Support lifetime parameters in TypeEq derive macro

Summary:
The TypeEq derive macro previously rejected lifetime generic parameters
with "Unsupported generic parameter". This adds support for lifetimes by passing
them through to the impl block without trait bounds, which is needed for the
upcoming Type<'t> migration.

Reviewed By: yangdanny97

Differential Revision: D92713866

fbshipit-source-id: 70a28ce033570dbfc42d498a570710fe99502e30

Author: ndmitchell

crates/pyrefly_derive/src/type_eq.rs

@@ -28,9 +28,13 @@ pub(crate) fn derive_type_eq(input: proc_macro::TokenStream) -> proc_macro::Toke
 fn generics(
     generics: &Generics,
 ) -> syn::Result<(proc_macro2::TokenStream, proc_macro2::TokenStream)> {
+    let mut lifetimes = Vec::new();
     let mut ts = Vec::new();
     for param in &generics.params {
         match param {
+            GenericParam::Lifetime(l) => {
+                lifetimes.push(&l.lifetime);
+            }
             GenericParam::Type(t) if t.bounds.is_empty() => {
                 ts.push(&t.ident);
             }
@@ -42,8 +46,9 @@ fn generics(
             }
         }
     }
-    let before = quote_spanned! { generics.span() => < #(#ts: crate::equality::TypeEq),* > };
-    let after = quote_spanned! { generics.span() => < #(#ts),* > };
+    let before =
+        quote_spanned! { generics.span() => < #(#lifetimes,)* #(#ts: crate::equality::TypeEq),* > };
+    let after = quote_spanned! { generics.span() => < #(#lifetimes,)* #(#ts),* > };
     Ok((before, after))
 }
 

crates/pyrefly_types/src/equality.rs

@@ -6,6 +6,7 @@
  */
 
 use std::hash::Hash;
+use std::marker::PhantomData;
 use std::sync::Arc;
 
 use compact_str::CompactString;
@@ -147,6 +148,8 @@ impl TypeEq for String {}
 impl TypeEq for CompactString {}
 impl TypeEq for str {}
 
+impl<T> TypeEq for PhantomData<T> {}
+
 impl TypeEq for Name {}
 impl TypeEq for ModuleName {}
 impl TypeEq for TextRange {}
@@ -319,6 +322,12 @@ mod tests {
     #[derive(TypeEq, PartialEq, Eq, Debug)]
     struct Generic<T>(T);
 
+    #[derive(TypeEq, PartialEq, Eq, Debug)]
+    enum WithLifetime<'t> {
+        Unused(std::marker::PhantomData<&'t ()>),
+        Value(i32),
+    }
+
     #[test]
     fn test_type_eq() {
         let mut ctx = TypeEqCtx::default();
@@ -363,6 +372,13 @@ mod tests {
         );
         assert!(Generic(1).type_eq(&Generic(1), &mut ctx));
         assert!(!Generic(1).type_eq(&Generic(2), &mut ctx));
+
+        assert!(WithLifetime::Value(1).type_eq(&WithLifetime::Value(1), &mut ctx));
+        assert!(!WithLifetime::Value(1).type_eq(&WithLifetime::Value(2), &mut ctx));
+        assert!(
+            !WithLifetime::Value(1)
+                .type_eq(&WithLifetime::Unused(std::marker::PhantomData), &mut ctx)
+        );
     }
 
     #[test]