { expr, .. } => collect_assigns_inner(expr, set),
ExprKind::Field { expr, .. } => collect_assigns_inner(expr, set),
ExprKind::Index { expr, index } => {
collect_assigns_inner(expr, set);
collect_assigns_inner(index, set);
}
ExprKind::Call { callee, args } => {
collect_assigns_inner(callee, set);
for a in args {
collect_assigns_inner(a, set);
}
}
// Leaves (literals, ident, bool, error) don't assign anything
_ => {}
}
}

View File

@@ -3,6 +3,7 @@ use std::{fs, process};
use crate::parser::Parser;
pub mod ast;
pub mod checker;
pub mod cli;
pub mod diagnostics;
pub mod lexer;
@@ -24,7 +25,13 @@ fn main() {
had_errors = true;
}
println!("{program:#?}");
if parser.errors.is_empty() {
let sema_errors = checker::check(&program);
for diag in &sema_errors {
eprint!("{}", diag.render(&content, path));
had_errors = true;
}
}
}
if had_errors {