macros: fix syn patch version

CHANGELOG.md

@@ -11,8 +11,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Fixed
 
 - Considered `PYTHONFRAMEWORK` when cross compiling in order that on macos cross compiling against a [Framework bundle](https://developer.apple.com/library/archive/documentation/MacOSX/Conceptual/BPFrameworks/Concepts/FrameworkAnatomy.html) is considered shared. [#2233](https://github.com/PyO3/pyo3/pull/2233)
-
 - Panic during compilation when `PYO3_CROSS_LIB_DIR` is set for some host/target combinations. [#2232](https://github.com/PyO3/pyo3/pull/2232)
+- Correct dependency version for `syn` to require correct minimal patch version 1.0.56. [#2240](https://github.com/PyO3/pyo3/pull/2240)
 
 ### Added
 

pyo3-macros-backend/Cargo.toml

@@ -19,7 +19,7 @@ proc-macro2 = { version = "1", default-features = false }
 pyo3-build-config = { path = "../pyo3-build-config", version = "0.16.2", features = ["resolve-config"] }
 
 [dependencies.syn]
-version = "1"
+version = "1.0.56"
 default-features = false
 features = ["derive", "parsing", "printing", "clone-impls", "full", "extra-traits"]
 

pyo3-macros/Cargo.toml

@@ -21,5 +21,5 @@ pyproto = ["pyo3-macros-backend/pyproto"]
 [dependencies]
 proc-macro2 = { version = "1", default-features = false }
 quote = "1"
-syn = { version = "1", features = ["full", "extra-traits"] }
+syn = { version = "1.0.56", features = ["full", "extra-traits"] }
 pyo3-macros-backend = { path = "../pyo3-macros-backend", version = "=0.16.2" }

pyo3-macros/src/lib.rs

@@ -38,11 +38,11 @@ pub fn pymodule(args: TokenStream, input: TokenStream) -> TokenStream {
     let mut ast = parse_macro_input!(input as syn::ItemFn);
     let options = match PyModuleOptions::from_attrs(&mut ast.attrs) {
         Ok(options) => options,
-        Err(e) => return e.to_compile_error().into(),
+        Err(e) => return e.into_compile_error().into(),
     };
 
     if let Err(err) = process_functions_in_module(&mut ast) {
-        return err.to_compile_error().into();
+        return err.into_compile_error().into();
     }
 
     let doc = get_doc(&ast.attrs, None);
@@ -114,7 +114,7 @@ pub fn pyclass(attr: TokenStream, input: TokenStream) -> TokenStream {
         Item::Enum(enum_) => pyclass_enum_impl(attr, enum_, methods_type()),
         unsupported => {
             syn::Error::new_spanned(unsupported, "#[pyclass] only supports structs and enums.")
-                .to_compile_error()
+                .into_compile_error()
                 .into()
         }
     }