lang: allow cfg_attr for the ix data structs

CHANGELOG.md

@@ -12,6 +12,7 @@ The minor version will be incremented upon a breaking change and the patch versi
 
 ### Features
 
+- lang: Allow to conditionally include attributes in the autogenerated instruction data structures ([#2963](https://github.com/coral-xyz/anchor/pull/2963)).
 - idl: Allow overriding the idl build toolchain with the `RUSTUP_TOOLCHAIN` environment variable ([#2941](https://github.com/coral-xyz/anchor/pull/2941])).
 - avm: Support customizing the installation location using `AVM_HOME` environment variable ([#2917](https://github.com/coral-xyz/anchor/pull/2917)).
 - idl, ts: Add accounts resolution for associated token accounts ([#2927](https://github.com/coral-xyz/anchor/pull/2927)).

lang/syn/src/codegen/program/instruction.rs

@@ -10,6 +10,7 @@ pub fn generate(program: &Program) -> proc_macro2::TokenStream {
         .iter()
         .map(|ix| {
             let name = &ix.raw_method.sig.ident.to_string();
+            let ix_cfg_attrs = &ix.cfg_attrs;
             let ix_name_camel =
                 proc_macro2::Ident::new(&name.to_camel_case(), ix.raw_method.sig.ident.span());
             let raw_args: Vec<proc_macro2::TokenStream> = ix
@@ -43,6 +44,7 @@ pub fn generate(program: &Program) -> proc_macro2::TokenStream {
             if ix.args.is_empty() {
                 quote! {
                     /// Instruction.
+                    #(#ix_cfg_attrs)*
                     #[derive(AnchorSerialize, AnchorDeserialize)]
                     pub struct #ix_name_camel;
 
@@ -51,6 +53,7 @@ pub fn generate(program: &Program) -> proc_macro2::TokenStream {
             } else {
                 quote! {
                     /// Instruction.
+                    #(#ix_cfg_attrs)*
                     #[derive(AnchorSerialize, AnchorDeserialize)]
                     pub struct #ix_name_camel {
                         #(#raw_args),*

lang/syn/src/lib.rs

@@ -26,8 +26,8 @@ use syn::punctuated::Punctuated;
 use syn::spanned::Spanned;
 use syn::token::Comma;
 use syn::{
-    Expr, Generics, Ident, ItemEnum, ItemFn, ItemMod, ItemStruct, LitInt, PatType, Token, Type,
-    TypePath,
+    Attribute, Expr, Generics, Ident, ItemEnum, ItemFn, ItemMod, ItemStruct, LitInt, PatType,
+    Token, Type, TypePath,
 };
 
 #[derive(Debug)]
@@ -63,6 +63,7 @@ pub struct Ix {
     pub raw_method: ItemFn,
     pub ident: Ident,
     pub docs: Option<Vec<String>>,
+    pub cfg_attrs: Vec<Attribute>,
     pub args: Vec<IxArg>,
     pub returns: IxReturn,
     // The ident for the struct deriving Accounts.

lang/syn/src/parser/program/instructions.rs

@@ -2,8 +2,11 @@ use crate::parser::docs;
 use crate::parser::program::ctx_accounts_ident;
 use crate::parser::spl_interface;
 use crate::{FallbackFn, Ix, IxArg, IxReturn};
-use syn::parse::{Error as ParseError, Result as ParseResult};
-use syn::spanned::Spanned;
+use syn::{
+    parse::{Error as ParseError, Result as ParseResult},
+    spanned::Spanned,
+    Attribute,
+};
 
 // Parse all non-state ix handlers from the program mod definition.
 pub fn parse(program_mod: &syn::ItemMod) -> ParseResult<(Vec<Ix>, Option<FallbackFn>)> {
@@ -27,12 +30,14 @@ pub fn parse(program_mod: &syn::ItemMod) -> ParseResult<(Vec<Ix>, Option<Fallbac
             let (ctx, args) = parse_args(method)?;
             let interface_discriminator = spl_interface::parse(&method.attrs);
             let docs = docs::parse(&method.attrs);
+            let cfg_attrs = parse_cfg_attr(method);
             let returns = parse_return(method)?;
             let anchor_ident = ctx_accounts_ident(&ctx.raw_arg)?;
             Ok(Ix {
                 raw_method: method.clone(),
                 ident: method.sig.ident.clone(),
                 docs,
+                cfg_attrs,
                 args,
                 anchor_ident,
                 returns,
@@ -132,3 +137,14 @@ pub fn parse_return(method: &syn::ItemFn) -> ParseResult<IxReturn> {
         )),
     }
 }
+
+fn parse_cfg_attr(method: &syn::ItemFn) -> Vec<Attribute> {
+    method
+        .attrs
+        .iter()
+        .filter_map(|attr| match attr.path.is_ident("cfg_attr") {
+            true => Some(attr.to_owned()),
+            false => None,
+        })
+        .collect()
+}

lang/syn/src/parser/program/mod.rs

@@ -12,11 +12,31 @@ pub fn parse(program_mod: syn::ItemMod) -> ParseResult<Program> {
         ixs,
         name: program_mod.ident.clone(),
         docs,
-        program_mod,
+        program_mod: remove_cfg_attr_from_fns(program_mod),
         fallback_fn,
     })
 }
 
+fn remove_cfg_attr_from_fns(program_mod: syn::ItemMod) -> syn::ItemMod {
+    let mut program_mod = program_mod;
+    if let Some((brace, items)) = program_mod.content.as_mut() {
+        for item in items.iter_mut() {
+            if let syn::Item::Fn(item_fn) = item {
+                let new_attrs = item_fn
+                    .attrs
+                    .iter()
+                    .filter(|attr| !attr.path.is_ident("cfg_attr"))
+                    .cloned()
+                    .collect();
+                item_fn.attrs = new_attrs;
+                *item = syn::Item::Fn(item_fn.clone());
+            }
+        }
+        program_mod.content = Some((*brace, items.to_vec()));
+    }
+    program_mod
+}
+
 fn ctx_accounts_ident(path_ty: &syn::PatType) -> ParseResult<proc_macro2::Ident> {
     let p = match &*path_ty.ty {
         syn::Type::Path(p) => &p.path,

tests/misc/programs/misc/Cargo.toml

@@ -10,11 +10,12 @@ crate-type = ["cdylib", "lib"]
 name = "misc"
 
 [features]
+default = ["my-feature-derive"]
 no-entrypoint = []
 no-idl = []
 cpi = ["no-entrypoint"]
-default = []
 idl-build = ["anchor-lang/idl-build", "anchor-spl/idl-build"]
+my-feature-derive = []
 
 [dependencies]
 anchor-lang = { path = "../../../../lang", features = ["init-if-needed"] }

tests/misc/programs/misc/src/context.rs

@@ -751,3 +751,6 @@ pub struct TestUsedIdentifiers<'info> {
     /// CHECK: ignore
     pub test4: AccountInfo<'info>,
 }
+
+#[derive(Accounts)]
+pub struct EmptyWithCloneDerived {}

tests/misc/programs/misc/src/lib.rs

@@ -385,4 +385,11 @@ pub mod misc {
     ) -> Result<()> {
         Ok(())
     }
+
+    #[cfg_attr(feature = "my-feature-derive", derive(Clone))]
+    pub fn test_derive_feature(_ctx: Context<EmptyWithCloneDerived>) -> Result<()> {
+        let ix_data = instruction::TestDeriveFeature {};
+        let _ = ix_data.clone();
+        Ok(())
+    }
 }