runtime, vm: write thunk results back to the forcing stack slot

fix-runtime/src/machine.rs

@@ -75,6 +75,7 @@ pub trait Machine<'gc> {
             pc: ret_pc,
             thunk: _,
             env,
+            depth: None,
         }) = self.pop_call_frame()
         else {
             unreachable!()

fix-runtime/src/state.rs

@@ -59,8 +59,9 @@ pub struct ErrorFrame {
 #[collect(no_drop)]
 pub struct CallFrame<'gc> {
     pub pc: usize,
-    pub thunk: Option<Gc<'gc, Thunk<'gc>>>,
     pub env: GcEnv<'gc>,
+    pub thunk: Option<Gc<'gc, Thunk<'gc>>>,
+    pub depth: Option<usize>,
 }
 
 #[derive(Debug)]

fix-runtime/src/value.rs

@@ -26,11 +26,11 @@ pub trait ValueVariant<'gc>: private::Cealed {
         private_bounds,
         reason = "Storable is a sealed implementation detail of the value system"
     )]
-    type Ty: Storable + 'gc;
+    type Ty: Storable<'gc>;
     const TYPE: NixType;
 }
 
-trait Storable: private::Cealed {
+trait Storable<'gc>: TryFrom<Value<'gc>> + Into<Value<'gc>> + private::Cealed + 'gc {
     fn is(raw: &RawBox) -> bool;
 
     fn to_raw_box(self) -> RawBox;
@@ -46,7 +46,7 @@ macro_rules! define_value_types {
         gc { $($gtype:ty => $gtag:path, $gty:path, $gname:literal;)* }
     ) => {
         $(
-        impl Storable for $itype {
+        impl Storable<'_> for $itype {
             #[inline(always)]
             fn is(value: &RawBox) -> bool {
                 value.tag() == Some($itag)
@@ -80,7 +80,7 @@ macro_rules! define_value_types {
         }
         )*
         $(
-        impl Storable for Gc<'_, $gtype> {
+        impl<'gc> Storable<'gc> for Gc<'gc, unelide_lifetimes!('gc; $gtype)> {
             #[inline(always)]
             fn is(value: &RawBox) -> bool {
                 value.tag() == Some($gtag)
@@ -202,7 +202,7 @@ define_value_types! {
 
 impl private::Cealed for f64 {}
 
-impl Storable for f64 {
+impl Storable<'_> for f64 {
     #[inline(always)]
     fn is(value: &RawBox) -> bool {
         value.is_float()
@@ -224,7 +224,14 @@ impl<'gc> ValueVariant<'gc> for f64 {
     const TYPE: NixType = NixType::Float;
 }
 
-impl<'gc, T: Storable + 'gc> From<T> for Value<'gc> {
+impl<'gc> TryFrom<Value<'gc>> for f64 {
+    type Error = ();
+    fn try_from(value: Value<'gc>) -> Result<Self, Self::Error> {
+        value.downcast::<f64>().ok_or(())
+    }
+}
+
+impl<'gc, T: Storable<'gc>> From<T> for Value<'gc> {
     fn from(value: T) -> Self {
         Value::new(value)
     }
@@ -260,7 +267,7 @@ impl<'gc> Value<'gc> {
         private_bounds,
         reason = "Storable is a sealed implementation detail of the value system"
     )]
-    pub fn new<T: Storable>(val: T) -> Self {
+    pub fn new<T: Storable<'gc>>(val: T) -> Self {
         Self {
             raw: val.to_raw_box(),
             _marker: PhantomData,
@@ -380,7 +387,7 @@ impl StaticValue {
         private_bounds,
         reason = "Storable is a sealed implementation detail of the value system"
     )]
-    pub fn new<T: Storable + 'static>(val: T) -> Self {
+    pub fn new<T: Storable<'static>>(val: T) -> Self {
         Self(Value::new(val))
     }
 
@@ -597,14 +604,6 @@ pub struct Env<'gc> {
 }
 pub type GcEnv<'gc> = GcRefLock<'gc, Env<'gc>>;
 
-#[derive(Collect, Debug)]
-#[collect(no_drop)]
-pub struct WithEnv<'gc> {
-    pub env: Value<'gc>,
-    pub prev: Option<GcWithEnv<'gc>>,
-}
-pub type GcWithEnv<'gc> = Gc<'gc, WithEnv<'gc>>;
-
 impl<'gc> Env<'gc> {
     pub fn empty() -> Self {
         Env {
@@ -722,6 +721,13 @@ impl<'gc> From<StrictValue<'gc>> for Value<'gc> {
     }
 }
 
+impl<'gc> TryFrom<Value<'gc>> for StrictValue<'gc> {
+    type Error = Gc<'gc, Thunk<'gc>>;
+    fn try_from(value: Value<'gc>) -> Result<Self, Self::Error> {
+        value.restrict()
+    }
+}
+
 impl fmt::Debug for StrictValue<'_> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         fmt::Debug::fmt(&self.0, f)