Use async move block to fix borrowing issues

Author: KaiJewson

src/lib.rs

@@ -71,7 +71,7 @@ pub fn context(args: TokenStream, input: TokenStream) -> TokenStream {
             }
             syn::ReturnType::Type(_, return_ty) => {
                 input.block.stmts = syn::parse_quote!(
-                    let result: #return_ty = async { #body }.await;
+                    let result: #return_ty = async move { #body }.await;
                     result.map_err(|err| err.context(format!(#args)).into())
                 );
             }

tests/async_borrowing.rs

@@ -0,0 +1,9 @@
+use fn_error_context::context;
+
+#[context("context")]
+async fn borrows(val: &mut u32) -> anyhow::Result<&u32> {
+    Ok(&*val)
+}
+
+fn main() {
+}

tests/tests.rs

@@ -17,4 +17,5 @@ fn tests() {
     tests.pass("tests/fmt_named_arg.rs");
     tests.compile_fail("tests/async_without_return.rs");
     tests.compile_fail("tests/preserve_lint.rs");
+    tests.pass("tests/async_borrowing.rs");
 }