Fix contractimpl macro composability with third party macros (#1510)

### What
Add a test vector that demonstrates a composability issue with third
party function macros. Apple the existing filtering of which attributes
get applied to the generated exported functions also to the generated
spec constant.

  ### Why
In #1427 I moved where the attributes were used as part of fixing
another bug, and inadvertently moved the expansion of the attributes to
the line before where the attributes are filtered. The filter ensures
that only a specific set of attributes get applied to the generated
code. The attributes still need to go through the filter for their use
on the spec constant and it was an error on my part not to also move the
filter.

Close #1509

Author: leighmcculloch

.github/workflows/rust.yml

@@ -124,7 +124,7 @@ jobs:
       run: cargo-hack hack --feature-powerset --exclude-features docs build --target ${{ matrix.sys.target }}
     - if: "matrix.sys.cdylib-cross-compile-workaround"
       name: Build for native
-      run: cargo-hack hack --feature-powerset --exclude-features docs rustc --workspace --exclude soroban-sdk-macros --crate-type lib --target ${{ matrix.sys.target }}
+      run: cargo-hack hack --feature-powerset --exclude-features docs rustc --workspace --exclude soroban-sdk-macros --exclude proc_macros --crate-type lib --target ${{ matrix.sys.target }}
     - if: startsWith(matrix.sys.target, 'x86_64')
       name: Run tests
       run: cargo-hack hack --feature-powerset --ignore-unknown-features --features testutils --exclude-features docs test --target ${{ matrix.sys.target }}

Cargo.lock

@@ -157,6 +157,12 @@ pub fn derive_fn_spec(
         return Err(quote! { #(#compile_errors)* });
     }
 
+    // Filter attributes to those that should be passed through to the generated code.
+    let attrs = attrs
+        .iter()
+        .filter(|attr| pass_through_attr_to_gen_code(attr))
+        .collect::<Vec<_>>();
+
     let exported = if export {
         Some(quote! {
             #[doc(hidden)]
@@ -170,12 +176,6 @@ pub fn derive_fn_spec(
         None
     };
 
-    // Filter attributes to those that should be passed through to the generated code.
-    let attrs = attrs
-        .iter()
-        .filter(|attr| pass_through_attr_to_gen_code(attr))
-        .collect::<Vec<_>>();
-
     // Generated code.
     Ok(quote! {
         #exported

soroban-sdk-macros/src/derive_spec_fn.rs

@@ -0,0 +1,20 @@
+[package]
+name = "test_macros"
+description = "A test vector for testing the interactions of the soroban-sdk macros with third-party macros, validating that they are composable and compatible."
+version.workspace = true
+authors = ["Stellar Development Foundation <info@stellar.org>"]
+license = "Apache-2.0"
+edition = "2021"
+publish = false
+rust-version.workspace = true
+
+[lib]
+crate-type = ["cdylib"]
+doctest = false
+
+[dependencies]
+soroban-sdk = {path = "../../soroban-sdk"}
+proc_macros = {path = "./proc_macros"}
+
+[dev-dependencies]
+soroban-sdk = {path = "../../soroban-sdk", features = ["testutils"]}

tests/macros/Cargo.toml

@@ -0,0 +1,17 @@
+[package]
+name = "proc_macros"
+description = "A collection of proc-macros used by the test_macros test vector to validate that the soroban-sdk macros are composable and compatible with a variety of other macros."
+version = "0.0.0"
+authors = ["Stellar Development Foundation <info@stellar.org>"]
+license = "Apache-2.0"
+edition = "2021"
+publish = false
+rust-version.workspace = true
+
+[lib]
+proc-macro = true
+doctest = false
+
+[dependencies]
+quote = "1.0"
+syn = { version = "2.0", features = ["full"] }

tests/macros/proc_macros/Cargo.toml

@@ -0,0 +1,12 @@
+/// A collection of proc-macros used by the test_macros test vector to validate that the
+/// soroban-sdk macros are composable and compatible with a variety of other macros.
+use proc_macro::TokenStream;
+use quote::quote;
+use syn::{parse_macro_input, ItemFn};
+
+/// An attribute macro that expects to be used on a function.
+#[proc_macro_attribute]
+pub fn parse_item_fn(_metadata: TokenStream, input: TokenStream) -> TokenStream {
+    let item = parse_macro_input!(input as ItemFn);
+    quote! { #item }.into()
+}

tests/macros/proc_macros/src/lib.rs

@@ -0,0 +1,32 @@
+// A test vector for testing the interactions of the soroban-sdk macros with third-party macros,
+// validating that they are composable and compatible.
+
+#![no_std]
+use proc_macros::parse_item_fn;
+use soroban_sdk::{contract, contractimpl};
+
+#[contract]
+pub struct Contract;
+
+#[contractimpl]
+impl Contract {
+    // Test that attribute macros that expect to be used on fns are composable with contractimpl.
+    #[parse_item_fn]
+    pub fn empty() {}
+}
+
+#[cfg(test)]
+mod test {
+    use soroban_sdk::Env;
+
+    use crate::{Contract, ContractClient};
+
+    #[test]
+    fn test_empty() {
+        let e = Env::default();
+        let contract_id = e.register(Contract, ());
+        let client = ContractClient::new(&e, &contract_id);
+
+        client.empty();
+    }
+}

tests/macros/src/lib.rs

@@ -0,0 +1,77 @@
+{
+  "generators": {
+    "address": 1,
+    "nonce": 0,
+    "mux_id": 0
+  },
+  "auth": [
+    [],
+    []
+  ],
+  "ledger": {
+    "protocol_version": 23,
+    "sequence_number": 0,
+    "timestamp": 0,
+    "network_id": "0000000000000000000000000000000000000000000000000000000000000000",
+    "base_reserve": 0,
+    "min_persistent_entry_ttl": 4096,
+    "min_temp_entry_ttl": 16,
+    "max_entry_ttl": 6312000,
+    "ledger_entries": [
+      [
+        {
+          "contract_data": {
+            "contract": "CAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAD2KM",
+            "key": "ledger_key_contract_instance",
+            "durability": "persistent"
+          }
+        },
+        [
+          {
+            "last_modified_ledger_seq": 0,
+            "data": {
+              "contract_data": {
+                "ext": "v0",
+                "contract": "CAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAD2KM",
+                "key": "ledger_key_contract_instance",
+                "durability": "persistent",
+                "val": {
+                  "contract_instance": {
+                    "executable": {
+                      "wasm": "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855"
+                    },
+                    "storage": null
+                  }
+                }
+              }
+            },
+            "ext": "v0"
+          },
+          4095
+        ]
+      ],
+      [
+        {
+          "contract_code": {
+            "hash": "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855"
+          }
+        },
+        [
+          {
+            "last_modified_ledger_seq": 0,
+            "data": {
+              "contract_code": {
+                "ext": "v0",
+                "hash": "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855",
+                "code": ""
+              }
+            },
+            "ext": "v0"
+          },
+          4095
+        ]
+      ]
+    ]
+  },
+  "events": []
+}