diff --git a/examples/deref_assign.rs b/examples/deref_assign.rs
index aad858cc16bbd554ea620a225d1ea712129cd235..c915288c2867a519709259ad7dae7407561439f0 100644
--- a/examples/deref_assign.rs
+++ b/examples/deref_assign.rs
@@ -1,6 +1,6 @@
-fn main() -> i32 {
+fn main() {
let mut a = 7;
let b = &mut a;
*b = 9;
- a
+ let c = a;
}
diff --git a/examples/deref_assign2.rs b/examples/deref_assign2.rs
index 2d6189d2c98e2837a3790d441d3119ba3e70743d..53a1872cdf55a3827ffd761a6fc681dc96afd13e 100644
--- a/examples/deref_assign2.rs
+++ b/examples/deref_assign2.rs
@@ -1,7 +1,7 @@
-fn main() -> i32 {
+fn main() {
let mut a = 7;
- let b = &a;
- let c = &b;
- **c = 9;
- a
+ let mut b = &a;
+ let c = &mut b;
+ *(*c) = 9;
+ let d = a;
}
diff --git a/examples/ref_err4.rs b/examples/ref_err4.rs
new file mode 100644
index 0000000000000000000000000000000000000000..2c105f44cba6e9cfe4ad4406c2f45ab42a567555
--- /dev/null
+++ b/examples/ref_err4.rs
@@ -0,0 +1,5 @@
+fn main() {
+ let mut a = 1;
+ let b = &a;
+ let mut c: &mut &i32 = &mut b;
+}
diff --git a/src/check.rs b/src/check.rs
index 18c42be5f4caca3f1749045cf1bb52fd551807a4..0fe868dabb40c4e5a5db5b9eb9b84d98cb17d836 100644
--- a/src/check.rs
+++ b/src/check.rs
@@ -183,149 +183,6 @@ fn strip_mut(t: Type) -> Type {
}
}
-// // walk the left hand expression in an assignment.
-// // Ok(Type), the type of the left hand
-// // Err(), illegal left hand
-// fn left_expr_type(e: &Expr, to_type: Type, var_env: &mut VarEnv) -> Result<(), Error> {
-// match e {
-// Expr::Id(id) => {
-// match var_env.get(id.clone()) {
-// Some((true, Some(t))) => {
-// match *t == to_type {
-// true => Ok(()), // mutable, defined of same type
-// false => Err("types differ".to_string()),
-// }
-// }
-// Some((true, None)) => unimplemented!(),
-// Some((false, _)) => Err("variable declared immutable".to_string()),
-// None => Err("variable not in scope".to_string()),
-// }
-// }
-// Expr::DeRef(ref_mut_e) => {
-// let e: &Expr = &*ref_mut_e;
-// trace!("DeRef({})", e);
-// match e {
-// Expr::RefMut(e) => left_expr_type(&*e, to_type, var_env),
-// _ => Err("cannot deref left hand expression".to_string()),
-// }
-// // }
-// // let ref_mut_id = left_expr_type(ref_mut_e, var_env)?;
-// // trace!("left: RefMut({})", ref_mut_id);
-
-// // match var_env.get(ref_mut_id) {
-// // Some(Val::Ref(id)) => {
-// // println!("Ref id {}", id);
-// // id.clone()
-// // }
-// // Some(Val::RefMut(id)) => {
-// // println!("RefMut id {}", id);
-// // id.clone()
-// // }
-// // _ => panic!("deref failed"),
-// // }
-
-// // Ok(ref_mut_id)
-// }
-
-// // let ev = eval_left_expr(e, m, fn_env);
-// // println!("eval_left {:?}", ev);
-
-// // match m.get(ev) {
-// // Some(Val::Ref(id)) => {
-// // println!("Ref id {}", id);
-// // id.clone()
-// // }
-// // Some(Val::RefMut(id)) => {
-// // println!("RefMut id {}", id);
-// // id.clone()
-// // }
-// // _ => panic!("deref failed"),
-// // }
-// _ => Err(format!("illegal left hand expression {}", e)),
-// }
-// }
-
-// walk the left hand expression in an assignment.
-// Ok(Type), the type of the left hand
-// Err(), illegal left hand
-fn left_expr_type(e: &Expr, var_env: &mut VarEnv) -> Result<Id, Error> {
- match e {
- Expr::Id(id) => Ok(id.to_owned()),
- // match var_env.get(id.clone()) {
- // Some((true, Some(t))) => {
- // match *t == to_type {
- // true => Ok(()), // mutable, defined of same type
- // false => Err("types differ".to_string()),
- // }
- // }
- // Some((true, None)) => unimplemented!(),
- // Some((false, _)) => Err("variable declared immutable".to_string()),
- // None => Err("variable not in scope".to_string()),
- // }
- // }
- Expr::DeRef(ref_mut_e) => {
- trace!("DeRef({})", ref_mut_e);
- let lh = left_expr_type(ref_mut_e, var_env)?;
- trace!("DeRef({})", lh);
- match var_env.get(lh) {
- Some(t) => {
- trace!("t {:?}", t);
- panic!();
- }
- // match *t == to_type {
- // true => Ok(()), // mutable, defined of same type
- // false => Err("types differ".to_string()),
- // }
- // }
- // Some((true, None)) => unimplemented!(),
- // Some((false, _)) => Err("variable declared immutable".to_string()),
- None => Err("variable not in scope".to_string()),
- }
- }
-
- // match e {
- // Expr::RefMut(e) => left_expr_type(&*e, to_type, var_env),
- // _ => Err("cannot deref left hand expression".to_string()),
- // }
- // }
- // println!("eval_left deref e {:?}", e);
-
- // let ev = eval_left_expr(e, m, fn_env);
- // println!("eval_left {:?}", ev);
-
- // match m.get(ev) {
- // Some(Val::Ref(id)) => {
- // println!("Ref id {}", id);
- // id.clone()
- // }
- // Some(Val::RefMut(id)) => {
- // println!("RefMut id {}", id);
- // id.clone()
- // }
- // _ => panic!("deref failed"),
- // }
-
- // Ok(ref_mut_id)
- // }
-
- // let ev = eval_left_expr(e, m, fn_env);
- // println!("eval_left {:?}", ev);
-
- // match m.get(ev) {
- // Some(Val::Ref(id)) => {
- // println!("Ref id {}", id);
- // id.clone()
- // }
- // Some(Val::RefMut(id)) => {
- // println!("RefMut id {}", id);
- // id.clone()
- // }
- // _ => panic!("deref failed"),
- // }
- _ => Err(format!("illegal left hand expression {}", e)),
- }
-}
-
pub fn check_stmts(
stmts: &Stmts,
fn_env: &FnEnv,
@@ -369,13 +226,22 @@ pub fn check_stmts(
}
Assign(lh, e) => {
- let expr_type = expr_type(&*e, fn_env, type_env, var_env)?;
- trace!("expr_type = {}", expr_type);
- trace!("v = {:?}", lh);
+ let e_type = expr_type(&*e, fn_env, type_env, var_env)?;
+ trace!("e_type = {}", e_type);
+ trace!("lh = {:?}", lh);
- let id = left_expr_type(&*lh, var_env)?;
- // var_env.update(id, expr_type)?;
- Ok(Type::Unit)
+ let lh_type = expr_type(lh, fn_env, type_env, var_env)?;
+ trace!("lh_type {}", &lh_type);
+
+ if match &lh_type {
+ Type::Mut(t) => **t == e_type,
+
+ _ => Err(format!("assignment to immutable"))?,
+ } {
+ Ok(Type::Unit)
+ } else {
+ Err(format!("cannot assign {} = {}", &lh_type, e_type))
+ }
}
While(e, block) => match expr_type(&*e, fn_env, type_env, var_env) {
diff --git a/tests/test_check.rs b/tests/test_check.rs
index 659152a951d52b193d05de1937e63c86c242e7b6..844b0b1395d6d8b47a3b8abb5a52e84cb206b7a2 100644
--- a/tests/test_check.rs
+++ b/tests/test_check.rs
@@ -144,3 +144,8 @@ fn check_ref_err2() {
fn check_ref_err3() {
assert!(check(&read_file::parse("examples/ref_err3.rs")).is_err());
}
+
+#[test]
+fn check_ref_err4() {
+ assert!(check(&read_file::parse("examples/ref_err4.rs")).is_err());
+}