From 997a731456d467252086bedf56d1d574d7433eed Mon Sep 17 00:00:00 2001
From: ilyalesokhin-starkware <ilya@starkware.co>
Date: Tue, 9 Apr 2024 15:57:43 +0300
Subject: [PATCH] Add phantom types to sierra-gen. (#5382)

---
 crates/cairo-lang-semantic/src/types.rs          | 12 +++++++++++-
 crates/cairo-lang-sierra-generator/src/db.rs     | 16 +++++++++++++++-
 .../src/replace_ids.rs                           |  3 ++-
 crates/cairo-lang-sierra-generator/src/types.rs  |  7 +++++++
 4 files changed, 35 insertions(+), 3 deletions(-)

diff --git a/crates/cairo-lang-semantic/src/types.rs b/crates/cairo-lang-semantic/src/types.rs
index 094f024c181..789449050fd 100644
--- a/crates/cairo-lang-semantic/src/types.rs
+++ b/crates/cairo-lang-semantic/src/types.rs
@@ -5,7 +5,7 @@ use cairo_lang_defs::ids::{
 };
 use cairo_lang_diagnostics::{DiagnosticAdded, Maybe};
 use cairo_lang_proc_macros::SemanticObject;
-use cairo_lang_syntax::attribute::consts::MUST_USE_ATTR;
+use cairo_lang_syntax::attribute::consts::{MUST_USE_ATTR, PHANTOM_ATTR};
 use cairo_lang_syntax::node::ids::SyntaxStablePtrId;
 use cairo_lang_syntax::node::{ast, TypedStablePtr, TypedSyntaxNode};
 use cairo_lang_utils::{define_short_id, try_extract_matches, OptionFrom};
@@ -219,6 +219,16 @@ impl ConcreteTypeId {
             )
         }
     }
+
+    /// Returns whether the type has the `#[phantom]` attribute.
+    pub fn is_phantom(&self, db: &dyn SemanticGroup) -> Maybe<bool> {
+        match self {
+            ConcreteTypeId::Struct(id) => id.has_attr(db, PHANTOM_ATTR),
+            ConcreteTypeId::Enum(id) => id.has_attr(db, PHANTOM_ATTR),
+            ConcreteTypeId::Extern(id) => id.has_attr(db, PHANTOM_ATTR),
+        }
+    }
+
     /// Returns whether the type has the `#[must_use]` attribute.
     pub fn is_must_use(&self, db: &dyn SemanticGroup) -> Maybe<bool> {
         match self {
diff --git a/crates/cairo-lang-sierra-generator/src/db.rs b/crates/cairo-lang-sierra-generator/src/db.rs
index 43c767a5d61..fc4ba3749ff 100644
--- a/crates/cairo-lang-sierra-generator/src/db.rs
+++ b/crates/cairo-lang-sierra-generator/src/db.rs
@@ -25,6 +25,9 @@ pub enum SierraGeneratorTypeLongId {
     Regular(Arc<cairo_lang_sierra::program::ConcreteTypeLongId>),
     /// The long id for cycle breakers, such as `Box` and `Nullable`.
     CycleBreaker(semantic::TypeId),
+    /// This is a long id of a phantom type.
+    /// Phantom types have a one to one mapping from the semantic type to the sierra type.
+    Phantom(semantic::TypeId),
 }
 
 #[salsa::query_group(SierraGenDatabase)]
@@ -198,6 +201,16 @@ fn get_type_info(
                 zero_sized: false,
             }));
         }
+        SierraGeneratorTypeLongId::Phantom(ty) => {
+            let long_id = db.get_concrete_long_type_id(ty)?.as_ref().clone();
+            return Ok(Arc::new(cairo_lang_sierra::extensions::types::TypeInfo {
+                long_id,
+                storable: false,
+                droppable: false,
+                duplicatable: false,
+                zero_sized: false,
+            }));
+        }
     };
     let concrete_ty = cairo_lang_sierra::extensions::core::CoreType::specialize_by_id(
         &SierraSignatureSpecializationContext(db),
@@ -219,6 +232,7 @@ pub fn sierra_concrete_long_id(
 ) -> Maybe<Arc<cairo_lang_sierra::program::ConcreteTypeLongId>> {
     match db.lookup_intern_concrete_type(concrete_type_id) {
         SierraGeneratorTypeLongId::Regular(long_id) => Ok(long_id),
-        SierraGeneratorTypeLongId::CycleBreaker(type_id) => db.get_concrete_long_type_id(type_id),
+        SierraGeneratorTypeLongId::Phantom(type_id)
+        | SierraGeneratorTypeLongId::CycleBreaker(type_id) => db.get_concrete_long_type_id(type_id),
     }
 }
diff --git a/crates/cairo-lang-sierra-generator/src/replace_ids.rs b/crates/cairo-lang-sierra-generator/src/replace_ids.rs
index 864ec7cd193..ac227235e30 100644
--- a/crates/cairo-lang-sierra-generator/src/replace_ids.rs
+++ b/crates/cairo-lang-sierra-generator/src/replace_ids.rs
@@ -105,7 +105,8 @@ impl SierraIdReplacer for DebugReplacer<'_> {
         id: &cairo_lang_sierra::ids::ConcreteTypeId,
     ) -> cairo_lang_sierra::ids::ConcreteTypeId {
         match self.db.lookup_intern_concrete_type(id.clone()) {
-            SierraGeneratorTypeLongId::CycleBreaker(ty) => ty.format(self.db.upcast()).into(),
+            SierraGeneratorTypeLongId::Phantom(ty)
+            | SierraGeneratorTypeLongId::CycleBreaker(ty) => ty.format(self.db.upcast()).into(),
             SierraGeneratorTypeLongId::Regular(long_id) => {
                 let mut long_id = long_id.as_ref().clone();
                 self.replace_generic_args(&mut long_id.generic_args);
diff --git a/crates/cairo-lang-sierra-generator/src/types.rs b/crates/cairo-lang-sierra-generator/src/types.rs
index 43942bcb0c6..09428dec8b4 100644
--- a/crates/cairo-lang-sierra-generator/src/types.rs
+++ b/crates/cairo-lang-sierra-generator/src/types.rs
@@ -36,6 +36,13 @@ pub fn get_concrete_type_id(
         ) if db.is_self_referential(type_id)? => {
             Ok(db.intern_concrete_type(SierraGeneratorTypeLongId::CycleBreaker(type_id)))
         }
+
+        semantic::TypeLongId::Concrete(concrete_type_id)
+            if concrete_type_id.is_phantom(db.upcast())? =>
+        {
+            Ok(db.intern_concrete_type(SierraGeneratorTypeLongId::Phantom(type_id)))
+        }
+
         _ => Ok(db.intern_concrete_type(SierraGeneratorTypeLongId::Regular(
             db.get_concrete_long_type_id(type_id)?,
         ))),