Preserve cfg attrs for contracttrait default functions

soroban-sdk-macros/src/derive_args.rs

@@ -3,7 +3,7 @@ use proc_macro2::{Span, TokenStream};
 use quote::{format_ident, quote};
 use syn::{Error, FnArg, Lifetime, Type, TypePath, TypeReference};
 
-use crate::syn_ext;
+use crate::{attribute::pass_through_attr_to_gen_code, syn_ext};
 
 pub fn derive_args_type(ty: &str, name: &str) -> TokenStream {
     let ty_str = quote!(#ty).to_string();
@@ -23,6 +23,11 @@ pub fn derive_args_impl(name: &str, fns: &[syn_ext::Fn]) -> TokenStream {
         .iter()
         .map(|f| {
             let fn_ident = &f.ident;
+            let fn_attrs = f
+                .attrs
+                .iter()
+                .filter(|attr| pass_through_attr_to_gen_code(attr))
+                .collect::<Vec<_>>();
 
             // Check for the Env argument.
             let env_input = f.inputs.first().and_then(|a| match a {
@@ -78,6 +83,7 @@ pub fn derive_args_impl(name: &str, fns: &[syn_ext::Fn]) -> TokenStream {
                 .multiunzip();
 
             quote! {
+                #(#fn_attrs)*
                 #[inline(always)]
                 #[allow(clippy::unused_unit)]
                 pub fn #fn_ident<#fn_input_lifetime>(#(#fn_input_fn_args),*)

soroban-sdk-macros/src/derive_contractimpl_trait_default_fns_not_overridden.rs

@@ -9,8 +9,7 @@ use crate::{
 use darling::{ast::NestedMeta, Error, FromMeta};
 use proc_macro2::{Ident, TokenStream as TokenStream2};
 use quote::quote;
-use std::collections::HashSet;
-use syn::{ext::IdentExt as _, LitStr, Path, Type};
+use syn::{parse_quote, Attribute, LitStr, Path, Type};
 
 // See soroban-sdk/docs/contracttrait.md for documentation on how this works.
 
@@ -53,14 +52,40 @@ fn derive(args: &Args) -> Result<TokenStream2, Error> {
     let spec_export = args.spec_export.unwrap_or(true);
 
     let trait_default_fns = syn_ext::strs_to_fns(&args.trait_default_fns)?;
-    let impl_fn_idents: HashSet<_> = args.impl_fns.iter().map(|s| s.value()).collect();
+    let impl_fns = syn_ext::strs_to_fns(&args.impl_fns)?;
 
     // Filter the list of default fns down to only default fns that have not been redefined /
     // overridden in the input fns.
     let fns = trait_default_fns
         .into_iter()
-        .filter(|f| !impl_fn_idents.contains(&f.ident.unraw().to_string()))
-        .collect::<Vec<_>>();
+        .filter_map(|mut f| {
+            // No matching impl means keep the default. An unconditional impl drops it.
+            // Cfg-gated impls only override the default when their cfg is active, so the
+            // default is kept behind `not(cfg)` to remain available when the impl is absent.
+            let impl_fns = impl_fns
+                .iter()
+                .filter(|impl_fn| impl_fn.ident == f.ident)
+                .collect::<Vec<_>>();
+            if impl_fns.is_empty() {
+                return Some(Ok(f));
+            }
+
+            let mut cfgs = Vec::new();
+            for impl_fn in impl_fns {
+                match cfg_condition(&impl_fn.attrs) {
+                    Ok(Some(cfg)) => cfgs.push(cfg),
+                    Ok(None) => return None,
+                    Err(e) => return Some(Err(e)),
+                }
+            }
+            f.attrs
+                .extend(cfgs.into_iter().map(|cfg| parse_quote!(#[cfg(not(#cfg))])));
+            Some(Ok(f))
+        })
+        .collect::<Result<Vec<_>, Error>>()?;
+    if fns.is_empty() {
+        return Ok(quote! {});
+    }
 
     let mut output = quote! {};
     output.extend(derive_pub_fns(
@@ -81,8 +106,21 @@ fn derive(args: &Args) -> Result<TokenStream2, Error> {
         &args.crate_path,
         &impl_ty,
         Some(trait_ident),
-        fns.iter().map(|f| &f.ident),
+        &fns,
     ));
 
     Ok(output)
 }
+
+fn cfg_condition(attrs: &[Attribute]) -> Result<Option<TokenStream2>, Error> {
+    let cfgs = attrs
+        .iter()
+        .filter(|a| a.path().is_ident("cfg"))
+        .map(|a| a.parse_args::<TokenStream2>().map_err(Error::from))
+        .collect::<Result<Vec<_>, Error>>()?;
+    Ok(match cfgs.as_slice() {
+        [] => None,
+        [cfg] => Some(quote! { #cfg }),
+        _ => Some(quote! { all(#(#cfgs),*) }),
+    })
+}

soroban-sdk-macros/src/derive_contractimpl_trait_macro.rs

@@ -1,10 +1,13 @@
-use crate::{attribute::is_attr_doc, default_crate_path, syn_ext};
+use crate::{attribute::pass_through_attr_to_gen_code, default_crate_path, syn_ext};
 use darling::{ast::NestedMeta, Error, FromMeta};
 use heck::ToSnakeCase;
 use proc_macro2::{Ident, TokenStream as TokenStream2};
 use quote::ToTokens;
 use quote::{format_ident, quote};
-use syn::{ext::IdentExt as _, parse2, ImplItemFn, ItemTrait, Path, TraitItem, TraitItemFn, Type};
+use syn::{
+    ext::IdentExt as _, parse2, Attribute, ImplItemFn, ItemTrait, Path, TraitItem, TraitItemFn,
+    Type,
+};
 
 // See soroban-sdk/docs/contracttrait.md for documentation on how this works.
 
@@ -49,10 +52,7 @@ fn derive(args: &Args, input: &ItemTrait) -> Result<TokenStream2, Error> {
             sig,
             attrs,
             ..
-        }) => {
-            let doc_attrs: Vec<_> = attrs.iter().filter(|a| is_attr_doc(a)).collect();
-            Some(quote!(#(#doc_attrs)* #sig).to_token_stream().to_string())
-        }
+        }) => Some(fn_string(sig, attrs)),
         _ => None,
     });
 
@@ -90,6 +90,11 @@ fn derive(args: &Args, input: &ItemTrait) -> Result<TokenStream2, Error> {
     Ok(output)
 }
 
+fn fn_string(sig: &syn::Signature, attrs: &[Attribute]) -> String {
+    let attrs = attrs.iter().filter(|a| pass_through_attr_to_gen_code(a));
+    quote!(#(#attrs)* #sig).to_token_stream().to_string()
+}
+
 pub fn generate_call_to_contractimpl_for_trait(
     trait_ident: &Path,
     impl_ident: &Type,
@@ -98,19 +103,26 @@ pub fn generate_call_to_contractimpl_for_trait(
     args_ident: &str,
     spec_ident: &str,
 ) -> TokenStream2 {
-    let impl_fn_idents = pub_methods.iter().map(|f| f.sig.ident.unraw().to_string());
+    let impl_fns = pub_methods.iter().map(impl_fn_string);
     quote! {
         #trait_ident!(
             #trait_ident,
             #impl_ident,
-            [#(#impl_fn_idents),*],
+            [#(#impl_fns),*],
             #client_ident,
             #args_ident,
             #spec_ident,
         );
     }
 }
 
+fn impl_fn_string(f: &ImplItemFn) -> String {
+    let attrs = f.attrs.iter().filter(|a| pass_through_attr_to_gen_code(a));
+    let ident = &f.sig.ident;
+    // Args and return type are stripped; the receiver only needs attrs and ident for override matching.
+    quote!(#(#attrs)* fn #ident()).to_token_stream().to_string()
+}
+
 fn macro_ident(trait_ident: &Ident) -> Ident {
     let lower = trait_ident.unraw().to_string().to_snake_case();
     format_ident!("__contractimpl_for_{lower}")

soroban-sdk-macros/src/derive_fn.rs

@@ -238,21 +238,13 @@ pub fn derive_contract_function_registration_ctor<'a>(
     crate_path: &Path,
     ty: &Type,
     trait_ident: Option<&Path>,
-    method_idents: impl Iterator<Item = &'a Ident>,
+    fns: impl IntoIterator<Item = &'a syn_ext::Fn>,
 ) -> TokenStream2 {
     if cfg!(not(feature = "testutils")) {
         return quote!();
     }
 
     let ty_str = ty_to_safe_ident_str(ty);
-    let (idents, wrap_idents): (Vec<_>, Vec<_>) = method_idents
-        .map(|ident| {
-            let ident_str = ident.unraw().to_string();
-            let wrap_ident = format_ident!("__{}__{}__invoke_raw_slice", ty_str, ident_str);
-            (ident_str, wrap_ident)
-        })
-        .multiunzip();
-
     let trait_str = trait_ident
         .map(|p| {
             p.segments
@@ -262,21 +254,37 @@ pub fn derive_contract_function_registration_ctor<'a>(
                 .join("_")
         })
         .unwrap_or_else(|| "".to_string());
-    let methods_hash = format!("{:x}", Sha256::digest(idents.join(",").as_bytes()));
-    let ctor_ident = format_ident!("__{ty_str}__{trait_str}__{methods_hash}_ctor");
+
+    let ctors = fns
+        .into_iter()
+        .map(|f| {
+            let ident = f.ident.unraw().to_string();
+            let wrap_ident = format_ident!("__{}__{}__invoke_raw_slice", ty_str, ident);
+            let attrs = f
+                .attrs
+                .iter()
+                .filter(|attr| pass_through_attr_to_gen_code(attr) && !attr.path().is_ident("doc"))
+                .collect::<Vec<_>>();
+            let methods_hash =
+                format!("{:x}", Sha256::digest(quote!(#ident #(#attrs)*).to_string()));
+            let ctor_ident = format_ident!("__{ty_str}__{trait_str}__{methods_hash}_ctor");
+            quote! {
+                #[doc(hidden)]
+                #(#attrs)*
+                #[#crate_path::reexports_for_macros::ctor::ctor(crate_path=#crate_path::reexports_for_macros::ctor)]
+                #[allow(non_snake_case)]
+                fn #ctor_ident() {
+                    <#ty as #crate_path::testutils::ContractFunctionRegister>::register(
+                        #ident,
+                        #[allow(deprecated)]
+                        &#wrap_ident,
+                    );
+                }
+            }
+        })
+        .collect::<Vec<_>>();
 
     quote! {
-        #[doc(hidden)]
-        #[#crate_path::reexports_for_macros::ctor::ctor(crate_path=#crate_path::reexports_for_macros::ctor)]
-        #[allow(non_snake_case)]
-        fn #ctor_ident() {
-            #(
-                <#ty as #crate_path::testutils::ContractFunctionRegister>::register(
-                    #idents,
-                    #[allow(deprecated)]
-                    &#wrap_idents,
-                );
-            )*
-        }
+        #(#ctors)*
     }
 }

soroban-sdk-macros/src/lib.rs

@@ -289,7 +289,7 @@ pub fn contractimpl(metadata: TokenStream, input: TokenStream) -> TokenStream {
                 crate_path,
                 ty,
                 trait_ident,
-                pub_methods.iter().map(|m| &m.sig.ident),
+                &pub_methods_fns,
             );
             output.extend(quote! { #cfs });
 

soroban-sdk/docs/contracttrait.md

@@ -87,7 +87,11 @@ macro_rules! __contractimpl_for_pause {
 pub use __contractimpl_for_pause as Pause;
 ```
 
-The `trait_default_fns` contains stringified signatures (and documentation) of all functions with default implementations. We serialize function signatures and their documentation into strings because the tooling used to parse macros and values doesn't handle raw tokens well as parameters. This information is "remembered" by the declarative macro for later comparison.
+The `trait_default_fns` contains stringified signatures and pass-through attributes of all functions with default implementations. We serialize function signatures and supported attributes into strings because the tooling used to parse macros and values doesn't handle raw tokens well as parameters. This information is "remembered" by the declarative macro for later comparison.
+
+Direct `#[cfg(...)]` attributes on default functions are preserved in the generated code. For cross-crate traits, function-level cfgs inside a `#[contracttrait]` are evaluated in the implementing contract crate's configuration context when generating wrappers. Shared trait crates should prefer applying cfg to the whole trait item, or require implementing contracts to define matching features when function-level cfgs are needed.
+
+`cfg_attr` is not interpreted by the bridge. Avoid using `cfg_attr` to conditionally add `cfg` to `#[contracttrait]` default functions or `#[contractimpl]` functions, because generated wrappers may not agree with whether Rust compiles the original function. Use direct `#[cfg(...)]` instead.
 
 ### Stage 3: `#[contractimpl(contracttrait)]` calls the trait macro
 
@@ -115,6 +119,8 @@ Pause!(
 );
 ```
 
+Direct `#[cfg(...)]` attributes on overriding impl functions are preserved, so a cfg-disabled override does not suppress the trait default function.
+
 ### Stage 4: The trait macro calls `contractimpl_trait_default_fns_not_overridden`
 
 The `Pause!` macro expands to call the proc macro `contractimpl_trait_default_fns_not_overridden!` with both:

tests-expanded/test_account_tests.rs

@@ -328,6 +328,7 @@ impl Contract {
 }
 impl<'a> ContractClient<'a> {}
 impl ContractArgs {
+    #[allow(non_snake_case)]
     #[inline(always)]
     #[allow(clippy::unused_unit)]
     pub fn __check_auth<'i>(
@@ -408,8 +409,9 @@ pub extern "C" fn __Contract____check_auth__invoke_raw_extern(
 }
 #[doc(hidden)]
 #[allow(non_snake_case)]
+#[allow(non_snake_case)]
 #[allow(unused)]
-fn __Contract__CustomAccountInterface__d465b6861ce11142d9f64c1622e1ad88ae003d910de0a8493889a96a23449736_ctor(
+fn __Contract__CustomAccountInterface__1cb152b3d7e456ec2ef6550a76691e16248c4973551c0ab421ef85c852910b2a_ctor(
 ) {
     #[allow(unsafe_code)]
     {
@@ -422,7 +424,7 @@ fn __Contract__CustomAccountInterface__d465b6861ce11142d9f64c1622e1ad88ae003d910
             #[allow(non_snake_case)]
             extern "C" fn f() -> ::ctor::__support::CtorRetType {
                 unsafe {
-                    __Contract__CustomAccountInterface__d465b6861ce11142d9f64c1622e1ad88ae003d910de0a8493889a96a23449736_ctor();
+                    __Contract__CustomAccountInterface__1cb152b3d7e456ec2ef6550a76691e16248c4973551c0ab421ef85c852910b2a_ctor();
                 };
                 core::default::Default::default()
             }

tests-expanded/test_account_wasm32v1-none.rs

@@ -223,6 +223,7 @@ impl Contract {
 }
 impl<'a> ContractClient<'a> {}
 impl ContractArgs {
+    #[allow(non_snake_case)]
     #[inline(always)]
     #[allow(clippy::unused_unit)]
     pub fn __check_auth<'i>(

tests-expanded/test_add_i128_tests.rs

@@ -310,7 +310,7 @@ pub extern "C" fn __Contract__add__invoke_raw_extern(
 #[doc(hidden)]
 #[allow(non_snake_case)]
 #[allow(unused)]
-fn __Contract____7e9e5ac30f2216fd0fd6f5faed316f2d5983361a4203c3330cfa46ef65bb4767_ctor() {
+fn __Contract____7b8a6f33b43ca26a3f2aa73e408748f9ceb391ac21dfe746c94563016ab72f85_ctor() {
     #[allow(unsafe_code)]
     {
         #[link_section = ".init_array"]
@@ -322,7 +322,7 @@ fn __Contract____7e9e5ac30f2216fd0fd6f5faed316f2d5983361a4203c3330cfa46ef65bb476
             #[allow(non_snake_case)]
             extern "C" fn f() -> ::ctor::__support::CtorRetType {
                 unsafe {
-                    __Contract____7e9e5ac30f2216fd0fd6f5faed316f2d5983361a4203c3330cfa46ef65bb4767_ctor();
+                    __Contract____7b8a6f33b43ca26a3f2aa73e408748f9ceb391ac21dfe746c94563016ab72f85_ctor();
                 };
                 core::default::Default::default()
             }

tests-expanded/test_add_u128_tests.rs

@@ -310,7 +310,7 @@ pub extern "C" fn __Contract__add__invoke_raw_extern(
 #[doc(hidden)]
 #[allow(non_snake_case)]
 #[allow(unused)]
-fn __Contract____7e9e5ac30f2216fd0fd6f5faed316f2d5983361a4203c3330cfa46ef65bb4767_ctor() {
+fn __Contract____7b8a6f33b43ca26a3f2aa73e408748f9ceb391ac21dfe746c94563016ab72f85_ctor() {
     #[allow(unsafe_code)]
     {
         #[link_section = ".init_array"]
@@ -322,7 +322,7 @@ fn __Contract____7e9e5ac30f2216fd0fd6f5faed316f2d5983361a4203c3330cfa46ef65bb476
             #[allow(non_snake_case)]
             extern "C" fn f() -> ::ctor::__support::CtorRetType {
                 unsafe {
-                    __Contract____7e9e5ac30f2216fd0fd6f5faed316f2d5983361a4203c3330cfa46ef65bb4767_ctor();
+                    __Contract____7b8a6f33b43ca26a3f2aa73e408748f9ceb391ac21dfe746c94563016ab72f85_ctor();
                 };
                 core::default::Default::default()
             }