From e1774c8ee563e794e8f2a25823f3c8dfca8036ae Mon Sep 17 00:00:00 2001
From: DaniPopes <57450786+DaniPopes@users.noreply.github.com>
Date: Tue, 4 Jun 2024 09:29:01 +0200
Subject: [PATCH] fix(sol-macro): allow deriving `Default` on contracts (#645)

---
 .../sol-macro-expander/src/expand/contract.rs | 27 ++++++++++++++++---
 crates/sol-macro-input/src/attr.rs            |  9 ++++---
 crates/sol-macro-input/src/lib.rs             |  2 +-
 crates/sol-types/tests/macros/sol/mod.rs      | 20 ++++++++++++++
 4 files changed, 51 insertions(+), 7 deletions(-)

diff --git a/crates/sol-macro-expander/src/expand/contract.rs b/crates/sol-macro-expander/src/expand/contract.rs
index b45fa3bac..4790e3a84 100644
--- a/crates/sol-macro-expander/src/expand/contract.rs
+++ b/crates/sol-macro-expander/src/expand/contract.rs
@@ -138,23 +138,44 @@ pub(super) fn expand(cx: &ExpCtxt<'_>, contract: &ItemContract) -> Result<TokenS
     }
 
     let enum_expander = CallLikeExpander { cx, contract_name: name.clone(), extra_methods };
+    // Remove any `Default` derives.
+    let mut enum_attrs = item_attrs;
+    for attr in &mut enum_attrs {
+        if !attr.path().is_ident("derive") {
+            continue;
+        }
+
+        let derives = alloy_sol_macro_input::parse_derives(attr);
+        let mut derives = derives.into_iter().collect::<Vec<_>>();
+        if derives.is_empty() {
+            continue;
+        }
+
+        let len = derives.len();
+        derives.retain(|derive| !derive.is_ident("Default"));
+        if derives.len() == len {
+            continue;
+        }
+
+        attr.meta = parse_quote! { derive(#(#derives),*) };
+    }
 
     let functions_enum = (!functions.is_empty()).then(|| {
-        let mut attrs = item_attrs.clone();
+        let mut attrs = enum_attrs.clone();
         let doc_str = format!("Container for all the [`{name}`](self) function calls.");
         attrs.push(parse_quote!(#[doc = #doc_str]));
         enum_expander.expand(ToExpand::Functions(&functions), attrs)
     });
 
     let errors_enum = (!errors.is_empty()).then(|| {
-        let mut attrs = item_attrs.clone();
+        let mut attrs = enum_attrs.clone();
         let doc_str = format!("Container for all the [`{name}`](self) custom errors.");
         attrs.push(parse_quote!(#[doc = #doc_str]));
         enum_expander.expand(ToExpand::Errors(&errors), attrs)
     });
 
     let events_enum = (!events.is_empty()).then(|| {
-        let mut attrs = item_attrs;
+        let mut attrs = enum_attrs;
         let doc_str = format!("Container for all the [`{name}`](self) events.");
         attrs.push(parse_quote!(#[doc = #doc_str]));
         enum_expander.expand(ToExpand::Events(&events), attrs)
diff --git a/crates/sol-macro-input/src/attr.rs b/crates/sol-macro-input/src/attr.rs
index a7ab4dd3d..eefc15707 100644
--- a/crates/sol-macro-input/src/attr.rs
+++ b/crates/sol-macro-input/src/attr.rs
@@ -57,9 +57,12 @@ pub fn derives(attrs: &[Attribute]) -> impl Iterator<Item = &Attribute> {
 /// Returns an iterator over all the rust `::` paths in the `#[derive(...)]`
 /// attributes.
 pub fn derives_mapped(attrs: &[Attribute]) -> impl Iterator<Item = Path> + '_ {
-    derives(attrs).flat_map(|attr| {
-        attr.parse_args_with(Punctuated::<Path, Token![,]>::parse_terminated).unwrap_or_default()
-    })
+    derives(attrs).flat_map(parse_derives)
+}
+
+/// Parses the `#[derive(...)]` attributes into a list of paths.
+pub fn parse_derives(attr: &Attribute) -> Punctuated<Path, Token![,]> {
+    attr.parse_args_with(Punctuated::<Path, Token![,]>::parse_terminated).unwrap_or_default()
 }
 
 // When adding a new attribute:
diff --git a/crates/sol-macro-input/src/lib.rs b/crates/sol-macro-input/src/lib.rs
index ed0e7c505..f6fa4a540 100644
--- a/crates/sol-macro-input/src/lib.rs
+++ b/crates/sol-macro-input/src/lib.rs
@@ -18,7 +18,7 @@ extern crate syn_solidity as ast;
 
 /// Tools for working with `#[...]` attributes.
 mod attr;
-pub use attr::{derives_mapped, docs_str, mk_doc, ContainsSolAttrs, SolAttrs};
+pub use attr::{derives_mapped, docs_str, mk_doc, parse_derives, ContainsSolAttrs, SolAttrs};
 
 mod input;
 pub use input::{SolInput, SolInputKind};
diff --git a/crates/sol-types/tests/macros/sol/mod.rs b/crates/sol-types/tests/macros/sol/mod.rs
index a6504b629..ae79a5a9f 100644
--- a/crates/sol-types/tests/macros/sol/mod.rs
+++ b/crates/sol-types/tests/macros/sol/mod.rs
@@ -876,3 +876,23 @@ fn event_overrides() {
     assert_eq!(two::TestEvent_1::SIGNATURE, "TestEvent(bytes32,bytes32)");
     assert_eq!(two::TestEvent_1::SIGNATURE_HASH, keccak256("TestEvent(bytes32,bytes32)"));
 }
+
+#[test]
+fn contract_derive_default() {
+    sol! {
+        #[derive(Debug, Default)]
+        contract MyContract {
+            function f1();
+            function f2();
+            event e1();
+            event e2();
+            error c();
+        }
+    }
+
+    let MyContract::f1Call {} = MyContract::f1Call::default();
+    let MyContract::f2Call {} = MyContract::f2Call::default();
+    let MyContract::e1 {} = MyContract::e1::default();
+    let MyContract::e2 {} = MyContract::e2::default();
+    let MyContract::c {} = MyContract::c::default();
+}