Implement OrdWithEngines for some types (#4082)

## Description

This PR is a subset of #3744. It adds a `OrdWithEngines` for the types
required in #3744. Note---this isn't a necessary change into master
right at this current moment, just simply a way of breaking up #3744 😄

## Checklist

- [x] I have linked to any relevant issues.
- [x] I have commented my code, particularly in hard-to-understand
areas.
- [ ] I have updated the documentation where relevant (API docs, the
reference, and the Sway book).
- [ ] I have added tests that prove my fix is effective or that my
feature works.
- [x] I have added (or requested a maintainer to add) the necessary
`Breaking*` or `New Feature` labels where relevant.
- [x] I have done my best to ensure that my PR adheres to [the Fuel Labs
Code Review
Standards](https://github.com/FuelLabs/rfcs/blob/master/text/code-standards/external-contributors.md).
- [x] I have requested a review from the relevant team or maintainers.

Author: emilyaherbert

sway-core/src/engine_threading.rs

@@ -87,6 +87,24 @@ impl<T: PartialEqWithEngines> PartialEq for WithEngines<'_, T> {
 
 impl<T: EqWithEngines> Eq for WithEngines<'_, T> {}
 
+impl<T: OrdWithEngines> PartialOrd for WithEngines<'_, T>
+where
+    T: PartialEqWithEngines,
+{
+    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
+        Some(self.thing.cmp(&other.thing, self.engines.te()))
+    }
+}
+
+impl<T: OrdWithEngines> Ord for WithEngines<'_, T>
+where
+    T: EqWithEngines,
+{
+    fn cmp(&self, other: &Self) -> Ordering {
+        self.thing.cmp(&other.thing, self.engines.te())
+    }
+}
+
 pub(crate) trait DisplayWithEngines {
     fn fmt(&self, f: &mut fmt::Formatter<'_>, engines: Engines<'_>) -> fmt::Result;
 }
@@ -141,7 +159,7 @@ pub trait PartialEqWithEngines {
 }
 
 pub trait OrdWithEngines {
-    fn cmp(&self, rhs: &Self, type_engine: &TypeEngine) -> Ordering;
+    fn cmp(&self, other: &Self, type_engine: &TypeEngine) -> Ordering;
 }
 
 impl<T: EqWithEngines + ?Sized> EqWithEngines for &T {}
@@ -151,8 +169,19 @@ impl<T: PartialEqWithEngines + ?Sized> PartialEqWithEngines for &T {
     }
 }
 impl<T: OrdWithEngines + ?Sized> OrdWithEngines for &T {
-    fn cmp(&self, rhs: &Self, type_engine: &TypeEngine) -> Ordering {
-        (*self).cmp(*rhs, type_engine)
+    fn cmp(&self, other: &Self, type_engine: &TypeEngine) -> Ordering {
+        (*self).cmp(*other, type_engine)
+    }
+}
+
+impl<T: OrdWithEngines> OrdWithEngines for Option<T> {
+    fn cmp(&self, other: &Self, type_engine: &TypeEngine) -> Ordering {
+        match (self, other) {
+            (Some(x), Some(y)) => x.cmp(y, type_engine),
+            (Some(_), None) => Ordering::Less,
+            (None, Some(_)) => Ordering::Greater,
+            (None, None) => Ordering::Equal,
+        }
     }
 }
 
@@ -174,11 +203,11 @@ impl<T: PartialEqWithEngines> PartialEqWithEngines for [T] {
     }
 }
 impl<T: OrdWithEngines> OrdWithEngines for [T] {
-    fn cmp(&self, rhs: &Self, type_engine: &TypeEngine) -> Ordering {
+    fn cmp(&self, other: &Self, type_engine: &TypeEngine) -> Ordering {
         self.iter()
-            .zip(rhs.iter())
+            .zip(other.iter())
             .map(|(x, y)| x.cmp(y, type_engine))
             .find(|o| o.is_ne())
-            .unwrap_or_else(|| self.len().cmp(&rhs.len()))
+            .unwrap_or_else(|| self.len().cmp(&other.len()))
     }
 }

sway-core/src/language/ty/declaration/enum.rs

@@ -1,4 +1,7 @@
-use std::hash::{Hash, Hasher};
+use std::{
+    cmp::Ordering,
+    hash::{Hash, Hasher},
+};
 
 use sway_error::error::CompileError;
 use sway_types::{Ident, Span, Spanned};
@@ -154,6 +157,32 @@ impl PartialEqWithEngines for TyEnumVariant {
     }
 }
 
+impl OrdWithEngines for TyEnumVariant {
+    fn cmp(&self, other: &Self, type_engine: &TypeEngine) -> Ordering {
+        let TyEnumVariant {
+            name: ln,
+            type_argument: lta,
+            tag: lt,
+            // these fields are not compared because they aren't relevant/a
+            // reliable source of obj v. obj distinction
+            span: _,
+            attributes: _,
+        } = self;
+        let TyEnumVariant {
+            name: rn,
+            type_argument: rta,
+            tag: rt,
+            // these fields are not compared because they aren't relevant/a
+            // reliable source of obj v. obj distinction
+            span: _,
+            attributes: _,
+        } = other;
+        ln.cmp(rn)
+            .then_with(|| lta.cmp(rta, type_engine))
+            .then_with(|| lt.cmp(rt))
+    }
+}
+
 impl SubstTypes for TyEnumVariant {
     fn subst_inner(&mut self, type_mapping: &TypeSubstMap, engines: Engines<'_>) {
         self.type_argument.subst_inner(type_mapping, engines);

sway-core/src/language/ty/declaration/struct.rs

@@ -1,4 +1,7 @@
-use std::hash::{Hash, Hasher};
+use std::{
+    cmp::Ordering,
+    hash::{Hash, Hasher},
+};
 
 use sway_error::error::CompileError;
 use sway_types::{Ident, Span, Spanned};
@@ -161,6 +164,28 @@ impl PartialEqWithEngines for TyStructField {
     }
 }
 
+impl OrdWithEngines for TyStructField {
+    fn cmp(&self, other: &Self, type_engine: &TypeEngine) -> Ordering {
+        let TyStructField {
+            name: ln,
+            type_argument: lta,
+            // these fields are not compared because they aren't relevant/a
+            // reliable source of obj v. obj distinction
+            span: _,
+            attributes: _,
+        } = self;
+        let TyStructField {
+            name: rn,
+            type_argument: rta,
+            // these fields are not compared because they aren't relevant/a
+            // reliable source of obj v. obj distinction
+            span: _,
+            attributes: _,
+        } = other;
+        ln.cmp(rn).then_with(|| lta.cmp(rta, type_engine))
+    }
+}
+
 impl SubstTypes for TyStructField {
     fn subst_inner(&mut self, type_mapping: &TypeSubstMap, engines: Engines<'_>) {
         self.type_argument.subst_inner(type_mapping, engines);

sway-core/src/semantic_analysis/namespace/trait_map.rs

@@ -1,4 +1,7 @@
-use std::collections::{BTreeMap, BTreeSet};
+use std::{
+    cmp::Ordering,
+    collections::{BTreeMap, BTreeSet},
+};
 
 use sway_error::error::CompileError;
 use sway_types::{Ident, Span, Spanned};
@@ -23,10 +26,10 @@ impl PartialEqWithEngines for TraitSuffix {
     }
 }
 impl OrdWithEngines for TraitSuffix {
-    fn cmp(&self, rhs: &Self, type_engine: &TypeEngine) -> std::cmp::Ordering {
+    fn cmp(&self, other: &Self, type_engine: &TypeEngine) -> std::cmp::Ordering {
         self.name
-            .cmp(&rhs.name)
-            .then_with(|| self.args.cmp(&rhs.args, type_engine))
+            .cmp(&other.name)
+            .then_with(|| self.args.cmp(&other.args, type_engine))
     }
 }
 
@@ -38,11 +41,11 @@ impl<T: PartialEqWithEngines> PartialEqWithEngines for CallPath<T> {
     }
 }
 impl<T: OrdWithEngines> OrdWithEngines for CallPath<T> {
-    fn cmp(&self, rhs: &Self, type_engine: &TypeEngine) -> std::cmp::Ordering {
+    fn cmp(&self, other: &Self, type_engine: &TypeEngine) -> Ordering {
         self.prefixes
-            .cmp(&rhs.prefixes)
-            .then_with(|| self.suffix.cmp(&rhs.suffix, type_engine))
-            .then_with(|| self.is_absolute.cmp(&rhs.is_absolute))
+            .cmp(&other.prefixes)
+            .then_with(|| self.suffix.cmp(&other.suffix, type_engine))
+            .then_with(|| self.is_absolute.cmp(&other.is_absolute))
     }
 }
 
@@ -55,10 +58,10 @@ struct TraitKey {
 }
 
 impl OrdWithEngines for TraitKey {
-    fn cmp(&self, rhs: &Self, type_engine: &TypeEngine) -> std::cmp::Ordering {
+    fn cmp(&self, other: &Self, type_engine: &TypeEngine) -> std::cmp::Ordering {
         self.name
-            .cmp(&rhs.name, type_engine)
-            .then_with(|| self.type_id.cmp(&rhs.type_id))
+            .cmp(&other.name, type_engine)
+            .then_with(|| self.type_id.cmp(&other.type_id))
     }
 }
 

sway-core/src/type_system/info.rs

@@ -8,12 +8,13 @@ use sway_error::error::CompileError;
 use sway_types::{integer_bits::IntegerBits, span::Span, Spanned};
 
 use std::{
+    cmp::Ordering,
     collections::HashSet,
     fmt,
     hash::{Hash, Hasher},
 };
 
-#[derive(Debug, Clone, Hash, Eq, PartialEq)]
+#[derive(Debug, Clone, Hash, Eq, PartialEq, PartialOrd, Ord)]
 pub enum AbiName {
     Deferred,
     Known(CallPath),
@@ -146,7 +147,7 @@ pub enum TypeInfo {
 
 impl HashWithEngines for TypeInfo {
     fn hash<H: Hasher>(&self, state: &mut H, engines: Engines<'_>) {
-        std::mem::discriminant(self).hash(state);
+        self.discriminant_value().hash(state);
         match self {
             TypeInfo::Str(len) => {
                 len.hash(state);
@@ -313,7 +314,95 @@ impl PartialEqWithEngines for TypeInfo {
             (TypeInfo::Storage { fields: l_fields }, TypeInfo::Storage { fields: r_fields }) => {
                 l_fields.eq(r_fields, engines)
             }
-            (l, r) => std::mem::discriminant(l) == std::mem::discriminant(r),
+            (l, r) => l.discriminant_value() == r.discriminant_value(),
+        }
+    }
+}
+
+impl OrdWithEngines for TypeInfo {
+    fn cmp(&self, other: &Self, type_engine: &TypeEngine) -> Ordering {
+        match (self, other) {
+            (
+                Self::UnknownGeneric {
+                    name: l,
+                    trait_constraints: ltc,
+                },
+                Self::UnknownGeneric {
+                    name: r,
+                    trait_constraints: rtc,
+                },
+            ) => l.cmp(r).then_with(|| ltc.cmp(rtc, type_engine)),
+            (Self::Placeholder(l), Self::Placeholder(r)) => l.cmp(r, type_engine),
+            (
+                Self::Custom {
+                    call_path: l_call_path,
+                    type_arguments: l_type_args,
+                },
+                Self::Custom {
+                    call_path: r_call_path,
+                    type_arguments: r_type_args,
+                },
+            ) => l_call_path.suffix.cmp(&r_call_path.suffix).then_with(|| {
+                l_type_args
+                    .as_deref()
+                    .cmp(&r_type_args.as_deref(), type_engine)
+            }),
+            (Self::Str(l), Self::Str(r)) => l.val().cmp(&r.val()),
+            (Self::UnsignedInteger(l), Self::UnsignedInteger(r)) => l.cmp(r),
+            (
+                Self::Enum {
+                    call_path: l_call_path,
+                    type_parameters: ltp,
+                    variant_types: lvt,
+                },
+                Self::Enum {
+                    call_path: r_call_path,
+                    type_parameters: rtp,
+                    variant_types: rvt,
+                },
+            ) => l_call_path
+                .suffix
+                .cmp(&r_call_path.suffix)
+                .then_with(|| ltp.cmp(rtp, type_engine))
+                .then_with(|| lvt.cmp(rvt, type_engine)),
+            (
+                Self::Struct {
+                    call_path: l_call_path,
+                    type_parameters: ltp,
+                    fields: lf,
+                },
+                Self::Struct {
+                    call_path: r_call_path,
+                    type_parameters: rtp,
+                    fields: rf,
+                },
+            ) => l_call_path
+                .suffix
+                .cmp(&r_call_path.suffix)
+                .then_with(|| ltp.cmp(rtp, type_engine))
+                .then_with(|| lf.cmp(rf, type_engine)),
+            (Self::Tuple(l), Self::Tuple(r)) => l.cmp(r, type_engine),
+            (
+                Self::ContractCaller {
+                    abi_name: l_abi_name,
+                    address: _,
+                },
+                Self::ContractCaller {
+                    abi_name: r_abi_name,
+                    address: _,
+                },
+            ) => {
+                // NOTE: we assume all contract callers are unique
+                l_abi_name.cmp(r_abi_name)
+            }
+            (Self::Array(l0, l1), Self::Array(r0, r1)) => type_engine
+                .get(l0.type_id)
+                .cmp(&type_engine.get(r0.type_id), type_engine)
+                .then_with(|| l1.val().cmp(&r1.val())),
+            (TypeInfo::Storage { fields: l_fields }, TypeInfo::Storage { fields: r_fields }) => {
+                l_fields.cmp(r_fields, type_engine)
+            }
+            (l, r) => l.discriminant_value().cmp(&r.discriminant_value()),
         }
     }
 }
@@ -505,6 +594,35 @@ impl UnconstrainedTypeParameters for TypeInfo {
 }
 
 impl TypeInfo {
+    /// Returns a discriminant for the variant.
+    // NOTE: This is approach is not the most straightforward, but is needed
+    // because of this missing feature on Rust's `Discriminant` type:
+    // https://github.com/rust-lang/rust/pull/106418
+    fn discriminant_value(&self) -> u8 {
+        match self {
+            TypeInfo::Unknown => 0,
+            TypeInfo::UnknownGeneric { .. } => 1,
+            TypeInfo::Placeholder(_) => 2,
+            TypeInfo::Str(_) => 3,
+            TypeInfo::UnsignedInteger(_) => 4,
+            TypeInfo::Enum { .. } => 5,
+            TypeInfo::Struct { .. } => 6,
+            TypeInfo::Boolean => 7,
+            TypeInfo::Tuple(_) => 8,
+            TypeInfo::ContractCaller { .. } => 9,
+            TypeInfo::Custom { .. } => 10,
+            TypeInfo::SelfType => 11,
+            TypeInfo::B256 => 12,
+            TypeInfo::Numeric => 13,
+            TypeInfo::Contract => 14,
+            TypeInfo::ErrorRecovery => 15,
+            TypeInfo::Array(_, _) => 16,
+            TypeInfo::Storage { .. } => 17,
+            TypeInfo::RawUntypedPtr => 18,
+            TypeInfo::RawUntypedSlice => 19,
+        }
+    }
+
     /// maps a type to a name that is used when constructing function selectors
     pub(crate) fn to_selector_name(
         &self,