Resolve types at fragment-combine time (#1060)

Signed-off-by: Craig Disselkoen <cdiss@amazon.com>
Co-authored-by: John Kastner <130772734+john-h-kastner-aws@users.noreply.github.com>

cedar-policy-core/Cargo.toml

@@ -20,6 +20,7 @@ lalrpop-util = { version = "0.20.0", features = ["lexer"] }
 lazy_static = "1.4"
 either = "1.8"
 itertools = "0.13"
+ref-cast = "1.0"
 rustc_lexer = "0.1"
 thiserror = "1.0"
 smol_str = { version = "0.2", features = ["serde"] }

cedar-policy-core/src/ast/entity.rs

@@ -24,6 +24,7 @@ use crate::transitive_closure::TCNode;
 use crate::FromNormalizedStr;
 use itertools::Itertools;
 use miette::Diagnostic;
+use ref_cast::RefCast;
 use serde::{Deserialize, Serialize};
 use serde_with::{serde_as, TryFromInto};
 use smol_str::SmolStr;
@@ -35,9 +36,10 @@ use thiserror::Error;
 pub static ACTION_ENTITY_TYPE: &str = "Action";
 
 /// Entity type names are just [`Name`]s, but we have some operations on them specific to entity types.
-#[derive(Serialize, Deserialize, PartialEq, Eq, Debug, Clone, Hash, PartialOrd, Ord)]
+#[derive(Serialize, Deserialize, PartialEq, Eq, Debug, Clone, Hash, PartialOrd, Ord, RefCast)]
 #[cfg_attr(feature = "arbitrary", derive(arbitrary::Arbitrary))]
 #[serde(transparent)]
+#[repr(transparent)]
 pub struct EntityType(Name);
 
 impl EntityType {
@@ -59,15 +61,14 @@ impl EntityType {
         self.0.as_ref().loc()
     }
 
-    /// Calls [`Name::qualify_with`] on the underlying [`Name`]
+    /// Calls [`Name::qualify_with_name`] on the underlying [`Name`]
     pub fn qualify_with(&self, namespace: Option<&Name>) -> Self {
-        Self(self.0.qualify_with(namespace))
+        Self(self.0.qualify_with_name(namespace))
     }
 
     /// Wraps [`Name::from_normalized_str`]
     pub fn from_normalized_str(src: &str) -> Result<Self, ParseErrors> {
-        UncheckedName::from_normalized_str(src)
-            .and_then(|n| n.try_into().map(Self).map_err(ParseErrors::singleton))
+        Name::from_normalized_str(src).map(Into::into)
     }
 }
 
@@ -77,6 +78,12 @@ impl From<Name> for EntityType {
     }
 }
 
+impl From<EntityType> for Name {
+    fn from(ty: EntityType) -> Name {
+        ty.0
+    }
+}
+
 impl AsRef<Name> for EntityType {
     fn as_ref(&self) -> &Name {
         &self.0

cedar-policy-core/src/ast/expr.rs

@@ -1463,6 +1463,16 @@ impl From<Var> for Id {
     }
 }
 
+// PANIC SAFETY Tested by `test::all_vars_are_ids`. Never panics.
+#[allow(clippy::fallible_impl_from)]
+impl From<Var> for UnreservedId {
+    fn from(var: Var) -> Self {
+        // PANIC SAFETY: `Var` is a simple enum and all vars are formatted as valid `UnreservedId`. Tested by `test::all_vars_are_ids`
+        #[allow(clippy::unwrap_used)]
+        Id::from(var).try_into().unwrap()
+    }
+}
+
 impl std::fmt::Display for Var {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         match self {
@@ -1487,6 +1497,7 @@ mod test {
     fn all_vars_are_ids() {
         for var in all_vars() {
             let _id: Id = var.into();
+            let _id: UnreservedId = var.into();
         }
     }
 

cedar-policy-core/src/ast/id.rs

@@ -19,7 +19,7 @@ use smol_str::SmolStr;
 
 use crate::{parser::err::ParseErrors, FromNormalizedStr};
 
-use super::{ReservedNameError, UncheckedName};
+use super::{InternalName, ReservedNameError};
 
 const RESERVED_ID: &str = "__cedar";
 
@@ -106,13 +106,19 @@ impl TryFrom<Id> for UnreservedId {
     type Error = ReservedNameError;
     fn try_from(value: Id) -> Result<Self, Self::Error> {
         if value.is_reserved() {
-            Err(ReservedNameError(UncheckedName::unqualified_name(value)))
+            Err(ReservedNameError(InternalName::unqualified_name(value)))
         } else {
             Ok(Self(value))
         }
     }
 }
 
+impl AsRef<Id> for UnreservedId {
+    fn as_ref(&self) -> &Id {
+        &self.0
+    }
+}
+
 impl AsRef<str> for UnreservedId {
     fn as_ref(&self) -> &str {
         self.0.as_ref()